University of the Witwatersrand, Johannesburg

Department of Physics

SCHONLAND RESEARCH CENTRE FOR NUCLEAR SCIENCES

ANNUAL REPORT

for the year 1997

INDEX

Introduction............................................................................................................................3 - 4

Applied and Environmental Physics Research Unit ...........................................................5 - 26

Ion Implantation and Surface Studies Research Programme...........................................27 - 31

Nuclear Physics Research Programme.............................................................................32 - 34

Wits -Northern Accelerator Research Centre....................................................................35 - 63

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Introduction

The year 1997 was a period of a final restructuring of the Schonland Centre. At the end of 1996, the Faculty of Science and the University Research Committee approved a plan for a new structure for the Schonland Centre, proposed by the Department of Physics. A key component of the Physics Department plan was the transfer of the funding of two of the remaining three permanent academic posts in the Centre from the University Research Committee to the Department of Physics in the Faculty of Science.The URC funds freed in this way would be used towards the running costs and the strengthening of the research infrastructure in the Centre, with particular emphasis on the EN Tandem accelerator. Negotiations of the terms of the transfer of the two posts between the academics concerned and the Physics Department were completed in the second half of 1997. As from January 1998, the Physics Department plan for the Centre has been put formally in place.

The main features of the new Schonland structure are as follows.a) The Schonland Research Centre for Nuclear Sciences is now an umbrella of autonomous research entities, each with its own leader, research programme, and an independent recognition by and funding from the University Research Committee; each research entity independently seeks and receives funding from sources outside the University. The research facilities in the Centre are currently operated and managed by the individual research entities. b) The coordination of the research activities in the Centre, and the management and sharing of its technical, administrative and support infrastructure is vested in the Schonland Coordination Committee. The members of the SCC are the leaders of the URC-recognized research entities within the Centre, the chairman of the technical subcommittee, a Physics Department representative, a Science Faculty representative, and a representative of the postgraduate students in the Centre (this last membership is on a request from the students and has been approved by the Dean of the Science Faculty). The SCC elects a chairman on a rotating basis with two-year periods.c) After three years of the new Schonland structure, each research entity in the Centre will be independently reviewed.

There are currently four URC-recognized research entities in the Centre:1) Applied and Environmental Physics Research Unit;

leader Professor J.I.W. Watterson (Department of Physics);2) Ion Implantation and Surface Studies Research Programme;

leader Professor T.E. Derry (Department of Physics).3) Nuclear Physics Research Programme;

leader Professor V. Hnizdo (Department of Physics).4) Wits-Northern Accelerator Research Centre;

director Dr. S.H. Connell (Department of Physics).The first three entities have the formal URC status of a research programme,the fourth one is a URC research group.

The three main research facilities in the Centre are organized as follows:1) The Accelerator Laboratory, with a 6 MV Tandem Van de Graaff accelerator, a 2,5 MV

Van de Graaff accelerator. is managed by its director Dr. S.H. Connell, appointed to this position directly by the URC. A major interdisciplinary research facility within the Accelerator laboratory has merited Dr E Sideras-Haddad as its Research Manager.

2) The Ion Implanter Laboratory, with a 200 kV ion implanter and a 1.4 MV Cockcroft-Walton accelerator, is operated by the Ion Implantation and Surface Physics Research Programme under the leadership of Professor T.E. Derry.

3) The Environmental Isotope Laboratory is operated by the Applied and Environmental Physics Research Unit under the leadership of Professor B Th Verhagen.

The current members of the Schonland Coordinating Committee are:

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Professor V. Hnizdo (chair), Dr. S.H. Connell, Professor T.E. Derry (deputy chair), Professor J.I.W. Watterson, Professor H. J. Annegarn, Mr. A.H. Andeweg (Chief Technician, Chairman of the Technical Subcommittee), Professor B.J. Cole (Head, Department of Physics), Professor U. Reimold (Department of Geology), and Mr. I. Machi (postgraduate student representative).

In the transition year 1997, the Centre was governed by the Interim Governing Committee of Professor J.D. Comins (Committee Chair, then Head of Department of Physics), Professor H.J. Annegarn, Professor TE Derry, Dr. S.H. Connell, Professor J.I.W. Watterson (Chair, Management Subcommittee), Professor V. Hnizdo (Department of Physics), Professor D.S. McLachlan (Department of Physics), Dr. J.F. Prins (De Beers Industrial Diamonds), Dr. R.J. Hart (Council of Geosciences),T.L. Nam (Health Physics Service), Professor H.M. Marques (Deputy Dean of Science) and Professor M. Viljoen (Department of Geology).

While the new Schonland structure came formally into effect only at the beginning of 1998, the research groups in the Centre had functioned de facto autonomously already throughout 1997, and this Annual Report already reflects this structure by reporting on the activities and outputs of the four research entities in the Centre separately.

V. HnizdoChairman, Schonland Coordinating CommitteeAugust 1998

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APPLIED AND ENVIRONMENTAL PHYSICS RESEARCH UNIT

IntroductionThis Research entity was formed at the end of 1997 when the Schonland Centre was re-established as an umbrella body. It incorporates three active research groups of the former Schonland Centre. These are the Environmental Isotopes Group, the Aerosol Physics and PIXE Group, and the Nuclear Geophysics Group.

The rationale of this group is to undertake research in interdisciplinary areas involving physics for the measurement and understanding of areas of applied science Ð with a particular emphasis on problems of practical importance in industry and the environment. The Group makes extensive, but not exclusive, use of the methods of Nuclear Physics. This provides a wide scope for the formulation of fundable projects that are scientifically interesting and academically relevant.

There are three University Analytical facilities at the Schonland Centre and one of these, the Environmental Isotope Laboratory, is operated by this research group.

Members

Member Title Staff No. Department

Prof. H.J. Annegarn Associate Professor Schonland Centre

Prof B. Th Verhagen Honorary Research Associate 00911324 Schonland Centre

Prof J.I.W. Watterson Associate Professor (Director) Department of Physics.

Students

Student Degree Department Student No. Comment

Mr R.A. Ambrosi PhD Physics

Mr H Rahmanian PhD Physics

Mr AS Tsela PhD Physics Submitted

Mr J Guzek PhD Part time Physics

Dr M. Grant PhD Metallurgy Graduated 1996

Mr D. Maina PhD Part time Physics Kenya

Mr T. Magagula MSc Physics Swaziland, Submitted 1998

Mr E Vera Imana MSc Chemistry Graduated 1998

Mr M Butler MSc Geology 8605190A Submitted

Mr I Mahomed MSc Geology 9110155J

Ms J Kotze PhD I.G.S. Joint supervisor

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Research Projects

Environmental Physics Ð Air PollutionParticle-induced x-ray emission (PIXE)

PIXE has been used as a routine analytical technique, concentrating on the analysis of time-sequence streaker samples. For these samples, there is no competitive technique, and the unique contributions from the streaker PIXE combination continues to provide valuable atmospheric data.

Soweto Air Monitoring - Project SAMRoutine monitoring of particulate matter in the Soweto atmosphere continues to be carried out by the Soweto Health Department. Data from the monitoring programme has been used as input to the Low Smoke Coal Initiative of the Department of Mineral and Energy Affairs.

SAFARI Research Alliance and remote sampling

The sampling of biomass related emissions, large scale atmospheric processes and long range atmospheric transport studies that were started under the SAFARI 92 multi-national programme, have continued, under the coordination of Stuart Piketh.

To obtain empirical verification of the synoptic climatology predictions of Tyson, Stuart Piketh established a continuous streaker monitoring site at Ben McDhui, the highest peak of the southern Drakensberg, to sample aerosols exiting off the south east coast of Africa. Financial support was obtained for the sampling by Prof Tyson from Eskom TRI. Initial results from PIXE streaker analyses were promising, but indicated also that a fuller understanding of atmospheric processes would require measurement of additional physical and chemical parameters. Under the auspices of the SA'ARI Research Alliance, an informal collaboration of South African atmospheric scientists, Stuart Piketh organized two intensive sampling expeditions to Ben McDui, during April and June 1996.

Vaal Air Characterisation Study

Air quality in the Vaal Triangle has been quantified through earlier studies of our group and others. Work is continuing along three thrusts.

Dust from Surface Mining

After township coal smoke and vehicle emissions, wind blown dust from tailing dams are regarded as one of South Africa's more serious air quality issues. Alain Mizelle (MSC Mining Engineering) will combine empirical dust measurements, dispersion modelling and GIS to represent the impact of tailing dam dust.

Industrial Hygiene

Aerosol measurements using a streaker sampler have been carried out in a large engineering works in Bloemfontein to evaluate health risks to welders and foundry workers. Parallel samples of blood and urine were collected to establish correlations between airborne concentrations and inhalation exposure. The study will contribute to quantifying health risks in this large industrial sector, and lead to better protection measures to protect quality of work and life. The student involved (D van de Heever) has submitted a first draft of his DTech thesis.

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Applied and Industrial PhysicsNeutron radiography and tomographyThis project is being undertaken in collaboration with De Beers. It has lead to innovative work in the fields of neutron production, accelerator physics, target technology and science and the understanding of the imaging process and modelling in fast neutron radiography. The field of resonance neutron imaging has been pioneered as a part of this project and it has lead to the several patents and the presentation of three invited papers (two of these will be presented in 1998). Three PhD students are involved in this project and it is the focus of THRIP funding.

Neutron induced prompt gamma-ray analysis

This project is the focus of a collaboration with the University of Swaziland and it forms part of the basis for an application to the DACST Innovation Fund together with De Beers.

The excitation and application of isomeric states.Research in this area is also the focus of work that forms the basis of an application to the Department of Arts, Culture, Science and Technology. The details of neutron production through 7Li(p,n)7Be were examined in an MSc programme. The results of this programme were presented at the ECAART Conference in Eindhoven in 1997. The dissertation was submitted in 1998 and is at present being examined.

Monitoring of radioactive mineralsWith the establishment of the Post-Graduate Course in Radiation Protection this project has grown in importance. A standard method for the monitoring of gamma-radiation has been established and has been applied to tailings samples from the Richard's bay mine.

Measurement of radon emanationThis forms the basis for the PhD project of Alex Tsela. A special method was developed for the determination of radon emanation from very small samples.

Nuclear methods in palaeo-metallurgy.This project was completed in 1996 and Dr Mike Grant was awarded his PhD on the use of neutron activation analysis in paleo-archaeology.

The physics of radon-aerosol interactions and human dosimetryThis project is the basis of Mr D. Maina's PhD work. It will form the focus of collaborative work between the University of the Witwatersrand and the Institute of Nuclear Physics in Nairobi.

Chemical - metallurgical studies of gold.Mr Erik Vera-Imana submitted his dissertation on this project in 1997 and he was awarded his MSc in 1998

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Environmental Isotope GroupB Th Verhagen (Group Leader), J A Geyer (Senior Technician), O H T Malinga (Technician), M J Butler(Junior Research Officer)

Students: M J Butler, I Mahomed, J Kotze

Collaborators:

M Levin, I Venter (Africon, Pretoria), K Froehlich, P Aggarwal, Y Yurtsever (IAEA, Vienna), D Eshete, Y Belete (Geological Survey, Addis Ababa), J O Bassey, J O Adesuyi (Water Resources Development, Abuja), C Tindimugaya (Water Resources, Entebbe), T S McCarthy, S Master, (Dept. Geology, Wits), Z M Dziembowski, E van Wyk (Dept. Water Affairs, Pretoria), J C Kotze (Steffen Robertson and Kirsten, Cape Town), M Simonic (Hydromedia Solutions, Pretoria), G Martinelli, G Hubert (E Martinelli and Assoc., Johannesburg), J Farr, R Gumiremhete (Wellfield Interconsult. Gaborone), C Marobela (Geoflux, Gaborone) A Bittner (Department of Water Affairs, Windhoek) D B Bredenkamp (Water Resources Evaluation and Management, Pretoria), S Pretorius, J Myburgh (GeoCon), Y Bouabdallaoui, (Direction Generale de l'Hydrauliques Rabat ), R Bush (Civil Engineering, Anglo American Corporation, Johannesburg). S Sunguro (Water Development, Harare). D Ploethner (Institute for Geosciences, Hanover). S Talma (CSIR, Pretoria). R Heard, P Pirow (Atomic Energy Corporation, Pelindaba). A Issar (Ben Gurion University, Israel)

Introduction

Small changes in the isotope ratios of light elements (H, C, N, O, S) resulting from isotope fractionation and radioactive decay, provide invaluable information on processes in the environment. Environmental isotope research in the Centre has over the past three decades made major contributions in the field of geohydrology, especially the understanding of arid-zone processes, for which the Schonland Environmental Isotope Group has become internationally recognised. Recently, greater attention is being given to the solution of problems concerning the protection of vital ground water resources, ground water pollution and urban hydrology. Other environmental isotope studies by the Group are in the fields of biology, geology, palaeoclimatology and archaeology.

The Group conducts several of its own research projects, participates in sponsored research programmes associated with ground water development and has attracted research contracts from the Water Research Commission (WRC), the International Atomic Energy Agency (IAEA), Government and the private sector. This affords unique opportunities in e.g. geohydrology, both for conducting fundable studies of hydrological systems under conditions unattainable in in-house research situations, and for the involvement of students in operational projects. Income generated covers the entire running costs and staff salaries of the Environmental Isotope Laboratory and thus channels a significant amount of vital external funding into the research programme of the University.

The Group participates in an international coordinated research programme in the field of isotope hydrology sponsored by the IAEA. It also contributes to the IAEA RAF/8/022 regional model project on isotope hydrology in north Africa and project RAF/8/026, concerned with the investigation of the leakages from storage dams. During the period covered by this report, the Group Leader visited Ethiopia, Nigeria, Mali, Uganda, Morocco and Namibia as an expert under this project. He also attended a workshop in Wallingford, UK, and, with a student, a research coordination meeting in Vienna on unsaturated zone studies, contributes chapters in two textbooks on isotope hydrology and has presented papers at various international and local conferences. Two post-graduate students were selected for an IAEA training course in Morocco and two staff members are to attend a training course on laboratory techniques in Vienna in October 1998.

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There is a growing interest in environmental isotopes as efficient tools in the development and assessment of ground water resources in South Africa, - a major concern in the Reconstruction and Development Programme. Increasing enquiries are also being received for cooperation from African countries and elsewhere. Two trainees under the IAEA fellowship programme were accomodated in 1997 and two further trainees are expected later in 1998.

The state-of-the-art Packard Tri-Carb 2770 TR/SL liquid scintillation spectrometer has been in routine operation for two years and some 1000 environmental tritium and 200 radiocarbon measurements have been performed. The purchase of the instrument was financed partly from the Group's reserves, and partly through an interest-bearing loan. The loan has been fully redeemed from the University's research funds, for which the Group expresses its gratitude to the Faculty of Science and the Research Office.

With the re-organisation of the Research Entities in the Schonland Research Centre, the Environmental Isotope Group has joined the Applied and Environmental Physics Group under the leadership of Prof JIW Watterson. An announcement to this effect elicited letters of support and encouragement from 20 collaborators and colleagues, both local and abroad.

The Group and its analytical facilities have been identified by the IAEA as being a centre of excellence which is to support a new southern and eastern African regional project on isotope hydrology. Analytical, scientific and training contributions are being sought from the Group, which can expect an upgrading of its facilities in support for this initiative.

The Group Leader was appointed an Honorary Research Fellow of the University as from 1 January 1998.

Global Network of Isotopes in Precipitation (GNIP)

Schonland Environmental Isotope Group; IAEA/WMO

The Environmental Isotope Laboratory is the official measuring station for the IAEA/World Meteorological Organisation Global Network of Isotopes in Precipitation (GNIP). The ratios 2H/1H, 3H/1H and 18O/16O are measured in monthly precipitation samples received from the world-wide IAEA/WMO survey stations: Pretoria, Cape Town, Windhoek, Marion Island, Gough Island and occasionally Harare. The results are published periodically in the IAEA (Vienna) Technical Report Series.

A major international service over the past two decades, this South African contribution continues to be rendered free of charge by the Wits Environmental Isotope Group.

Stable isotope studies in geology and the Okavango Delta

S Master, T S McCarthy (Dept. Geology); B Th Verhagen

Carbon and oxygen isotope measurements in archaean carbonates are producing increasing evidence that a major carbon isotope excursion, at first thought to be a local characteristic of the Lomagundi dolomites in Zimbabwe, was a more general and possibly global phenomenon at around 2000 Ma. Several conference presentations have been given on this work.

Ongoing isotopic studies of ground water and carbonates of islands/én the Okavango Delta are being conducted in order to test models of the development and hydrology of such islands.

Save River alluvial aquifer, Zimbabwe

B Th Verhagen, K Froehlich (International Atomic Energy Agency, Vienna), S Sunguro (Dept. of Water Development, Zimbabwe),

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The Save River valley, one of the main irrigation areas of Zimbabwe, is experiencing major degradation of ground water quality. Originally proposed by the Project Leader as one of two IAEA Technical Cooperation projects, it is now to be incorporated into the new eastern and southern African IAEA regional project. The Schonland Group is expected to provide expert and technical input under this project.

Recharge assessment at Orapa mine, Botswana

D B Bredenkamp (Water Resources Evaluation and Management), B Th Verhagen (Wits), L Botha, R Bush (Anglo American Corp., Johannesburg)

A one-year final data gathering and further data evaluation phase of this project, supported by the Water Research Commission, was modified into a comparison of the cumulative rainfall departure method with isotope assessment of the recharge to the Karoo aquifers at Orapa diamond mine, Botswana. The cumulative rainfall departure method, and allied historical abstraction data, require many years of observational records. Isotope data obtained for a number of boreholes in the area could be interpreted i.t.o. recharge. The results were in good general agreement with the long-term data, emphasising once again the power of this method, as highlighted in several other studies. The final report on the project "Response of a multi-layered fractured aquifer to long-term abstraction" has been thoroughly reworked and submitted to the WRC. A concept of recharge in this part of the Kalahari, proposed by the Group on the basis of seminal work done at Orapa in the early 70's is to be tested at the hand of new samples to be taken in cooperation with Anglo American Corporation.

Urban hydrology - Tracing mains water leakage in the PWV area

M J Butler and B Th Verhagen (Wits)

This project, subject of a final report to the Water Research Commission, employed the distinct 2H, 18O isotopic signature of the Rand Water mains supply. Not only did the isotopic signal differ substantially from most ground occurrences; it can also be distinguished from water altered by surface evaporation. It was realised that this quality allows for identifying the presence, and tracing the movement, of mains water in the sub-surface. This feasibility study was conducted in Pretoria and Johannesburg.

In a fairly dense coverage of data from private boreholes in northern suburbs of Pretoria, both diffuse and point source input of mains water to the underlying ground water have been established. In addition to proving the presence of both diffuse and point source input of mains water, interesting features of the natural hydrology were discovered. The underlying concept has already been successfully applied to a number of environmental impact studies.

The exceptional rainy season of 1995/96 has isotopically reset the Vaal Dam. The new isotope signal has already been found in ground water, previously identified as completely derived from mains leakage. The dam is gradually regaining its former unique isotope signal.

Isotope and hydrochemical studies of the Table Mountain Sandstone, Little Karoo

B Th Verhagen; J Kotze (Steffen, Robertson and Kirsten); M Simonic (Hydromedia Solutions); A Issar (Ben Gurion University, Israel)

The ground water potential of the Table Mountain Sandstone aquifer in the Little Karoo is being investigated to develop a conceptual and management model for its exploitation, a study conducted under contract to the International Atomic Energy Agency, the Water Research Commission and the Department of Water Affairs.

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Structural investigations have indicated that regional interconnections of ground water may exist. This concept has been confirmed by environmental isotope and hydrochemical studies, centered in the region around Dysselsdorp and van Rynsdorp in the Little Karoo. Residence time and water balance considerations have shown that ground water storage in the Kammanassie Mountain is much higher than estimates based on structural considerations.

This work is ongoing and being extended to beyond the original scope as it is seen as providing pivotal information for a management plan for the Little Karoo water supply scheme.

Projects under the eagis of the International Atomic Energy Agency

1. Ethiopia

Part of a regional north African isotope hydrology model project, organised and sponsored by the International Atomic Energy Agency, in which the Group has been invited to cooperate. Other participating countries are Egypt, Morocco, Senegal, Nigeria, Niger, Mali and Algeria. The 3 year Ethiopian project has now been completed and a final report has been produced under the guidance of the Group Leader.

The Moyale region of southern Ethiopia is experiencing a major increase in population, requiring an expansion of its water resources. The Group Leader established during a first field visit that the hydrology of the region is not coherent and that smaller units need to be investigated. In two subsequent visits, an analysis of the isotope (3H, 2H, 18O and 14C) data revealed that ground water recharge is about one order of magnitude less than suggested in the Hydrogeological Map of Ethiopia. This is of fundamental importance to development planning for the region. It was furthermore established that recharge to the more productive sedimentary aquifers in the region is local and of little areal extent, requiring further caution in the planned intensification of exploitation.

The salination and rapid rise in water level of Lake Beseka was discussed during the same visit. A novel two-phase stability model for the lake,, proposed by the Group Leader in 1996, is still seen as the best approach. It is being developed further in cooperation with Dr C. Barnes (CSIRO, Canberra) and is to be tested by field observations.

2. Morocco

An IAEA RAF/8/022 project in which the Group and its Leader produce analytical data and provide scientific input. Two project areas are being investigated: in north-eastern Morocco the In the Guelmim area of the south-west, the hydrological question revolves around the recharge effected by the control of seasonal floods by a recently-completed storage dam. Recharge in the quaternary sediments was shown by isotopic measurements to be very patchy, depending on local conditions in the subsurface. There is little evidence of significant sub-surface ground water transport from the higher-lying areas to the north.

In the Tafilalt area in the east of the country the question regarding the salination of ground water to south of releases of deep saline artesian has been successfully addressed through the use of isotopes.

3. Uganda

The geohydrology of various areas of Uganda is being investigated with the use of environmental isotopes as part of an IAEA technical cooperation project UGA/8/002. In addition to analytical data, the Group and its Leader have been requested to assist the counterparts in Entebbe twice, in July 1997 and again in January 1998. During these visits the various project areas were inspected and recommendations on the further conduct of the project made. The aquifers of Uganda are almost exclusively in igneous rocks, covered by regolith. The particular method of well construction formerly employed presents a unique

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challenge in the interpretation of isotope and hydrochemical data. Analysis of a second set of samples has recently been completed.

4. Nigeria

Ground water salination in the fadama irrigation area at Wurno in north-western Nigeria is being studied under the IAEA regional model project (RAF/8/022) in which the Group participates. The area, in the flood plain of the Sokoto River, receives irrigation from natural seasonal flooding, from surface water impoundments and from ground water. The Group Leader participated in the first sampling campaign, advised the counterparts on investigation procedures and lectured on isotope techniques at Water Resources headquarters in Abuja and to a large audience at the Water Research Institute. Kaduna. Stable isotope data on a first suite of samples from the project area has shown a very large range of values in the expected end members as well as in various ground water occurrences promise a very successful application of isotopic techniques to a complex hyrogeological problem.

5. Dam Projects

A new initiative of the IAEA is to apply nuclear techniques to the investigation of leakages from dams. Through AFRA a preliminary international multidisciplinary task team was assembled for the investigation of African dams (RAF/8/026) in which the Group through its Leader was requested to participate. Thusfar dams in Morocco and Namibia have been investigated. Environmental isotope analyses, conducted in the Group's laboratories, contributed in both cases to setting limits to mechanisms of leakage.

6. Unsaturated zone

MJ Butler, B Th Verhagen, JA Geyer

The Environmental Isotope Group was requested by the IAEA to participate in this international survey of isotopes in unsaturated zone profiles as the only representatives of and site in the southern Hemisphere. A principal aim of the project is to utilise what remains of thermonuclear tritium in order to assess soil moisture transport and ground water recharge. Two deep (up to 18 m) and two shallow profiles were hand-augered in a Kalahari sand covered region in NW Province in July 1997. Stable isotope, moisture content and chloride concentration profiles were obtained. In the process various new sample preparation methods were developed (see Methodological Innovations). The results were reported to the first Research Coordination Meeting (RCM) held in Vienna in December 1997. Further work has been performed on the existing sample material and a new set of profiles has been collected in August 1998 for analysis and interpretation for the second RCM to be held in Tunisia in November 1998.

Methodological innovations

J Geyer, O Malinga, MJ Butler, B Th Verhagen (Wits)

a) Radiocarbon sample preparation

With the recently-commissioned liquid scintillation spectrometer, the need arose for a different form of sample preparation for radiocarbon analysis. The well-known absorption method was introduced, but found to have distinct drawbacks in sample handling. The method has now been further developed, in that the carbon dioxide derived from the field sample is absorbed in the Carbosorb/Instagel cocktail in the counting vial itself. Effectively 100% absorption of 1L STP CO2 is achieved with no transfer losses, which produces excellent reproducibility of sample size and counting characteristics, with minimal sample preparation time - a significant advance on the standard methodology

b) Deuterium and oxygen-18 in soil moisture

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The stable isotopes of hydrogen and oxygen in soil moisture are powerful indicators of rainfall infiltration conditions in the natural environment. A major drawback has tradionally been that small amounts of water experience isotope fractionation when distilled from soil/sand samples before analysis. An innovation by the Wits lab has been to equilibrate the in situ moisture in a soil sample directly with the carbon dioxide used for measurement. This allows for much simplified, rapid and more reproducible isotopic measurements.

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Tritium in landfill leachates

B Th Verhagen (Wits); M Levin (Africon); AJ Fourie (Civil Engineering, Wits)

During studies conducted under contract to the Water Research Commission at two landfill sites near the City of Bloemfontein, it was discovered in 1993 that leachate from these landfills was introducing tritium at well above normal environmental level into local ground water. Since that time, numerous landfills have been identified which produce leachate with variable levels of tritium, up to 105 TU. This discovery is of great importance, as tritium is a conservative and unique constituent of water, independent of chemical processes. Traditional attempts at tracing leachate for pollution studies using conventional chemical methods has rarely produced unequivocal data. There is as yet uncertainty regarding the source(s) of this artificial tritium, but luminous signs, toys and medical waste are possible

In the first practical application to a landfill site in Natal, tritium concentrations of about 100 000 TU were observed in leachate collecting downstream of the site. Individual leachate see pages from different sections of the site have widely differing tritium values, suggesting that the source(s) of tritium in the waste are localised. In samples from all available ground water monitoring points at the site, tritium values ranged from 0 TU up to a maximum of 2 TU - a very sensitive indication that no significant leachate was reaching the saturated zone. This is in accord with what could be expected due to the argillaceous nature of the sub-surface.

S&E African IAEA Regional Project

The Environmental Isotope Group recently hosted an IAEA planning workshop in Johannesburg, attended by representatives of Madagascar, Kenya, Tanzania, Uganda, Zimbabwe, Namibia and South Africa. Each country proposed a ground water development project which will involve an environmental isotope component. The South African project, to be conducted in NW Province, was designed in cooperation with the Group Leader. Together, these projects will be regionally coordinated, an endeavour in which the Wits Group is seen to be pivotal, both in scientific support and in the provision of analytical capabilities. The potential for regional self-sufficiency will thereby be enhanced, particularly when the Group's laboratories will receive support under the 2-year programme, which is scheduled to commence in 1999.

VisitorsDr K. Skornik - IAEA

Dr R.C. Lanza - MIT

Dr K. Frochlick - IAEA

Dr A. Boussaha - IAEA

Prof A. Issar - Ben Gurion University

Publications

Chapters in Books

Verhagen, B Th (1998) Environmental isotope hydrology: Principles and application to geohydrology in the Karoo. (Invited) Chapter in: The Hydrogeology of the Karoo Supergroup (Eds: Woodford et al.) WRC, Pretoria. In press.

Ingraham, N L and Verhagen, B Th (1998) Arid catchment basins. (Invited) Chapter in: Isotope Tracers in Catchment Hydrology (Eds: McDonnell and Kendall) Elseviers. In press.

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Refereed Conference Proceedings

Verhagen, B Th and Butler, M J (1998) Environmental isotope studies of urban and waste disposal impact on groundwater resources in South Africa. In: Isotope Techniques in the Study of Environmental Change, 411-422. IAEA, Vienna

Verhagen, B Th (1998) Isotope hydrology: applications to mining, urban,and pollution problems in southern Africa (Invited). International Conference on Applications of Radioisotopes and Radiation in Industrial Development, Mumbai. February 1998.ICARID

Butler, M J and Verhagen, B Th (1997) Emvironmental isotopic tracing of water in the urban environment of Pretoria, South Africa. Groundwater in the Urban Environment Vol.1. 101-106. (J Chilton et al. Eds.) Balkema

Conference Proceedings

Verhagen, B Th (1998) Arid zone isotope hydrology - Cooperation with the Geological Survey, Botswana. International Conference on the Role of National Geological Survey in Sustainable Development, Gaborone. Department of Geological Survey, Lobatse 37-40.

Verhagen, B Th (1998) Environmental isotope hydrology: Past, present and future impacts on ground water studies in mining, the urban environment and understanding hydrochemistry. Geocongress 1998. Extended abstracts. 285-288.

Verhagen, B Th (1997) Groundwater recharge research in the Kalahari in the early days (Invited). GRES Symposium: "Groundwater Recharge and Resources Assessment", Gaborone, November 1997

Verhagen, B Th, Levin, M and Fourie, A (1998) High level tritium in leachate from landfill sites in the RSA with emphasis on its distribution and value as a natural tracer WISA-May '98 Conference, Cape Town, 10pp.

Fourie, A, Verhagen, B Th, Levin, M and Robinson, H D (1998) Tritium as an indicator of contamination from landfill leachate. Wastecon ‘98 Conference, Kempton Park.

Reports

Verhagen, B Th (1997) End of mission report to the IAEA. Project Number: RAF/8/022 - 13 (Morocco) Project Title: Water resources assessment in arid and semi-arid regions of Africa. Mission Period: 2 - 9 June 1997

Verhagen, B Th (1997) End of mission report to the IAEA. Project Number: UGA/8/002 - 01 (Uganda) Project Title: Isotopes for groundwater development. Mission Period: 30/06/1997 - 12/07/1997

Verhagen, B Th (1997) End of mission report to the IAEA. Project Number: UGA/8/002 - 01 (Uganda). Project Title: Isotopes for groundwater development. Mission Period: 10.01.1998 - 18.01.1998

Verhagen, B Th (1997) End of mission report to the IAEA. Project Number: RAF/8/026-02 01 (Morocco). Project Title: Investigation of leakage in dams & reservoirs (AFRA IV-22). Evaluation of leakages in the dam of Aoulouz Mission Period: 25 October - 2 November 1997

Verhagen, B Th (1997) End of mission report to the IAEA. Project Number: RAF/8/022 - 14 (Nigeria). Project Title: Water resources assessment in arid and semi-arid regions of Africa. Mission Period: 23 May - 1June 1997

Verhagen, B Th (1997) End of mission report to the IAEA on RAF/08/026 mission to Namibia.(With: Y Bouabdallaoui (Morocco), C Gaye (Senegal) and A Plata-Bedmar (Spain). Project

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title: To investigate leakages from the Aonob dam, near Rehobot, Namibia. Mission Period: 15 - 19 December 1997

Aerosol Physics and PIXE Group

HJ Annegarn (Group Leader)

Outputs for the year under review:

Research ProgressThe Transboundary Air Pollution Project (TAPP) has proceeded well on several of its basic projects and achieved major strides in integrating these into a far-reaching, multi-national and inter-disciplinary research initiative - SAFARI-2000. In the short summary, I shall highlight progress in some of the individual projects before describing the SAFARI-2000 initiative.

Ben MacDhui High Altitude Trace Gas and Transport Experiment (BHATTEX)Further analysis has been done on the samples collected continuously through 1996 and 1997 and the intensive sampling campaigns of 1997. The original aim, namely to obtain empirical verification of trajectory model calculations of atmospheric long-range transport, has been achieved. Several conference and refereed publications have been presented and / or submitted.

Zambian Copperbelt Emission Inventory This project had two components, namely the calculation of emission inventories of sulphur dioxide from the Central African Copperbelt; and empirical measurements of smelter and background sulphate aerosols in the region. These results are important for the South African context since this regional source is comparable in strength to coal-fired power plant emissions from South Africa and hence necessary for any evaluation of transboundary pollution studies. The inventory is nearing completion. Results of the aerosol measurements were presented at the International PIXE Conference, Sweden, June 1998.

Mount Kenya mid-Tropospheric SamplingA solar-powered, aerosol sampler was commissioned at a high-altitude site on Mount Kenya during 1997 to measure mid-tropospheric air masses in the region of the inter-tropical convergence zone (ITZ). First samples have been PIXE analysed and interpreted in terms of synoptic weather patterns and air mass trajectory analysis. Results of the air mass trajectory analysis for Mount Kenya have been submitted to the Journal of Geophysical Research and presented at several conferences.

Air mass trajectory analyses performed both for this sub-project and by S Piketh (a student in this group) on behalf of Eskom TRI have shown trajectories originating over the South African Highveld to proceed to Kenya with about 5 % frequency. A most unexpected result and of great significance in terms of this trans-boundary air pollution investigation.

Mozambique Aerosol SamplingA short-term sampling expedition to central Mozambique (15 o South latitude) retrieved streaker samples from a truly remote region. This study is being pursued by a staff member from the University of Eduardo Mondlane, Maputo, registered at Wits for an MSc. Preliminary results will be presented at the World Clean Air Conference in September 1998, Durban. Further sampling in Mozambique will take place closer to Maputo, mainly for logistical reasons.

Aerosol Recirculation and Rainfall Experiment (ARREX)The ARREX project, launched in 1997, is based on the use of an airborne sampling platform, namely the South African Weather Bureau’s (SAWB) Aerocommander Research Aircraft. The project is a collaboration between the Climatology Research Group, Wits; the Schonland

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Research Centre, Wits; the Rainfall Modification Research Group of the SAWB, based in Bethlehem; the University of Potchefstroom and the Max Planck Institute for Chemistry, Mainz. Two successful field campaigns have been conducted - December 1997 and May 1998. Each phase involved approximately 25 hours in-flight time. The first data workshop has being held and data interpretion is under way. Further funding has been applied for from the Water Research Commission (WRC) to support flight campaigns in 1999 and 2000. Several post-graduate students from the various institutions have been involved.

SAFARI-2000Arising from the collaborations of the SAFARI-92, BHATTEX and ARREX projects, interest in Southern Africa has increased among scientists at the University of Virginia, NASA GSFC and others. This has resulted in Southern Africa being selected as one of the regions for the ground validation of new generation of earth-observing satellites (EOS) to be launched in 1999 and 2000. The initial modest, ground-based validation project, under the title “Southern African validation of EOS” (SAVE), has been expanded into a large-scale regional initiative involving ground-based, intensive and extensive field measurements, participation of four air-borne sampling platforms (x2 SAWB Aerocommanders, x1 University of Washington Convair-490 research aircraft and the NASA ER2 high-altitude research aircraft) and various satellite remote sensing instruments. Several supplementary proposals have been submitted to NASA, the US National Science Foundation, the FRD and other funding agencies. SAFARI-2000 has been placed on Eskom TRI’s Strategic Research Plan for the next five years.

The first major science planning meeting for the SAFARI-2000 project took place during July 1998 at Blydepoort. This meeting was attended by 65 delegates from ten countries: Namibia, Botswana, Zambia, Zimbabwe, Mozambique, Kenya, Malawi, USA, England, and South Africa. Eight South African tertiary institutions were represented, including three HDU’s. A significant feature of the meeting was the strong delegation of senior US scientists, 23 in all, from NASA and various universities. The main funding for the meeting was provided by US National Science Foundation (US $30 000), FRD, Commonwealth Science Council, University of Utrecht and others.

The Aerosol Group of the Schonland Research Centre, Wits, has been the focal point for developing this international project. The Blydepoort Planning Workshop was organised jointly by R Swap of the University of Virginia and an Honorary Research Fellow at the Schonland Research Centre, Yvonne Scorgie, a student in the group and H J Annegarn. The support from Eskom TESP was a significant factor in enabling us to pursue these opportunities and bring them to fruition.

Outcomes of the Blydepoort Planning Meeting include the SAFARI Science Plan, which was presented in outline to the FRD on the 23rd of July and will be presented to the International IGP-BIBEX community in Seattle, USA on the 23rd of August. To support South African participation in the SAFARI-2000 initiative, a co-ordinated proposal has been submitted to the Department of Arts, Culture, Science and Technology under their Lead Project call for proposals. This project, submitted through Environmentek of the CSIR, is for approximately R1 000 000 per year for the next three years.

Human Resources Development

Workshops and Conferences Organised:

Ben MacDhui BHATTEX Data Workshop. April 1997. Duration: 1 day.Number of delegates: 12.Attended by Climatology Research Group, Eskom TRI, CSIR Environmentek, University of Potchefstroom, Port Elizabeth Technikon.

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NCCC/SANCO Environmental Capacity Building Conference. 25-27 April 1997. Duration: 3 days. Number of delegates: 60. The aim of the workshop was to inform community structures of the science and policy implications of various topical atmospheric issues including climate change, acid deposition and township pollution. As a result of this workshop, a joint effort between the National Committee for Climate Change, the National Association for Clean Air, South African National Civics Organisation and the Group for Environmental Monitoring and various trade unions, significant progress was made in communicating the technical issues and establishing trust between community environmental organisations and government departments (DEAT and Foreign Affairs). South Africa subsequently ratified the Framework Convention on Climate Change in September 1997 with full community support. The initiative to organise this conference and the organisers were members of the Aerosol Research Group.

Environmental Award System for Youth (EASY) - Gauteng Networking Workshops. 11 - 14 August 1997, Germiston, Soweto, Johannesburg, Pretoria. Duration: 4 days. Number of delegates: 80.Valerie Pitcher, a member of Annegarn’s research team, organised a series of workshps at different locations in Gauteng, to further the EASY system of environmental education, which had been successfully developed over a number of years in Pietermaritzburg. The materials developed by EASY fulfilled many of the needs in the emerging schools environmental curricula. By networking and distributing existing tested and proven materials, the series of workshops promoted environmental education in the province.

Workshop on Scientific Writing, Institute of Nuclear Science, University of Nairobi, Kenya: 19 - 22nd January 1998. Duration: 4 days. Number of Participants: 26.This workshop aimed to improve the scientific writing skills of atmospheric scientists in Kenya. The workshop was organised jointly by the Kenya Meteorological Department, the Institute of Nuclear Science, Kenya Meteorological Society and the University of Witwatersrand. The 22 participants gained entry by presenting an article of writing in progress. Workshop resource persons were Prof M Garstang, University of Virginia, Charlottesville and Editor-in-Chief of the Journal of Applied Meteorology; Prof S Pendlebury, University of Witwatersrand, former editor of Perspectives in Education; Mrs J Menasce, free-lance editorial consultant; and H J Annegarn. The conference Chairman and Organiser was C Gatebe, a PhD student with the Aerosol Research Group. Subsequent to the Workshop, several of the participants have submitted their re-worked manuscripts for journal publication.

CALPUFF Dispersion Modelling Workshop, University of Witwatersrand, May 1998. Duration: 3 days. Number of delegates: 15.This workshop was a joint initiative between the Aerosol Research Group and Environmentek CSIR (Peter D’Abreton). US Environmental Protection Agency has commissioned the development of a new generation of general purpose atmospheric dispersion models. CALPUFF, shortly to be specified as an approved model, will become the next dispersion modelling standard. The workshop was presented by Mr J Scire (USA), one of the model developers, and Dr Jenny Godfrey of the National Institute of Water and Air Research, New Zealand. Participants represented Eskom TRI, CSIR, University of Zululand, University of Witwatersrand and environmental consultants. The technology transfer facilitated by this workshop will ensure that South African Atmospheric Scientists are up to date with the latest scientific and regulatory trends in dispersion modelling.

SAFARI-2000 Planning Workshop, Blydepoort, 11-18 July 1998The scope and significance of this is most easily presented in the summary statement below, inserted in full:

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LAUNCH OF THE SAFARI-2000 REGIONAL SCIENCE INITIATIVEStatement prepared for the USA – RSA Bi-National Commission, at the invitation of Dr C Schaeffer, Department of Arts, Culture, Science and Technology

Wise stewardship of the environment, appropriate responses to global climate change and sustainable use of natural resources require an understanding of the links between physical, chemical and biological processes - including human impacts - on global, regional and local scales. Arising from the Southern African Fire/Atmosphere Research Initiative (SAFARI 92), an international field campaign conducted in 1992, scientists now comprehend that the thin layer of the atmosphere acts as a web linking regions of southern Africa up to thousands of kilometers apart. The transport of moisture and trace chemicals in the atmosphere influences processes as diverse as the global radiation balance and agricultural practices involving frequent veldt burning. As the atmospheric environment of southern Africa respects no political boundaries, to achieve the objective of understanding the effects of biomass burning, industrial and biogenic emissions on the southern African system requires a continental scale, multi-disciplinary investigation.

In a series of stakeholder workshops, held during June and July 1998, scientists from southern Africa and the United States have laid the foundations for a large regional science initiative – SAFARI 2000 - to take place in southern Africa over the next three years. The purpose is to understand the operation of the southern African system, stretching from the equator southwards, as an integrated, interconnected system. SAFARI 2000 will comprise a number of linked ground based short and long-term field campaigns to measure biological, soil, atmosphere and radiation processes. A fleet of USA and South African research aircraft will probe the vertical and horizontal properties of the lower and middle troposphere during two intensive field campaigns to take place in the dry winter burning season and the wet summer season. The whole campaign will be supported by intensive meteorological measurements.

These ground and airborne measurements will be complemented by remote sensing observations from NASA’s next generation of Earth Observing Satellites (EOS), scheduled for launch in 1999 and 2000. In turn, the earth and atmosphere based observations of SAFARI 2000 will validate the remote sensed satellite observations. SAFARI 2000 will constitute worldwide the largest validation campaign for the EOS series satellites. In the longer term, the wide area coverage and continuous series of EOS satellite measurements will facilitate monitoring of southern Africa on a continental scale.

The nature of SAFARI 2000 as an integrated regional science initiative requires participation on a multi-national level. The first major science meeting accordingly took place in southern Africa, with the scientists from the following countries and institutions:

USA: NASA Goddard Space Flight Centre, University of Virginia, University of Maryland, University of Washington, College of William and Mary, Clarke University, US Forest ServiceSouth Africa:University of the Witwatersrand, South African Weather Bureau, Council for Scientific and Industrial Research, University of Pretoria, University of Stellenbosch, University of Zululand, Vista University, University of Natal, University of Western Cape, University of Cape Town, University of Potchefstroom, Port Elizabeth Technicon, Eskom TRI.Southern Africa: Etosha Ecological Institute, NamibiaUniversity of BotswanaUniversity of ZimbabweMeteorological Services, Zambia Eduardo Mondlane University, MozambiqueNational Institute of Meteorology, MozambiqueEurope: University of Leicester, University of Edinburgh, EnglandMax Planck Institute for Chemistry, Mainz, Germany

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A corollary objective of SAFARI 2000 is to encourage both capacity recognition and enhancement from both north to south and south to north.

The products of SAFARI 2000 will contribute to the scientific basis of future International Panel on Climate Change (IPCC) efforts within the region. Regional research will benefit from training and technology transfer in the use of a new generation of satellite derived products. This in turn will contribute to formulation of appropriate policies and responses to manifestations of climate change and international treaties relating to global environmental issues. Information from SAFARI 2000 will be disseminated regionally and internationally via the inter-net as well through the distribution of CD-ROMS. The results from SAFARI 2000 should also provide a knowledge base that can begin to address the impact of the region on global change.

It is fitting in 1998, South Africa’s Year of Science and Technology, that this major new scientific and environmental cooperative venture should be launched under the auspices of the Gore-Mbeki Bi-national Commission.

Soweto Air Monitoring Project Training Workshop, 24 and 25 August 1998, University of Witwatersrand, Johannesburg. Duration: 2 days. Number of delegates: 20, comprising local environmental health officials.This workshop is intended as a skills development workshop for atmospheric environmental monitoring. The officials will have a better understanding of the nature of urban air pollution and better skills for ensuring high-quality sampling and data collection. They will be in a better position to provide environmental education to membes of their communities.

11th World Clean Air Conference, Durban, 13 - 18 September 1998. Duration: 5 days. Number of delegates: est 450, 400 papers.HJ Annegarn is on the organising committee of this international conference. He is persnally responsible for inviting one keynote speaker and two other delegates from the USA and has arranged for them to consult with various other industrial and government institutions before and after the conference. During the conference, he is co-convenor of a working group on vehicle emissions. HJ Annegarn has, from contract resources, financed the participation of approximately 10 local authority environmental health officials, both black and white, to enable them to benefit from exposure to the international visitors.

6th International Microprobe Analysis Conference, Stellenbosch - 11-16th October 1998. Duration: 5 days. Number of delegates: 200. HJ Annegarn is a member of the organising committee, together with Dr V Prozevski of the National Accelerator Centre, devised a mentorship scheme, approved and funded by the FRD, whereby students and junior staff members from HDU’s would be supported to attend the conference to enable them to benefit from interaction with international scientists. In return the conference organisers undertook to identify a senior scientist who would mentor such individuals during the conference and, if possible, make an academic visit to their home institution before or after the conference. Five South African and five foreign African participants will benefit from FRD support at this conference. If successful, this scheme will be used at other international conferences held in South Africa as one means of promoting a culture of research at the HDU’s.

Publications and conference contributions (1997, 1998 and submitted)

Refereed publicationsP58. I Salma, W Maenhaut, HJ Annegarn, MO Andreae, FX Meixner, M Garstang.

Combined application of INAA and PIXE for studying the regional aerosol composition in Southern Africa. J Radioanal Chem, 216 (1997) 143-148.

P59. P Formenti, HJ Annegarn, SJ Piketh, Time-resolved aerosol monitoring in the urban centre of Soweto. Nucl Instr & Meth in Phys Res B 136-138 (1998) 948-954.

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P60. P Formenti, D van den Heever, HJ Annegarn, Source profile derivation for an arc welding shop using time sequenced sampling and PIXE analysis. Nucl Instr & Meth in Phys Res B 136-138 (1998) 961-965.

P62. P Formenti, HJ Annegarn, P Prati, A Zucchiatti, F Lucarelli, PA Mando, Source apportionment by receptor models in a study of Genova aerosol via streaker sampling and PIXE analysis. Physica Medica XIII (1997) 101-109.

P66. B Holynska, J Ptasinski, W Maenhaut and HJ Annegarn, Energy-dispersive X-ray fluorescence spectrometer with capillary optics for the chemical analysis of atmospheric aerosols with high time resolution. J Aerosol Sci 28 8 (1997) 1455-1463.

P71. F Amponsah-Dacosta, HJ Annegarn, Assessment of fugitive dust emissions from an opencast coal mine. J Mine Ventilation Soc S Afri, 51 (1998) 5-11.

P72. V Yousefi, HJ Annegarn, Aerodynamic aspects of exhaust ventilation. J Mine Ventilation Soc S Afri, 51 (1998) 5-11.

Submitted (date submitted)P61. M Wentzel, HJ Annegarn, G Helas, S Weinbruch, AG. Balogh, JS. Sithole, Giant

dendritic carbonaceous particles in Soweto aerosols. S Afr J Sci (Accepted Nov 97 1997).

P63. G Kirkman, HJ Annegarn, G Helas, Airborne studies of vertical and lateral concentrations and aerosol size distributions over southern Africa. J Geophys Res. (July 1997).

P64. MO Andreae, TW Andreae, HJ Annegarn, JUM Beer, H Cachier, P le Canut, W Elbert, W Maenhaut, I Salma, F Wienhold and T Zenker, Airborne studies of aerosol emissions from savanna fires in southern Africa: 2. Aerosol chemical composition. J Geophys Res, (March 1998).

P65. SJ Piketh, HJ Annegarn, W Maenhaut, G Helas and MA Kneen, Source determination and transport characterisation of aerosols during SAFARI-92. J Geophys Res. (April 1998).

P67. SJ Piketh, HJ Annegarn and PD Tyson, Lower-tropospheric aerosol loadings over South Africa: the relative impacts of aeolian dusty, industrial emissions and biomass burning. J Geophys Res. (April 1998).

P68. SJ Piketh, P Formenti, HJ Annegarn, PD Tyson, Industrial aerosol characterisation at a remote site in South Africa, Nucl Instr & Meth B. (June 1998).

P69. P Formenti, SJ Piketh, HJ Annegarn, Detection of non-sea salt sulphate aerosol at a remote coastal site in South Africa: a PIXE study, Nucl Instr & Meth B. (June 1998).

P70. SJ Meter, P Formenti, SJ Piketh, HJ Annegarn and MA Kneen, PIXE investigation of aerosol elemental concentrations in the Zambian Copperbelt, Nucl Instr & Meth B (June 1998).

P73. CK Gatebe, PD Tyson, HJ Annegarn, S Piketh, G Helas, A seasonal air transport climatology for Kenya. J Geophys Res. (July 1998).

Unrefereed journal publicationsU02. HJ Annegarn, N Robbins, R Stein, P Terblanche, Clean Diesel for South Africa.

Clean Air J 9 (1997) 3-7.

U03. HJ Annegarn, Y Scorgie. An air quality management strategy for the Vaal Triangle Part I. Clean Air J 9 (1997) 9-17.

U04. HJ Annegarn, Y Scorgie. An air quality management strategy for the Vaal Triangle Part II. Clean Air J 9 (1997) 9-17.

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U05. HJ Annegarn, Y Scorgie. An air quality management strategy for the Vaal Triangle Part III. Clean Air J 10 (1997) 3-17.

Policy documentsThis category includes reports and submissions prepared as part of policy development at

international, national, provincial and local levels, not necessarily as part of paid contracts

PD02 Vaal Triangle Air Quality Management: an Implementation Strategy. HJ Annegarn and AP Terblanche. National Association for Clean Air. 11 June 1997, 9 pp..

Conference proceedings - full report published in proceedings C54 SJ Piketh, P Formenti, RJ Swap, CA Anderson, PD Tyson, HJ Annegarn, W

Maenhaut. Identification and transport of industrial aerosols at a remote site in South Africa. 5th Int Conf on Southern Hemisphere Meteorology and Oceanography, Pretoria, Apr 1997.

C55 SJ Piketh, P Formenti, PD Tyson, RJ Swap, HJ Annegarn, W Maenhaut. Subcontinents scale transport of aerosols over Southern Africa. Earth-Ocean-Atmosphere forces for change, Melbourne, 1-9 July 1997.

C66 HJ Annegarn and Y Scorgie. Modern concepts of air quality management - Relevance to RSA. Proc EnviroQuest/NACA Seminar, Port Elizabeth Technikon, 23 October 1997.Invited keynote paper.

C67 HJ Annegarn. A bird’s eye view of air pollution in South Africa. Proc NACA Annual Conf, Vereeniging, 21 November 1997. Invited keynote paper.

Conference proceedings: extended abstracts in proceedings and/or presented personally 1997 and 1998E145 HJ Annegarn, Management of Urban Air Pollution by Civic-Industrial Partnerships,

Symp Environmental Science and Industry in South Africa, Univ Vista, Mamelodi, 22 July 1997.Invited presentation.

E146 HJ Annegarn, M Wentzel, G Helas, S Weinbruch, AG. Balogh, JS. Sithole. Giant dendritic carbonaceous particles in Soweto aerosols. Sixth Int Conf on Carbonaceous Particles in the Atmosphere, 22-24 Sep 1997, Vienna.

E147 M de Villiers, M Wicken-Baird, R Dutkiewicz, HJ Annegarn. Cape Town Brown Haze - a fine particle study. PM2.5 Implementation Conference, Los Angeles, 25-28 January 1998.

E148 SJ Piketh, P Formenti, HJ Annegarn, PD Tyson, Industrial aerosol characterisation at a remote site in South Africa, 8th Int PIXE Conf, Lund, Sweden, 14-18 June 1998.

E149 P Formenti, SJ Piketh, HJ Annegarn, Detection of non-sea salt sulphate aerosol at a remote coastal site in South Africa: a PIXE study, 8th Int PIXE Conf, Lund, Sweden, 14-18 June 1998.

E150 SJ Meter, P Formenti, SJ Piketh, HJ Annegarn and MA Kneen, PIXE investigation of aerosol elemental concentrations in the Zambian Copperbelt, 8th Int PIXE Conf, Lund, Sweden, 14-18 June 1998.

E151 C Gatebe, HJ Annegarn, PD Tyson. Air parcel trajectory analsyis for Mount Kenya. INDOEX Workshop, Utrecht, 22-24 June 1998.

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Student theses and reports prepared under Annegarn’s supervision

Theses / dissertations: graduatedT5. D van den Heever. Thesis: The effect of aerosol exposure on foundry workers and

arc welders at a large engineering plant in South Africa.Doctor Technologiae Environmental Health (Technikon Free State) 1997.(Co-Promoter: Professor JG Barnard, Dept Environmental Sciences, Technikon Free State.)

T6. G Munyai. Dissertation: Implementation of corporate environment policies.MBA (Witwatersrand) 1997.(Co-supervisor: Mr MTH Pycraft, Wits Business School).

T7. A R N Mizelle-Ntaloulou. Dissertation: Study of air and water dust pollution induced by the Witwatersrand mining industries applying the geographical information systems.MSc (Witwatersrand) 1997.(Co-supervisor: Mr R M Davis, Department of Mining Engineering, University of Witwatersrand).

T8. M A Kneen. Dissertation: Computational aspects of environmental air pollution analysis, data handling and interpretation. MSc (Witwatersrand) 1997.(Co-supervisor: Dr N Pendock, Department of Applied Mathematics, University of Witwatersrand).

T9. F Amponsah-Dacosta. Dissertation: Cost effective strategies for mine dust control in an open cast mine. MSc (Witwatersrand) 1997.(Co-supervisor: Dr RCA Minnitt, Dept Mining Engineering, University of the Witwatersrand)

T10. EK Dyssel. Dissertation: Risikobepaling van respiratoriese mynstof afkomstig vanaf mynhope en slykdammeMTech: Environmental Health (Technikon Witwatersrand) 1997.(Co-supervisor: Dr JJ Schoeman, Faculty of Health and Biotechnology, Technikon Witwatersrand).

T17. G Kirkman. Dissertation: Graduating December 1998.MSc (Wits). 1998. (Co-supervisor: Prof PD Tyson, Climatology Research Group, Department of Geography and Environmental Sciences, University of Witwatersrand).

Theses / dissertations: in progress as of July 1998T11. SJ Piketh. Thesis: Transport of aerosols and trace gases over Southern Africa.

PhD (Witwatersrand). Anticipated submission date: September 1998.(Co-supervisor: Professor PD Tyson, Department of Geography and Environmental Science, University of Witwatersrand).

T12. C Gatebe. Thesis: Characterisation and transport of atmospheric aerosols at a high altitude on Mount Kenya. PhD (Witwatersrand). Anticipated submission date December 1998: First registration 1996 part-time. (Co-supervisor: Professor PD Tyson, Department of Geography and Environmental Science, University of Witwatersrand).

T13. Y Scorgie. Dissertation: Development of a methodological framework and supporting data base for air pollution impact scoping in SA Industrial Planning.MSc (Witwatersrand). Anticipated submission date: September 1998.(Co-supervisor: Mrs C Vogel, Department of Geography and Environmental Science, University of Witwatersrand).

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T14. SL Meter. Dissertation: Sulphur emissions from Africa as a source of global aerosols.MSc (Witwatersrand). Anticipated submission date: December 1998.(Co-supervisor: Professor PD Tyson, Department of Geography and Environmental Science, University of Witwatersrand).

T15. N M van der Merwe. Dissertation: Distribution and deposition of coal burning emissions from the highveld plateau using large scale circulation projections and GIS.MSc (RAU). Anticipated submission date: Oct 1998.(Co-supervisor: Dr J Meeuwis, Department of Geography, Randse Afrikaanse Universiteit).

T16. H Enslin. Dissertation: What are the unique capability of the GIS for presenting environmental information using air quality data from the Vaal Triangle? MSc (RAU). Anticipated submission date: Oct 1998.(Co-supervisor: Prof LGC Scheepers and Dr J Meeuwis, Department of Geography, Randse Afrikaanse Universiteit).

T18 P Goyns. Dissertation. Effects of variable valve timing on the efficiency and emissions of a spark emission engine. MScEng (Witwatersrand). First registered Jan 1998 F/T.(Co-supervisor Prof C Rallis, Dept Mechnical Engineering, University of the Witwatersrand)

T19 J Cumbane. Dissertation. PIXE based study of air quality over Mozambique.MSc (Witwatersrand). First registered Jan 1998 P/T, Dept Physics, Univ Witwatersrand

T20. F Amponsah-Dacosta. Thesis: Stability of mine tailings against water and wind erosion. PhD (Witwatersrand) First registered F/T July 1997.(Co-supervisor: Prof G Blight, Dept Civil Engineering, University of the Witwatersrand)

T21 C Ncube. Thesis. Long-range transport and transformation of sulphur in the atmosphere (provisional title). PhD (Potchefstroom) Part time. First registered July 1998.(Supervisor: Prof J Pienaar, Chemistry, Univ Potchefstroom; Co-supervisors: Prof G Helas, MPI Mainz; HJ Annegarn).

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Post-Graduate Students - Complement, Race and Gender

Students supervised or co-supervised by HJ Annegarn registered in 1997 and 1998

SURNAME GENDER

NAMES OF SUPERVISORS DEGREE/DIPLOMA DATE OF FIRST FULL/PART

BLACK/

STATUS AS OF

OF STUDENT (F/M) FOR WHICH REGISTERED REGISTRATION TIME WHITE

JUNE 1998

& INSTUTION & DEPT (F/P) OR ESTIMATED COMPLETION

GRADUATED JAN 1997 TO JUNE 19981.1 VAN DEN HEEVER D M BARNARD, JG; ANNEGARN, HJ DTECH, TECH OFS 1996/01/01 P W GRADUATED 1997 1.2 MUNYAI GLP M PYCRAFT, M; ANNEGARN, HJ MBA, WITS BUSINESS

MANAGEMENT1996 P B GRADUATED JULY 1997

1.3 MIZELLE A M ANNEGARN, HJ; DAVIS, R MSC ENG, WITS MINING ENG 1995/04/01 F B GRADUATED DEC 971.4 DACOSTA F M ANNEGARN; HJ; MINNIT, R MSC ENG, WITS MINING ENG 1995/01/01 F B GRADUATED DEC 971.5 KNEEN MA F ANNEGARN, HJ; PENDOCK, N MSC, WITS COMPUTAT. MATHS 1995/01/31 F W GRADUATED MAY 19981.6 DYSSEL E M SCHOEMAN, J; ANNEGARN, HJ MTECH, WITS TECH 1995/01/01 P W GRADUATED MAY 1998

TOPIC RELEVANT TO TRANSBOUNDARY AIR POLLUTION / TESP - WORK IN PROGRESS2.1 SCORGIE Y F ANNEGARN, HJ; VOGEL C MSC, WITS GEOG 1994/07/01 F W FINAL DRAFT

SUBMITTED. SEP 982.2 PIKETH SJ M TYSON, PF; ANNEGARN, HJ PHD, WITS GEOG 1996/07/01 F W WRITING - SEP 982.3 KIRKMAN G M MASON, S; ANNEGARN, HJ MSC, WITS GEOG 1997/01/01 F W GRADUATING DEC

982.4 VAN DE

MERWENM F ANNEGARN, HJ; MEEUVIS,

JMSC, RAU GEOG 1995/01/01 F W OCTOBER 98

2.5 METER S F ANNEGARN, HJ; TYSON, PD

MSC, WITS GEOG 1996/01/01 F W DECEMBER 1998

2.6 GATEBE C M ANNEGARN; HJ, TYSON, PD

PHD, WITS GEOG 1996/03/01 P B DECEMBER 1998

2.7 CUMBANE J M ANNEGARN, HJ, HELAS, G MSC, WITS, PHYSICS 1998/04/01 P B 19992.8 NCUBE C M PIENAAR, J, ANNEGARN, HJ PHD, POTCH CHEM 1998/07/01 P B 2000

TOPIC NOT DIRECTLY RELATED TO TRANSBOUNDARY AIR POLLUTION / TESP - WORK IN PROGRESS3.1 ENSLIN H F ANNEGARN, HJ; MEEUVIS J MSC, RAU GEOG 1995/01/01 F W OCTOBER 983.2 GOYNS P M RALLIS, C, ANNEGARN, HJ MSC ENG MECH 1998/01/01 F W APRIL 19993.3 DACOSTA F M BLIGHT, G; ANNEGARN; HJ PhD ENG, WITS CIVIL

ENG1997/09/01 F B 2000

National and International Contacts and Liaison (networking with other technikons and universities)National contacts

Professor H Winckler, Physics Department, University of Vista, Soweto. Dr D van den Heever, Environmental Health, Technikon OFS.Professor M Fey, Geological Sciences, University of Cape Town.Professor J Willis, Geological Sciences, University of Cape Town.Professor R Dutkiewicz, Energy Research Institute, University of Cape Town.Professor J K Pienaar, Chemistry Department, University of Potchefstroom.Dr J W Przybylowicz, National Accelerator Centre, Faure.Professor J Meeuwis, Geography and Environmental Sciences, Rand Afrikaans University.Dr S O’Beirne, Environmentek, CSIR.Dr G Held, Atmospheric Research, Eskom TRI.Dr P Terblanche, Foodtek, CSIR.Mr J S Sithole, Health Department, Johannesburg Southern Metropolitan Local Council.Dr D Terblanche, RMRG Weather Bureau, Bethlehem.Mr G Tosen, Eskom TRI.See also statement on SAFARI-2000 above.

Interdepartmental contacts, University of WitwatersrandProfessor P D Tyson, Climatology Research Group.Mr D Limpitlaw, Department of Mining Engineering.Dr D Chipolet, Department of Mechanical EngineeringProfessor G Blight, Department of Civil EngineeringDr Mike Grant, Department of Chemical Engineering and Material Science

International contacts

The scientists listed are all involved in recent or current collaborative projects or publications.

Professor G Helas, Max Planck Institute for Chemistry, Mainz, Hon Prof. Department of Chemistry and SRCNS, Wits.Professor W Maenhaut, Institute of Nuclear Sciences, Univ of Gent; Hon Research Associate, SRCNS, Wits.Professor J Chow, Desert Research Institute, University of Nevada, Reno and Hon Research Associate, SRCNS.Dr R Swap, Department of Environmental Sciences, University of Virginia, Charlottesville, Hon Research Associate, SRCNS.Professor S Weinbruch, Department of Material Sciences, University of Darmstadt.Professor R E van Grieken, Department of Chemistry, University of Antwerp.Mr R Egami, Desert Research Institute, University of Nevada, Reno.Professor J W Nelson, Department of Physics, Florida State University, USA.Professor M Garstang, Department of Environmental Sciences, Univ of Virginia, Charlottesville, USA.Dr B Dodderidge, Department of Meteorology, University of Maryland, USA.Dr J Privette, Goddard Space Flight Centre, NASA, Maryland, USA.Mr Brent Holbern, Goddard Space Flight Centre, NASA, Maryland, USA.Dr A Zucchiatti, INFN, University of Genoa, Italy.Ms P Formenti, Max Planck Institute for Chemistry, Mainz.Professor P Hobbs, University of Seattle, Washington.Mr C Gatebe, Institute of Nuclear Sciences, University of Nairobi, Kenya.Mr J Cumbane, Department of Physics, University of Eduardo Mondlane, Mozambique.

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ION IMPLANTATION AND SURFACE STUDIES RESEARCH PROGRAMME

Leader: Prof. T.E. Derry, Physics Department.

Participating academics: _______________________________________________________________ name |department |staff no. | time spent~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (Prof) T.E. Derry | Physics |00 911 502 | 50 % (Prof) J.F. Prins | Schonland (sec) | | 90 % (Prof) J.D. Comins | Physics | | 5 % (Dr) G. Hearne | Physics | | 5 % (Prof) A.T. Davidson | Zululand Univ. | | (Prof) J.F. van der Veen | Amsterdam Univ | |-------------------------------------------------------------------------------------------------------

Research Projects:

1. (a) Determine structure of clean & metallized diamond surfaces Using synchrotron X-raysPersonnel: T.E. Derry + J.F. van der Veen + overseas collaborators International collaboration, important for diamond semiconductor industry.This subproject completed and papers accepted by respected journals.

(b) Investigate bonding of oxygen on diamond surfaces Using Rutherford backscattering and resonant ion scatteringPersonnel: T.E. Derry, D.B. Rebuli (student) Implications for chemical-vapour deposited diamond layer industry.The M.Sc + papers are being written up and work is continuing.A collaboration with Tuebingen University (involving T.E.D.) is now looking at the functional form of the oxygen.

2. (a) Carbon (diamond) epitaxy on copper Implantation, Auger spectroscopyPersonnel: J.F. Prins, S.R. Naidoo (student)Industry collaboration (De Beers); key to diamond semiconductor industry.The Auger hardware and software have been upgraded using THRIP money.To be continued in 1998 using ion channelling as well (T.E. Derry)

(b) Improvement of diamond doping Implantation, electrical measurements J.F. Prins, S.R. Naidoo (student), H. van Heerden Industry collaboration (De Beers); diamond semiconductors.The current phase has produced excellent p- and n-type doping.

(c) Electron-injection junctions in diamond Implantation, electrical measurementsJ.F. Prins, S.R. Naidoo (student) Industry collaboration (De Beers); diamond semiconductors.Blue light-emitting diodes have been produced and are being optimized.

3. (a) Radiation damage in alkali halides Implantation, optical spectroscopyJ.D. Comins, T.E. Derry, A.T. Davidson (Zululand) + studentsUniversity of Zululand collaboration.Current phase completed and written up in papers and a thesis(G.S. Blieden, final corrections pending submission)

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(b) Radiation damage in ionic oxides / Implantation, optical spectroscopyA.T. Davidson (Zululand) + students, T.E. Derry, J.D. Comins University of Zululand collaboration.

4. (a) High pressure diamond anvil cell studies Ion implantation of electrical contacts into the cellG. Hearne + students, S.R. Naidoo, T.E. Derry

5. (a) Metal alloying and defects Implantation, Moessbauer, ion channellingH. Pollak, T.E. Derry, J.K. Dewhurst (student), H. de Waard (Groningen)Cross-disciplinary + overseas networking.Results have been presented at an overseas conference.

(b) Tungsten carbide: inhibition of stress corrosion cracking Using ion implantationS.B. Luyckx, T.E. Derry, L. Makhele (Hons student) Possible industrial importance.Work successfully completed, presented overseas and a paper published.

(c) Surface engineering for industry Using ion implantation Personnel: T.E. Derry, H. van Heerden, S.B. Luyckx Industry collaboration possibilities with FRD to facilitate.No new projects have been offered as yet.

6. Synthesis and promotion of catalysts by novel routes Implantation (incl. powders), XPSN.J. Coville (Chemistry), T.E. Derry, H. van Heerden Cross-disciplinary networking, industry collaboration.Prof. Coville has been on sabbatical; still of interest.

7. Services to continue: --Support of other universities by provision of service implants (e.g. Pretoria, Cape Town, Durban-Westville): regularly continuing.

Publications

1996 A.T. Davidson, A.G. Kozakiewicz, J.D. Comins, T.E. DerryNucl. Instr. & Meth. B116 (1996) 216-219"Optical Effects in NaF Crystals Implanted with 100 keV Ions."

T.E. DerryPhilips Koerier, 26th April 1996, p.4"Christine 35 jaar oud en `student-proof'."

D.B. Rebuli, T.E. Derry41st Annual Conference of the SAIP, Pretoria, July 1996"Oxygen on Diamond Surfaces."

L. Makhele, S.B. Luyckx, T.E. Derry41st Annual Conference of the SAIP, Pretoria, July 1996"Inhibition of Stress Corrosion Cracking Using Ion Implantation."

J. E. Lowther, T.E. Derry41st Annual Conference of the SAIP, Pretoria, July 1996"Gallium on Diamond(111): Ab-initio Modelling."

L. Makhele-Lekala, S.B. Luyckx, T.E. Derry10th Internat. Conf. on Ion Beam Modification of Materials (IBMM'96), Albuquerque, September 1996"Inhibition of Stress Corrosion Cracking in WC-Co by means ofIon Implantation."

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T.E. DerrySchonland Report SRCNS 96/10 (1996), 5ppFeasiblity Study (confidential): "Industrial Implantation into Granular Material."

T.E. Derry, J.E. LowtherDiamond & Related Materials 5 (1996) 1473-1477"Relaxation of Gallium and Hydrogen on a (111) Diamond Surface."

W.J. Huisman, M. Lohmeier, H.A. van der Vegt, T.E. Derry, V.H. Etgens, J.F. van der VeenESRF Annual Report 1996, R99Progress Report.

JF PrinsDiamond & Related Materials 5 (1996) 907 - 913“Increased band A cathodoluminescence after carbon ion implantationand annealing of diamond

JF PrinsIndustrial Diamond Review 56 (1996) 22 - 29“Diamond as an active electronic material: prospects for n-type doping.”

T Tshepe, JF Prins, MJR HochJournal of Physics 46: pp2441 - 2442, 1996“Percolative transition in carbon-ion implanted type Iia diamond.”

T Tshepe, JF Prins, MJR HochCzechoslovak Journal of Physics, 46: pp 2439 - 2440, 1996Transport studies in boron-ion implanted type Iia diamond.”

JF PrinsSymposium as “particle and radiation interaction with materials”SAIP 2nd July 1996.“The engineering of point defect interactions to activate phosphorusand boron dopant atoms in ion implanted diamonds”

JF PrinsInt School of Physics “Enrico Fermi” Varenna, Italy 23 July - 2 August 1996.“Applications of diamond films in electronics”

JF PrinsDiamond Conference, Cambridge, England, 7 - 10 July 1996.“Improved phosphorous - doping of diamond.”

1997 L. Makhele-Lekala, S.B. Luyckx, T.E. DerryNucl. Instr. & Meth. B127/8 (1997) 770-774"Inhibition of Stress Corrosion Cracking in WC-Co by means of Ion Implantation."

T.E. DerrySchonland Report SRCNS 97/01 (1997) 4pp"Analyses of Boronized Tungsten Carbide Samples."

D.B. Rebuli, T.E. Derry13th Internat. Conf. on Ion Beam Analysis (IBA-13), Lisbon, July 1997"RBS on Diamond Surfaces."

D.B. Rebuli, T.E. Derry42nd Annual Conference of the SAIP, Durban, July 1997"RBS on Diamond Surfaces."

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W.J. Huisman, J.F. Peters, S.A. de Vries, E. Vlieg, W-S Yang, T.E. Derry, J.F. van der Veen42nd Annual Conference of the SAIP, Durban, July 1997"Structure and Morphology of the as-Polished Diamond(111)-1x1 Surface."

W.J. Huisman, J.F. Peters, M.J. Zwanenburg, S.A. de Vries, T.E. Derry, D. Abernathy, J.F. van der Veen42nd Annual Conference of the SAIP, Durban, July 1997"Layering of a Liquid Metal in Contact with a Hard Wall."

W.J. Huisman, J.F. Peters, S.A. de Vries, E. Vlieg, W-S Yang, T.E. Derry, J.F. van der VeenSurface Science 387 (1997) 342-353"Structure and Morphology of the as-Polished Diamond(111)-1x1 Surface."

T.E. Derry2nd African Convention for Non-destructive Testing, Fourways, November 1997"Depth Profiles of Boronized Layers using Ion Beam Analysis."

T.E. DerryProceedings: 2nd African Convention for Non-destructve Testing, Fourways, November 1997 (Viaduct Communications)"Depth Profiles of Boronized Layers using Ion Beam Analysis."

W.J. Huisman, J.F. Peters, M.J. Zwanenburg, S.A. de Vries, T.E. Derry, D. Abernathy, J.F. van der VeenNature 390 (Nov 1997) 379-381 (letter)."Layering of a Liquid Metal in Contact with a Hard Wall."

T Tshepe, MJR Hoch, JF PrinsSAIP Conference, Durban, 2 - 4 July 1997“Annealing Studies on Boron-ion implanted Type Iia Diamond.”

JF PrinsProceedings of the Int School of Physics, IOS Press, Amsterdam 1997, 411 - 484.“ Applications of Diamond Films in Electronics.”

SR Naidoo, JF PrinsSAIP Conference, Durban, 2 - 4 July 1997.“Electron injection junctions in diamond.”

JF PrinsEuropean Patent, Patent No. 0,573, 312, A2.“Diamond Doping”

JF PrinsSouth African Patent, Patent no 96/5026“Doping of Crystaline Substrates”

1998 W.J. Huisman, M. Lohmeier, H.A. van der Vegt, J.F. Peters, S.A. de Vries, E. Vlieg, V.H. Etgens, T.E. Derry, J.F. van der VeenSurface Science 396 (1998) 241-252"Evidence for Tilted Chains on the Diamond(111)-2x1 Surface."

W.J. Huisman, J.F. Peters, S.A. de Vries, E. Vlieg, J.F. van der Veen, T.E. DerryDiamond Conference, London, July 1998"Synchrotron Radiation Determination of Atomic Positions on the Diamond(111) Surface Before and After Reconstruction."

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E. Sideras-Haddad, D. Rebuli, T.E. Derry, S.H. Connell, J.P.F.Sellschop, B. Doyle, R. MaclearDiamond Conference, London, July 1998"Oxygen on Diamond".

X. Zhang, J.D. Comins, A.G. Every, P.R. Stoddart, W. Pang,T.E. DerryPhys. Rev. B15 (1998) in press"Surface Brillouin Scattering Study of the Surface Excitations in Amorphous Silicon Layers Produced by Ion Bombardment"

D. Rebuli, E. Sideras-Haddad, B. Doyle, R. Maclear, T.E. Derry, S.H. Connell, P. Aggerholm, J.M. Butler, J.P.F. SellschopMicroprobe Conference, Cape Town, August 1998"Oxygen Surface Studies in Ultra-thin Diamonds usingTransmission Channnelled Rutherford Forward Scattering"

D.B. Rebuli, T.E Derry, E. Sideras-Haddad, B.P. Doyle, R.D.Maclear, S.H. Connell, J.P.F. SellschopInternational Conference on New Diamond Science andTechnology, Pretoria, September 1998"Oxygen on Diamond Surfaces"

Conferences and Visits

IBA-13: 13th Internat Conf on Ion Beam Analysis, Lisbon, July 1997Attended by D.B. Rebuli, paper presented.

SAIP Conf, Durban, July 1997Attended by TED, JFP, JDC, ATD and students SRN and DBR; several paperspresented including the prizewinning M.Sc paper by S.R. Naidoo.

Diamond 1997: 8th European Conf on Diamond, Diamond-like and Related Materials, Edinburgh, August 1997Attended by J.F. Prins (invited paper) and D.B. Rebuli

Wilsdorf Celebration Conference on Crystal Defects, University ofVirginia, August 1997Attended by J.F. Prins; talk on luminescence from defects inboron-ion implanted diamonds using low fluences.

2nd African Convention for Non-Destructive Testing, Fourways, November 1997Attended by T.E. Derry, paper presented.

Post-graduate Students

G.S. Blieden (Ph.D); registered Jan 1988; submission awaiting a few final corrections:"Study of Defects in Ion Implanted Lithium Fluoride Crystals"Supervisors: J.D. Comins and T.E. Derry.

S.R. Naidoo (M.Sc (to be converted)); registered Jan 1995 (part-time):Implantation of carbon in copper single crystalsSupervisor: J.F. Prins

D.B. Rebuli (M.Sc); registered Jan 1996; submission August 1998:"Ion Beam Analysis of Oxygen on Diamond Surfaces"Supervisor: T.E. Derry.

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NUCLEAR PHYSICS PROGRAMME

Leader: Professor V. Hnizdo, Department of Physics (staff no. 976448)

Participating Academics: Name Department Staff No. Dr. J. Carter Physics 603953

Associate Members: Dr. R. W. Fearick Physics, UCTProf. B. Spoelstra Physics, U. Zululand

General

The Nuclear Physics Programme is one of the four research entities in the Schonland Research Centre recognized by the University Research Committee. It has an active experimental programme to investigate nuclear structure at low and medium energies.

For the low-energy work it makes use of a beam line on the tandem Van de Graaff accelerator at the Schonland Centre. Work at medium energies is carried out at the National Accelerator Centre at Faure.

Use is also made of the facilities at the Florida State University, Tallahassee, USA, and a collaboration is in progress with the Triangle Universities Nuclear Laboratory, Duke University, Durham, USA. There are also strong links with the Institut fuer Kernphysik, Technische UniversitatDarmstadt, Germany.

Research Projects

1) Light heavy-ion scattering, low energy nuclear physics(J. Carter, V. Hnizdo, R.W. Fearick (UCT), J. Madonsela)

An M.Sc. research project of J. Madonsela, "The (p,alpha) reaction on 9Be in inverse kinematics at centre-of-mass energies 1.5--3.5 MeV", based on heavy-ion scattering studies undertaken by the nuclear structure group at the Tandem accelerator of the Schonland Centre over the last years, has been completed.

2) Polarization heavy ion physics(V. Hnizdo)

The collaboration with the heavy-ion polarization group at the Florida State University continued in 1996-97; this research activity has now moved from polarization studies that employed polarized and aligned 6Li beams to studies that employ 7Li beams, using which analyzing powers of up to rank 3 can be generated.

3) General physics, electrodynamics(V. Hnizdo)

Research into the implications of the so-called hidden mechanical momentum of macroscopic bodies in relativistic classical electrodynamics has continued, yielding a series of papers in American Journal of Physics.

4) Medium-energy proton induced reactions(J. Carter)

This work is carried out at the cyclotron facility of the National Accelerator Centre and is a collaboration between the TH Darmstadt, the NAC and the Universities of Cape Town and Stellenbosch. The data obtained in 1993 for the 40Ca(p,p'x) reaction using the K = 600 magnetic spectrometer and three silicon surface-barrier detectors are currently being analyzed. The first

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results of an analysis of the data were presented in refs. [1,2]. This was followed by the submission of a paper during sabbatical leave (J. Carter) whilst in Darmstadt, Germany, July/August 1997 ref. [3].

Preliminary investigations were undertaken in August 1994 using the 48Ti(p,p'n) reaction at Ep = 100 MeV to determine the feasibility of the 48Ca (p,p'n) experiment. Again, the K = 600 magnetic spectrometer was used with a liquid scintillator neutron detector in coincidence with the spectrometer. Good neutron-gamma discrimination was obtained using the pulse-shape discrimination method [1,2]. A new scattering chamber was designed and installed allowing the experiment to be run September/October 1997. Dr von Neumann-Cosel and two PhD students brought with them from Darmstadt a set of neutron detectors, related equipment and the 48Ca target for the measurement.

[1] P. von Neumann-Cosel, J. Carter, F.D. Brooks, A. Buffler, A.A. Cowley, H. Diesener, R.W. Fearick, S.V. Foertsch, M.N. Harakeh, J.J. Lawrie, S.J. Mills, R.T. Newman, J.V. Pilcher, A. Richter, F.D. Smit, G.F. Steyn, S. Strauch and D.M. Whittal,"Excitation and decay of giant resonances in 40,48Ca from the (p,p'x) reaction Ep = 100 MeV", NAC Annual Report NAC/AR/96-01 (1996)

[2] J. Carter, P. von Neumann-Cosel, F.D. Brooks, A. Buffler, A.A. Cowley, H. Diesener, R.W. Fearick, S.V. Foertsch, M.N. Harakeh, .J. Lawrie, S.J. Mills, R.T. Newman, J.V. Pilcher, A. Richter, .D. Smit, G.F. Steyn, S. Strauch and D.M. Whittal,Excitation and decay of giant resonances in 40,48Ca from the (p,p'x) reaction Ep = 100 MeV", 41st SAIP Conference, University of Pretoria, Pretoria, July 1996

[3] J. Carter, A.A. Cowley, H. Diesener, R.W. Fearick, S.V. Foerstsch, .N. Harakeh, J.J. Lawrie, S.J. Mills, P. von Neumann-Cosel, .T. Newman, J.V. Pilcher, A. Richter, K. Schweda, .D. Smit, G.F. Steyn, S. Strauch and D.M. Whittal,Isoscalar quadrupole strength in 40Ca from the (p,p'alpha0) reaction at Ep = 100 MeV", Nucl. Phys. A submitted 1997 (in press)

Publications

P. L. Kerr, K. W. Kemper, P. V. Green, K. Mohajeri, E. G. Myers, B. G. Schmidt and V Hnizdo, "6Li +12C inelastic scattering at 30 and 50 MeV," Phys. Rev. C 54, 1267--1281 (1996)

V. Hnizdo, ``Hidden momentum and the electromagnetic mass of a charge and current carrying body" Am. J. Phys. 65, 55--65 (1997)

V. Hnizdo, ``Hidden momentum of a relativistic fluid carrying current in an external electric field”, Am.J. Phys. 65, 55 - 65 (1997) V. Hnizdo, ``Hidden mechanical momentum and the field momentum in stationary electromagnetic and gravitational systems," Am. J. Phys. 65, 515--518 (1997)

V. Hnizdo, ``EPR and the Copenhagen interpretation," Eur. J. Phys. 18, 404--406 (1997)

V. Hnizdo, ``Covariance of the total energy-momentum four-vector of a charge and current carrying macroscopic body," Am. J. Phys. 66, 414--418 (1998)

V. Hnizdo, ``Radiation from circling relativistic charges; comment on a paper by Gordeyev," Am. J. Phys., in press

V. Hnizdo, ``Comment on: An exactly solvable two-body problem with retarded interactions and radiation reaction in classical electrodynamics," J. Math. Phys., in press

V. Hnizdo, ``Common misrepresentation of the Einstein-Podolsky-Rosen argument," Found. Phys. Lett., in press

V. Hnizdo, ``Geometric factors in the Bohr--Rosenfeld analysis of the measurability of the electromagnetic field," J. Math. Phys., submitted

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J. Carter, A.A. Cowley, H. Diesener, R.W. Fearick, S.V. Foerstsch, M.N. Harakeh, J.J. Lawrie, S.J. Mills, P. von Neumann-Cosel, R.T. Newman, J.V. Pilcher, A. Richter, K. Schweda, F.D. Smit, G.F. Steyn, S. Strauch and D.M. Whittal, "Isoscalar quadrupole strength in 40Ca from the (p,p'alpha0)reaction at Ep = 100 MeV", Nucl. Phys. A submitted 1997 (in press)Conferences and Visits

V. Hnizdo:Research visit to Florida State University, Tallahassee, June--July 1997;Research visit to Triangle Universities Nuclear Laboratory, Duke University, Durham, North Carolina, July 1997;Seminar "Hidden momentum and the electromagnetic mass of a charge and current carrying body," given at the Faculty of Mathematics and Physics, Charles University, Prague, Czrch Republic

J. Carter: Sabbatical visit July--August 1997 at Institut fuer Kernphysik, Technische Universitaet, Darmstadt, Germany;Sabbatical research work September/October/November 1997 at the National Accelerator Centre, Faure

J. Madonsela (M.Sc. student):SAIP Annual Conference, July 1997

Visiting Scientists

Dr P von Neumann-Cosel (senior scientist);Mr K Schweda (PhD student);Mr S Strauch (PhD student);all from TU Darmstadt visited NAC September/October/November 1997 to participate in a collaboration with Dr. Carter.

Students

J. Madonsela, 9411102A, M.Sc., registered Jan. 1994, will graduate December 1998;Research report: "The (p,alpha) reaction on 9Be in inverse kinematics at centre-of-mass energies 1.5--3.5 MeV";supervisor V. Hnizdo

B. Nangu (University of Zululand), part-time MSc student;soon to submit dissertion on analysis of intermediate-mass-fragments experiments done at the NAC;supervisors J. Carter and B. Spelstra (U. Zululand)

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WITS-NORTHERN ACCELERATOR RESEARCH CENTRE(Director : Dr SH Connell)

The WITS-Northern Accelerator Research Centre research entity provides a common home for a range of research groups spanning basic physics, applied physics, industrial physics and various interdisciplinary sciences, such as nuclear geology and nuclear techniques in industry, bio-medicine, metallurgy and the environment.

· The Particle-Solid Interactions Research Group·

(Leader : Dr SH Connell) : focuses on the phenomena associated with the interaction of accelerated beams and radiation with ordered materials. In the case that the material properties are well understood, then the basic physics aspects of the interaction are studied. In the inverse situation, the goal is materials physics. In all cases the research methodology involves accelerated beams, nuclear instrumentation, highly automated computer controlled data acquisition and processing, sophisticated engineering in the equipment construction and finally data interpretation via simulation of the experimental observables based on modern quantum mechanical models. Most of the work is carried out at the SRCNS, but where appropriate, regular use is made of CERN, TRIUMF, PSI and other major international facilities.

·· Nuclear-Interdisciplinary Science based on Ion-Beam Microscopies·

(Leader : Dr E Sideras-Haddad) : applies nuclear and atomic physics phenomena in the interaction of focused beams with small samples to perform a range of novel microscopies in collaborative interdisciplinary research projects. Accelerator Mass Spectrometry capability is currently being developed

·· The Nuclear Diamond Physics Research Group·

(Leader : Prof JPF Sellschop) : focuses particularly on new physics and resulting applications in specific areas at the interface of nuclear and diamond physics. Most of the work is carried out at the SRCNS, but where appropriate, regular use is made of CERN, TRIUMF, PSI, Grenoble, GSI Darmstadt and other major international facilities.

·· The Nuclear Geology Research Group·

(Leader : Dr RJ Hart) : pursues global geological topics relevant to modern theories of crustal and earth forming processes. Primarily geologists, they benefit from the synergy of a close association with novel nuclear techniques for a vital part of their sample characterisation.

The synergy, mutual co-operation and interdependence between these research groups includes the following points:· Nuclear and particle physics knowledge is either a goal or an important tool of the research

thrust.· Nuclear techniques (accelerated particle beams, radioactivity, nuclear electronics and detection

systems and computer systems for data processing, visualisation and process control) are used in the research programmes.

· Common major facilities. The most important major equipment items here are the two Van de Graaff accelerators with their associated infrastructure.

· Postgraduate student training. The research group leaders believe the open environment of a large research facility facilitates the development of students due to the points mentioned above.

· Coherence. The whole is greater than the sum of the parts.

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Group Membership

Name Department Staff No. Percentage TimeDr SH Connell Physics : Senior

Lecturer08800031 40% lecturing

25% Lab Management35% Research

Dr E Sideras-Haddad Physics : Senior Research Officer

00675961 30% lecturing25% Lab Management45% Research

Prof JPF Sellschop Physics : Emeritus Professor

00911272 75% Research25% National Advisory

CommitteesDr RJ Hart Secondment :

Council of Geosciences

09000631 40% Research15% CGS line function25% Lab Man20% International Collaboration

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Research Projects

Impurity Chemistry and Dynamics in Diamond by In-beam Molecular Complex SpectroscopyStaff : SH Connell, JPF Sellschop, E Sideras-Haddad.Students : MG Bossenger, BP Doyle.Collaborators : H Appel (KFK Karlsruhe), K Bharuth-Ram (UDW), W Verwoerd (UNISA).

This work involves basic research into the behaviour of defects and impurities in insulators and wide-band gap semiconductors. Defects and impurities play an important role in determining the physical, electrical, optical and chemical properties (among others) of materials. Using the EN-Tandem Accelerator, radioactive impurities are recoil-implanted into materials to study their geometrical, chemical and dynamical relationships in the host lattice and as complexes with other defects. A unique opportunity to visualise transient and stable molecular complexes formed immediately after ion-implantation is afforded (hot-atom chemistry). The data is reconstructed using the details of the hyperfine interaction of the probe nucleus with local fields. Diamond, other carbon allotropes, as well as various carbon containing molecules have been targeted as important materials for research. During the review period, attention has focused on analysis of previous data, writing papers, design and fund-raising for development of a heavy-ion pulsing system for the EN-Tandem (THRIPP program with DeBeers) as well as organising the 11th International Conference on Hyperfine Interactions at the end of August 1998.

Impurity Chemistry and Dynamics in Diamond by Perturbed Angular CorrelationsStaff : SH Connell, JPF Sellschop, E Sideras-Haddad.Students : BP Doyle, EJ StorbeckCollaborators : K Bharuth-Ram (UDW), H Pattyn (Leuven), W Verwoerd (UNISA), U Wahl (Leuven)

This is the off-line source based activity version of the previous measurements, enabling later time windows to be accessed, allowing solid-state reactions to occur. A PAC project on 111In in diamond is ongoing as a complementary technique to the CEEC measurements mentioned further on. A new PAC facility has been developed. Conventional systems rely on many crates of fast electronics to process the signals. Our system is novel in that buffered event-by-event acquisition (COLLECT - see later section), enables software logic to extensively replace the expensive hardware systems, while still maintaining the data-rate of the larger systems. The project has been given a large boost with access being granted to the ISOLDE facility, CERN, Switzerland for implantation of exotic radioactive species. New software for the analysis of this data is being developed. These analyses are compared to the CEEC data taken on the same systems, and with theoretical calculations that have been made in collaboration with the Physics Department. Subsequently double implant experiments will also be done with the aim of studying the dynamical behaviour of In-X complexes. The PAC technique can label various complexes and follow their behaviour through various sample treatments with particularly simple sample preparation for the measurement process. These studies illuminate processes of diffusion, decoration, complexation, dissociation, trapping and detrapping in the solid state. This information is relevant to processes which lead to doping, passivation and poisoning phenomena in semi-conductors (in our case, semi-conducting diamond). There was substantial experimental activity during the year, and the results are being presented at the conference mentioned above, as well as being prepared for more detailed exposure in journals.

Positron Spectroscopy studies of pure diamond, dilute bulk defects and surfaces.Staff : SH Connell, JPF Sellschop.Students : RWN Nilen, CG FischerCollaborators : A Alam (Bristol), W Anwand (Rosendorf), K Bharuth-Ram (UDW), G Brauer

(Rossendorf), DT Britton (UCT), P Coleman (East Anglia), F Malik (East Anglia), K Maier (Bonn, J Major (MPI-Stuttgart), A Seeger (MPI-Stuttgart), E Sendezera (U Zululand), H Stoll (MPI-Stuttgart), W Verwoerd (UNISA).

Positrons implanted into solids thermalise, diffuse rapidly, and finally form well defined configurations with the host lattice or its defects. Observation of the properties of the annihilation radiation allows a reconstruction of the local microscopic configuration by means of quantum mechanical models. In this way, detailed information concerning solid state parameters is measured. Spectra taken for the diamond host matrix demonstrate severe and hitherto unexplained anomalies. This anomalous behaviour of the positron in diamond has now been resolved following our measurements, calculations, and the calculations of our collaborators. Many papers have been published or are in preparation, including a review article. Following these advances, our programme has broadened

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from the positron-pure-bulk-diamond interaction to the studies of positron-defect and positron-surface interactions. A detailed set of experiments probing lattice effects in extended damage transport during ion-implantation, photochromic defects and surface structures as well as near-surface defects has been performed this year. The results are currently being published and prepared for publication.

Conversion electron emission channeling spectroscopyStaff : SH Connell, JPF Sellschop.Students : BP Doyle, EJ Storbeck.Collaborators : K Bharuth-Ram (UDW), H Hofsass (Konstanz), H Pattyn (Leuven), W Verwoerd

(UNISA), U Wahl (Leuven).

Ion implantation in diamond of radioactive nuclides such as 111In can be exploited to provide information on the environment in which the nuclide resides. In the emission of conversion electrons from the nuclide at its characteristic lattice sites in the diamond, the electrons are sensitive to the source-lattice configuration as well as the structure of the crystal through the channeling, blocking and flux peaking effects. The CEEC research is entirely complementary to the PAC study mentioned above, and the projects will be run simultaneously. The same comments apply then with respect to future research, as in the PAC section. A two-dimensional position and energy sensitive PAD detector was developed at CERN, Switzerland, originally as a high-energy physics tool, but now available to CEEC measurements. This detector is the first of its kind to be used in this way and now allows the rapid collection of 2-dimensional channeling spectra. In two dimensions one is able to see both the axial and planar effects in channeling, enabling a more complete picture of the impurity lattice site. A profitable collaboration with K.U. Leuven has enabled the ISOLDE facility at CERN to be exploited by us. This allows implantation of the radioactive probe ions to the stringent specifications required for CEEC measurements. In order to explain the experimental results it is necessary to use solutions to the quantum mechanical theory of electron channeling. This demanded the development of an analysis program that takes into account the quantum nature of electron channeling. An important recent contribution is the inclusion of molecular effects in the construction of the transverse channeling potential, using Fourier methods based on the output from self-consistent quantum chemical simulations of large diamond-like molecules. There is experimental evidence that this was necessary, particularly in the case of channeling in diamond (<110> direction), where the electronic structure is not well approximated by the normal methods based on atomic scattering factors. Analysis of the large data sets obtained is well advanced. Results thus far indicate new perspectives on the annealing of the implant damage and concur with recent density functional theory calculations on the stable lattice site for the implanted and annealed In. This research is entirely complementary to the PAC study mentioned above, and the projects have been run simultaneously. The same comments as with regards future research apply here, as in the PAC section.

Muon Spin Rotation/Relaxation/Resonance (MSR) spectroscopy in diamondStaff : SH Connell, JPF Sellschop.Students : BP Doyle, CG Fischer, IZ Machi, RD Maclear, RWN NilenCollaborators : JM Baker (Oxford), K Bharuth-Ram (UDW), JE Butler (NRL-Washington), SFJ Cox

(Rutherford Lab), TL Estle (Rice U), T. Jestadt (Oxford). R Kiefl (TRIUMF), J Major (MPI-Stuttgart), P. Murphy (Oxford), R Scheuermann (MPI-Stuttgart), A Seeger (MPI-Stuttgart),

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Muonium-defect interactions as well as muonium dynamics are being explored using Muon Spin Rotation/Relaxation/Resonance (MSR) spectroscopy. The current program takes advantage of the unique properties of the muon to probe the behaviour of the hydrogen-like atom in diamond. The importance of hydrogen as an impurity in diamond is widely appreciated. Its important catalytic role in the metastable synthesis of diamond, as well as its anticipated significance regarding the electronic properties of future diamond devices are two examples. Despite the relevance of hydrogen to diamond growth, properties and engineering, comparatively little is known about it, and it has proved to be a most difficult impurity to study using conventional techniques. On the other hand, most of the information on hydrogen in diamond has been inferred by the indirect technique of the MSR, which is sensitive, robust, accurate, and has a low background. Clear examples of muonium diffusion, trapping and detrapping, and possibly even Ionisation reactions at B acceptors in semi-conducting diamond have been both observed and modelled. The transparency of diamond and the photochromicity of certain defects was used to illuminate some of the processes involved. A new muonium site in diamond containing substantial amount of nitrogen-related defects was discovered. This has provided evidence for a new deep trap for hydrogen in diamond, as well as a new way to study one of the nitrogen related defects whose structure is much debated.

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Thin diamond crystals - the doorway to new diamond physicsStaff : SH Connell, JPF Sellschop, E Sideras-Haddad.Students : BP Doyle, IZ Machi, RD Maclear, DB RebuliCollaborators : P Aggerholm (Aarhus), M Rebak (DeBeers), J.E. Butler (NRL-Washington)

If thin, that is to say micron and sub-micron thickness, diamond of high quality, were to become available it would make possible a large suite of research opportunities in both atomic and nuclear physics, as we have long appreciated. Conventional polishing techniques become problematic for thicknesses below 20 microns, owing to increasing difficulties with plastic deformation of the diamond remnant. We have made substantial progress in this quest through a new approach : carbon ions are implanted into a prepared diamond at an energy selected to place the Bragg peak at a depth below surface corresponding to the thickness of the final diamond sliver required. A dose of incident ions is delivered that is adequate to amorphise the layer corresponding to the Bragg peak. The diamond is then heated to about 1200C to both make the amorphisation more complete and to restore the crystal perfection of the superficial layer of any small amount of radiation damage by annealing. This is followed by an electrochemical etch in pure water whereby the amorphous layer is removed, allowing the superficial layer to float free. Special techniques are necessary to handle the sub-micron to few-micron thick diamonds. In this manner we have successfully prepared diamond targets of 1 to 3 microns thickness.

Some of the new suite of research possibilities enabled by these exciting samples involves applying any of Ion Beam Analysis (IBA) measurement technologies in channeling mode. This delivers lattice structural information about defects and impurities, in addition to the normal analytical information. Channeling Rutherford Backscattering Spectroscopy is used to study the details of the thin crystal production process and to optimise it. Channelling-ERDA has been applied to identify hydrogen structures in diamond. Transmission Channeling Forward Scattering is being used to study oxygen termination structures on diamond.

A new concept in creating thin single crystal samples will shortly be explored in which the implanted ion species is helium and the superficial layer is removed by the application of heat alone, as successfully demonstrated in the case of silicon.

Hydrogen dynamics and chemistry by micro-scanned Elastic Recoil Detection AnalysisStaff : SH Connell, JPF Sellschop, E Sideras-Haddad.Students : BP Doyle, CG Fischer, IZ Machi, RD Maclear, RWN Nilen, DB RebuliCollaborators : P Aggerholm (Aarhus) K Bharuth-Ram (UDW), JE Butler (NRL-Washington), E

Fritsch (Institut de Matériaux de Nantes)

Diamond has many physical and chemical properties attractive to the semi-conductor industry. The presence of hydrogen in the diamond lattice influences these properties. Its presence is known to affect the hardness of the material, it passivates active dopants and changes the optical transmission of diamond. Theoretically, hydrogen is a simple example of an atom in a covalently bonded macro-molecule, and is therefore instructive to model. The unique capability to perform 3-dimensional microscopy of trace hydrogen distributions has been developed at the EN-Tandem accelerator to a level of sophistication unmatched elsewhere in the world. This has enabled a coherent program focusing on hydrogen dynamics and chemistry in diamond, supported as well by the other projects using muons, positrons and radioactive ions described above. The new method has been called mERDA (see the title of this section for expansion). In one programme of measurements, phenomena like hydrogen stability, diffusion, trapping, detrapping, decoration, complexation and so on are studied. In another set, hydrogen distributions were evaluated to characterise natural and synthetic processes leading to hydrogen incorporation into diamond. This has relevance to metastable synthesis of diamond as well as the natural genesis environment of diamond. This program has recently been extended to include the channeling phenomenon, due to the availability of thin single crystal diamond, as described in the previous research project. Channeling-ERDA measurements will give a much improved picture of the crystallographic location of hydrogen in diamond. The possibility of measuring the exact location of the hydrogen allows measurements of other important phenomena involving hydrogen in the diamond lattice, for example, hydrogen diffusion pathways and complexation modes with other defects.

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European synchrotron radiation facility (Grenoble)Staff : JPF SellschopCollaborators : A Freund (ESRF)

Work over the past few years has continued in pursuit of using diamond in critically sensitive areas in this powerful third generation radiation source. Diamond is usually compared with silicon and germanium in its application as a monochromator for synchrotron radiation. Some of the physical constants for which diamond is greatly superior to the other two are· the linear absorption coefficient (and consequently the absorption length) for, say, 8 keV X-rays

diamond is enormously transparent for these wavelengths· the Debye temperature for diamond is very high, and consequently the thermal vibration

amplitude is very low indeed· the thermal expansion coefficient is very low· the heat conductivity is very high· the Darwin band width is smallThe usually accepted figure of merit in such applications for diamond is some 600 times superior to silicon, and 2000 times better than germanium. With the deployment of especially-grown diamond with very small mosaic spread, tests have been carried out on the use of diamond as a high heat load monochromator. Rocking curves confirmed the high quality of the diamond materials selected. In heat load tests the rocking curve width remained constant over a wide range of beam intensities, quite unlike silicon. The highest intensity, namely 3.5 kW / mm2, tested is to put it mildly most impressive, since it corresponds to an energy density that exceeds that at the surface of the Sun !Diamond proves to be radiation hard in this application also with very little evidence of damage over prolonged periods of beam exposure. A second research thrust has been in an attempt to bend diamond to provide saggital focusing of the monochromatised x-ray beam. A crystal bender was especially designed, a diamond of high quality was configured to dimensions 10 mm x 5 mm x 67 micrometer with the large face the {111} orientation. This diamond was successfully and repeatedly bent to a radius of curvature of 0.9 meter, giving a demagnification (focusing) factor of 20 times ! This field has proved to be a fruitful one and will be continued. Two invited papers were presented at the recent SPIE conference in San Diego (July 1998).

Coherent, correlated phenomena resulting from the Incidence of High Energy Leptons and Photons on Oriented CrystalsStaff : SH Connell, JPF Sellschop.Students : ZZ VilakaziCollaborators : K Kirsebom (ISA-Århus), R. Medenwaldt (ISA-Århus), U. Mikkelsen (ISA-Århus), SP

Møller (ISA-Århus), E Uggerhøj (ISA-Århus), T Worm (ISA-Århus), S Ballestrero (INFN-Florence), P Sona (INFN-Florence), K Elsener (CERN), YuV Kononets (RRC Khurtarchov Institute), A Apyan (Yerevan Physics Institute), RO Avakian (Yerevan Physics Institute), AE Avetisian (Yerevan Physics Institute), KA Ispiyran (Yerevan Physics Institute), C Biino (INFN-Turin)

The Research programme is founded predominantly in fundamental Physics, embracing both the local and the overseas capacity in a co-ordinated way. The scope of the research addresses all phenomena associated with lepton-photon processes resulting from the incidence of ultra-relativistic particles on highly-ordered crystalline materials. Scattering in a well aligned crystal geometry is extended to investigate coherent and correlated versions of the basic theory of electromagnetic processes viz. quantum electrodynamics (QED) at higher energies. QED is a highly developed field theory and has been investigated experimentally to very stringent detail. In recent years it has become technically possible to investigate QED processes in very strong crystalline electromagnetic fields. In short, new phenomena and physics do arise, opening up a plethora of new concepts to be explored therein inter alia Strong Field QED. This programme is undertaken at the CERN-SPS in the multi-national NA43 collaboration. The results show either very strong enhancements or losses in the cross-sections, as well as changes in the shape of the cross-sections. This in turn leads to new phenomena, which deepen an understanding of fundamental theories, as well as allowing new theoretical tests and new applications. The NA43 experiment has essentially completed its brief. The investigations which were carried out throughout the period that covered most of the period reported herein are: Establishing and studying the occurrence of a very new effect, the production of linearly polarised, partially monochromatic ultra-hard single photons by electron aligned incidence on crystals of very specific relative orientation to the beam. Studying coherent enhancements in both pair-production and brehmsstrahlung at ultra-relativistic energies. Realising and studying for the first time in the laboratory under well characterised conditions the occurrence of super-critical fields and their

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effect on energy loss mechanisms. Studying channeling in bent crystals for super-relativistic particles. Most of these new phenomena have lead to remarkable new devices which have already found application in other High Energy Physics experiments, or are in a proposal stage which may lead to new HEP capabilities. Of special mention : One new proposal is intended to lead to the use of the ultra-high energy (polarised) photons produced as described above as a tool to study the gluon contribution to nucleon spin. Another proposal would like to extract parasitic beam from the LHC accelerator for fixed target experiments using bent diamonds.

Apart from the good physics delivered by the CERN programme, there has also been significant technology transfer. The Physics Analysis Workstation (PAW) package was ported to a graphical Linux-PC environment by S Ballestrero during a working visit of his to the SRCNS. This was the first time the entire CERN Libraries became available on PC in a graphical environment. Previously, only mainframes or mini-computers could access the physics capability of this software. The port was welcomed by the international (HEP) group and the CERNLIB's on Linux-PC's became officially supported by the CERN Computer Group from then on. S Ballestrero also developed a Data Acquisition System (DAQ) that front-ends PAW to small lab detector systems. This gave the SRCNS (and any other small lab) essentially the same data capture power as the large CERN experiments for an incredibly reduced price. This innovation has been released via a WW page, and other labs are now sharing in it. This development has allowed us to run the CERN Monte Carlo package GEANT (which simulates many physics processes from keV to TeV interaction energies) and to contribute effectively to the analysis of data taken at CERN in our own local environment, by having a local PAW capability. It also enabled us to take the lead internationally in certain of our Physics Experiments based locally at our microprobe. Part of this programme is discussed in a separate section.

The Physics foothold at CERN will be extended when the ex-PhD student ZZ Vilakazi takes up a Post Doc position on four CERN-HEP experiments later this year. An initiative to synergise our efforts with the local theoreticians and other interested groups in other Universities in the country is in progress.

Alkali Halide Materials and Super-Ionic ConductorsStaff : DJ Comins, SH Connell, TE Derry, JPF Sellschop.Students : CG Fischer, RWN NilenCollaborators : EJ Sendezera (U Zululand), AT Davidson (U Zululand)

The use of positrons as a microscopic probe for the investigation of defects in crystal and amorphous systems, allows a study of the kinetics of creation and annealing out of defects. In particular, for the Super-Ionic materials, an enhanced conductivity mechanism occurs which is not yet fully understood, and is an issue of great current importance. An experiment using Positron Spectroscopy is being developed as it is believed it can provide information on the role of vacancies in this phenomenon.

Non-Stochastic Ion-Implantation - Industrial Collaborative R&DStaff : SH Connell, JPF Sellschop.Collaborators : W Wesch (Jena), Leonard C. Feldman (Nashville)

The aim is to develop and study non-stochastic systems for maskless implantation of dopants for situations of small feature size (<500 nm) and a large degree of integration (1x109 devices per chip). The possibility of dopant implantation via shape pre-programmed raster scanning with highly focused ion beams has already been postulated. We are exploring a non-stochastic method for maskless implantation to improve device integrity.

The COLLECT Data Acquisition SystemStaff : SH ConnellStudents : BP Doyle, IZ Machi, RD MaclearCollaborators : S. Ballestrero (INFN-Florence)

COLLECT is a powerful multi-parameter data acquisition (DAQ) system, running on a Linux PC. It was developed in order to serve the ever more complex data sets that are being taken at the SRCNS. COLLECT front-ends to the Physics Analysis Workstation (PAW/PAW++), a powerful data manipulation/visualisation tool, developed at CERN. The PAW system can be used as an online presenter as well as for offline replay of the data. COLLECT therefore delivers the computing power in DAQ previously known only on powerful computers at major high energy physics facilities to a PC

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and CAMAC based system affordable by a small lab. COLLECT can be easily configured to any desired experiment. Work is being done on a GUI version with a more easily configured CAMAC event cycle and data n-tuple. This project was jointly funded by The University of the Witwatersrand and The University of Durban Westville in South Africa. The system was published via the web, and has been attracted much interest. For example, we recently received a request for it from CALTECH. It has laid the foundation for a new generation of experiments at Schonland. For example, it enabled the event reconstruction that allowed us to do micro-scanned imaging of trace hydrogen distributions in diamond (discussed above). This capability attracted a director of an American Lab to do a 6 month sabbatical at Schonland, which in turn led to additional foreign funding of the project by nearly R100 000.00. This is one of the technology transfers enabled by the CERN research programme (discussed above).

The Schonland EN-Tandem Accelerator Control SystemStaff : AH Andeweg, JUM Beer, SH Connell, K Coone, E Rood JPF Sellschop, E Sideras-

Haddad.Students : RD MaclearCollaborators : P Aggerholm (Aarhus), M Hogan (NAC), F Weehuizen (NAC)

Currently the 6MV EN-Tandem of the Accelerator Laboratory at the Schonland Research Centre for Nuclear sciences is being upgraded for control via a Graphical User Interface (GUI) computer system. The system is based on distributed network control via an OS/2 network messaging system. Control of the electronic equipment is done over a RS-232/RS-485 link to digital and analogue control modules. The benefits of a computer controlled accelerator include: better quality ion beam; faster set-up time; decreased operator reliance; increased accessibility to outside users; introduction of intelligent control algorithms; automation of routine procedures; and upgrade of all power supplies. The control program has the properties of using a high degree of commercially manufactured software; is highly modular; based on object oriented programming code; is network based using distributed intelligence; is highly customisable; exploits the messaging, prioritising, queuing and resource sharing of the OS/2 operating system; and can be sequentially phased in with no major equipment down-time. All the current power supplies will be replaced with modern, stable power supplies. Control of the power supplies will be done using harsh environment capable ADAM/NUDAM modules on a RS-485 drop-down network. The modules are extremely stable and highly modular with only 3 types of modules needed to aontrol all power supplies (analogue output, analogue input and digital input/output). Voltage ramping of power supplies is built into the modules and no extra code is needed for this. The modules connect directly to the RS-232 port of a PC and no complicated interfaces or drivers are needed. The network messaging system, or Variable Table, is used to broadcast instructions to the various power supplies. The table contains reference and actual values for every control object in the network. The GUI console program updates the variable table when a user wishes to change the value of a power supply. Notification queues notify clients (control applications running on equipment-local computers) when a value in the table and changed, and the required action is taken by the clients. Clients update the variable table when a value is read from a power supply, and the GUI displays these values to the user. A relational SQL database is used for storing all the information about the control system. The database is accessed by the variable table, clients and user console at startup to retrieve this information. Based on this information, various power supplies can be controlled in a predefined manner. The database also defines how the user interface behaves and appears to the user. Expanding or modifying the system to include more control objects or differently configured control objects is simply a matter of editing the database, not the software.

Most of the systems software concepts have been developed at the National Accelerator Centre. Its implementation at Schonland has been modified to further distribute intelligence in control operations, display a higher reliance on cheaper modular commercial components and a greater reliance on the GUI for the User interface. The design and implementation of the client programs, the console program, the installation of the NAC-developed Variable Table, and the installation of the commercial database and networking software has been part of the MSc and PhD program of the student. The control electronics, cabling and cabinetry were developed by the technical staff.

Generic client control applications for the objects controlling Analogue input, output and digital input/output have been written for these basic types of operations on power supplies modules. These generic objects are resource file customised via the database to create a control application for any given power supply, with no further programming (only editing of the accelerator database). The server application accessed by these clients for communication with all the control modules

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belonging to a single node via the COM port of a PC has been written. Instructions are passed to the server via a prioritised queue, and extracted to the modules according to their priority in the queue. A Mark I user interface has been written for testing the control of power supplies via the multiple-clients-server system. All control electronics and new / modified stabilised power-supply implementations for the hardware component of the control of the Duoplasmatron, the gas ion source of the accelerator facility, have been completed. The Full Duoplasmatron electronics is therefore mounted into a single rack and equipped with dummy loads, and connected to the node computer. This system has been fully tested on the complete Duoplasmatron electronics rack using a standalone node computer. All conceivable faults have been simulated, and the exception handling and error recovery have functioned as planned. The speed of the system under load conforms to design specifications. We are therefore ready to install the first control node and electronics. Following a test and evaluation period under running conditions, we will proceed sequentially to implement the entire 6-node control system. Subsequent control nodes will be replications of this first control node, customised by extending the accelerator database. In preparation for this, the network-wide variable table communication program has also been installed and is running over the OS/2 sub-network using NetBIOS. Network-aware database access has been established and implemented into the clients. The new control console cabinetry has been designed and constructed and is currently being equipped with the hardwired segment of the control-system (fast-safety systems, analogue feedback systems etc). We expect to be operating with the first control node later this year. We are investigating industrial interest in this control system.

Heavy-ion Nuclear Reaction MechanismsStaff : SH Connell, JPF Sellschop.Students : TG StevensCollaborators : V Allori (Milano), C Birattari (Milano), M Bonardi (Milano), M Cavinato (Milano), F

Cerutti (Milano), A Di Filippo (Milano), E Fabrici (Milano), E Gadioli (Milano), E Gadioli Erba (Milano), SV Fortsch (NAC), JJ Lawrie (NAC), SJ Mills (NAC), FM Nortier (NAC), I Schroeder (NAC), GF Steyn (NAC), AA Cowley (Stellenbosch).

Since January of 1993 this collaboration has been involved in a comprehensive study aimed at a better understanding of the important mechanisms of heavy ion reactions and de-excitation in processes initiated by projectile energies between the coulomb barrier and the fission threshold. A starting point has been the concepts derived from the study of light particle induced reactions. These have been extended with modification, as well as with the introduction of new concepts, to heavy ion induced reactions. Experimentally we have studied the interaction of 16O and 12C, incident on the medium mass, mono-isotopic 103Rh. We have adopted and developed the powerful activation technique to obtain the comprehensive data set necessary to rigorously test the theoretical interpretation of these reactions as developed by a group at the University of Milan. More than thirty reactions representing excitation functions, angular distributions and residue recoil energy distributions over the entire energy discussed above have been accumulated. In addition, this data set is accurate in absolute terms to 20%. The uniform theoretical framework that has been gradually developed, is now capable of describing the data to a remarkable degree. The processes of excitation described by a mean-field approach, is considered separately to that of de-excitation where a time stepped Monte Carlo analysis based on the Boltzman Master Equations is used. The matching of the theory to the data did not proceed via adjustment of free parameters, but rather via careful selection of the major reaction and de-excitation mechanisms. Finally we could conclude that the major reaction mechanisms include only complete fusion, partial fusion of alpha like components, and proton and neutron transfer. The de-excitation requires pre-equilibrium emission to be considered over the whole energy range as well as ultimately statistical emission from the equilibrated nucleus. The mean field energy evolution could be established.

The latest and most striking results of these experiments and the subsequent theoretical interpretation demanding our current attention in the next beam-times, is the investigation of a novel de-excitation mechanism revealed by our research. This relates to the fast re-emission of alpha-like fragments, after very few nuclear interactions. This process has been found to be distinct from break-up and also pre-equilibrium emission. Following the incomplete fusion of an a particle or two loosely bound a's in the form of a 8Be, the re-emission of a fusing a particle with a large fraction of its initial energy, is very important. In fact the probability of this phenomenon is even greater than that observed in a particle induced reactions since these incomplete fusion processes occur in a low density, peripheral region of the target nucleus. Consequently, as these incomplete fusion processes become more important with increasing projectile energy, we find with increasing 12C energy an

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increasingly high number of low energy equilibrated nuclei with mass and charge close to that of the target. Their further decay via evaporation leads to the dominant formation of near target nuclei.

Following the success of these earlier measurements, subsequent experiments have been proposed to and enthusiastically received by the Physics Advisory Committee (PAC) of the National Accelerator Centre. These proposals included the measurement of a particles emitted in the interaction of 12C with 93Nb (PR27a) and the spectra of projectile fragments emitted in the interaction of 12C and 16O with 93Nb (Pr32a). Each of these measurements were successfully completed and this data is currently in the process of being analysed and compared to the theoretical interpretation. In addition to these measurements, we have proposed setting up a new Recoil Particle Spectrometer (RPS) facility using silicon microstrip detectors, in order to measure 8Be inclusive spectra in the bombardment of a 93Nb target with 12C beams, detecting the unbound 8Be as two breakup a particles in coincidence. This facility is currently in an advanced stage of preparation and we expect to begin testing in September of 1998 followed by measurements in the early part of 1999. The work has led to many publications and conference presentations.

Inter-disciplinary Research, Industrial Collaborations, Service Analysis using the Ion Micro-Beam FacilityStaff : AH Andeweg, JUM Beer, SH Connell, K Coone, RJ Hart, E Rood JPF Sellschop, E

Sideras-Haddad.Students : BP Doyle, CG Fischer, IZ Machi, RD Maclear, DB Rebuli, TG Stevens, ZZ VilakaziCollaborators : P Aggerholm (Aarhus) K Bharuth-Ram (UDW), JE Butler (NRL-Washington),

E Sendezera (University of Zululand), MHB Breese (SPM Unit, Oxford) G Bench (Lawrence Livermore National Laboratory), A Antolak and D Morse (Sandia National Laboratory).

The 6MV Tandem accelerator and the 2.5MV single ended POTCH accelerator provide the beams which are used by the Micro-Scanning Ion Beam Analysis Facility (Figure 1). These beams can be focused to micron or in some cases to submicron dimensions, and rastered over the sample, where “fingerprint” radiation from some kind of physics phenomena is excited, labelling the elements in the sample. The analysis is also a (trace level) quantitative microscopy. The computer acquisition system can correlate the beam scan position and the amount of “fingerprint” radiation with pixel colour levels in a visual image. The current quantitative microscopies available at the facility are :

m-PIXE Proton Induced X-ray Emission : Quantitative analysis and mapping of heavy elements (Z ³ 13) with as low as 1 ppm sensitivity. The probed volume is from surface to about 30 mm. The microscopy is based on the fluorescence of atomic X-rays by the interaction of the beam of protons or heavier projectiles on the sample.m-STIM Scanned Transmission Ion Beam Microscopy : Quantitative 3-Dimensional mapping of the sample density using Computed Tomographic Reconstruction. This microscopy is based on the energy loss of beam traversing thin samples (F < 50 mm)m-RBS Rutherford Back Scattering : Quantitative analysis and mapping of elements heavier than the matrix. Depth dependence from surface to 10 mm is resolved and measurements on a microscanning mode enable 3-D imaging. This microscopy is based on simple kinematics models and makes use of reliable software analysis packages.m-NRA Nuclear Reaction Analysis : Quantitative analysis and mapping of some elements (B, F, N, O etc) down to few tens ppm levels. This microscopy is based on nuclear reactions between the beam and selected elements in the sample.m-ERDA Elastic Recoil Detection Analysis : 3-D quantitative analysis and mapping of very light elements. This microscopy is based on simple kinematics and is particularly suitable for hydrogen analyses. Current detection limits are around 100 ppm. m-Channeling in conjunction with PIXE, ERDA, NRA and RBS: This microscopy enables lattice locations of elements to be determined, suppression of matrix element signals and evaluation of lattice integrity. This microscopy exploits the crystalline structure of the matrix.m-SecEM Secondary Electron Microscopy : Mapping of surface morphology. This microscopy is based on collection and analysis of secondary electrons ejected out of the sample by the beam.

The nuclear microprobe facility is currently used in research applications which cover the fields of geosciences, metallurgy, earth sciences, environmental studies, paleoclimatic research, biology and biomedicine. In addition there are projects in the field of nuclear-solid state research and particularly in studies of diamond physics. New analytical methodology has been established, which is based on ion-solid interactions and is applied in impurity studies in diamond as well as hydrogen and oxygen diffusion.

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Development of Accelerator Mass Spectrometry for Ultra-trace and dating studies in Interdisciplinary Research Staff : AH Andeweg, JUM Beer, SH Connell, K Cooney, RJ Hart, E Rood JPF Sellschop, E

Sideras-Haddad.Collaborators : P Aggerholm (Aarhus), T. Brown (Lawrence Livermore National Laboratory), J

Southon (Lawrence Livermore National Laboratory), S Freeman (Lawrence Livermore National Laboratory), J Butler (Naval Research Laboratory), S Sie (CSIRO, Australia)

Modern AMS is a new state-of-the-art technology for ultra-trace and dating studies in interdisciplinary sciences. It is highly fundable as well as very marketable. Its target User group find it easier to comprehend than other nuclear science based interdisciplinary technologies. In addition the potential User group also contains large industrial concerns. Development of the WITS-Northern Accelerator Facility to the level of AMS capability is one of the key features of a long term plan to stabilise the funding and upgrade the performance of the Tandem Accelerator. AMS is an exceptionally efficient use of beam-time, and is accommodated very well along with other research programmes on the same facility. Besides providing excellent new interdisciplinary research opportunities, it is expected that the project will benefit all the research based at the accelerator, as it will provide the funding to upgrade the facility and acquire further staff.

While conventional mass spectrometry techniques, such as SIMS, ICP-MS and SRIMP, and decay counting are efficient for determining isotopic ratios as low as 10-9 in microgram to nanogram samples, they cannot detect efficiently long-lived isotopes (mean lives from tens to million of years), especially with isotopic ratios as low as 10-9 to 10-15. An additional problem in ultrasensitive mass spectrometry measurements is that the rare isotope signal is very small as compared to those of interfering atoms and molecules with very similar masses, which are impossible to be filtered out. It is in this ultra sensitive regime with long lived radioisotopes that Accelerator Mass Spectroscopy or briefly AMS, came to play a very important role with some unpredictable revolutionary applications, especially in the field of biomedicine. The extracted ions, in the form of a negative beam, are accelerated to high kinetic energies by a positive electric field of some million volts in a nuclear electrostatic accelerator. In the centre of the accelerator, a cell containing a small volume of gas or a thin carbon foil is located. The accelerated incoming ions undergo collisions, losing one or more electrons and become positive ions exhibiting a range of charge states. In this way, all molecular species dissociate and cannot interfere with the isotope of interest any more. However, atomic isobaric interference still remain. To completely resolve these, the isotopes have their mass, energy, velocity and charge determined by standard nuclear physics instrumentation techniques. This is possible because of the high energy of the ion-beam. The result is an AMS instrument with a sensitivity typically six orders of magnitude greater than that of conventional mass spectrometry techniques.

The User base is being canvassed. Applications to external funding sources are in progress. Support from National and International institutes is currently being negotiated. A pilot project is being supported using outside funds. The initial design for the system is also in progress. At this stage the response from potential users and funders, as well as the support from various national and international institutions is very encouraging. The Vice president of the CSIR has fully supported the planned development and has taken a leadership role in promoting it as well as forming a development partnership whereby CSIR sample preparation facilities and recognised expertise will form part of the final joint facility. The international community has also been extremely enthusiastic, and more than three tons of very sophisticated equipment has been donated by various foreign AMS laboratories. The combined value of this equipment, some of which has already arrived, is over $500 000.00. The CSIR have funded the shipment costs. The progress in computerisation of the current facility is proceeding very well, and has already been discussed. The market survey and business plan generation components are also currently underway.

A brief mention of topics to be addressed follows : · Research in Global and Regional Climate Change· Characterisation of atmospheric pollution in terms of anthropogenic activities· Characterisation of Regional Groundwater Systems· Anthropology, History and Preservation Technology· AMS in Biomedical Dosimetry· Applications of AMS in Geosciences and Isotope Geology· Ultra-Trace Elemental Analysis

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· Isotope-Geochronometry and TracersThese topics have been given more detailed profile elsewhere.

Projects in (Nuclear) GeologyStaff : RJ HartStudents :Collaborators : SH Connell (WITS), E SIderas-Haddad (WITS), M Tredoux, M de Wit (UCT), R.

Hargraves and M. Cloete (Council for Geoscience) DG Pearson (Dept of Terrestrial Magnetism, Carnegie Institution of Washington), M Cloete and M Drury (Utrecht), D Moser (Royal Ontario Museum), E Eida (Norwegian Geological Survey), M. Rebak (de Beers)

Sulphide Inclusions in DiamondProton-induced X-ray emission (micro-PIXE) and instrumental neutron activation analysis (INAA) methods are used to obtain information about the platinum-group elements (PGE; Pt, Pd, Rh, Ru, Os, and Ir), and sometimes Au and Re also, in microscopic sulphide inclusions from diamonds. Samples of known paragenesis have to be selected. The research project is long term aimed at mantle PGE chemistry as well as the genesis mechanisms of diamond. A study of the magnetic anomaly near the centre of the Vredefort structure Ongoing research on the Vredefort structure has been conducted by our group for many years. Current active areas are the following :-a) Transmission Electron Microscope work on the orientation of magnetic minerals in relation to shock deformation features in quartz.a) Atomic magnetic force analyses on magnetic thin sections in order to determine the source of high remanence in the rocks from the Vredefort basement.Regional geology - Investigation of the Morokweng structureThe Morokweng structure, located in the North West province of South Africa, stands out clearly on the regional aeromagnetic map of southern Africa as a ~70 km diameter circular feature made up of concentric magnetic anomalies. The region is almost entirely covered by post-Cretaceous Kalahari beds, and interpretation of the subsurface stratigraphy beneath the Kalahari sands relies on the scant outcrop, chips from geohydrological boreholes and geophysical data. The rocks beneath the Kalahari cover consist largely of Archaean granites and rocks of the Kraaipan Group, composed of banded ironstones, meta-volcanics and minor ultramafics. Away from the structure to the south and west the crystalline basement rocks are overlain by gently dipping Proterozoic sediments. The circular structure was initially interpreted as an igneous intrusion. However, the superficial similarity of the aeromagnetic signature to other known impact sites and the identification of planar deformation features (PDFs) and other shock deformation phenomena found in surface pebbles and in rocks recovered from boreholes. has led to the reinterpretation of the feature as an impact structure. This study includes the following.a) Proton probe analyses of Platinum rich phases recovered from boreholes.b) U-Pb analyses of zircons recovered from a postulated impact melt.c) Ar-Ar analysis of biotites recovered from a postulated impact melt sheet

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Origin of the quartz noriteThe quartz norite is an unusual lithology in the context of regional geology of the western Kaapvaal craton. It is more basic than the underlying basement granites, yet it contains more quartz than typical mafic and ultramafic rocks of the Kraaipan group. Although the mineralogy and textures of the quartz norite superficially resemble those of plutonic rocks such as silica-rich norites or rocks of charnocitic affinity, they have concentrations of some siderophile and chalcophile elements more characteristic of mafic or even ultramafic rocks such as basalts or peridotites. Similarly, the Ni-rich phases (e.g. liebenburgite and the Ni-oxides) hosted by the quartz norite are exceptionally rare. The origin of the quartz norite is uncertain however, the shape of the body (the absence of any discernible roots) the chilled basal margin and the evidence for shock metamorphism in the basement, has led to the conclusion that these rocks represent an impact melt sheet. Both the clear, undeformed, prismatic zircons, and the primary biotites exhibit the morphology of minerals that crystallised from a magma. These minerals provide indistinguishable ages using two different dating systems and we interpret this circa 145 Ma age as the time of crystallisation of an impact melt. In view of recent speculation that meteorite impacts could cause flood basalts and major rifting events, the late Jurassic age for the Morokweng impact is very interesting, because this period is generally considered to be a time of accelerated global geological activity. This is especially true in the southern hemisphere, where this time period coincides with the break-up of the Gondwana super continent. In the context of the dramatic geological activity at the time, it is interesting to note that the JurassicÐCretaceous (JÐK) extinction event is listed by Raup and Sepkoski (1986) as one of the eight major episodes. The exact nature of this extinction and its absolute age are both still a matter of keen debate: International collaborative study on Cretaceous -Tertiary (K-T) boundary samples recovered from the ocean floor The objective is to analyse samples from Leg 165 from a trans-Atlantic traverse, as well as K/T sections on land in Mexico and Belize will be analysed for ultra-low level Ir concentrations.This is a new international collaboration on the nature of the ocean floor deposits of the Cretaceous-Tertiary (K/T) boundary. The purpose of this project is too analyse ocean floor deposits associated with the K/T boundary for Ir, thought to be indicative of an impact event. The section comes from a deposit about 1500 km from the Chicxulub crater, the proposed impact site for the K-T extinction event. The section has a well developed tectite layer, in which we found shocked quartz. There are limestones of varying descriptions either side.

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Accelerator Facility Equipment Inventory

1 6 MV EN-Tandem Van de Graaff accelerator with 8 beamlinesa Neutron activation + remote measurement facilityb Neutron radiography linec Quantitative analytical Heavy-Ion Microprobed Nuclear-Solid State Physics TDPAD facilitye High Energy Heavy-Ion Implantation Facilityf PIXE analysis of Environmental Aerosolsg Pure Nuclear Physics Experimentsh Oxygen and Nitrogen analysis

2 2.5 MV Van de Graaff acceleratora Dual injector to the Ion-Microprobe (high resolution analytical microscopy)

3 Off-line counting systemsa gamma spectroscopyb positron spectroscopy

4 Nuclear data processing instrumentation a +/- 500 pulse processing modules

5 Computerised Data Acquisitiona CAMAC based Physics Analysis Workstation (PAW ex CERN)b OMDAQ dedicated to Microprobe projectsc The GeniePC Spectroscopy Suite for singles measurements

6 Tandem Peer-to-Peer LAN (Unix, OS/2, W95 lab services cluster)a WWW serverb FTP, Program and file Serverc CDROM burnerd DAQ workstationse Analysis workstations

7 Neutron Activation Analysis Facilitya sample preparationb automated sample changerc gamma spectroscopy d on-line Analysis System

Accelerator Facility Status Report1 6 MV EN-Tandem Van de Graaff accelerator with 8 beamlines

Excellent performance with all beams. In particular, the accelerator has operated near its design voltage with heavy-ion beams at high charge states and currents with impressive stability, reliability and requiring very little operator intervention. This is attributed to :

a the husbanding of the new tubes, belt and column resistors installed a few years agob the new management culture with a unified technical vision and upgrading during

repairs and developmentsc better vacuum practice as allowed by increased running cost allocationsd new skills (eg sabbatical of P Aggerholm (Denmark) and acquisition of E Rood)

The beam-lines and target stations currently in use are in good working order, and some have received major development as part of the implementation of new projects.

2 2.5 MV Van de Graaff acceleratorInstallation as dual injector to the Ion-Microprobe for high resolution analytical microscopy is complete. There has been both H and He beams into the chamber of impressive brightness and stability. However operation continues to be unreliable. The HV platform electronics, vacuum and gas supply equipment have now all been overhauled or replaced. Recent air tests are now delivering reliable operation, and tests under pressure are in progress. The EN-Tandem has had to carry all the Ion-Microprobe projects during this period, and this has been very strenuous. However, we have every expectation that the “Potch” machine will soon be operational. It is supposed to have a legendary reliability and require very low overheads in its operation. It is intended to be deployed for the routine proton-Microprobe work at very high spatial resolutions and rapid turn-around times.

3 Off-line counting systems

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These are state-of the art systems and in good operating order and regularly used. Accreditation by the CNS for IGP purposes is in progress.

4 Nuclear data processing instrumentation These are state-of the art systems and in good operating order and regularly used.

5 Computerised Data AcquisitionThese are state-of-the-art systems and in good operating order and regularly used. The COLLECT DAQ system is an innovation, discussed above.

6 Tandem Peer-to-Peer LAN (Unix, OS/2, W95 lab services cluster)Most of the facilities still represent high-end computers, due to the upgrade following the theft of 11 computers from the laboratory in early 1996. In some cases finances for further upgrades have been applied for.

7 Neutron Activation Analysis FacilityAs part of the restructuring of the Schonland, the NAA facility was recently relocated to the old Neutrino Surface Station Laboratory. This has resulted in a cleaner and redesigned installation, in a very low background environment. The DAQ software server is currently being upgraded. This system is in almost continual use.

PIXE Detector

RBS Detector

X Rays

BackscatteredbeamRBS

SEM Detector

Secondaryelectron

emission (SEM)NRA Detector

ERDA Detector

Optical / CCD

Forwardscatteredlight ions

Transmitted H.I.beam

Nuclear reactionproducts

Ion Beam Microbeam1-10 mm

Focussingquadrupolemagnets

Analysing Magnet

Switcher Magnet

6 MV EN Tandem Accelerator

2.5 MVVan de Graaff

Accelerator

Microprobeend station

Quadrupoledoublet

Cooledprotection

slits

90 degreebending magnet Analyser

slits

Object slits

Post Acceleration Stripper

6.8 m

Pneumaticvalve

Collimator slits

Analyser slits

Object Slits

ObjectSlits

Schematic representation of the Accelerator Laboratory, showing mainly the Ion-Microprobe Facility. The inset is a schematic diagram of the focused ion-beam exciting radiation from a sample, leading to various (trace) quantitative microscopies. The other 7 available beamlines are shown schematically and truncated.

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Usage of the Accelerator Laboratory (1997-1998 2-year average)

Project Group Proposers PercentageMany projects under the programme:mERDA for H in Diamond

Particle-Solid Interactions SH Connell, BP Doyle, IZ Machi, RD Maclear JPF Selschop E Sideras-Haddad all WITS-PhysicsJE Butler NRL-Washington

25%

Many projects under the programme:PIXE analysis of time dependent aerosol streaker samples

Environmental Aerosols HJ Annegarn, SJ Piketh, S Meter, P FormentiWITS-Physics, WITS Climatology

20%

Many projects using the Ion-Microprobe

Council for GeosciencesAtomic Energy CorporationBOART hard materialsSA Inst of Med. Res.Anglo American Res LabsInst Mineralogie - HannoverDevelopment, Calibration

D De BruynM Andreoli

S Luyckx : WITS-MetallurgyS LeeC SmithA Wittenberg

SH Connell, E Sideras-Haddad

20%

Neutron Radiography Applied Neutron Physics JIW Watterson WITS-Physics 5%Neutron Activation Applied Neutron Physics JIW Watterson WITS-Physics 5%Many projects under the programme:High Energy Heavy-Ion Implantation

Lattice effects in II damage propagationHEHI in Semi-conductorsHEHI in Alkali HalidesHEHI in thin filmsThin Diamond production

CG Fischer WITS-Physics

S Goodman : UPretoria-PhysicsA Davidson : UZululand-PhysicsM Maaza : WITS-PhysicsJPF Sellschop : WITS-Physics

5%

Scheduled maintenance AH Andeweg, JUM Beer, E Rood 10%Unscheduled 10%

SchonLAN Computer facilitiesLAN Supervisor : BP DoyleLAN Assistant Supervisor : RD MaclearComputer Representative : SH ConnellElectronics : AH Andeweg, K CooneyThe computer facilities at the SRCNS can be divided into two major sections: the SchonLAN Novell server and the workstations which connect to it, and the UNIX network. There are also a few off-line PCs (mainly used for data acquisition).The SchonLAN Novell NetworkThe SchonLAN network runs under Novell 4.11 and has about 75 users. The majority of people at the SRCNS use this network for their printing, applications and e-mail needs. The server itself is a Pentium 100 with 64MB RAM, 5GB of hard drive space, a DAT 2 tape drive and a CD-ROM (all SCSI). The physical cabling system is 10MB 10 Base-T. This machine is also a file server for shared data and certain applications (MS-Office, user authored applications etc.).UNIX (LINUX) NetworkOver the last few years there has been a rapid development of a UNIX network at the SRCNS. This has mainly been due to the powerful data acquisition and manipulation software that has become available. The network consists of 8 PCs running Linux. This network utilises the same cabling system as the SchonLAN. This network hosts the WWW servers, FTP servers, amongst other specialised servers for Unix environments.

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Publications (1996-present)

1. B.P. Doyle, J.K Dewhurst, J.E. Lowther and K. Bharuth-RamLattice locations of indium implanted in diamondPhys. Rev. B, 57 (1998) 4965-4967.

2. K Kirsebom, U Kononets, U Mikkelsen, SP Moller, E Uggerhoj, T Worm, C Biino K Elsener, S Ballestrero, P Sona, SH Connell, JPF Sellschop, ZZ Vilakazi, A Apyan, RO Avakian, K Ispirian.Pair production by 5-150 GeV Photons in the strong crystalline fields of germanium, tungsten and iridiumNucl Instr. & Meth. in Phys. Res. B 135 (1998) 143-148

3. Damarupurshad, R.J. Hart, J.P.F. Sellschop and H.O. MeyerThe application of INAA to the geochemical analysis of single diamondsJ. Radioanalytical and Nuclear Chemistry 219 (1997) 33-39

4. B. Itterman, K. Bharuth-Ram, H. Metzner, M. Fullgrabe, M. Heemeier, F. Kroll, F. Mai, K. Marbach, P. Meier, Peters, H. Thiess, H. Ackermann, H-J Stockmann and J.P.F. SellschopBoron Implantation doping of diamondApplied Physics Letters 71 (1997) 3658-3660

5. SH Connell, J.P.F. Sellschop, R.D. Maclear, B.P. Doyle, I.Z. Machi, R.W.N. Nilen, R.W.N. Nilen, J.E. Butler and K Bharuth-RamHydrogen and hydrogen-like defects in diamondMat. Sc. Forum Vols 258-263 (1997) 751-756

6. RD Maclear, JE Butler, S.H. Connell, B.P. Doyle, I.Z. Machi, J.E. Butler, S.R. Naidoo, J.P.F. Sellschop and E Fritsch.Quantitative trace hydrogen distributions in natural and Synthetic Diamond using 3D-micro-ERDA microscopyNucl. Inst. & Meth. in Phys. Res. B 136-138 (1998) 579-582

7. RW Nilen, SH Connell, DT Britton, CG Fischer, EJ Sendezera, P Schaaff, JPF SellschopInvestigation of lattice impurities and photochromic centres in diamond with high resolution positron annihilation spectroscopyDiamond and Related Materials 6 (1997) 1777-1783

8. RWN Nilen, SH Connell, DT Britton, CG Fischer, EJ Sendezera, WG Schmidt, JPF Sellschop, WS VerwoerdA high resolution investigation of the anisotropic electron-positron momentum distribution in diamondMat. Sc. Forum. Vols 255-257 (1997) 475-478

9. E Gadioli, C Birattari, M Cavinato, E Fabrici, E Gadioli Erba, E Allori,V Ceruti, A Di Filippo, E Galbiati, TG Stevens, SH Connell, JPF Sellschop, Sj Mills, FM Nortier, GF Steyn, C MarchettaA comprehensive study of the interaction of 12C with 103Rh up to 33 MeV/nucleonRicerca Scientifica ed Educazione Permanente Supplemento N.111 (1977) 271-281

10. JPF Sellschop and S.H. Connell.Carbon ! .... and its analysisNucl. Inst. & Meth. in Phys. Res. B136-138 (1998) 1253-1258

11. RWN Nilen, SH Connell, D Britton, CG Fischer, EJ Sendezera, P Schaaff, W Schmidt, JPF Sellschop and WS Verwoerd. The Anisotropic Electron - Positron Momentum Density Distribution In DiamondJ Phys. Condens. Matter 9 (1997) 6323-6333.

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12. JPF Sellschop, SH ConnellRecent applications of energetic particle beams with diamond targetsProceedings of Physics at the Turn of the Millenium: Structure of the Vacuum and Elementary Matter, World Scientific Publishing Co. Pte. Ltd. Ed. H Stöker, A Gallmann and JH Hamilton. (1997) 171 - 177

13. A Baurichter, K Kirsebom, U Kononets, R Medenwaldt, K Kirsebom, U Mikkelsen, SP Moller, E Uggerhoj, T Worm, K Elsener, S Ballestrero, P Sona, J Romano, SH Connell, JPF Sellschop, RO Avakian, AE Avetisian, SP Taroian.Radiation emmission and its influence on the motion of multi-GeV electrons and positrons in strong crystalline fileds. Phys. Rev. Lett. 79 (1997) 3415-3418

14. IZ Machi, P Schaaff, SH Connell, BP Doyle, P Formenti, RD Maclear, JPF Sellschop, K Bharuth-RamHydrogen mobility in diamond studied using HI-ERDA microscopy Nucl. Inst. & Meth. in Phys. Res. B127/128 (1997) 212-216

15. Sideras-Haddad, D Heikkinen, SH Connell, MW Caffee, ML Roberts, GS Bench, A Meike and W Bourcier.Application of Elastic Recoil Detection Analysis for materials used in the YUCCA mountain waste repository Nucl Instr. & Meth. in Phys. Res. B (1997) pages

16. AH Andeweg, S Ballestrero, JUM Beer, J.E. Butler, MBH Breese, SH Connell, L Dini, BP Doyle, ML Drummond, P. Formenti, RJ Hart, I.Z. Machi, R.D. Maclear, ID McQueen, P Schaaff, E Sideras-Haddad, JPF Sellschop, and G Wernick.The Schonland Micro-Scanning Ion Beam Analysis FacilityNucl Instr. & Meth. in Phys. Res. B130 (1997) 37-44

17. Formenti, M.B.H. Breese, S.H. Connell, B.P. Doyle, M.L. Drummond, I.Z. Machi, R.D. Maclear, P. Schaaff, J.P.F. Sellschop, G. Bench, E. Sideras-Haddad, A. Antolak and D. MorseHeavy ion and proton beams in high resolution imaging of a fungi spore specimen using STIM tomography Nucl Instr. & Meth. in Phys. Res. B130 (1997) 230-236

18. Doyle, R.D. Maclear, S.H. Connell, P. Formenti, I.Z. Machi, J.E. Butler, P. Schaaff, J.P.F. Sellschop, E Sideras-Haddad and K Bharuth-Ram3D-micro-ERDA microscopy of trace hydrogen distributions in diamond using a 2-D PSD with event reconstruction Nucl Instr. & Meth. in Phys. Res. B130 (1997) 204-210

19. A Wittenberg, SH Connell, P Formenti, RJ Hart, JPF SellschopProton probe quantitative trace elemental microscopy of polymineralic kyanite bearing eclogytic samples Nucl Instr. & Meth. in Phys. Res. B130 (1997) 641-648

20. K Bharuth-Ram, R Scheuermann, IZ Machi, SH Connell, J Major, JPF Sellschop, A SeegerMuon behaviour in diamond grown by chemical vapour depositionHyperfine Interactions 105 (1997) 339-344

21. U Lauff, RWN Nilen, SH Connell, H Stoll, K Bharuth-Ram, A Siegle, H Schneider, P Harmat, P Wesolowski, JFP Sellschop, A SeegerAge-Momentum Correlation Experiments On Industrial Grade DiamondApplied Surface Science 116 (1997) 268-272

22. RWN Nilen, U Lauff, S Aonnell, H Stoll, A Siegle, H Scheider, P Castellaz, J Kraft, K Bharuth-Ram, JPF Sellschop, A SeegerThe Effect Of Light On Positron Annihilation In Natural DiamondApplied Surface Science 116 (1997) 198-202

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23. RWN Nilen, SH Connell, W Schmidt, D Britton, W Verwoerd, JPF Sellschop, S ShrivastavaElectron - Positron Momentum Density Distribution In DiamondApplied Surface Science 116 (1997) 330-334

24. E Gadioli, C Birattari, M Cavinato, E Fabrici, E Gadioli Erba, V. Allori, C Bovati, F Cerutti, A DI Filippo, E Galbiati, TG Stevens, SH Connell, JPF Sellschop, SJ Mills, FM Nortier, GP Steyn, C MarchettaComprehensive Study of the Reactions Induced by 12C on 103Rh up to 33 MeV/NucleonPhys. Lett. B. 394 (1997) 29-36

25. WG Schmidt, WS Verwoerd, RWN Nilen, SH Connell, DT BrittonDelocalized positrons in diamond: lifetime and momentum distributionProc. of the 23rd Int Conference on the Physics of Semiconductor, Berlin, July 1996

26. C Birattari, M Bonardi, M Cavinato, E Fabrici, E Gadioli, E Gadioli Erba, F Groppi, M Bello, C Bovati, A Di Filippo, TG Stevens, SH Connell, JPF Sellschop, Sj Mills, FM Nortier, GF Steyn, C MarchettaPre-equilibrium processes in the fusion of 12C with 103Rh up to 20 MeV/nucleonPhys Rev C 54 (1996) 3051 - 3055

27. K Kirsebom, R Medenwaldt, U Mikkelsen, SP Moller, K Paludan, E Uggerhoj, T Worm, K Elsener, S Ballestrero, P Sona, J Romano, SH Connell, JPF Sellschop, RO Avakian, AE Avetisian, SP TaroianExperimental investigation of photon multiplicity and radiation cooling for 150 GeV electrons/positrons traversing diamond and Si crystalsNucl Instr & Methods in Phys Res B 119 (1996) 79 - 95

28. SH Connell, E Sideras-Haddad, CG Smallman, JPF Sellschop, IZ Machi, K Bharuth-Ram3D-microERDA microscopy of implanted H-distributions in diamondNucl Instr & Methods in Phys Res B 118 (1996) 332-337

29. CG Smallman, SH Connell, CCP Madiba, JPF SellschopTrapping of implanted hydrogen in type Ia diamondNucl Instr and Methods in Phys Res B 118 (1996) 688-692

30. CG Smallman, SH Connell, K Bharuth-Ram, JPF Sellschop, RWN Nilen, M Hampele, J Major, R Scheuermann, A Seeger, T StammlerMuonium-defect interactions in natural diamondHyp. Int. (C) 1 (1996) 440-443.

31. MG Bossenger, S.H. Connell, E. Sideras-Haddad,H. Appel, B.P. Doyle, W. Verwoerd, K. Bharuth-Ram and J.P.F. SellschopTDPAD study of the 19F interaction in C60 and C70Hyp. Int. (C) 1 (1996) 452-455.

32. R Moore, MA Parker, A Baurichter, K Kirsebom, R Medenwaldt, U Mikkelsen, SP Moller, E Uggerhoj, T Worm, N Doble,K Elsener, S Ballestrero, P Sona, VM Strakhovenko, C Biino, Z VilakaziMeasurement of pair-production by high energy photons in an aligned tungsten crystalNucl Instr and Methods B 119 (1996) 149 -155

33. A Baurichter, K Kirsebom, R Medenwaldt, Sp Moller, T Worm, E Uggerhoj, C Biino, M Clement, N Doble, K Elsener, L Gatignon, P Grafstrom, U Mikkelsen, Z Vilakazi, P Siffert, M Hage-AliNew results from the CERN-SPS Beam Deflection Experiments with Bent CrystalsNucl Instr Methods B 119 (1996) 172 - 180

34. A Baurichter, U Mikkelsen, K Kirsenbom, R Medenwaldt, S Moller, E Uggerhoj, T Worm, K Elsener, S Ballestrero, P Sona, J Romano, C Biino, R Moore, ZZ VilakaziEnhancement of electromagnetic showers initiated by ultrarelativistic electrons in

56

aligned thick germanium crystalsNucl Instr and Methods in Phys Res B 119 (1996) 143 - 148

35. Bharuth-Ram, M. Hartick, C.Dorn, P. Held, E. Kankelheit, J.P.F. Sellschop, R. Sielemann, L. Wende and J. KublerIn-beam Mössbauer study of Fe-57 implanted in diamondProc. Int. Conf. on Applications of the Mössbauer Effect, Rimini, Italy, August 1995and Il Nuovo Cimento Conference Proceedings, 50 (1996) 683-686

36. Genz, L. Groening, P. Hoffmann-Stascheck, A. Richter, M. Hoefer, J. Hormes, U. Nething, J.P.F. Sellschop, C. Toeppfer and M. WeberChanneling radiation of electrons in natural diamond crystals and their coherence and occupation lengthsPhys. Rev. B 53 (1996) 8922-8936

37. Freudenberger, M. Galemann, H. Genz, L. Groening, P. Hoffmann-Stascheck, V.V. Morokhovskii, U. Nething, H. Prade, A. Richter, J.P.F. Sellschop and R. ZahnExperimental determination of the linewidth of parametric X-ray radiation at electron energies belwo 10 MeVNucl. Instr. and Meth. B 115 (1996) 408-410

38. Freudenberger, H. Genz, L. Groening, P. Hoffmann-Stascheck, W. Knupfer, V.L. Morokhovskii, V.V. Morokhovskii, U. Nething, A. Richter and J.P.F. SellschopChanneling radiation and parametric X-radiation at electron energies below 10 MeVNucl. Instr. and Meth. B 119 (1996) 123-130

Refereed Papers in Press

1 E Gadioli, C Birattari, M Cavinato, E Fabrici, E Gadioli Erba, V Allori, C Bovati, F Ceruti, A Di Filippo, E Galbiati, TG Stevens, SH Connell, JPF Sellschop, Sj Mills, FM Nortier, GF Steyn, C MarchettaA comprehensive study of the interaction of 12C with 103Rh up to 33 MeV/nucleonProceedings of the Brolo Conference 1996, World Scientific (Singapore)

2 JE Butler, RD Maclear, SH Connell, BP Doyle, IZ Machi and JPF SellschopDetection of Hydrogen Spatial Distributions in CVD Diamond by Elastic Recoil Detection using a 2 Dimensional Particle Detector.presented at Diamond 97 (Edinburgh, July 97)

3 E Gadioli, C Birittari, M Cavinato, E Fabrici, E Gadioli Erba, V Allori, F Cerutti, A Di Filippo, S Vailati, TG Stevens, SH Connell, JPF Sellschop, FM Nortier, GF Steyn and C MarchettaAngular Distributions and Forward Recoil Range Distributions of Residues Created in the Interaction of 12C and 16O with 103RhNuclear Physics A

57

Conferences and Visits

International Conferences 1998

International Workshop on Radiation Physics with Relativistic Electrons, Tabarz, Germany 9 - 12 June 1991. JPF Sellschop (Invited)

The productioin of thin and thick diamond targets for energetic electron and synchrotron radiation studies

2. ZZ Vilakazi, SH Connell, JPF Sellschop, U Mikkelsen, U Kononets, K Kirsebom, SP Moller, E Uggerhoj, T Worm, K Elsener, S Ballestrero, P Sona, C Biino, R Moore, RO Avakian, K Ispirian, A ApyanInvestigation of pair production and its dependence on correlated effects when multi-GeV photons are incident on Ge crystal

Diamond Conference, London, England, July 1998

1. B Doyle, R Maclear, JPF Sellschop, SH Connell, E Sideras-Haddad and JE ButlerWhere is the hydrogen in CVD diamond?

2. JM Baker, IZ Machi, SH Connell, K Bharuth-Ram , JE Butler, SFJ Cox, CG Fischer, T Jestadt, RWN Nilen and JPF SellschopLongitudinal field muon spin relaxation (LF-mSR) measurements in type IA diamond

3. E Sideras-Haddad, D Rebuli, SH Connell, JPF Sellschop, B Doyle and R Maclear, TE DerryOxygen on diamond

4. IZ Machi, SH Connell, J Major, CG Smallman, JPF Sellschop, K Bharuth-Ram, R Maclear, BP Doyle, JE Butler, R Sheuerman and A SeegerStudy of diamond and its defects using transverse field muon spin rotation (TF-mSR)

5. CG Fischer, SH Connell and JPF SellschopNear surface to bulk characterisation of diamond by positron annihilation

6. JPF Sellschop, A Freund, W Greiner and M RebakOn the bending of diamond

7. SH Connell, IZ Machi, CG Smallmann, JPF Sellschop, K Bharuth-Ram, RWN Nilen , J Major, R Scheuerman and A SeegerQuantum diffusion of the interstitial muonium (MuT) in diamonds with induced vacancies

8. E Storbeck, B Doyle, SH Connell, JPF Sellschop and U WahlLattice location studies of In-111 in diamond using the Isolde facility at CERN

9. JM Baker, P Murphy, IZ Machi, SH Connell, K Bharuth-Ram, SFJ Cox, JE Butler, CG Fischer, T Jestadt, RWN Nilen and JPF SellschopMuonium at a site of rhombic symmetry in type Ia diamond

International Conferences 1997

Diamond 97 (Edinburgh, July 97)1 JE Butler, RD Maclear, SH Connell, BP Doyle, IZ Machi and JPF Sellschop

Detection of Hydrogen Spatial Distributions in CVD Diamond by Elastic Recoil Detection using a 2 Dimensional Particle Detector.

Int. Conf on Defects in Semi-conductors 19, Portugal 21-25 July 19971 SH Connell, J.P.F. Sellschop, R.D. Maclear, B.P. Doyle, I.Z. Machi, R.W.N. Nilen, R.W.N. Nilen,

J.E. Butler1 and Bharuth-RamHydrogen and hydrogen-like defects in diamond

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13th International Conference on Ion Beam Analysis, IBA-97 in Lisbon, Portugal 27.7.97 - 1.8.971 RD Maclear, JE Butler, S.H. Connell, B.P. Doyle, I.Z. Machi, J.E. Butler, S.R. Naidoo, J.P.F.

Sellschop and E Fritsch.Quantitative trace hydrogen distributions in natural and Synthetic Diamond using 3D-micro-ERDA microscopy

2 Sellschop and S.H. Connell. (Invited)Carbon ! .... and its analysis

International Conference on Atomic Collisions on Solids, Beijing, China1. K Kirsebom, U Kononets, U Mikkelsen, SP Moller, E Uggerhoj, T Worm, C Biino K Elsener, S

Ballestrero, P Sona, SH Connell, JPF Sellschop, ZZ Vilakazi, A Apyan, RO Avakian, K IspirianRadiation emmission by multi-GeV electrons and positrons in strong crystalline fileds (ZZ Vilakazi must supply corrected Title)

Varenna Conference on Nuclear Physics, 19971 E Gadioli, C Birattari, M Cavinato, E Fabrici, E Gadioli Erba, V Allori, F Ceruti, A Di Filippo, TG

Stevens, SH Connell, JPF Sellschop, FM Nortier, GF Steyn, C MarchettaA comprehensive study of the interaction of 12C with 103Rh.

International Conference on Positron Annihilation. Missouri, Kansas City, May 25-30, 19971 RWN Nilen, SH Connell, DT Britton, CG Fischer, EJ Sendezera, WG Schmidt, JPF Sellschop,

WS VerwoerdA high resolution investigation of the anisotropic electron-positron momentum distribution in diamond

2 CG Fischer, SH Connell, C Hugenschmidt, JPF Sellschop, RWN Nilen, DT BrittonDepth dependent defect profiling of the diamond surface and near surface region with a slow position beam

Diamond Conference, Bristol, England, July 1997

1 RWN Nilen, SH Connell, DT Britton, CG Fischer, EJ Sendezera, WG Schmidt , JPF Sellschop and WS Verwoerd A high resolution investigation of the anisotropic electron-positron momentum distribution in diamond

2 CG Fischer , SH Connell , C Hugenschmidt, JPF Sellschop and RWN Nilen Depth dependent defect profiling of the diamond surface and near surface region with a slow positron beam

3 JE Butler, RD Maclear, SH Connell, BP Doyle, IZ Machi and JPF SellschopStudy of the mobility and trapping of minor hydrogen concentrations in diamond in three dimensions using quantitative ERDA spectroscopy

4 K Bharuth-Ram, B Itterman, H Metzner, JPF Sellschop, H Ackerman, M Fuellgrabe, F Kroll, F Mai, K Marbachb-NMR investigation of ion-implanted boron in diamond

5 JM Baker, K Bharuth-Ram, JE Butler, SH Connell, SFJ Cox, CG Fischer, T Jestadt, RW Nilen, IZ Machi and JPF SellschopMuon spin relaxation in type Ia diamond in longitudinal field

International Conferences 1996

USR '96 Conference, Nikko, Japan, 15 - 19 April 19961 SH Connell, IZ Machi, RWN Nilen K Bharuth-Ram, JPF Sellschop, R Scheuermann, J Major, A

SeegerMuonium diffusion and interaction with defects in diamond

2 K Bharuth-Ram, R Scheuermann, IZ Machi, SH Connell, J Major, JPF Sellschop, A SeegerMuon behaviour in diamond growth by chemical vapour deposition

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Gordon Conference, 4 - 9 August 1996, Plymouth College, New Hampshire1 JPF Sellschop, SH Connell

Some comparative Nuclear Probe studies with CVD, synthetic and natural Diamond

Physics at the Turn of the Millenium: Structure of the Vacuum and Elementary Matter, World Scientific (Singapore) 19961 JPF Sellschop, SH Connell

Recent applications of energetic particles with diamond targets

5th Int Conference on Nuclear Microprobe Technology and Applications Sante Fe', New Mexico - USA, 10 - 15 November 19961. AH Andeweg, S Ballestrero, JUM Beer, J.E. Butler, MBH Breese, SH Connell, L Dinia, BP

Doyle, ML Drummond, P. Formenti, RJ Hart I.Z. Machi, R.D. Maclear, ID McQueen, P Schaaff, E Sideras-Haddad, JPF Sellschop, and G Wernick.The Schonland Micro-Scanning Ion Beam Analysis Facility

2. Formenti, M.B.H. Breese, S.H. Connell, B.P. Doyle, M.L. Drummond, I.Z. Machi, R.D. Maclear, P. Schaaff, J.P.F. Sellschop, G. Bench, E. Sideras-Haddad, A. Antolak and D. MorseHeavy ion and proton beams in high resolution imaging of a fungi spore specimen using STIM tomography

3. Doyle, R.D. Maclear, S.H. Connell, P. Formenti, I.Z. Machi, J.E. Butler, P. Schaaff, J.P.F. Sellschop, E Sideras-Haddad and K Bharuth-Ram3D-micro-ERDA microscopy of trace hydrogen distributions in diamond using a 2-D PSD with event reconstruction

4 A Wittenberg, SH Connell, P Formenti, RJ Hart, JPF SellschopProton probe quantitative trace elemental microscopy of polymineralic kyanite bearing eclogytic samples

International Conference on Large Scale Collective Motion ofAtomic Nucleii, Brolo 19961. E Gadioli, C Birittari, M Cavinato, E Fabrici, E Gadioli Erba, V Allori, C Bovati, F Cerutti, A Di

Filippo, E Galbiati, TG Stevens, SH Connell, JPF Sellschop, SJ Mills, FM Nortier, GF Steyn and C MarchettaComprehensive Study of the Reactions Induced by 12C on 103Rh up to 33 Mev/nucleon

SLOPOS 7, Switzerland, 2 - 7 June 19961 RWN Nilen, U Lauff, SH Connell, H Stoll, A Siegle, H Scheider, P Castellaz, J Kraft, K Bharuth-

Ram, A SeegerThe effect of light on positron annihilation in natural diamond

2 U Lauff, RWN Nilen, SH Connell, H Stoll, K Bharuth-Ram, A Siegle, H Schneider, P Harmat, P Wesolowski, JPF Sellschop, A SeegerAge-momentum correlation experiments on industrial grade diamond

3 RWN Nilen, SH Connell, WG Schmidt, D Britton, W Verwoerd, JPF Sellschop, S ShrivastavaElectron - positron momentum density distribution in diamond

23rd Int Conference on the Physics of Semiconductor, Berlin, July 19961 WG Schmidt, WS Verwoerd, RWN Nilen, SH Connell, DT Britton

Delocalized positrons in diamond: lifetime and momentum distribution

10th Int Conference on Ion Beam Modification of Materials, Alburquerque 19961 IZ Machi, P Schaaff, SH Connell, BP Doyle, P Formenti, RD Maclear, JPF Sellschop, K Bharuth-

RamHydrogen mobility in diamond studied using HI-ERDA microscop

Diamond Conference, Cambridge, England, 8 - 10 July 1996

1 SH Connell, CG Smallman, JPF Sellschop, RWN Nilen, IZ Machi, K Bharuth-Ram, J Major, R Scheuerman, A SeegerDiffusion and trapping behaviour of the hydrogen-like atom (muonium) in diamond

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2 SH Connell, JPF Sellschop, BP Doyle, RD MaClear, P Schaaff, P FormentiMicro- scanned heavy ion elastic recoil detection analysis imaging of hydrogen in diamond

3 JPF Sellschop, ZZ Vilakazi, SH ConnellPolarization and multipolarity of ultra-hard photons emitted during oriented scattering of multi-hundred GeV electrons off diamond

4 SH Connell, ZZ Vilakazi, JPF SellschopOriented electron scattering off high-quality aligned diamond crystals: a new opportunity to explore fundamental quantum processes

5 SH Connell, RWN Nilen, M Bossenger, JPF Sellschop, IZ Machi and K Bharuth-Ram Muon trapping in gamma irradiated diamond

6 SH Connell, CG Smallman, JPF Sellschop, RWN Nilen, M Bossenger, IZ Machi and K Bharuth-Ram A comparison of PC-CVD diamond muon spin rotation with that from well characterised natural diamond

7 RWN Nilen, SH Connell, JPF Sellschop Positron trapping at photochromic defects in diamond

Local Conferences

SAIP Conf, UCT, 8-10 July 1998

1. Maclear, S.H. Connell, M. Hogan, A.H. Andeweg, J.P.F. Sellschop and F. Weehuizen, The Schonland Research Centre EN-Tandem Accelerator Control System,South African Institute of Physics Conference, Cape Town, 8-10 July, 1998

2. Doyle, S.H. Connell, J.P.F. Sellschop and U. Wahl,PAC study of indium-defect interactions in diamond

3. Doyle, E.J. Storbeck, U. Wahl, S.H. Connell and J.P.F. Sellschop,Study of indium-defect interactions in diamond using 2-D CEEC

4. Storbeck, U. Wahl, B.P. Doyle, S.H. Connell and J.P.F. Sellschop.A 2-D CEEC study of the second configuration observed for indium implanted into pure diamond

5. Doyle, J.E. Butler, S.H. Connell, I.Z. Machi , R.D. Maclear, J.P.F. Sellschop and E. Sideras-Haddad,

Diffusion Characteristics of Hydrogen in CVD Diamond6. Sideras-Haddad, S.H. Connell, J.P.F. Sellschop, R. Hart and M.Tredoux,

Anomalous Fe and Mn zoning observed in microscopic inclusions in diamond using nuclear microscopy

7. JM Baker, IZ Machi, SH Connell, K Bharuth-Ram, JE Butler, SFJ Cox, CG Fischer, T Jestadt, RWN Nilen, and JPF Sellschop,Longitudinal Field - Muon Spin Relaxation (LF-mSR) measurements in type Ia diamond

8. IZ Machi, SH Connell, J Major, CG Smallman, JPF Sellschop, K Bharuth-Ram, RD Maclear, BP Doyle, JE Butler, R Scheuermann, and A Seeger,Muonium studies of p-type semi-conducting diamond under conditions of UV-visible illumination

9. R.D.Maclear, S.H. Connell, E. Sideras-Haddad, D.B. Rebuli, B.P. Doyle, I.Z. Machi, J.E. Butler, P. Aggerholm and J.P.F. Sellschop,Channeling studies of ultra-thin diamond films

10. E Gadioli, C Birattari, M Cavinato, E Fabrici, E Gadioli Erba, E Allori,V Ceruti, A Di Filippo, E Galbiati, TG Stevens, SH Connell, JPF Sellschop, Sj Mills, FM Nortier, GF Steyn, C MarchettaA comprehensive study of the interaction of 12C with 103Rh up to 33 MeV/nucleon

SAIP Conf, Durban Westville, 2-4 July 1997

1. SH Connell, JPF Sellschop, RD Maclear, BP Doyle, IZ Machi, RWN Nilen, JE Butler, K Bharuth-Ram, Hydrogen and hydrogen-like defects in diamond

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2. IZ Machi, SH Connell, CG Smallman, RW Nilen, CG Fischer, JPF Sellschop, K Bharuth-Ram, J Major, R Scheuermann, A SeegerMuonium-Boron interaction in Diamond

3. IZ Machi, JE Butler, SH Connell, RD Maclear, BP Doyle, JPF Sellschop, K BharuthStudy of Hydrogen on Diamond Surfaces using the microHI-ERDA Technique

4. CG Fischer, SH Connell, C Hugenschmidt, JPF Sellschop, RWN NilenDepth dependent profiling of the diamond surface and near surface region

5. RD Maclear, JE Butler, SH Connell, BP Doyle, IZ Machi, SR Naidoo, JPF SellschopQuantitative trace hydrogen distributions in natural and synthetic diamond using 3D-micro-erda microscopy

6. E Sideras-Haddad, D Heikkinen, SH Connell, MW Caffee, ML Roberts, GS Bench, A Meike, W Bourcier3-D Micro-ERD Analysis of Hydrogen in Materials for Use in the Yucca Mountain Nuclear Waste Repository

7. RWN Nilen, SH Connell, Dt Britton, CG Fischer, EJ Sendezera, WG Schmidt, JPF Sellschop, WS VerwoerdThe Anisotropic Electron-Positron Momentum Distribution in Diamond

SAIP Conf, Pretoria, 3 - 5 July 1996

1. IZ Machi, SH Connell, K Bharuth-Ram, JPF Sellschop, R Scheurmann, J Major, A SeegerMuonium Behaviour In Polycrystalline Chemical Vapour Deposited (PC-CVD) Type Ib Diamond.

2. SH Connell, TG Stevens, JPF Sellschop, SJ Mills, GF Steyn, FM Nortier, E Gadioli, E Gadioli Erba, C Birararri, M Bonardi, M Cavinato, E Fabrici, C Bovati, C Brusati, A Di FilippoA Comprehensive Study Of The Reactions Induced By 12C And 16O Ions On 103Rh From The Coulomb Barrier Up To 400 Mev

3. IZ Machi, SH Connell, RWN Nilen, K Bharuth-Ram, JPF Sellschop, R Scheuermann, J Major, A SeegerMuonium Diffusion And Interaction With Defects In Diamond

4. ZZ Vilakazi, SH Connell, JPFSellschop, R Medenwaldt, SP Moller, VM Strakhovenko, E Uggerhoj, T Worm, K Elsener, P Sona, K Kirsenbom, A Baurichter, U Mikkelsen, S Ballestrero, SP Taroian, K Ispiryan, RO AvakianInvestigation Of The Coherent Hard Photons Emissions And Other QED Processes For High Energy Electrons Incident On Crystals

5. M Drummond, SH Connell, BP Doyle, I Machi, R Maclear, P Schaaff, P Formenti, M Breese, JPF SellschopThe Schonland Micro-Scanning Ion Beam Analysis Facility

6. EJ Storbeck, BP Doyle, Sh Connell, JPF Sellschop, W VerwoerdMolecular Effects In Mev Electron Channeling In Diamond

7. BP Doyle, SH Connell, P Formenti, IZ Machi, RD Maclear, P Schaaff, JPF Sellschop3D-Micro ERDA Microscopy Of Hydrogen Distributions In Diamond Using A 2D-PSD With Event Reconstruction

8. IZ Machi, SH Connell, BP Doyle, P Schaaff, P Formenti, RD Maclear, JPF Sellschop, K Bharuth-RamHydrogen Mobility In Diamond Studied Using HI-ERDA Microscopy

9. RWN Nilen, SH Connell, M Stoll, U Lauff, A Siegle, H Schneider, K Bharuth-Ram, JPFSellschop, A SeegerAMOC In Diamond

10. RWN Nilen, SH Connell, M Stoll, U Lauff, A Siegle, H Schneider, K Bharuth-Ram, JPFSellschop, A SeegerModelling Positron Spectroscopy Observables In Diamond

11. A Wittenberg, RJ Hart, SH Connell, JPFSellschopProton Probe Quantitative Trace Elemental Microscopy Of Polymineralic Kyanite Bearing Eccogytic Samples

12. P Formenti, A Antolak, G Bench, MBH Breese, SH Connell, BP Doyle, ML Drummond, IZ Machi, RD Maclear, D Morse, P Schaaff, E Sideras-Haddad, JPF SellschopHeavy Ion And Beams In High Resolution Imaging Of A Fungi Spore Specimen Using STIM Tomography

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Visiting Scientists to WITS

Sabbatical Visits

1. P Aggerholm(Senior Technician : Institute for Physics and Astronomy, University of Aarhus, Denmark)One year sabbatical, starting January 1998. Working on development and procedures for the 6.0 MV EN-Tandem and the 2.5 MV VdG accelerators, design of AMS facility, thin single crystal diamond project. His visit is also part of an ongoing collaboration with his Institute.

2. EJ Sendezera(Professor : Physics Department, University of Zululand)One year sabbattical starting August 1997)Working on the positron and microprobe projects studying alkali halides, Super-ionic conductors and diamond.

3. JE Butler(Director : Gas/Surface Dyanamics Section, Chemistry Division, Naval Research Laboratory, Washington DC, USA)Four month sabbatical starting September 1996, working on diamond physics.

Working Visits

1. Prof. E gadioli, Prof C C Birattari and student(s)(INFN-Milano)Two working visits per year of three weeks each in February and September, 1996-1998, working on collaborative projects in Nuclear Physics at NAC, studying reaction, mechanisms and de-excitation mechanisms.

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Visits of Staff and students to International Institutions

Conferences Attended and Institutions visited 1998

Date Institution Country PurposeMarch (1 week)ZZ VilakaziSH Connell

INFN - Florence Italy NA43 collaborators’ meeting

May (1week)IZ Machi

PSI-Zurich Switzerland Expt Evaluation Committee Meeting

June (1 week)ZZ VilakaziJPF Sellschop

Tabarz Germany International Workshop -Rad. Phys. with rel. e-

June (1.5 months)CG Fischer

Uni-BristolUni-East AngliaRossendorf

England and Germany

Working visits on ACAR and SlowPos Spectroscopy

June/July (2 weeks)BP Doyle

ICTP Trieste Italy Electronic Structure Calculations Workshop and Hyperfine Interactions conference

Conferences Attended and Institutions visited 1997

Date Institution Country Purpose

April ZZ Vilakazi (4 weeks)SH Connell (2 weeks)

CERN Switzerland NA43 experiment beam time

May (1 week)CG Fischer, RW Nilen

Kansas USA Int. Conf on Pos Annihilation

June (1 week)SH Connell, IZ Machi, CG Fischer, RW Nilen, JPF Sellschop

Rutherford AL England Working VisitMSR in diamond beam time

Sept (1 week)TG Stevens

New London, New hampshire

USA Gordon Conference on Nucl Chemistry

July (2 weeks)RD Maclear, BP Doyle

Lisbon Portugal Int. Conf on Defects in Semi-conductors 19.13th International Conference on Ion Beam Analysis

August (1 week)SH Connell JPF Sellschop, IZ Machi, RD Maclear, BP Doyle

PSI-Zurich Switzerland Working VisitMSR in diamond beam time

Nov (1 month) EJ Storbeck

ISOLDE-CERN. Switzerland CEEC experimentPAC Implantations.

Conferences Attended and Institutions visited 1996

Date Institution Country PurposeJan (2 weekends)SH Connell

NAC South Africa Nuclear Physics Expt

Jan (3 weeks)TG Stevens

NAC South Africa Nuclear Physics Expt

July (2 months)TG Stevens

Milano University Italy Nuclear Physics Expt, data analysis

April (1 month)SH Connell, ZZV

CERN Switzerland

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Oct (1 weekend)SH Connell

NAC South Africa Nuclear Physics Expt

Sept/Oct (3 weeks)TG Stevens

NAC South Africa Nuclear Physics Expt

Nov (1 week) BP Doyle, P Formenti

Lawrence Livermore Natl Lab.

USA Nuclear Microprobe Expt.

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Post Graduate Students

Students (graduated in 1997)Name Supervisor TitleCG SmallmanPhD (WITS)(FT)

SH ConnellJPF Sellschop

Jul 1992-Jun 1997

The behaviour of Hydrogen in diamond and its role in diamond growthCurrently employed at DeBeers

I. Z. MachiMSc (UDW) (FT)

K Bharuth-RamSH Connell

Jan 1995-Mar 1997

Hydrogen and Muonium in diamond

M Bossenger(MSc-WITS)(FT)

SH Connell,JPF Sellschop

Jan 1994 Dec 1997

Site occupancy and molecular complexation of impurity ions in diamond studied by hyperfine interactions Currently employed at FNB.

Students not yet graduated by 1998Name Supervisors Thesis Title StatusE StorbeckMsc,PhD -WITS)Jan 1991 -(PT)

SH Connell,JPF Sellschop

Study of wide-band gap semi-conductors, specifically diamond, through emission electron channeling.

Currently employed at SAMES.Registered PTWriting 2nd draft of Thesis

T Stevens(Msc, PhD - (WITS)Jan 1993 - (PT)

SH Connell,JPF Sellschop

Nuclear reaction mechanisms by stacked foil techniques

Completed expt work, analysis + interpretation. Well advanced with 1st draft of Thesis.

R Nilen(MSc,PhD-WITS)Jan 1994 -

SH Connell,JPF Sellschop

Positron Spectroscopy in Diamond Thesis with examiners.

Z Vilakazi(PhD-WITS)Jul 1994 -

SH Connell,JPF Sellschop

Radiation from Multi-Hundred GeV electrons and positrons incident on Crystals

Thesis examined, completing corrections.Due to take up a CERN PostDoc

B Doyle(Msc, PhD-WITS)1995 -(FT)

SH Connell,JPF Sellschop

Impurity reactions in diamond Excellent progress, Experimental work complete. Analysis + write-up in progress

I. Z. Machi(PhD - WITS)1995 -(FT)

SH Connell,K. Bharuth - Ram

Hydrogen and Muonium in diamond Excellent progress, Experimental work complete. Analysis + write-up in progress

R.D. Maclear(Msc, PhD - WITS)(FT)

SH Connell,JPF Sellschop

Excellent progress, Experimental work almost complete.

C.G. Fischer(Msc, PhD - WITS)(FT)

SH Connell,DJ Britton

Excellent progress, Experimental work complete. Analysis + write-up in progress

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