Nuclear Decay Data at NPL

Paddy ReganNPL Radioactivity Group, AIR Division

& Department of Physics,

University of Surrey

Nuclear Data?• ‘Nuclear Data’ and its evaluation underpin many areas of both

applied and fundamental nuclear science, including– Nuclear (waste) fuel assay & fission fragment identification– Nuclear forensics– Nuclear reactor operation / efficiency modelling– Radioisotope production (e.g., reaction cross-sections)– Radiopharmaceutical applications (activity standardisations, dosimetry

calculations)– Identification and characterisation of ‘new’ radio-isotopes– Fundamental studies of nuclear structure physics

– Input into International nuclear databases e.g., NEA / IAEA / JENDL/ NNDC

What is nuclear data?• Measured values of a range of nuclear energy and time parameters, including

– Nuclear ground state masses, decay modes (a, b, fission,,..) and decay energies.

– Nuclear decay lifetimes and partial decay modes • Competing internal decays verses beta/alpha decay modes.• Beta-delayed neutron probabilities, Pn(%) values, in fission fragments.

– Nuclear reaction probabilities (‘cross-sections’) as a function of energy, (n,f), (p,f) reactions etc., e.g., thermal neutron capture cross-sections.

– Reaction product distributions from e.g. thermal and fast-neutron fission.– Excited state properties of nuclei, characteristic gamma-ray energies,

relative P g (%) values, transition rates from nuclear excited states (lifetimes range from ~10-15 s 1010 secs) internal conversion coefficients and gamma-ray decay multipolarities.

– Magnetic and quadrupole moments of nuclear excited and ground states.– …lots more.

Examples of recent ‘nuclear data’ standardisations from NPL

• Lifetime of the decay of 223Ra.• Gamma-ray emission probablilities in the

decay of 111Ag.• 236Np production and separation.• Evaluation of fission fragment distributions

from 25 MeV protons on Natural Uranium.• First identification and structure information

on 162Sm, 166Gd (RIKEN, Japan)

Some recent (2014 ff) papersre nuclear data from the NPLGroup.

223Ra half-life

NPL has led workshops which have brought together nuclear physics researchers from academia and national research laboratories with end-user stakeholders (e.g., EdF. IAEA, CCFE/UKAEA) who are interested in the accurate measurement and application of nuclear data to present the current status and discuss ongoing needs and possible future collaboration in this developing area.

Aspects of nuclear data-related research which were presented included: i) Measurements of nuclear fission residues and neutron capture cross-sections; ii) Nuclear decay data information from spent fission fuels including decay heat etc.;iii) Nuclear databases, who maintains them & what information do they contain and need? ; iv) The new decay spectroscopy of exotic, neutron-rich isotopes at new radioactive beam facilities world-wide; v) Standardisations of medical radiopharmaceutical and naturally occurring radioisotopes; vi) Areas of nuclear data needs from various end-user stakeholders such as EDF and NIRO.

Hosted IoP/NNL/NPL sponsored

Workshop on Nuclear Data, Current Data, Uncertainties, Applications and Needs

30 October 2014

IoP/NNL/NPL Nuclear Data Workshop30th Oct 2014 > 80 external delegates

‘Recent’ NPL involvement in ‘state of the art’ nuclear spectroscopy programmes

RIBF, RIKEN, Japan, EURICA,New isotopes and spectroscopy of fission fragments (Nov 2014).

Isolde Decay Station, CERN, Switzerland. Decay spectroscopyof 207Hg & 207Tl (Aug. 2014)

NANA:The NAtional Nuclear Array

Compact, high-efficiency, good granularity, acceptable resolution gamma-ray spectrometer array.

Gamma-ray detection both in g-g coincidence mode (and later) for use in beta-gamma

Current design, 12 LaBr3(Ce) in close geometry,

Space for additional ‘gating’ detectors (HpGe, or Si beta-detector) to be added later,

Robert Shearman, NDA-NNL funded PhD student, based at NPL, registered at University ofSurrey, working on ‘Development of a Novel Gamma-ray Detection System For Fission Fragment Management and Evaluation’. Begun Oct. 2014.NNL supervisor, Dr. Robert Mills ; NPL Supervisor, Dr. Steven Judge ;NPL/U.Surrey supervisor: Prof. Paddy Regan

Courtesy:R.ShearmanNDA / NNL funded PhD Student at NPL &U. Surrey

Conceptual design, for NANA.

Initial design:12 detectors in fixed geometry with source in central position.

Cylindrical LaBr3(Ce)Scintillation crystals, 1.5” diameter and 2.0” in length.

Digital time stamped DAQUsing CAEN 1 GHzDigitisers.

Development of novel spectrum and coincidence analysis techniques.

Time-correlated (1 GHz samples) gamma-ray coincidence analysis using LaBr3(Ce) Detectors. Analysis done on ‘list mode data’ and analysed ‘event by event’.Uses ROOT software (from CERN).

Fast-neutron induced fission on 238U studies at IPN Orsay, ongoing right now. Investigation of ‘in-beam’ prompt gamma-ray flux and overall prompt fission gamma-ray spectrum. (Also new data on neutron-rich fission isotopes for future characterisations).Currently using MINIBALL gamma-ray detectors; workshop at NPL 19-20 March 2015 to discuss wider programme using NANA detectors.

Future uses and applications of NANA array and detectors?

Fast-timing Gamma-ray Spectroscopy Nuclear Physics Workshop to be held at NPL 19-20 March 2015.

Proposals for a range of experimental programmes linked to Nuclear DataMeasurement with Fast-timing LaBr3(Ce) gamma-ray spectrometer arrays:

1) 252Cf fission source decay (at Argonne National Lab, USA).2) Fast-neutron fission on 238U and 232Th (LICORNE @ IPN-Orsay, France).3) Decay spectroscopy at the CERN-ISOLDE decay station.4) AGATA+FATIMA @ GANIL, France for precision structure studies of neutron-rich isotopes (fission radionuclides).5) Decay spectroscopy and beta-decay lifetimes of neutron-rich fission fragments (RIKEN, Japan & FAIR-GSI, Germany)