Journal of Research of the National Institute of Standards and Technology … · 1997-05-08 ·...

Volume 102, Number 1, January–February 1997Journal of Research of the National Institute of Standards and Technology

General DevelopmentsInquiries about News Briefs, where no contact personis identified, should be referred to the Managing Editor,Journal of Research, National Institute of Standardsand Technology, Building 820, Room 126, Gaithersburg,MD 20899-0001; telephone: 301/975-3572.

NIST TO PLAY LEADERSHIP ROLE IN ILACA NIST representative was unanimously elected vice-chair of the International Laboratory AccreditationCooperation at the 14th meeting of ILAC in Amster-dam, the Netherlands, recently. As a result, the NISTrepresentative becomes the chair-elect and will assumethat position when the group meets in Australia in 1998.ILAC was established in 1977 as the InternationalLaboratory Accreditation Conference. The name waschanged to “cooperation” at the recent meeting, and amore formal structure was established in recognition ofthe importance of laboratory accreditation worldwide.Under the World Trade Organization and provisions ofthe agreement on Technical Barriers to Trade, confor-mity assessment practitioners are required to create anefficient, transparent, fair, and harmonized means forthe international acceptance of trade goods. The labora-tory accreditation community has been cited as acrucial element in a worldwide system needed tofacilitate trade.

DIRECTORY OF U.S. STANDARDSORGANIZATIONS UPDATEDOne of NIST’s most popular and widely distributedpublications, Standards Activities of Organizations inthe United States (NIST SP 806), has been updated andwill be available shortly. This is the seventh edition ina series begun in 1941 and was prepared for the NISTOffice of Standards Services. The new directory listsgovernmental and non-governmental organizationsengaged in mandatory and voluntary standards activi-

News Briefs

ties at the national level. It includes more than 700descriptive entries concerning the development of morethan 93000 U.S. standards. Other standards-relatedactivities (e.g., testing, certification, or accreditation)also are indicated. There is a section on sources forstandards and related information, a subject index,listings of acronyms and initials, former names of someorganizations, and other relevant information. In manysectors, particularly in sectors with rapidly developingtechnologies,consortia, user groups, and ad hoc taskgroups have emerged as significant forces in standardsdevelopment and adoption activities. Most of these non-traditional standards developers function outside theformal standards development framework. Specialeffort has been made to identify and include them.

DIRECTORY OF PRIVATE-SECTOR PRODUCTCERTIFICATION PROGRAMS UPDATEDThe revised Directory of U.S. Private-Sector ProductCertification Programs now lists 178 organizations thatprovide product certification services in the UnitedStates. NIST Special Publication 903 is designed tomeet the needs of federal agencies and standards writersas well as manufacturers, engineers, purchasing agents,distributors, and others concerned with product-relatedcertification procedures. The directory summarizes theactivities of organizations that operate within the UnitedStates, those that operate at both the U.S. and interna-tional levels, and those that operate as the U.S. compo-nent of an international program. It includesorganizations that administer a certification programand certify that products meet some criteria; administera program using an independent, third party certifier; orserve as the independent, third party certifier for a pro-gram administered by another organization. Entriesdescribe the type and purpose of each organization, thenature of the activity, products certified, standards usedin the assessment, certification requirements, anyaccreditation or recognition by a U.S. or foreignprivate-sector or government agency, availability of

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services, methods of cost determination, and other rele-vant details. Where available, a representation of the orga-nization’s mark is for the first time included with eachentry along with a pictorial index of all such marks.

GIQLP INFORMATION NOW ON-LINE FORPROCUREMENT OFFICIALS ANDGOVERNMENT SUPPLIERSInformation on the Government & Industry QualityLiaison Panel (GIQLP), a government and private-sector effort to develop a government-wide procurementpolicy for quality management system requirements, isnow available on-line through the World Wide Web.This interagency and industry partnership involves 12Federal agencies, three major industry associations, andrepresentatives from the American Society for QualityControl and the American National Standards Institute.The GIQLP home page describes the panel’s vision forquality in the 21st century and outlines a strategy toachieve this vision. The aim of the cooperative effort isto establish a single quality system within a contractor’sfacility with demonstrated capability for meeting bothgovernment and industry customer needs; recognitionand use of advanced quality concepts by governmentand industry in their procurement processes; and thedevelopment of uniform criteria and mechanisms withingovernment agencies whereby audits of basic qualitysystem requirements performed by one agency will beaccepted by all others.

Those with access to the World Wide Web can findinformation on GIQLP through the NIST TechnologyServices’ home page at http://ts.nist.gov/ts/htdocs/210/216/giqlp.htm.

NIST TBT AGREEMENT ACTIVITIES REPORTPUBLISHEDTBT Agreement Activities of the National Institute ofStandards and Technology 1995 (NISTIR 5898)describes the role of NIST’s National Center forStandards and Certification Information (NCSCI) insupport of the World Trade Organization (WTO) Agree-ment on Technical Barriers to Trade (TBT Agreement).NCSCI staff operate the U.S. WTO TBT inquiry pointfor information on standards, technical regulations, andconformity assessment procedures that might affectU.S. trade. Center staff also coordinate comments onforeign regulations, arrange for translations of foreigntechnical regulations and standards, and maintain theWTO (GATT) hotline (301) 975-4041 that provides thelatest information on proposed foreign governmenttechnical regulations issued by the WTO Secretariatin Geneva. In 1995, NCSCI staff responded to 329requests for TBT-related information, received 378

notifications of proposed technical regulations, andparticipated in activities to improve implementation ofthe TBT Agreement.

Copies of the annual report may be obtained bycontacting NCSCI, Room 164, NIST North, ext. 4040.

ENERGY-RELATED INVENTIONS PROGRAMMAKES RECOMMENDATIONSDuring September 1996, NIST recommended twoinnovative technologies forcommercialization to its De-partment of Energy partner under the Energy-Related Inventions Program. Viringe—a one-piece,plungerless, prefilled, sealed, and sterile syringe to beused to inject drugs into humans or to flush hospitalequipment such as catheters, and to replace traditionaltwo-piece plunger-type syringes. Harvesting Technol-ogy for Chinese Tallow Tree Oil Seeds—a machinefor harvesting oil seeds from Chinese tallow trees. Theoil bearing seeds are processed to obtain valuable oilsthan can be added to diesel fuel to extend supply.

FIRST FABRICATION OF HIGH-TEMPERA-TURE SUPERCONDUCTING JOSEPHSONJUNCTIONS ON SAPPHIRE BICRYSTALSUBSTRATESNIST scientists have fabricated the first grain-boundaryJosephson junctions on sapphire bicrystal substrates.The motivation for the work is to fabricate junctions inhigh-critical-temperature superconductors (HTS) forapplications requiring a large number of junctions, suchas voltage standards and programmable arrays.Successful operation at or near the temperature of liquidnitrogen, rather than at or near the temperature of liquidhelium, would enhance greatly the practicality andapplicability of Josephson-junction circuits. To date,most approaches to fabricating HTS junctions have notproduced devices with sufficiently uniform criticalcurrents for circuits containing more than a few junc-tions. Junctions fabricated across the grain boundary ofa bicrystal substrate have shown the promise of moreuniform properties. However, the substrate usually usedfor bicrystal junctions, SrTiO3 (STO), has very poormicrowave properties, which disqualifies it for voltage-standard applications. Sapphire is a candidate substratefor such high-frequency applications because it has alow dielectric constant and loss tangent.

The team fabricated junctions on commercial r-cutsapphire bicrystal substrates with a 248 grain boundarydown the center. To prevent reaction with the sapphire,an epitaxial CeO2 buffer layer was deposited prior to thegrowth of the YBa2Cu3O7 superconducting film. Thefilms were patterned into microbridges using standardphotolithography and ion milling. The resulting devices

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demonstrated “resistively shunted junction” characteris-tics with parameters comparable to bicrystal junctionson STO substrates but with somewhat larger spreads incritical currents. The team also demonstrated that agold overlayer can be used to reduce the resistance ofthe junctions without adversely affecting the criticalcurrent. Further, the layer protects the grain-boundaryjunction from environmental degradation. So far, theteam has produced junctions on sapphire that have thecharacteristic voltages necessary for voltage-standardoperation at a frequency of 20 GHz and an operatingtemperature of 60 K. However, further work is requiredto achieve the degree of critical current uniformitynecessary to fabricate a voltage standard demonstrationcircuit.

NIST LEADING INTERNATIONALCOMPARISON OF CAPACITANCE AT CCEREQUESTThe Consultative Committee on Electricity (CCE) ofthe International Bureau of Weights and Measures askedNIST to serve as the lead laboratory for an internationalcomparison of the electrical unit of capacitance, thefarad, and this comparison is under way. Its results,together with the results of a small number of compari-sons for other electrical quantities, are intended toprovide the basis for measurements supportinginternational trade in electronic and electrical products,including electronic instrumentation. The effort is beingorganized by a NIST scientist. The measurementsand analysis of results are expected to take 3 years tocomplete and will involve 13 countries in the fourgeographical regions of Western Europe, EasternEurope, the Asia-Pacific region, and North America.There has been unusually high interest in participating,with more requests to participate than could be accom-modated because of the 3-year time limit stipulated bythe CCE. Both the request and the interest reflect recog-nition of NIST’s leading position and expertise in capac-itance measurements. To date, the standards have beenmeasured by the National Measurement Laboratory inAustralia and the National Physical Laboratory in theUnited Kingdom and are now at the National ResearchCouncil in Canada.

The traveling capacitance standards that are usedin this comparison—two 10 pF fused-silica dielectriccapacitors in hermetically sealed, metal containers filledwith dry nitrogen—were developed and fabricated atNIST and are recognized as among the most stable andprecise capacitance standards in the world. Their SIcapacitance values have been determined from the NISTcalculable capacitor, which is characterized by the

lowest uncertainty assignment of any laboratory. Thesestandards have been used in international comparisonsbefore, but difficulties with shifts in the capacitancevalues were experienced. These shifts were attributed totemperature hysteresis effects induced by the largechanges in temperature associated with travel betweenlaboratories. To address this problem, a prescription fortemperature cycling was developed by NIST scientiststhat returns the standards to their normal state. In thepresent comparison, this temperature-cycling treatmentis being given to the standards as soon as they arrive ata participating laboratory.

NIST-ORGANIZED CONFERENCE ON THEFUTURE OF WIRELESS COMMUNICATIONSBRIEFS PARTICIPANTS WITH 50PRESENTATIONSThe wireless communications industry is evolving sorapidly that engineers and others involved are experienc-ing difficulty keeping abreast of developments. Tohelp address this situation, a NIST scientist recentlyorganized and served as chair of the 1996 WirelessCommunications Conference. This event was designedto provide a broad and integrated view of the technologyto its participants, with the goals of acceleratingindustry’s gravitation to superior technologies and thepromotion of standardization. Keynoter FederalCommunications Commission Chairman Reed E. Hundtaddressed the conference by videotape and emphasizedthat industry, not government, is responsible for develop-ing standards for the new wireless services. Fiftypresentations detailed developments to the 180 attendeeson a range of wireless technologies,including systems,active and passive components, measurements, packag-ing, antennas, and propagation. Many of the world’smajor wireless companies were represented in theprogram, which included two Japanese and twoEuropean speakers, and an exhibit offered a look at newcommercial technology. Aconference proceedings bookwas provided. Conference co-sponsors in addition toNIST were ISHM—The Microelectronics Society; theIEEE Components, Packaging, and ManufacturingTechnology Society of the Institute of Electrical andElectronics Engineers (IEEE); and the IEEE MicrowaveTheory and Techniques Society.

A conference highlight was the session held at NIST’sBoulder Laboratories, which featured four on-site labo-ratory presentations by NIST scientists. These talkshighlighted new developments in measurements forwireless communications. The closing session providedan overview of efforts to roadmap the wireless future.

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M 3 MEASURES GRATINGS FOR NASA’SAXAF PROJECTUsing the NIST Molecular Measuring Machine (M3),two gratings have been measured for NASA’s AdvancedX-ray Astrophysical Facility (AXAF) Project. Thegratings have lines that are nominally at 200 nm and 400nm pitches respectively. They are to be used as primarystandards in the production of high energy transmissiongratings (HETG) by the Center for Space Research atthe Masschusetts Institute of Technology. TheHETGsare an important component of the x-ray spectrometersystem on the AXAF-I space telescope. Launch ofthe AXAF-I satellite on the shuttle is scheduled forSeptember 1998.

To measure the average pitch of these primarystandard gratings, M3 used a single line scan operatingmode to count lines across a 10 mm span. This linecount was divided into the total distance, given by M3’shigh-resolution, Michelson interferometers, to yieldhighly precise measurements of the pitch. The analysisand cross checking of the pitch measurement data is stillin progress, but the preliminary measurement resultshave a fractional uncertainty of only 40310–6, far ex-ceeding the capabilities of any commercially availablescanning probe microscope. Further, the feature size isnot resolvable with most optical metrology systems andits long distance is outside the range of most electronmicroscope metrology systems.

HEAT-TREATED STEELS WITHROCKWELL-C-HARDNESSESMany precision components that must resist wear inharsh mechanical, thermal, and chemical environmentsare manufactured from heat-treated steels withRockwell-C-hardnesses in the range of 50-65. Typi-cally, to attain increased precision and good surfacefinishes, it is better to machine these components in thehardened state. In the past, the only reliable method fordoing so has been grinding. Due to the high costs asso-ciated with grinding, other methods are sought. Recentdevelopment of new, tougher tools has made it possibleto turn and mill steels in their hardened state. However,attainable precision and surface finish is limited bylarge cutting forces that can cause static and dynamicdistortion of machine, rapid tool wear, and unsteadymaterial flaw. Understanding these effects is necessaryif hard turning is to become an effective method forproducing high-precision components.

NIST scientists recently examined the dynamics ofmaterial flow in finish hard turning. They demonstrated

that, for most practical machining conditions, materialflow is dominated by the formation of segmented chipsdue to the formation of localized shear bands that format frequencies in the range of 50 kHz to 120 kHz. Tomeasure the corresponding temporal variations in thestresses acting on the tool during cutting, apolyvinylidine difluoride film was sandwiched betweenthe tool insert and the tool holder to provide a high-frequency sensor. Frequencies measured with thissensor corresponded well with estimates of segmenta-tion frequencies made from the study of the geometry ofchip segments. The sensor developed for this purposepotentially may be used as a process monitoring devicefor the detection of undesirable events such as tool wearand built-up edge.

CHARACTERIZATION AND HYBRIDIZATIONREACTIONS OF SURFACE-IMMOBILIZEDDNAScientists at NIST have developed a process for immo-bilizing single stranded DNA (probes) on metallicsurfaces, with precise control achieved over surfacecoverage. The orientations and conformations assumedby the surface-bound probes were determined, and therole of surface coverage on hybridization (defined asthe pairing of complementary, single-stranded DNAmolecules) was examined. Hybridization reactionsof DNA molecules immobi l ized on surfacesare currently of great interest in the developmentof novel genetic screening and sequencing technolo-gies.

Self-assembled monolayer technology was exploitedin the formation of a monolayer of surface-bound DNA.Thiol-derivatized, single-stranded DNA moleculeswere adsorbed on gold surfaces. The DNA moleculeswere diluted on the surface by co-adsorbing anotherthiol molecule, which served as a spacer on the surface.Significantly enhanced hybridization could be achievedby varying the relative surface concentrations of thethiol-derivatized DNA and the diluent thiol molecule. Italso has been determined that the adsorbed DNAmolecules interact with the surface primarily throughthe thiol functionality. The nucleotide bases of the DNAmolecule do not interact directly with the surface, withthe result that they are free to hybridize with comple-mentary DNA. The hybridization efficiencies obtainedfrom thiolated DNA/diluent thiol surfaces are muchgreater (two to five times more hybridization events)than have been observed for other DNA immobilizationstrategies.

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14C MEASUREMENTS TO INVENTORYATMOSPHERIC VOLATILE ORGANICCOMPOUNDS THAT CONTRIBUTE TOOZONE FORMATIONResearchers from NIST, the Environmental ProtectionAgency, and the Oregon Graduate Institute have devel-oped a method to isolate the volatile organic compoundfraction from whole air by chemical and cryogenicmeans and to measure its14C content accurately.Atmospheric volatile organic compounds (VOC) can beozone precursors, reacting with nitrogen oxides (NOx)in the presence of sunlight to produce ozone. Theprocess, known as photochemical smog, producesozone levels that often exceed the National Ambient AirQuality Standard (NAAQS) in many urban centers andrural areas throughout the United States. The NAAQSfor ozone is 0.12mL/L daily maximum over a 1 hperiod. The problem in regulating ozone concentrationslies in knowing to what extent do natural vegetativeemissions contribute to ozone formation. Accuratechemical measurements to determine the radiocarbon(14C) content of atmospheric VOC can give an accurateinventory of fossil and vegetative contributions andthus aid in more effective regulation of these ozoneprecursors.

The scientists reported on the first exploratory14C-VOC results from two composited urban tropo-spheric air samples, collected during the summer (1992)in Atlanta, GA. The upper limits of the percentage ofVOC originating from vegetative sources during themorning and evening hours in Atlanta were 9 % and17 %, respectively, measurements reported at the 95 %confidence level. Thus, at a minimum, 83 % of the VOCwere produced by fossil fuel emissions and could bereduced by effective control strategies. In theseexperiments designed to evaluate the entire VOC-14Cmeasurement process and obtain reliable estimates ofbiogenic contributions to atmospheric VOC, highprocess blanks (with concomitant high uncertainty)were measured. This emphasizes the importance ofcontrols throughout the multiple-step chemicalmeasurement process to ensure data quality. Additionalmeasurements on samples collected in Houston andNashville are under way to provide a measurementinfrastructure for the accurate determination of theseimportant atmospheric chemical species.

ACOUSTIC VIBRATIONS OF ABOSE-EINSTEIN CONDENSATEA NIST/University of Colorado team at its joint insti-tute JILA has recently observed collective excitations of

a Bose-Einstein condensate (BEC). The BEC producedat JILA consists of several thousand rubidium atomsconfined in a magnetic trap. When the trap is shaken,the BEC oscillates with characteristic frequencies, muchlike a bell rings with its natural tone when struck.

A theory that predicts the characteristic frequencieswas formulated by the Russian physicist Bogoliubov inthe 1950’s. Although Bogoliubov’s method is one ofthe cornerstones of the quantum theory of superfluids,it is strictly applicable only to weakly interacting Bosesystems. The gaseous BECs first produced at JILA in1995 are the first such systems in which it can be put toa stringent test. A theoretical group applied a modifiedversion of the Bogoliubov theory to the JILA BEC, andtheir predicted values of the characteristic frequenciesagree to within a few percent with the experimentalmeasurements. The experimental and theoretical resultswere published in separate papers in Physical ReviewLetters last summer; a team at MIT subsequently founda similar result for a BEC of sodium atoms. This worklays a foundation for quantitative exploration of thephysics of BECs.

MONITORING ULTRAVIOLET IRRADIANCEFROM THE SUNThe third North American Interagency Intercomparisonof Ultraviolet Monitoring Spectroradiometers,organized by NIST, was held June 17-24, 1996, at TableMountain, a plateau north of Boulder, CO. Its purposewas to characterize parameters that affect the accuracyof instruments deployed in solar ultraviolet (UV)monitoring networks and to compare the differentinstruments by making synchronized solar scans. Suchmonitoring networks, operated by the EnvironmentalProtection Agency, the National Science Foundation,the Smithsonian Institution, the Department of Agricul-ture, and the Atmospheric Environmental Service ofCanada, are used to measure the UV irradiance that maybe associated with changes in atmospheric ozone, theincidence of skin cancer, changes in the growth patternsof crops and forests, and other effects.

There was as much as 10 % variation between thespectral irradiance scales used by the networks and thescale maintained by NIST. Even with a common scaleand bandwidth, variations of approximately 4 % wereobtained among solar ultraviolet irradiances measuredby different instruments during the synchronizedmeasurements. The results indicate the need to maintaina consistent spectral irradiance scale over the long termwithin and between networks and to determine theresponsivities using this scale at the sites where theinstruments are deployed.

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NIST DEVELOPS HIGH-CONTRASTBROADBAND INFRARED POLARIZERDevelopment of polarization metrology in theinfrared atNIST is being driven by the needs of such diverse fieldsas optical communication, pharmacology, andinfraredimaging. Each of these applications depends on thequality and calibration of polarization components.NIST has constructed and tested a linear polarizer foruse with a broad range of visible and infrared radiation.The device uses Brewster angle reflections from fourgermanium plates arranged in a chevron geometry.Tests with 0.633mm (visible) and 3.39mm (infrared)wavelength lasers have shown very good extinctionratios, and the ratios are expected to be good out towavelengths up to at least 25mm. The high-qualitylinear polarizer that has been developed will be usedas a standard for calibrating commercially availablepolarizers.

INFRARED TRANSFER STANDARDDETECTORS DEVELOPEDInfrared detectors are now available that can provideNIST traceability for the wavelength range of 2.5mm to30 mm. The detectors have a blocked impurity banddesign employing arsenic-doped silicon. They weredeveloped at the NIST Low Background InfraredCalibration Facility (LBIR) in conjunction with aprivate company. Operating at 12 K, these detectors areunique in their spectral range; they have a high degreeof spatial uniformity and ultralow noise. These detec-tors meet the requirements of the aerospace industry andother government agencies to perform radiometriccalibrations of satellite sensors for a wide range of needsfrom environmental remote sensing to military applica-tions. The LBIR facility provides the basis for a numberof activities in the low-background infrared, such as thecalibration of cryogenic blackbody sources and spectralcharacterization of infrared optical components such asfilters and windows.

WORKSHOP HELD ON BONE PALLIATIONRADIOPHARMACEUTICALSAn estimated 80 000 people die of breast or prostatecancer in the United States every year. A significantnumber (60 % to 80 %) of these cases will experiencethe excruciating pain associated with bone metastases.Many new drugs in a class of radiopharmaceuticals,called bone palliation agents, are being developed in aneffort to relieve this condition. On Sept. 27, 1996, NISTand the Council on Ionizing Radiation Measurements

and Standards held a workshop to discuss the currentstatus of research in bone palliation radiopharmaceuti-cals and to identify future measurement needs in nuclearmedicine in general. Among the invited speakers wererepresentatives from the three nuclear reactor facilitiesin the United States as well as representatives from thetwo largest isotope-production facilities in Russia.Together, these facilities produce most of the radio-isotopes used in nuclear medicine in this country.

The workshop also was attended by representatives ofseveral radiopharmaceutical and instrument manufac-turers as well as the U.S. Government agencies involvedwith radiopharmaceutical production and regulation.Talks by the invited speakers allowed NIST’s radioactiv-ity group to set priorities for radionuclides to bestandardized in the next 2 to 3 years. The workshopconcluded with an open session to discuss attendees’concerns regarding measurement and regulation ofradiopharmaceuticals. Standardization of measurementprotocols can result in increased safety to the patient andto the hospital staff and can help to reduce patient costs.

NIST-INDUSTRY COLLABORATION LEADS TOIMPROVED RHEOLOGICAL MEASUREMENTCAPABILITYA joint effort between NIST and a private company hasresulted in a new transducer being marketed by thisleading manufacturer of rheological and thermal testingequipment. One of the major problems in rheologicalmeasurements is the large range of force or torque vari-ation in a single experiment, often covering three ormore orders of magnitude.

Accurate measurements require both good tempera-ture control of the sample and excellent long-time zerostability of the force transducer. One solution to the zerostability problem was the development of a force rebal-ance transducer (FRT) by the private company. Priorjoint research between NIST staff and engineers fromthe private company demonstrated anomalies in normalforce measurements with the force rebalance transducerunder certain experimental conditions. NIST and thecompany worked jointly to develop an interim solutionto the problem and informed, via joint publications andpresentations at technical meetings, the rheology andpolymer communities (major users of the FRT) of po-tential pitfalls in normal force measurements with theFRT as well as methods to work around the problemuntil a transducer upgrade was produced. The privatecompany has now brought to market a new transducerthat not only greatly improves the transducer normalforce capabilities but also increases the dynamic torquerange by more than an order of magnitude.

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HIGH-RE SOLUTION THERMAL IMAGINGSYSTEM DEMONSTRATED ON METALATOMIZATION PLUMEA new high-resolution thermal imaging system was usedto measure thermal emission from the spray plume ofNIST’s supersonic inert gas metal atomizer (SIGMA).Temperature and emissivity variations were measuredwith a spatial resolution of 100mm and a temperatureresolution of 10 K. This new technology, developedthrough the NIST Small Business Innovation Research(SBIR) program, uses a novel approach to capture twosimultaneous thermal images each at different wave-lengths in the near IR wave bands, at video framing rates(30 frames per second). The technology is targeted atprocess measurement and control for a variety of mate-rials processing devices such as atomization, sprayforming, thermal spray coating and welding where non-contact thermography of surfaces with varying emissiv-ity is required.

NEW NEUTRON REFLECTOMETERINSTALLED AT THE COLD NEUTRONRESEARCH FACILITYA neutron reflectometer recently was relocated from athermal beam tube in the NIST reactor hall to a coldneutron guide position in the Cold Neutron ResearchFacility (CNRF). This has resulted in a factor of fiveincrease in intensity with lower background—by far thebest achieved to date worldwide for this technologicallyimportant measurement method. This significantenhancement in performance is possible because of theincreased flux delivered by the new liquid hydrogencold source and the use of supermirror guide tubes,which effectively extend the angular range of reflection.This makes it possible to measure (for the first time withneutrons) reflectivities approaching 10–8 so that, forexample, it is now possible to probe the compositionalprofile across the thickness of single lipid bilayer filmswith a resolution of several tenths nanometers. Inaddition, non-specular reflectivity measurements onsuch systems, which can reveal critical structural infor-mation in these lipid layers, will now become feasible.

With the installation of new supermirror transmissionpolarizers, the reflectometer now has a polarized beamcapability where polarization efficiencies better than95 % can be achieved. These polarizers also have hightransmission efficiencies so that intense beams can beobtained. As a consequence, magnetic multilayersystems that exhibit giant magnetoresitive behavior,such as Fe/Cr, can be studied more effectively than everbefore to reveal, in microscopic detail, the magneticmoment magnitudes and orientations. The observedmagnetic behavior then can be correlated with the

measured structure, which can aid in the intelligentdesign of better layered materials for use in retrievinginformation stored magnetically on discs and tapes.

Other areas of important application for this improvedcold neutron measurement capability include studies ofdifferent oxide layers on silicon surfaces, which are ofinterest to the semiconductor industry, and the effect ofhydrogen interdiffusion on both the structural andmagnetic properties of a variety of thin film andmultilayer systems.

NIST STUDIES CARBON MONOXIDE INRESIDENTIAL BUILDINGSNIST recently completed a study of carbon monoxide inresidential buildings for the National Fire ProtectionResearch Foundation (NISTIR 5906). This studyfocused on the distribution of CO in residential build-ings as it relates to the installation of CO detectors. Thestudy was conducted to assess existing informationrelated to the questions of how many CO detectorsshould be installed in homes and where they should beinstalled to warn building occupants of a typical COconcentrations from, for example, furnace ventingfailures and attached garages. The study included aliterature review of the technical issues related to COdetection in homes, including residential CO sources,air movement and contaminant distribution in single-family residential buildings, and air and contaminantmixing in buildings.

While a number of studies relevant to CO mixing inhomes have been performed, the information is notsufficiently comprehensive to determine the appropriatelocation of these detectors in residential buildings. Anexperimental plan was developed for field measure-ments and computer modeling to obtain the technicalinformation necessary to make technically soundrecommendations on the installation of CO detectors inhomes. The project was overseen by a TechnicalAdvisory Committee consisting of detector manufactur-ers, organizations representing fire officials andbuilding code officials, and the Consumer ProductSafety Commission.

NIST SOFTWARE IMPROVES THE ACCURACYOF BRAIN PROBESNIST software recently proved to be a crucial factor inresolving unexplained accuracy issues discovered in thecalibration process and equipment at a Boulder, COfirm that designs, manufactures, and sells three-dimen-sional optical localizers for medical and industrialapplications. Their localizer is primarily used in neuro-surgery to allow a surgeon to track the location of a

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location of a probe within a patient’s skull. Obviously,such localizers must be calibrated to high accuracy.

ODRPACK, software developed by NIST, is uniquelywell-suited for modeling three-dimensional data such asthe data produced by localizers. By applying ODRPACKto their problem, the Boulder company was able to findand correct problems with their process. In addition,ODRPACK enabled them to develop new models for theoptical properties of their system. Now, every systemthey ship is tested and certified for accuracy usingsoftware built on ODRPACK.

ODRPACK solves the extended nonlinear leastsquares problem where both the explanatory as well asthe dependent variables have errors, a procedure some-times known as Orthogonal Distance Regression. Thealgorithm and the software were developed at NIST; thesoftware is available using the NIST Guide to AvailableMathematical Software (http://gams. nist.gov/).

NEW PUBLICATION FEATURESEXPERIMENTAL MODELS FORSOFTWARE DIAGNOSISNISTIR 5889, Experimental Models for SoftwareDiagnosis, explores the methods of collecting informa-tion within the software engineering community anddescribes the applicability of each method toward anunderstanding of the software development process.Experimentation and data collection are becomingaccepted practices within the software engineeringcommunity to determine the effectiveness of varioussoftware development practices. The document clarifiesthe concept of experimentation and identifies the bestdata collection techniques needed to validate softwaremethods that are effective. This understanding fosters abetter technical exchange of information betweenscientists and engineers in the software community.

ITL OFFICIALLY LAUNCHED AT NISTU.S. industries and companies that produce and useinformation technology will benefit from NIST’snew Information Technology Laboratory, which willproduce tests that encourage companies to developquality products and thus expedite technology’sentrance into the marketplace. NIST’s informationtechnology research will concentrate on developingtests and test methods for information technologies stillin the early stages of development. Research is underway in such areas as speech recognition, virtual realitymodeling language, digital video, cryptography, andmathematical modeling. The ITL works to promote the

development and use of information technologysystems that are interoperable, easily usable, scalableand secure. The ITL combines and expands the roles oftwo previous NIST entities: the Computer Systems andthe Computing and Applied Mathematics laboratories.In addition to working with partners in U.S. industry,ITL maintains its roles in serving other federal govern-ment agencies and in helping NIST’s own researcherseffectively use information technology. More informa-tion about ITL is available on the World Wide Web athttp://www.nist.gov/itl.

CONSORTIUM REPORTS ON INSTALLATIONEFFECTSSmall inaccuracies in flow meter measurements trans-

late into million-dollar errors for utility companies, fuelsuppliers, and manufacturers. That is why NIST’s FlowMeter Installation Effects Consortium is working tohelp improve the accuracy of flow meters installed inactual practice. The consortium’s newest report,Flowmeter Installation Effects Due to a Generic Header(NIST Technical Note 1419), describes how flowmetering accuracy can be altered by an upstream headerwith one inlet and two outlets. Headers are used tosubdivide large pipe flows into several smaller flowsto improve the measurement, reduce the cost of themetering or both. The new NIST report will help engi-neers compensate for pipe configurations that do notallow for ideal flow meter placement. Scientists studiedthe effects of the header using laser Doppler veloci-metry, an optical technique that can detect flowvelocities without inserting instrumentation into theflow. TN 1419 is available for $9 prepaid from theSuperintendent of Documents, U.S. GovernmentPrinting Office, Washington, DC 20402, (202)512-1800. Order by number 003-003-03415-1.

DIGEST AVAILABLE ON OPTICALFIBER MEASUREMENTSResearchers interested in the characterization of opticalfiber and related components will want a copy of thetechnical digest of the Ninth Symposium on OpticalFiber Measurements held at NIST’s Boulder, COlaboratories Oct. 1-3, 1996. Measurements of polariza-tion mode dispersion (PMD) and nonlinear processes inoptical fibers are two of the topics covered by sympo-sium papers. In the case of PMD, its statistical naturecomplicates measurement and makes accuracy verifica-tion difficult. Many of the papers, therefore, focus oncomparisons of measurement techniques. In wave-length division multiplexed systems employing optical

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amplification, high powers can lead to problems fromnonlinear processes such as Brillouin scattering andfour-wave mixing. These issues are included in severalpapers on the measurement of non-linear coefficientsand effective area. Technical Digest, Symposium on Op-tical Fiber Measurements, 1996, is available at no chargewhile supplies last. Contact the NIST OptoelectronicsDivision at (303) 497-5342.

NEW ANNEALING TECHNIQUE FOR OPTICALFIBER CURRENT SENSORSA NIST scientist recently completed work on a newtechnique for annealing optical fiber that permits thevirtually complete elimination of linear birefringence,even in moderately high birefringence fibers. Linearbirefringence is the condition in which specific orthog-onal linear polarizations of light propagate at slightlydifferent velocities, with the result that, in most cases,the polarization state will vary with propagation dis-tance. This condition is a problem in many optical fiberapplications, including the optical fiber current sensorsthat were the focus of the scientist’s work. Annealing toreduce birefringence in fiber was demonstrated at NISTin the mid 1980’s and subsequently developed suffi-ciently so that the process could be used in the fabrica-tion of commercial current sensors. One company isbeginning to manufacture sensors based on thistechnology, and several others are developing products.Unfortunately, not all optical fibers have been found tobe amenable to annealing, although the reason why wasnot well understood.

The scientist’s work has resulted in a new understand-ing that the ellipticity of the fiber core adds significantlyto fiber birefringence, even in fibers in which the ellip-ticity is too small to measure directly. Annealing effec-tively eliminates stress birefringence but has no effecton birefringence related to noncircular geometry. Asolution is to twist the optical fiber prior to annealing.The geometric birefringence is thereby averaged tozero, and the birefringence of almost any ordinaryoptical fiber effectively can be eliminated. A model ofthe twisted and annealed fiber has been developed thatfits experimental results for a variety of fiber types andtwisting rates and shows that the twisting rate needs toequal the geometric birefringence to achieve anisotropic fiber. Isotropic fiber coils provide the bestopportunity to evaluate the sensitivity of a fiber currentsensor, which is governed by a material parameterknown as the Verdet constant. Using a variety of twistedand annealed coils, the NIST scientist has been able tomeasure the Verdet constant of specific optical fibers

with a relative uncertainty of about 0.5 %, about a factorof six better than had been possible previously.

ELECTRON-COLLISION DATABASEDEVELOPED FOR GASES USED BY THESEMICONDUCTOR INDUSTRYNIST is in the process of building a new database ofcollision cross sections and transport data for electronsinteracting with gases used for the manufacturing ofsemiconductor devices. The data in this new databasewill be used primarily in the development of sophisti-cated plasma models for predicting the performance ofplasma processing reactors. Additionally, the in-depthanalysis associated with the synthesis of the data withinthe database will: (i) aid in the understanding of theproperties of low-temperature plasmas and the roleplayed by collision processes, (ii) help the developmentof more sophisticated in situ nonintrusive plasmadiagnostic techniques and plasma-reactor modeling, and(iii) impact our ability to provide a scientific under-pinning to the existing processing technologies andpromote the development of new plasma-assistedprocesses.

For this project, the available data are comprehen-sively synthesized, critically assessed, and distilled to arecommended set of cross sections and transport datathat accurately reflect the current state of knowledge forthe interactions of electrons with plasma processinggases. Work has been completed on the gases CF4 andCHF3.. The former is used widely in manufacturingsemiconductor devices and other applications, and thelatter has been proposed as a substitute of CF4 in theseapplications because the lifetime of CHF3 in the envi-ronment is much shorter (250 years) compared to that ofCF4 (50000 years). The completed work on both gasessoon will appear in two separate articles in the Journalof Physical and Chemical Reference Data and havebeen presented at the 1996 International Conference onPlasma Science and at the 49th Annual GaseousElectronics Conference. Sufficient data were availablefor CF4 to allow the synthesis of a complete set ofexperimental cross sections; however, only a verylimited amount of data were available for CHF3. Thesignificant gaps in knowledge concerning electron in-teractions with CHF3 that were exposed by this workhave prompted programs at several universities and na-tional laboratories to begin performing measurementsof unknown cross sections and transport processes. Therecommended data for both molecules have been madeavailable via the World Wide Web (at http://www.eeel.nist.gov/811/refdata) for easy access by all interestedusers.

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NEW DETERMINATION OF SI OHM YIELDSIMPROVED VALUE OF FINE-STRUCTURECONSTANTIn the International System of Units (SI), the unit ofresistance is the ohm. A new determination of the ohmusing the NIST calculable capacitor has recently beencompleted by NIST scientists. Comparison of the ohmwith the quantum Hall resistance (QHR) yields avalue for the von Klitzing constantRK. Assuming thetheoretical relationshipRK = h/e2, whereh is the Planckconstant ande is the elementary charge, a value for thefine-structure constant can be derived directly from theNIST calculable capacitor. The fine-structure constant isa fundamental measure of the interaction betweenatomic particles and atomic electromagnetic fields; italso can be obtained with high accuracy from certainexperiments using quantum electrodynamic (QED)theory. Thus, the new NIST determination of the finestructure constant can help test QED. The latest value isthe result of almost 3 years of work by NIST scientists.The ohm determination involves a long chain ofprecision measurements that start at the calculablecapacitor, where its capacitance value of 0.5 pF is deter-mined from a length measurement directly referred tothe meter. This SI value is then transferred to highervalue capacitance standards, then to resistancestandards, and eventually to a 1000V transportableresistor using ac transformer bridges. An ac-dc conver-sion then is made to obtain the dc value of the resistor.The comparison of the QHR with the realization of theohm through the calculable capacitor is made throughthe dc measurement of this 1000V transportableresistor.

The latest NIST value for the fine-structure constanta–1 is 137.036 003 760.000 003 3, which was pre-sented at the 1996 Conference on Precision ElectricalMeasurements. It compares favorably with a new similarexperimental determination by a scientist at the NationalMeasurement Laboratory in Australia and a new valuebased on QED and the experimental determination ofthe anomalous moment of the electron. The new NISTresult is believed to be more reliable than the previousNIST result, since that result was based on a singlemeasurement and the new result is based on a series ofmeasurements. The NIST work will provide data for theleast-squares adjustment of fundamental constants in1997. Any decrease in uncertainty for the experimentalvalue of the fine-structure constant enhances one’sability to determine many of the other fundamentalconstants and to test several of the basic physical laws ofnature.

NIST STANDARD RETARDER INCLUDED INTHE OPTICAL SOCIETY OF AMERICA’STIME CAPSULEA prototype standard optical retarder developed byNIST scientists was included in a time capsule recentlysealed by the Optical Society of America in commemo-ration of its 80th anniversary. The capsule will sit in thelobby of the OSA headquarters in Washington until thesociety’s 100th anniversary in 2016. Seventy itemswere selected by the Anniversary Committee fromsuggestions offered by society members.

An optical retarder is a device for providing a phaseshift between two orthogonal polarizations of light andcan be used to modify or determine the state of polariza-tion. The NIST standard retarder was developed at therequest of several companies. Manufacturers ofretarders (sometimes called waveplates) often havedifficulty in agreeing with their customers on theperformance of their products. Manufacturers of polar-ization measuring instrumentation need a calibrationstandard. The NIST device is intended to meet both ofthese needs. It was developed in part through a jointCooperative Research and Development Agreementwith two private companies and is expected to be avail-able soon as Standard Reference Material 2525. One ofthe companies will manufacture the SRMs; NIST willperform the characterization.

The NIST retarder derives its phase shift fromtotal internal reflection in a glass specially chosento minimize the effect of stress. It consists of twoconcatenated Fresnel rhombs carefully aligned so thatthe input and output beams are collinear. The retardanceis stable to within 0.18 retardance over input anglevariations of 618, wavelength variations exceeding50 nm, and temperature variations greater than 108C.The devices are designed to be nominally quarterwaveretarders (908628) at 1.3mm and have an accuratelymeasured retardance within an expanded uncertainty of0.18.

MANUFACTURER’S STEP TRANSLATIONCENTER RECEIVES CALS IMPLEMENTORAWARDA major automobile manufacturer received the CALSImplementor Honor Roll Award from the U.S. CALSIndustry Steering Group for using the new internationalstandard STEP (Standard for the Exchange of Productmodel data, officially ISO 10303) to transfer productdesigns between teams using different computer-aideddesign (CAD) systems. STEP replaces less effective

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methods of data exchange that have been barriers tostreamlining the process of developing new products.As a result of STEP, the automobile manufacturer andits suppliers are realizing reductions in costs and time tomarket, while enhancing the quality of their productsand agility of their processes. The auto manufacturer’sSTEP Translation Center is the means for exchangingdesigns for new products among its divisions, theircustomers, and their suppliers. The center is increasingthe degree of cooperation on the design of new products,which will move the products into production in lesstime and at a reduced cost.

NIST holds the Secretariat of the InternationalOrganization for Standardization Subcommittee onIndustrial Data (ISO TC184/SC4) under which STEPwas developed and has been a heavy technical contribu-tor to this international standard. Further, software toolsdeveloped under the Systems for Integrated Manufactur-ing Applications (SIMA) STEP Conformance Testingproject have been used extensively by industry. Thesetools isolate and enable rapid resolution of implementa-tion issues found in the commercial CAD translatorsthat are used by this center and others who are adoptingSTEP.

SMART TRANSDUCER INTERFACE DEMOAT SENSORS CONFERENCENIST, in cooperation with IEEE’s Technical Commit-tee on Sensor Technology of its Instrumentation andMeasurement Society, is developing a smart transducerinterface standard. A reference implementation of adraft protocol standard for digital communicationbetween sensors or actuators and microprocessorswas developed and demonstrated to the public onOct. 22-23, 1996 at the SENSORS Conference andExposition in Philadelphia, PA. The demonstrationconsisted of the integration of a NIST-implementedsmart transducer object model to two smart transducerinterface modules (STIM). The STIMs were developedseparately, by an instrumentation builder, and a sensorproducer. The proposed standard is anticipated tohave a significant impact. The instrumentation builderannounced it will market an STIM development kit inthe spring of 1997 in support of the standard. A privatecompany revealed the design of an interface chip thatimplements the standard, and an aircraft manufacturerdisclosed that it will implement the standard interface inits aircraft testing system.

LASER-DRIVEN THERMAL REACTORDEVELOPED FOR CHARACTERIZINGWASTES AND FUELSIn a collaboration with a private company, scientists atNIST have developed a new capability to determine thethermal properties and chemical reaction characteristicsof solid, liquid, and multiphase substances, such aschemical wastes, through rapid and controlled heatingwith laser radiation. The laser-driven thermal reactor(LDTR), for which the company holds a U.S. patent, isan off-line analytical device capable of providing nearlyreal time analyses of fuel streams.

The NIST LDTR is the first operational system to beassembled in theUnited States. Unlike conventionalthermal analysis techniques, which are designed to mea-sure a selected thermal or chemical property in a nom-inally constant temperature environment, the LDTRmeasures an integrated thermal response,representing the effects of multiple thermal and chemi-cal properties, in a dynamic environment characteristicof real-world reactors where the temperatures are highand rapidly changing. Temperatures in the LDTR rangeup to 2000 K and the heating rate can be as high asseveral hundred kelvins per second. This integrated, to-tal response of a substance to this dynamic temperatureenvironment is precisely the data needed to predict itsperformance in a full-scale chemical reactor.

The LDTR is composed of a disk-shaped substrate,on which rests the sample to be tested, that is contactedby a thermocouple and sits inside a sphere-shapedreactor. The assembly is mounted in achamber andheated by an infrared laser from opposing sides toachieve uniform temperature. Temperature measured bythe thermocouple is the response signature of the sub-stance. Additional information on the chemicalreaction can be gained from chromatography of thegases released during the process. The LDTR hasbeen demonstrated on nitro-compounds absorbed byactivated carbon, sulphur compounds in heavy fuel oil,and coals. The LDTR has the potential for becoming anon-line process control sensor that could be used tooptimize a thermal process, such as thermal oxidationor combustion, by monitoring the varying properties ofthe feed stream. An improved understanding of the ef-fects of heat rate and temperature on substance reactivebehavior, which will be gained from the LDTR,will suggest ways to enhance the energy efficiencyof a process and control the formation of chemicalbyproducts.

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FUNDAMENTAL CONSTANTSBIBLIOGRAPHIC DATABASE ONLINEFundamental physical constants, such as the speed oflight c, the Planck constanth, the Avogadro constantNA,and the mass of the electronme, are the links in thechain that binds science and technology together. Whileimproved values of the constants are required tochallenge the basic tenets of physics, they also arerequired for a wide variety of practical computations, forexample, the calculation of the excited states of atomsand molecules that play an important role in atmo-spheric chemistry and energy generation. Further, thesophisticated techniques that researchers mustdevelop to better determine the values of the constantshave significant impact in the field of metrology, wherethey change the nature of fundamental standards. The1983 redefinition of the meter in terms of the speed oflight and the 1990 introduction of practical representa-tions of the volt and of the ohm based respectively on theJosephson and von Klitzing constants are recent exam-ples.

To aid researchers in industry and academia, NISTrecently put online a bibliographic database on theconstants (http://physics.nist.gov/fundconbib). Thissearchable database gives citations for the most impor-tant theoretical and experimental publications in thefield since the mid-1980’s (with growing coverage ofearlier work). The database, which currently containsabout 1600 entries, is updated regularly.

The new bibliographic database complements thedatabase that gives the recommended values of theconstants themselves (http://physics.nist.gov/fundcon).This database has been online since October 1994 andreceives about 3000 queries each month.

SI ON THE INTERNETThe International System of units, universally abbrevi-ated SI (from the French Le Syste`me Internationald’ Unites), is the modern metric system of measure-ment. By law, “the metric system of measurement [is]the preferred system of weights and measures for UnitedStates trade and commerce.”

To aid the ever increasing number of SI users in theUnited States, NIST recently established an SI page onthe World Wide Web (http:// physics.nist.gov/SI). There,three important NIST publications on the SI maybe accessed directly: NIST Special Publication 811 (SP811), Guide to the International System of Units (SI);NIST SP 330,The International System of Units (SI);and the Federal Registernotice of Dec. 20, 1990(55 FR 52242-52245), which restates the interpretationof the SI for the United States by the Secretary of

Commerce. It is anticipated that this page, which alsocontains information on the role of the CGPM and theCIPM in maintaining the SI internationally, will becomerecognized throughout the country as the place to go forthe most definitive and up-to-date information on the SIand its proper use.

NIST COLLABORATES ON INSTRUMENTATIONFOR THE SOHO SATELLITEThe far UV physics group at NIST recently collaboratedwith researchers in the United States and Europe in thedevelopment and calibration of an instrument now inoperation aboard the Solar and Heliospheric Observa-tory (SOHO) satellite. The instrument, called the SolarEmission Monitor (SEM), is a filtered radiometerdesigned to monitor the extreme-UV solar flux in spaceby observation of He II 30.4 nm emission, as well as theintegrated flux from 0.1 nm to 82 nm. It uses a trans-mission grating, aluminum filters, and special siliconphotodiodes, all optimized for this task. The photo-diodes evolved from a prior collaboration between NISTand industry.

The flight SEM, several engineering versions of it,and the individual components (gratings, filters, anddetectors) were calibrated both monochromatically andwith undispersed radiation at the SURF II facility.

The satellite was launched in December 1995, andthe SEM, part of the Charge, Element, and IsotopeAnalysis System, is now providing valuable data fromwhich calibrations of other instruments can bederived. Details of the satellite, its experiments,and samples of data can be found on the World WideWeb at http://sohowww.nascom.nasa.gov/.

ELECTRONIC STRUCTURE CALCULATIONDATABASE RELEASEDFor calculating the structure of materials from firstprinciples, density functional theory is increasinglybecoming the method of choice. It has had great successrecently in explaining the properties of fullerene andamorphous and ferroelectric materials, and it requiresless demanding computations than do traditionalmethods of electronic structure calculation. However,its implementation relies on an approximation to thetotal electronic energy that is not uniquely defined inpractice. This makes it difficult for different practi-tioners to compare their results on a common basis.

NIST scientists addressed this problem by producinga World Wide Web accessible database that provideshigh-precision numerical data for all elements fromhydrogen through uranium, as computed in severalapproximations that are specified clearly. It may befound at http://math.nist.gov/DFTdata/.

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THREE TUNABLE X-RAY SPECTROMETERSDELIVERED TO NASANIST scientists have designed and delivered x-raymonochromators to support three NASA missions inx-ray astronomy. The AXAF (Advanced X-ray Astron-omy Facility), XTE (X-ray Timing Explorer), andAstro-E (scheduled for launch by Japan around theyear 2000) require widely tunable monochromaticx-radiation for pre-flight calibrations and subsystemdevelopment.

The AXAF instrument covers the range from 0.3 keVto 12 keV; it was installed at Marshall Space FlightCenter in late 1995. Scientists at the center credit theNIST-designed double-crystal monochromator to be avery useful calibration tool for AXAF and have postedtest results and photographs of the hardware on theWorld Wide Web (http://wwwastro.msfc. nasa.gov/xray/xraycal/xssrr/dcm/).

The large proportional counter array for the XTEmission was launched successfully on Dec. 30, 1995.One of the NIST-designed monochromators (1 keV to60 keV) is installed at Goddard Space Flight Centerwhere it is used to evaluate the performance of a dupli-cate instrument package.

NIST also supplied hardware for the Astro-E missionincluding, in addition to the basic monochromator, amulti-anode target array and electron gun to producelow intensity calibration points from 0.3 to 12 keV. Allmonochromators had dual pentagonal turrets for thediffraction crystals which were individually character-ized, and in some cases crystals and multilayers wereproduced in the group.

FIELD EMITTER ARRAYS FOR FLAT-PANELDISPLAYSField emission displays are being pursued by U.S.companies as a leap-frog technology with the potentialof negating the off-shore manufacturing advantage inactive matrix, liquid crystal flat-panel displays. Insupport of this developing industry, NIST scientistsstudy the physics of the field-emission cathodes used insuch displays.

One recent project modeled and tested the electronemission and electron trajectories from gated fieldemitter arrays. In another, field emitter cathodes werefabricated with integrated lenses co-planar to the gateelectrode for collimating electron beams from tips ofgated field emitter arrays. Linear planar lens electrodeson both sides of a line of emitters were demonstrated toprovide focusing by application of appropriate voltages.With focusing, the resulting line image was less than0.035 mm wide at 10 mm to 20 mm from the anode,compared to an unfocused image about 100 times

larger. This was the first demonstration of electron-beam focusing from field emitter arrays with anintegrated planar lens design in a well-documentedstudy with calibrated image registration.

LATTICE CHANGES IN SI EPILAYERS AND SISUBSTRATESCertain high-performance microprocessors are fabri-cated using epitaxially deposited thin silicon layersgrown on highly doped silicon wafers. In at least onecase, it was found that material from different vendorsgave differing production yields although all sourcesmet stated electrical criteria and appeared consistentusing the manufacturer’s current metrology toolbox.

In order to help diagnose this problem, NISTscientists examined the substrate crystal lattices usinghigh-resolution x-ray techniques developed at NIST.Measurements of the lattice spacing showed among thesources and even a rather large difference betweennominally identically processed samples from differentdiameter boules. In a second set of measurements, thelattice constant of the epilayer was measured withrespect to that of the substrate using conventional high-resolution double-crystal diffractometry. Fractionaldifferences obtained in these measurements range from20310–6 to 100310–6. The two measurements can becombined to obtain the lattice parameter of the epilayeritself.

There is some indication that the lattice parameterdifferences correlate with device yield, although theneeded control studies have not yet been undertaken.

NEW REPORT DESCRIBES IMPROVEDACCURACY IN OPTICAL RADIATIONAccurate measurements of infrared, visible, and ultravi-olet light are critical to our national defense, for remotesensing of environmental conditions, and for a widevariety of industrial processes. NIST provides opticalradiation standards and tests to ensure the accuracy ofthese measurements, and over the past few years, anaccumulation of technological advances has enabledNIST to switch to more accurate methods of transfer-ring calibration information to its customers.

NIST Technical Note 1421, A National MeasurementSystem for Radiometry, Photometry, and PyrometryBased Upon Absolute Detectors, has just been released.In it, the author describes these more accurate measure-ment methodologies in detail. For many years, calibra-tions have been performed on sources of optical radia-tion, such as standard lamps that are available throughthe NIST Calibration Program. However, calibrationsmade on detectors of optical radiation are often able to

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improve the accuracy of the measurement of the radio-metric, photometric, and pyrometric quantities ofinterest. As part of its responsibility to enable industryto adopt improved methods of metrology, NIST isencouraging its calibration customers to switch todetector-based methods of calibration, as described inthe Technical Note.

NEW PHOTOMETRIC CALIBRATIONCAPABILITIESNIST is responsible for the realization of the candela,one of the SI base units, and other photometric units forluminous flux, illuminance, luminance, and colortemperature. The NIST photometric units are based onstandard photometers traceable to NIST’s high-accuracycryogenic radiometer (HACR). Using detector-basedmethods to realize the photometric scales has reduceduncertainties of photometric calibrations and hasresulted in the availability of additional photometriccalibration services. Specifically, a new luminous fluxunit was realized recently using an innovative integrat-ing sphere method. Using this method, the NIST lumen,with improved accuracy, is now also traceable to theHACR.

A publication that provides extensive information onthe realizations of the NIST detector-based photometricunits and new calibration procedures for luminousintensity, illuminance, luminance, luminous flux, andcolor temperature is now available. NIST Special Publi-cation 250-37, Photometric Calibrations, replaces theprevious SP 250-15 (1987). These improved photo-metric measurements have been required for main-taining safety standards in the automotive and aircraftindustries. Improved photometric standards also aredriven by the lighting, display, and optical instrumenta-tion industries.

OPTICAL STANDARDS AID SEMICONDUCTORMANUFACTURERSDuring integrated circuit manufacturing, measurementsof the optical scatter of silicon wafers are oftenemployed inproduction-line diagnostics. However, thegeometry of commercial optical scatter instrumentationlacks standardization, making if difficult to comparevalues obtained by instruments made by differentmanufacturers. The bidirectional reflectance distribu-tion function, on the other hand, is a well-definedquantity and can be related to the power spectral density(PSD) of silicon wafer surface roughness and to theproduction-line optical measurements currently beingmade.

Researchers at NIST have developed an approach forcharacterizing low-level optical scatter instrumentationusing a spatial frequency response function. Thisfunction gives the sensitivity of an instrument with aspecified geometry to microroughness on differentlength scales, allowing the signal measured by theinstrument to be treated as an integration of the PSDwith the instrument’s response function. Algorithmswere developed for calculating this response function fordifferent geometries; and a computer program will bemade available, which will allow different instrumentmanufacturers to calculate the response function foreach of their products. This methodology is beingincorporated into ASTM documents describing thestandard practice for calibration of scanning surfaceinspection systems.

CIRMS HOLDS FIFTH ANNUAL MEETINGAT NISTThe Council on Ionizing Radiation Measurements andStandards (CIRMS) held its fifth annual meeting atNIST Nov. 12-14, 1996. The organization representsthousands of users of ionizing radiation and radioactivesources, who are engaged in industrial radiationprocessing and sterilization, medical radiation diagnos-tics and therapy, nuclear power, worker radiation protec-tion, and environmental measurement programs.CIRMS provides a forum for discussing ionizing radia-tion issues; identifying, defining, and prioritizingneeded work; disseminating information on standards;and organizing workshops and meetings to advanceionizing radiation technology. Thethrust of this year’sannual meeting was to discuss and prioritize the needsidentified in the CIRMS Report on National Needs inIonizing Radiation Measurements and to developspecific roadmaps for the most important needs in eachof four areas: radiation effects, medical applications,public and environmental radiation protection, andoccupational radiation protection.

More than 100 participants attended the meeting,which highlighted university contributions in radiationdosimetry and radioactivity measurements. Representa-tives attended from 15 corporations, eight federal andstate agencies, four national laboratories, and 20 univer-sities. A special session was included in this annualmeeting on standards activities in other professionalsocieties: ASTM, ANSI, the American Association ofPhysicists in Medicine, the Health Physics Society,and the National Council on Radiation Protection andMeasurements.

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OPTICAL FREQUENCY DIVISION BYA FACTOR OF THREENIST scientists, along with colleagues from the Univer-sity of Colorado, the University of Bonn, and theUniversity of Arizona, have developed a new scheme forcoherently connecting optical frequencies in a 3:1 ratio.They have demonstrated the method by locking theoutput of a Nd:YAG laser at 1064 nm with a CO over-tone laser at 3192 nm. This is a significant step in thedevelopment of simpler frequency-synthesis chains,since in combination with divide-by-two systems morerapid division convergence and greater flexibility indesign are achieved.

There are a number of examples where divisionby three is advantageous. For example, the opticalfrequency standard in Hg+ will use a very high-Q ultra-violet transition at 282 nm, and this will be excited witha twice-frequency-doubled Nd:FAP laser at 1126 nm.When this is divided by a factor of three, it results in awavelength of 3378 nm, which is close to a very impor-tant methane reference that can serve as a bridge to themicrowave region.

This work is part of a larger NIST effort to developnew methods and components that can contribute to thesimplification of optical frequency measurement andthe construction of much simpler frequency synthesischains. The long-term objective is a robust and simplechain linking the cesium frequency standard to theoptical region.

CALCIUM OPTICAL MOLASSESNIST scientists have achieved cooling and trapping ofcalcium using frequency-doubled diode lasers. Previoushigh-resolution spectroscopic studies of the 657 nmline in calcium were limited by the Ramsey-method,interaction-time linewidth to a few kilohertz. However,the cooled and trapped atoms should now allowmeasurements to the intrinsic linewidth of 400 Hz.Furthermore, the use of diode lasers at 423 nm for thecooling and trapping of the atoms and for interrogationof the 657 nm transition results in a relatively smallsystem that could be made transportable.

The system that generates the 423 nm radiation isparticularly efficient. Infrared diode-laser radiation isdoubled to 423 nm using a potassium niobate crystal.The fortuitous matching of this laser and nonlinearcrystal is such that the blue output is down in powerfrom the IR laser by only a factor of three.

This is a particularly attractive optical frequencystandard because the first-order Doppler shift isremoved by the trapping, the second-order shift is

reduced substantially by cooling, and the 657 nm line isonly slightly sensitive (in second order) to electric andmagnetic fields. In addition, the frequency (and hencevacuum wavelength) of the 657 nm transition is nowknown with a relative uncertainty of less than 1310–12,so it is immediately useful as a wavelength standard atthis uncertainty.

CRYSTALLINE NON-NEUTRAL PLASMASAn atomic frequency standard with good signal-to-noiseperformance can be constructed using large numbers ofions (>105) contained in a Penning trap (which achievestrapping using static magnetic and electric fields).However, to date it has been difficult to preciselycharacterize and control the Doppler shifts associatedwith the magnetron rotation of such a stored ion plasma.Recently, scientists at NIST have cooled such a plasma toform a rigid solid and have developed a method forcontrolling the rotation rate of this rotating solid. Theirmethods bring promise for the development of afrequency standard of high accuracy and excellentshort-term stability. In addition, they now have strongindications that their plasmas are sufficiently large thatthey exhibit bulk behavior and are characteristic ofinfinite, strongly coupled one-component plasmas. Thisis significant because such plasmas are models of denseastrophysical matter and this is the first laboratorysystem with the potential of generating them in thestrongly coupled regime.

The group had previously observed Bragg scatteringof laser light from crystallized plasmas, but the rotationof the plasma converted the usual Laue dot pattern toone of concentric rings. In recent experiments, they havegated (gate time small compared to the rotation period)an imaging system synchronously with the plasmarotation. This has allowed them to recover the Laue dotpattern and helped identify the favored lattice type asbody centered cubic. This is the predicted lattice for aninfinite, strongly coupled one-component plasma. Thegroup also has used a “rotating wall” to precisely con-trol the magnetron rotation of the crystalline plasma.The rotating wall is a rotating electric field generated bysix electrodes arranged around the equator of the trap.Bragg scattering studies show that the crystallineplasma orientation can be phase locked to the rotatingelectric field. This allows precise reproduction of thesame rotation rate from experiment to experiment, animportant step in controlling the time dilation shift dueto the plasma rotation. Other conditions that need to becontrolled to produce a constant time dilation shift arethe number of trapped ions and the strengths of thetrapping fields.

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DETECTION OF METHANE IN AIRIn a collaborative program with Rice University and theNational Oceanic and Atmospheric Administration,NIST has developed a laser-spectroscopy-based systemthat can determine methane concentration in air to1 n mol/mol. The approach is dramatically simpler andthe system is much more portable than the chemicalprocessing and gas chromatography methods usedcurrently. Furthermore, the new spectroscopic methodis a nondestructive, real-time measurement as opposedto the laborious analytical techniques now employed.

Methane in the atmosphere is believed to contributeto the greenhouse effect, so simpler methods for long-term monitoring are especially important. The normalconcentration of methane in air is about 2m mol/mol,and measurements over the past decade indicate that, forreasons that are not yet well understood, the averageconcentration has been increasing at a rate of about10 n mol/mol per year.

The spectroscopic system operates at a laser wave-length of approximately 3.3mm on a methane line thatis well separated from those of water, making themeasurements undisturbed by varying water concentra-tions. The 3.3mm radiation is generated by difference-mixing the outputs of a diode-pumped YAG laser at1.06mm and a diode laser operating at 805 nm. Thesystem easily could be designed to be transportable andalso could be installed at fixed locations to provide con-tinuous monitoring. An additional benefit ofspectroscopic monitoring is that the system can be tunedto be sensitive only to methane containing13C ratherthan the usual12C atoms. Thus, it should be possible touse this nonradioactive species in a method similar toradioactive labeling to monitor the movement of13C-la-beled methane through any type of system.

HIGHER FREQUENCY OBSERVATIONS USINGLASER MAGNETIC RESONANCEA NIST scientist and co-workers from Oxford Univer-sity and the University of Bonn recently have madespectral observations of the FeD2 molecule near6.9 THz (43mm) using laser magnetic resonance(LMR) spectroscopy. This required modification oftheir spectrometer so that it could be operated at thesehigh frequencies. To date, these are the highestfrequency FIR LMR observations and the first FIRobservations of a vibrational bending spectrum madeusing LMR spectroscopy. The FeD2 observations areimportant because they provide accurate spectral infor-mation for searches for the presence of iron in the inter-stellar medium where iron has never been observed.

Aside from the immediate value of this particularobservation, the development of a capability for higherfrequency observations opens up significant new oppor-tunities for measurements of importance to radio astron-omy and upper-atmospheric research. The modificationto the spectrometer allows measurements at frequenciesas high as 9 THz, just about the same upper limit forradio astronomy measurements. This expanded range ofLMR measurement now covers fine-structure transi-tions in a number of atoms and molecules, providing thepotential for making the exacting laboratory frequencymeasurements needed to support searches for theseatoms in space. Furthermore, ClO, a very importantmolecule in the upper atmosphere, has a fine structuretransition at 8.2 THz. This transition might provide thebest means for determining the abundance of thisspecies in the upper atmosphere, thus contributingneeded information on atmospheric chemistry relatingto depletion of the ozone layer.

HISTORIC BOSE-EINSTEIN EXPERIMENTPRESERVED BY SMITHSONIAN INSTITUTIONThe apparatus in which Bose-Einstein condensation(BEC) was first created in June 1995 will soon be on itsway to the Smithsonian Institution. Called JILA-1, itwas constructed in the JILA instrument shop for NISTand University of Colorado scientists who workedtogether on the successful experiment. The first BEC“blob” contained about 2000 rubidium atoms. WhenJILA-1 was “retired” recently, it was able to condenseabout 8000 atoms at about 3 minutes per data point. Thenewest generation of equipment, also constructed in theJILA instrument shop and called JILA-3, can condenseclose to 1 million atoms in less than 1 minute.

The Smithsonian sent two of its staff to JILA tophotograph and familiarize themselves with the experi-ment and the apparatus. The data gathered will preservethe record of the various steps leading to the experi-ment’s final success.

The Smithsonian has no immediate plans to displayJILA-1 but will hold it in quality storage either on theMall or at a well-maintained warehouse in FairfaxCounty, VA.

NIST COORDINATES INTERNATIONALPROJECT ON CHARACTERIZATION OFCERAMIC POWDERSAn international project on ceramic powder characteri-zation has been completed recently. Countries partici-pating in the joint project were Belgium, Sweden,Germany, Japan, and the United States. The project

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(Subtask 8) was conducted under the auspices of theInternational Energy Agency’s Implementation Agree-ment for a Programme of Research Development ofHigh Temperature Materials for Automotive Engines,with the U.S. Department of Energy as the operatingagent. The objective of the project was to evaluate thereliability and reproducibility of measurement methodsfor primary and secondary properties of six industriallyimportant ceramic powders and involved round-robintesting in industrial and government laboratories in thevarious countries. Primary properties are defined asdirect measurements on powders, e.g., particle sizedistribution, specific surface area, density, chemicalcomposition, and phase analysis. Secondary propertiesare those determined for powders suspended in waterand include surface chemistry, rheology, sedimentation,flow and compaction of granules, and the bulk densityand porosity of compacts. All studies of primary prop-erties have been completed, and the results are beingused to develop international standards and StandardReference Materials (SRMs). Studies of secondaryproperties will be continued in a subsequent project,which is now being initiated (Subtask 10).

CONSTITUTIVE EQUATIONS FOR STEELSAT HIGH TEMPERATURESConstitutive equations for steels at high temperatureshave been developed for the C-Mn and microalloyedsteels. These equations are used to calculate the stress-strain curves for a given steel as a function of tempera-ture, strain rate, and austenite grain size, in rangestypically encountered in steel rolling mills or forgingshops. The stress-strain response of a steel is importantbecause it determines the power requirements forrolling or forging, and it also reveals microstructuralchanges of the steel during deformation. Researchers atNIST developed these equations in collaboration withthe University of British Columbia (Canada) and thesteel industry under a joint project, “MicrostructuralEngineering in Hot-Strip Mills,” sponsored by theAmerican Iron and Steel Institute.

A computer program has been written to facilitate thestress-strain calculations, with input of steel grade,temperature, strain rate, and austenite grain size. Theprogram is being used by the steel industry as a stand-alone tool for the calculation of stress-strain curves andthe determination of critical strain for dynamic recrys-tallization. The program also has been incorporatedsuccessfully into a process model that simulates thesteel rolling process in hot-strip mills and calculates themechanical properties of the hot-rolled products.

METALLURGICAL ASPECTS OF THE SINKINGOF THE RMS TITANICOn April 14, 1912, the “unsinkable” RMS Titaniccollided with an iceberg in the north Atlantic southeastof Newfoundland and sank with a loss of more than1500 lives. In 1985, Robert Ballard, on board the Alvinfrom the WoodsHoleOceanographic Institute, found herunexpectedly broken in half under 12 000 m of water.This discovery concentrated scientific study of the sink-ing on the properties of the hull steel. Materials recov-ered in 1991 were subjected to a limited analysis bylaboratories in Canada, looking at microstructure andfracture toughness. The steel was found to be extremelybrittle at ice-brine temperatures.

NIST is cooperating with the Defense ResearchEstablishment Atlantic in Canada, the University ofMissouri2 Rolla, Bethlehem Steel, and the Society ofNaval Architects and Marine Engineers in a study todetermine more thoroughly the structure and propertiesof the hull steel used in the construction of the Titanic.Material recovered in August of 1996 is being tested fortensile strength and fracture toughness, and themicrostructure is being characterized thoroughly usingoptical metallography, as well as scanning and trans-mission electron microscopy. The Titanic material isbeing compared to hull steel from the RMS Nomadic (atender for the Titanic), the RMS Olympic (a sister shipto the Titanic), and after recovery of a fragment thissummer, the RMS Luisitania. All of these vessels werebuilt by the same shipbuilder with steel from the samefoundry within 5 years of each other, and a comparisonwill determine whether the steel used for the hull of theTitanic was of standard quality for 1912. Results of thisstudy will form part of a broadcast on the science ofthe sinking of the Titanic to be aired in April on theDiscovery Channel.

NIST COLLABORATES ON COMPOSITESPROCESS MONITORINGNIST has started a collaboration with a major carmanufacturer to test a fast optical fiber process moni-toring system in an industrial composites processingenvironment. The system was developed in response toa series of industry workshops in which processmonitoring and control were identified as critical needsfor composites manufacturing in the commercialmarketplace. Research at NIST led to the developmentof a fluorescence method that was able to monitor thecuring of several types of industrial resin systems underlaboratory conditions. The next step is to demonstratethe measurement system on processing equipmentsimilar to that used in production.

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The auto manufacturer’s laboratory is ideally suitedto test the capabilities of the NIST monitoring systembecause it is engaged in molding trials as part of anAdvanced Technology Program effort. The collabora-tion will test the NIST technology on at least twodiffer-ent resin systems, includinga private company’s cyclicpolyester and acommercial polyurethane during themolding of several hundred parts. The auto manufac-turer is particularly interested in the capability of theNIST method to monitor processing of the polyester.Conventional methods based on temperature measure-ments are ineffective in this polymer because this resinpolymerizes without heat release, an unusual character-istic. Preliminary work indicates that the NIST systemmay be able to reduce the time required to determine acritical property of the polyester, the molecular weight,from the currently required 8 h to less than 10 s.

For both resin systems processing speed isparamount, and the process monitoring system isdesigned to obtain complete spectra in less than 0.1 sand perform data processing to provide a controlvariable within another three seconds. The monitoringsystem also has been designed to interface with liquidmolding facilities unobtrusively, and, therefore, nomodifications were required to any processing equip-ment at the auto manufacturer. The optical fiber sensoris introduced into the molds through a standard thermo-couple port and is reusable for many molding cycles.

A NIST scientist is spending 6 months at the automanufacturer to participate in molding trials. Theimportant scientific issues to be addressed includeassessing the ability of the sensor system to provide themolecular weight of the private company’s material, thedegree of cure of the polyurethane system, the rugged-ness of the system, and the ease with which the automanufacturer can make use of the informationmeasured.

NIST HOSTS DARPA IC&V EVALUATION TEAMOn Nov. 4, 1996, NIST hosted a working meeting of theEvaluation Working Group (EWG) of the DARPA Intel-ligent Collaboration and Visualization (IC&V) Program.Working with other EWG participants from privateindustry, and the National Intelligence MappingAgency, NIST will develop methodologies, metrics, andtesting tools to evaluate generation-after-next collabora-tion systems and supporting infrastructural technologies.NIST’s EWG efforts focus on the development of testingand instrumentation technology that will enable collabo-ration systems developed through the DARPA IC&Vprogram to be evaluated in terms of objectives fortask performance, scalability, heterogeneity, and inter-operability.

CRADA PROJECT TO DEVELOP A MINIMUMINTEROPERABILITY SPECIFICATION OFPKI COMPONENTS COMPLETEDAs part of its efforts to assist in the development of aPublic Key Infrastructure (PKI), NIST produced aMinimum Interoperability Specification of PKI Com-ponents (MISPC) in cooperation with 10 industrypartners through Cooperative Research and Develop-ment Agreements (CRADAs), which provides a basisfor interoperable PKI components from differentvendors.

The MISPC specifies a minimal set of features, trans-actions, and data formats for the various certificatemanagement components that make up a PKI. Thespecification addresses certificate generation, renewal,and revocation; certificate and certification path valida-tion; signature generation and verification; and cross-certification. The goal of the specification is to furtherinteroperability among heterogeneous public keycertificate management systems, thus enabling largeuser communities to take advantage of digital signaturetechnology.

NEW PUBLICATION FOCUSES ONTECHNOLOGY REQUIRED FOR A COMPUTERTO READ HANDPRINTED PARAGRAPHSNISTIR 5894, Teaching Computers to Read Hand-printed Paragraphs, presents a set of algorithms requiredfor a computer to read a paragraph of unconstrainedhandprint. The process involves isolating the lines ofhandprint, segmenting the lines into character images,classifying the character images, and spell-correctingthe classifications. Applications that could benefitfrom this technology include the automated readinghandprinted messages sent via facsimile machine andthe processing of forms that contain multiple-lineresponses to open-ended questions.

NIST HOSTS PROTOTYPE CONFERENCINGPRODUCTS INTEROPERABILITY EVENTSMore than 20 hardware and software firms, telephonecompanies, and network service providers participatedin the recent Event-120, the industry’s second inter-operability testing event for providers of data confer-encing products and services. The event tested T.120-compliant, multipoint data conferencing applications.Of more than 3000 tests performed, 95 % resulted insuccessful links between vendors.

The International Multimedia TeleconferencingConsortium, Inc. (IMTC) organized the event tofacilitate the rapid development and delivery of T.120standards-based conferencing products and services,

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and to continue promoting the importance of industry-wide interoperability as a base for building consumerconfidence. Conferencing technologies are used inapplications such as distance learning, telemedicine,corporate training, and working collaboratively withdistant colleagues. T.120 applications currently includeshared whiteboarding and multipoint file transfer.Consumer-oriented applications that require real-time,multipoint data delivery, such as multiplayer games, on-line chat programs, and virtual reality simulations, alsoare expected to incorporate the T.120 standards, a seriesof standards for real-time, multipoint dataexchange. The evolving series, initially adopted by theInternational Telecommunication Union in March 1995,continues to be extended. Programs such as Event-120ensure that the standards are interpreted and imple-mented by different vendors in a way thatadvances industry-wide interoperability of theirproducts. As has been proven with other successfultechnologies,such as electronic mail and fax machines,interoperability of products and services is essential towidespread acceptance. A second test event was heldconcurrently, IMTC’s third H.324 Interoperability TestEvent. During the session, participants performedstructured interoperability tests between products basedon the ITU-T H.324 standard for videoconferencing.H.324 protocols tested were G.723, H.263, H.245 andH.223.

OPTICAL FINGERPRINT RECOGNITION INFINANCIAL AND INTERNET SECURITYAPPLICATIONSNIST researchers combined optical correlation methodsand digital neural networks to provide more accuratereal-time fingerprint matching for financial, credit, andInternet security applications. The Information Storageand Interconnect System Project, sponsored by theFederal Bureau of Investigation (FBI), explored howoptical methods of image storage and three-dimensionalholography can support various correlation methodsrecognizing unique patterns such as fingerprints. Suchmethods would be more accurate and user friendly thancurrent optical correlation or retinal scanning, in whicha laser beam is shot from a charged-couple device intothe subject’s eye for identification.

Fingerprints are differentiated by a process known asminutia matching, in which the coordinates of the ridgeending of the fingertips are used for differentiation.However, this method tends to result in a number offalse positives. In the past, when the FBI took a finger-print, it was compared with others that were filed, basedon basic physical characteristics, a time-consuming,costly, and inexact process.

In optical pattern recognition, the fingerprint image isloaded onto a liquid crystal spatial light modulator andis Fourier transformed into a three-dimensionalhologram by a system lens developed by a NISTscientist. Then, the correlation of the input is analyzedvia the output plane. The optical system can moreaccurately enter the input pattern into the neuralnetwork system, which in turn can recognize and differ-entiate a pattern when it is introduced to the systemagain. When used in addition to minutia matching, thetechnology adds another dimension to the identificationspecifications, allowing a more detailed search of theneural network.

Possible commercial applications include the use offingerprint images for credit card verification,automatic teller machine access, and Internet access inplace of or along with passwords. NIST researchers areseeking industry collaborators to move into theproject’s next phase of refining the neural network andtesting the prototype system in industry. NIST plans towork with the Financial Services Technology Consor-tium, an organization of banks, financial serviceproviders, technology companies, national laboratories,universities, and government agencies to advance thecommercialization of the technology.

PROCESS TO DEVELOP ADVANCEDENCRYPTION STANDARD BEGINSNIST recently launched a participatory process withAmerican industry to develop an Advanced EncryptionStandard, a means of scrambling data to protect vitalelectronic information with a high level of security. Anotice in the Jan. 2, 1997, issue of theFederal Registerinvites security product manufacturers, voluntarystandards organizations, government computer users,and others to comment on the draft minimum accept-ability requirements and draft evaluation criteriadescribed. These will help lay the groundwork forevaluating and choosing the mathematical formula, oralgorithm, to be specified publicly by the standard.

The AES will be a Federal Information ProcessingStandard, which applies to agencies of the FederalGovernment, and will be available for voluntary use bycompanies and others who wish to use a strong encryp-tion standard backed by the Federal Government. TheData Encryption Standard, for example, is a currentfederal standard that is used extensively by many orga-nizations, including the financial industry. Writtencomments on the draft criteria may be sent by April 2,1997, to the director of the Information TechnologyLaboratory, FIPS for AES Comments, A231 Technol-ogy Building, NIST, Gaithersburg, MD 20899-0001,e-mail: [email protected].

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INTERNATIONAL FIBER MEASUREMENTSCOMPARISON DONEAn international round robin to assess the quality ofmeasurements of polarization mode dispersion inoptical fibers has been coordinated by NIST and carriedout by 16 participants in the fiber manufacturing andinstrumentation industries.

Polarization mode dispersion can limit transmissioncapacity of optical fiber communication links. PMDresults when birefringence in the fiber causes a lightpulse’s propagation speed to be a function of itspolarization state. Over long distances, these pulses mayinterfere with the pulse ahead or behind, causing errors.

Accurate measurement of PMD in both optical fibersand other components is essential to determine acommunication system’s capacity and to designlong-haul systems with optimal spacing betweensignal-conditioning amplifiers. The manufacturers inthe United States, Europe and Japan who participated inthe round robin each measured PMD in three specimensusing up to four different measurement methods. Areport of the results is available from Paul Williams,MC 815.02, NIST, Boulder, Colo. 80303-3328,(303) 497-3805, fax: (303) 497-3387, e-mail:[email protected].

UPDATED “ONE-STOP” INDUSTRY GUIDETO NIST AVAILABLEThe newGuide to NIST, an update of the popular 1993“one stop” information resource, is now available tothose interested in the agency and its industrial partner-ship opportunities. The 164-page volume describeshundreds of different research projects, grants, industryoutreach programs, services, and facilities.

To facilitate finding specific data about NIST, theguide is divided into sections covering each of theagency’s four major programs: the Advanced Technol-ogy Program, the Manufacturing Extension Partnership,the National Quality Program and the multidisciplinaryLaboratory Program (describing cooperative researchefforts, research facilities and services for each ofNIST’s laboratory units).

Individual items include contact names, addresses,phone numbers, e-mail addresses and where present,World Wide Web URLs. A detailed subject index clearlymaps all paths to topics addressed in more than oneNIST program area. For a free printed copy, send aself-addressed mailing label to NIST Public andBusiness Affairs, A903 Administration Bldg., NIST,Gaithersburg, Md. 20899-0001 or fax requests to (301)926-1630. An electronic version of the Guide to NISTwill be online later this year at http://www.nist.gov.

MICROMECHANICAL TESTER AVAILABLEWITHOUT A LICENSEA micromechanical machine developed by NIST forassessing the tensile strength and other mechanicalproperties of thin films is available for commercial usewithout a license. The tester is operated in digitalclosed-loop control through a laboratory computer,which records such parameters as force and displace-ment five times per second. It is reproducible fromcommercially available or readily machinable compo-nents at reasonable cost.

The piezoelectric-actuated machine can apply forceup to 2 N with a measurement resolution of 0.0001 Nand can impose displacements of up to 50mm (with ameasurement resolution of 25 nm).

NIST uses the device to measure the mechanicalproperties of thin metal films produced by physicalvapor deposition (known as PVD) and electrodeposi-tion.

In this application, the tester uses a specially designedsilicon-frame tensile specimen that has been fabricatedusing microlithography. A special clamp holds thesilicon frame during cutting so that no tension is appliedto the thin film suspended across it. Force is measuredindirectly using an eddy-current sensor near a flexiblemeasuring beam cantilevered above the base plate.Grip displacement is measured using two similardisplacement sensors.

NEW SYSTEM TAKES TEMPERATURESON A ROLLDuring the processing of all commercial metals, an ac-curate knowledge of the processing temperature is crit-ical to achieving the final product’s desired properties.This is particularly true during the rolling of sheet alu-minum where temperature can influence formability,surface appearance and mechanical strength.

Under a cooperative research and developmentagreement, NIST and the Aluminum Association havedevised and eddy current probe that can operate in theharsh rolling mill environment and take a sheet’stemperature with making contact with the metal.

NIST uses the aluminum sheet itself as the basicelement of a resistance thermometer. The temperature isdeduced from the relationship between electricalresistivity and temperature. A standard deviation ofplus-or-minus 38C was achieved for exit temperatures(the temperature of the sheet as it leaves the rollingstand and is coiled for cooling and shipment).

NIST’s prototype measurement system was testedonline in an aluminum rolling mill. the eddy currenttechnique—that does not require metal contact or

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restrict metal movement during processing—achievedaccuracies approaching those of contact thermocouplesapplied to processed metal held stationary at the exitstand of the rolling mill. To obtain a copy of report no.38-96, which describes the new temperature measure-ment system, contact Sarabeth Harris, Div. 104,NIST, Boulder, CO 80303-3328, (303) 497-3237,e-mail: [email protected].

RESEARCHERS COLLIDE VIRUSES, CELLSWITH LASER TWEEZERSCells stick together, viruses stick to cells, and whiteblood cells stick to invading organisms. This ability tostick to another entity is what makes much of biologywork. To evaluate the ‘‘stickiness’’ of cells and viruses,researchers at NIST and Harvard University have devel-oped a new measurement technique.

Using two optical tweezers laser beams that trap aparticle at their focal point the researchers held a redblood cell and virus-coated microsphere stationary.While one optical tweezer kept the blood cell motion-less, the other moved a microsphere covered with virusparticles into a collision with the cell. In this way, theresearchers evaluated the effectiveness of highlypotent viral inhibitors to block viruses from attaching tored blood cells.

Results of the OPTCOL (for optically controlledcollision) experiment show that in low concentrationsof inhibitors, the moving microsphere captured the redblood cell, pulling it out of the trap, while high concen-trations prevented adhesion.

Optical tweezers were developed at a private labora-tory in the 1980’s, but this new research marks the firsttime they have been used for this type of measurement.The new technique allows measurements that could notbe performed using conventional methods.

CHICAGO CENTER HELPS FIRM INCREASESALES, JOBSCenters throughout the country affiliated with NIST’sManufacturing Extension Partnership (MEP) are help-ing America’s smaller manufacturers improve theircompetitiveness by adopting new technologies andmodern business practices.

For example, the Chicago Manufacturing Center(CMC), an MEP affiliate since 1994, recently helped aprivate manufacturing company achieve QS 9000certification. QS 9000 is a stringent quality certificationprocess designed especially for automotive equipmentmanufacturers. CMC provided the company with aninitial performance audit and then guided it through the

certification process. The company says it is the firstcircuit board company in the world to attain QS 9000certification.

The quality improvement effort has helped thecompany achieve new levels of satisfaction among itscustomers, win supplier awards and reduce customerreturns to fewer than 100 parts per 1 million parts.In 1996, sales increased 11 % and the company hired15 new employees.

NEW MEASUREMENT GIVES SHARPER LOOKTO FLAT PANELSNIST researchers have devised a technique that offersboth manufacturers and industrial customers a way tomore accurately measure the contrast ratios of displaysin laptops, airplane cockpits, home entertainmentcenters, and other applications.

The simple-to-implement measurement tool consistsof one or more specially designed, glossy black plasticcones that technicians place between the display and themeasuring device. The cones substantially shield themeasurement of dark areas from illumination by lighterareas. Additional cones can be inserted to reduce theglare to an insignificant amount.

Without the cones, illumination from nearby lighterareas on the display surface introduces reflections intothe lens of the measuring instrument. Contrast-enhanc-ing techniques, such as anti-reflection coatings or newerdisplay technologies exhibiting darker blacks, furtherincrease the error from conventional measurementmethods due to glare. The varying results have fueledcomplaints and made comparisons between brands ordifferent technologies difficult.

The Video Electronics Standards Association willvote later this year to include the NIST technique in itsnew flat-panel display measurement standard.

NACLA PROPOSAL ACCEPTED AT RECENTMEETINGRepresentatives of the nation’s conformity assessmentcommunity decided at an open forum on Jan. 7, 1997,to go forward with a proposal to establish the NationalCouncil for Laboratory Accreditation. NACLA will bea cooperative partnership between the public and pri-vate sectors to provide a comprehensive U.S. nationallaboratory accreditation infrastructure.

In the resulting system, the testing and calibrationdata from a laboratory accredited by a NACLA-recognized body will receive worldwide acceptancebased on the laboratory’s competence. The open forum,co-sponsored by NIST, ANSI and ACIL, was attended

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by more than 350 interested stakeholders from laborato-ries, accreditors and those who require accreditation,both from industry and government. Immediate planscall for the election of a balanced, interim board ofdirectors made up of members from the various stake-holders. The board will lay out a proposal for NACLAfunctions and a permanent structure. These proposalswill be reviewed by stakeholders at future publicmeetings.

OPTOELECTRONICS WORK HIGHLIGHTEDIN NEW BOOKA comprehensive overview of NIST’s optoelectronicsresearch is provided in a new publication entitledOptoelectronics at NIST (NISTIR 5054).

This work is spread through 18 divisions in sixresearch laboratories. The publication describes49 projects involving some 170 NIST staff. Eachdescription details the project’s size, objectives,constituency and major current tasks.

A limited number of copies are available fromthe Optoelectronics Division, NIST, Boulder, CO80303-3328, (303) 497-5342, e-mail: [email protected]. It also is available electronicallyat http://www.nist.gov/div815.

PLAN TO COORDINATE U.S. STANDARDSNOW ONLINEIn recent years, the competitiveness of the United Statesin the global marketplace has become more and moredependent on the standards and conformity assessmentsystems used by its industries. This growing linkbetween standards and competitiveness makes it vitalthat U.S. systems become more coordinated, worktoward an agreed-upon standards infrastructure,and blend public and private responsibilities andparticipants.

To help make the desired improvements, PresidentClinton signed the Technology Transfer and Advance-ment Act of 1995 (Public Law 104-113) on March 7,1996. The act directs NIST to lead a national effort tocoordinate standards and conformity assessment activi-ties among federal, state and local government agencies,and the private sector.

The implementation plan for this private/public teameffort was submitted to Congress and is now available onthe World Wide Web. The plan describes an approach todevising a U.S. system in and procedures for the areas ofvoluntary standards, product certification, accreditationof testing and calibration laboratories, registration of

quality and environmental management systems, andformal recognition of qualified private-sector bodiesenhancing U.S. competitiveness in world markets. Theimplementation plan for P.L. 104-113 is available on theNIST Office of Standards Services home page athttp://ts.nist.gov/ts/htdocs/210/plan.htm.

Standard Reference Materials

REVISED STANDARD TO HELP CURB DRUNKDRIVERSNIST issued its first Standard Reference Material forensuring the accuracy of breathalyzer and blood alcoholconcentration tests in 1985. Since then, laws regardingdrunk driving have become more sophisticated. Allstates have set presumptive blood alcohol concentrationlimits above which a driver is presumed drunk. Federallaws set limits for pilots, truck and bus drivers, and evenspecify separate levels for drivers carrying hazardousmaterials. Newly issued Standard Reference Material1828a (Ethanol in Water Solutions) will verify theaccuracy of breath and blood alcohol measurements overthe wide range of legal limits used by federal and statelaw enforcers. Crime labs can use the SRM as a bench-mark to check the accuracy of breathalyzer and bloodalcohol analyses. Medical laboratories can use thisSRM for checking the accuracy of clinical blood alco-hol tests. In addition, the food industry has found SRM1828a useful in determining the alcohol content offoods. SRM 1828a can be purchased for $165 fromthe NIST Standard Reference Materials Program,Room 204, Building 202, Gaithersburg, MD 20899-0001, (301) 975-6776, fax: (301) 948-3730, e-mail:[email protected].

Standard Reference Data

NIST COMPLETES NEW VERSION OFHIGH-TEMPERATURE SUPERCONDUCTORSPROPERTY DATABASEStandard Reference Database 62: High TemperatureSuperconductors, Version 2.0, has been completed byNIST scientists. This database provides evaluatedthermal, mechanical, and superconductor property data

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for the class of materials commonly called high temper-ature superconductors, including cuprates (e.g.,YBa2Cu3O7–x), bismuthates (e.g., Ba1–x K x BiO3), andthe relatively new borocarbides (e.g., YNi2B2C). Thematerials are described by specification and characteri-zation information that includes processing details andchemical compositions. Physical characteristics such asdensity and crystal structure are given in numerictables. All measured values are evaluated and supportedby descriptions of the measurement methods,procedures, and conditions. In all cases, the sources ofthe data are fully documented in a comprehensivebibliography.

Especially significant in Version 2.0 is an unusualcollection of data from the Science and TechnologyAgency (STA) of Japan. The STA data were produced ina Japanese study of the processing and properties ofhigh-TC materials and involved a unique coordination ofthe efforts of government laboratories, academia, andindustry. The result was a unique collection of propertyand characterization data for single batches of materials.The STA data were compiled by Japan’s NationalResearch Institute for Metals, in Japanese, and thoseresults were provided to NIST as part of a NIST-NRIMdata exchange agreement.

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March 3, 1997USABILITY ENGINEERING 2:

MEASUREMENT AND METHODS

Location: National Institute ofStandards and TechnologyGaithersburg, MD

Purpose: To bring together industry and government toexchange information and strategies for achievingeffectiveness, efficiency, and satisfaction in computer-based government systems. New for 1997 is a specialfocus on measurement and methods.Topics: Government usability success stories, webusability, expert review vs usability testing, customizingthe usability process for your project, developing guide-lines, applying standards, usability in legacysystems, evaluating collaborative tools, the bottom lineon usability, getting usability into the RFP, usability inEurope, and challenges in measurement and evaluation.Format: One day with keynote and plenary talks,parallel tracks for novices, experts, and managers.Audience: Project development managers, chief infor-mation officers, government contractors, procurementofficials, analysts and engineers, technical staff andresearchers, product vendors, consultants, policymakers, and users.Sponsor: NIST—The Natural Language Processingand Information Retrieval Group and the Visualizationand Virtual Reality Group, both of the InformationAccess and User Interfaces Division within the Infor-mation Technology Laboratory.Contacts: Laura Downey, NIST, Building 225,Room A216, Gaithersburg, MD 20899-0001,phone: 301/975-4659, fax: 301/840-1357, email:[email protected] Laskowski, NIST, Building 225, RoomA216, Gaithersburg, MD 20899-0001, phone: 301/975-4535, fax: 301/840-1357, email: [email protected].

Calendar

March 3-5, 1997THE NORTH AMERICAN ISDN

USERS’ FORUM (NIUF)

Location: Tampa, FL

Purpose: To address high-level concerns over a broadrange of Integrated Services Digital Network (ISDN)issues and to reach a consensus on ISDN Implementa-tion Agreements.Topics: Multimedia applications, messaging andanswering, mass marketing, wiring and powering, andsimplification of ISDN ordering.Format: Working (breakout) groups, executive steer-ing committees, and plenaries.Audience: ISDN users, ISDN implementors, ISDNservice providers, and Customer Premise Equipment(CPE) vendors.Sponsor: NIST.Contact: NIUF Secretariat, NIST, Building 820, Room445, Gaithersburg, MD 20899-0001, phone: 301/975-2937, fax: 301/926-9675, email: [email protected].

March 4-6, 1997RCS RANGE CERTIFICATION MEETING

Location: NIST-BoulderBoulder, CO

Purpose: To inform the RCS Community on RCSMeasurement range certification and support planningof the DOD RCS Certification Demonstration Program.Topics: Measurement Assurance/Improvement Plans(MAP) certifications; philosophy/procedures RCSCertification Demonstration Program.Format: Presentations and discussion.Audience: RCS Community.Sponsors: NIST, Wright Labs, and Wright-PattersonAFB.Contact: Lorant Muth, NIST, MC-813, 325 Broadway,Boulder, CO 80303, phone: 303/497-3603, fax: 303/497-3122, email: [email protected].

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May 19–23, 1997CONFERENCE ON RADIONUCLIDE

METROLOGY AND ITS APPLICATIONSICRM ‘97


Purpose: To provide an opportunity for the exchangeof information on techniques and applications ofradionuclide metrology, and toencourage internationalcooperation in this field.Topics: Alpha-particle spectrometry, gamma-ray andbeta-particle spectrometry, life science, low-levelmeasurements, radionuclide metrology techniques(including direct activity measurements), and nucleardecay data (measurements and evaluations).Format: Oral communications, poster presentations,and business meetings of the ICRM working groups onradionuclide metrology and itsapplications.Audience: Radionuclide metrologists.Sponsors: NIST and the International Committee forRadionuclide Metrology (ICRM).Contact: J. M. R. Hutchinson, NIST, Building 245,Room C114, Gaithersburg, MD 20899-0001, phone:301/975-5532, fax: 301/926-7416, email: [email protected].

June 6–8, 19971997 IEEE MTT-S

INTERNATIONAL MICROWAVE SYMPOSIUM

Location: Colorado Convention CenterDenver, CO

Purpose: The Institute of Electrical and ElectronicsEngineers (IEEE) and Microwave Theory and Tech-niques Society (MTT-S) International MicrowaveSymposium is the foremost and largest conference andexhibition of it’s kind in the world. It’s purpose is toprovide a forum for engineers and scientists to report onrecent microwave product development.Topics: Latest developments in microwave compo-nents, power generation, amplification, monolithictechnology, millimeter waves, field theory, computer-aided design, measurements, wireless communicationsand radio-frequency (rf) technology.Format: Symposium, workshops, exhibition.Audience: Microwave engineers.Sponsors: NIST and IEEE Microwave Theory andTechniques Society.

Contacts: Claude Weil, Chair, Electromagnetic FieldsDivision, NIST, 325 Broadway, Boulder, CO 80303-3328, phone: 303/497-5305, fax: 303/497-6665,email: [email protected] Marks, Vice-Chair, Electromagnetic FieldsDivision, NIST, 325 Broadway, Boulder, CO 80303-3328, phone: 303/497-3037, fax: 303/497-7828,e-mail: [email protected] Kanda, Vice-Chair, Electromagnetic FieldsDivision, NIST, 325 Broadway, Boulder, CO 80303-3328, phone: 303/497-5320, fax: 303/497-6665,email: [email protected].

June 9–10, 1997YEAR 2000 INTERNATIONAL

SYMPOSIUM


Purpose: To raise international awareness of the prob-lems that could arise from the millennium change from1999 to 2000. Discuss possible strategies and methodsfor correcting system date processing.Topics: Awareness of year 2000 problems, assessmentof the extent of the year 2000 problem, renovatingsystems, validating changes, and implementation ofsolutions.Format: General sessions and panel discussions,vendor software and computer exhibitors.Audience: International computer users and develop-ers.Sponsors: NIST, Data Administration ManagementAssociation National Capitol Region (DAMA-NCR),Interagency Working Group on the Year 2000, U.S.Office of Management and Budget, U.S. FederalAviation Administration, and U.S. Department ofDefense.Contact: Judith Newton, NIST, Building 820,Room 562, Gaithersburg, MD 20899-0001, phone:301/975-3256, fax: 301/948-6213, email: [email protected].

132


July 14–18, 1997FOURTH INTERNATIONAL MEETING

ON CHEMICAL KINETICS


Purpose: To bring together scientists from differentdisciplines who use chemical kinetics to explore areasof common interest.Topics: Free radical thermodynamics, reactions ofperoxyl radicals, halogen oxides, and others.Format: Lectures and posters.Audience: Scientists.Sponsors: NIST, Environmental Protection Agency(EPA), and National Aeronautics and Space Administra-tion (NASA).Contact: Robert Huie, NIST, Building 222, RoomA261, Gaithersburg, MD 20899-0001, phone: 301/975-2559, fax: 301/975-3672, email: [email protected].

August 4–6, 1997ULTRASONIC AND DIELECTRIC

CHARACTERIZATION TECHNIQUESFOR SUSPENDED PARTICULATES


Purpose: To provide a vehicle for the presentation anddiscussion of current research and future challenges infracture science. The focus is on the fundamentalaspects of fracture in the disciplines of mechanics,metallurgy, ceramics, polymer science, physics, andchemistry.Topic: Fracture in materials.Format: Lecture.Audience: Scientists.Sponsors: NIST and the Institute for Mechanics andMaterials, (IMMS).Contact: Robb Thomson, NIST, Building 223, RoomA124, Gaithersburg, MD 20899-0001, phone: 301/975-8349, fax: 301/926-5665, email: [email protected].

133

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May–June 1995

Volume 100, Number 3

Journal of Research of the

National

Institute of

Standards and

Technology

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National Institute of Standards and Technology

NISTTechnical PublicationsPeriodical

Journal of Research of the National Institute of Standards and Technology—Reports NIST researchand development in those disciplines of the physical and engineering sciences in which the Institute isactive. These include physics, chemistry, engineering, mathematics, and computer sciences. Papers cover abroad range of subjects, with major emphasis on measurement methodology and thebasic technologyunderlying standardization. Also included from time to time are survey articles on topics closely related tothe Institute’s technical and scientific programs. Issued six times a year.

Nonperiodicals

Monographs—Major contributions to the technical literature on various subjects related to theInstitute’s scientific and technical activities.Handbooks—Recommended codes of engineering and industrial practice (including safety codes) devel-oped in cooperation with interested industries, professional organizations, and regulatory bodies.Special Publications—Include proceedings of conferences sponsored by NIST, NIST annual reports, andother special publications appropriate to this grouping such as wall charts, pocket cards, and bibliographies.

National Standard Reference Data Series—Provides quantitative data on the physical and chemicalproperties of materials, compiled from the world’s literature and critically evaluated. Developed under aworldwide program coordinated by NIST under the authority of the National Standard Data Act (PublicLaw 90-396). NOTE: The Journal of Physical and Chemical Reference Data (JPCRD) is publishedbimonthly for NIST by the American Chemical Society (ACS) and the American Institute of Physics (AIP).Subscriptions, reprints, and supplements are available from ACS, 1155 Sixteenth St., NW, Washington, DC20056.Building Science Series—Disseminates technical information developed at the Institute on buildingmaterials, components, systems, and whole structures. The series presents research results, test methods, andperformance criteria related to the structural and environmental functions and the durability and safetycharacteristics of building elements and systems.Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment ofa subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of thesubject area. Often serve as a vehicle for final reports of work performed at NIST under the sponsorship ofother government agencies.Voluntary Product Standards—Developed under procedures published by the Department of Commercein Part 10, Title 15, of the Code of Federal Regulations. The standards establish nationally recognizedrequirements for products, and provide all concerned interests with a basis for common understanding ofthe characteristics of the products. NIST administers this program in support of the efforts of private-sectorstandardizing organizations.

Order thefollowing NIST publications—FIPS and NISTIRs—from the National Technical InformationService, Springfield, VA 22161.Federal Information Processing Standards Publications (FIPS PUB)—Publications in this seriescollectively constitute the Federal Information Processing Standards Register. The Register serves as theofficial source of information in the Federal Government regarding standards issued by NIST pursuant tothe Federal Property and Administrative Services Act of 1949 as amended, Public Law 89-306 (79 Stat.1127), and as implemented by Executive Order 11717 (38 FR 12315, dated May 11, 1973) and Part 6 ofTitle 15 CFR (Code of Federal Regulations).NIST Interagency Reports (NISTIR)—A special series of interim or final reports on work performed byNIST for outside sponsors (both government and nongovernment). In general, initial distribution is handledby the sponsor; public distribution is by the National Technical Information Service, Springfield, VA 22161,in paper copy or microfiche form.

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