journal of research of the national institute of standards ... · telecommunications industry—850...

Volume 105, Number 2, March–April 2000Journal 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 101, Room E215, Gaithers-burg, MD 20899-2500; telephone: (301) 975-3577.

NIST RADIO STATION NOW TRANSMITTINGAT FULL POWERAs a result of a recently completed upgrade, NIST’sstandard time and frequency radio station WWVB nowbroadcasts at over 50 kW, five times more power thanpreviously.

The upgrade, which included adding more powerfultransmitters and thoroughly refurbishing the systemantennas, extends the usable range of the 60 kHz stationnear Fort Collins, CO, to most of the North Americancontinent. It means that clock and watch manufacturerscan install tiny WWVB-receiving antennas in theirproducts that will automatically reset to track officialU.S. time. Similar receivers can be designed into almostany appliance that contains a clock, such as computers,kitchen ranges, microwave ovens, thermostats, tele-visions and video cassette recorders. One nicefeaturethe clock will reset automatically after a poweroutage once it has received the WWVB signal.

World War-II-era transmitters were replaced withmore modern, reconditioned Navy transmitters, whichallow WWVB to operate with greater reliability as wellas increased power. Antenna system improvementsincluded replacing 35-year-old, pole-mounted trans-mission lines with underground lines; redesigning andrefurbishing two huge antennas and their mountingsystems; and improving the antenna tuning coils andtheir servo controllers.

Technical questions regarding this project should bedirected to Wayne Hanson, NIST, MC 847.40, Boulder,

News Briefs

CO 80303-3337; (303) 497-5233; fax (303) 497-6461;[email protected] Contact: Fred McGehan, (303) 497-3246;[email protected].

NEW NIST EFFORT SEEKS TO IMPROVEUTILITY OF PROPERTY DATAMuch of science and technology owe their progress tothe careful collection, logging and interpretation of data.And as information technology becomes more efficient,so do the methods scientists use for sorting and access-ing data. Now hoping to improve the utility of elec-tronic materials property data, NIST scientists have justembarked on a project to standardize the way suchinformation is posted on the World Wide Web.

NIST is inviting others in the materials property datacommunity to join this effort called Materials PropertyData Markup Language, or MatML. The goal ofMatML is to create a standard markup language forweb-based materials property data collections. Whilecurrent hypertext markup language specifies elementsof web page design, it contains no mechanism fortagging or specifying any of the hundreds of materialsproperties that materials scientists and engineers need toknow. MatML will address interpretation and interoper-ability of this information.

The goal is to develop a markup language that willdescribe the data source, the material and its properties.Ultimately, this project could allow researchers toeasily use electronic materials property data frommultiple sources in models, simulations or distributeddatabases. For more information or to join theMatML effort, contact project leader Ed Begleyat NIST, (301) 975-6118, [email protected]. The MatMLweb site can be found at www.ceramics.nist.gov/matml/matml.htm.Media Contact: Linda Joy, (301) 975-4403; [email protected].

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NEW FEATURES FOR THE NIST ATPALLIANCE NETWORK SITEThe NIST Advanced Technology Program (ATP)has unveiled several new features and services on itsAlliance Network website. The Alliance Network wasestablished 2 years ago to help companies establish andmanage joint R&D projects by providing informationon the business, managerial, administrative and legalresources necessary for a successful joint venture.

Now, in addition to browsing such resources as acollection of joint venture “best practices” and hints onnavigating the ATP process, visitors to the AllianceNetwork web pages can:

• use anonymous posts and replies on the AllianceNetwork Collaboration Bulletin Board to seekpotential joint venture partners without immediatelyrevealing company R&D interests;

• join the Alliance Forum, a new list serve (Internet-based discussion group) on R&D alliances; or

• visit a special section on partnerships with universi-ties and non-profit organizations, including the latestdata on university participation in ATP; the benefitsto companies and non-profits of collaborating inATP projects; the rules regarding intellectual prop-erty when non-profits are involved; and some bestpractices for collaborative R&D between companiesand non-profits.

Access the ATP Alliance Network web site atwww.atp.nist.gov/alliance.

General information on the NIST Advanced Technol-ogy Program, including policy, procedures and projectsfunded to date, can be found on the ATP web site atwww.atp.nist.gov.Media Contact: Michael Baum, (301) 975-2763;[email protected].

OPTICAL FIBER POWER MEASUREMENTSEXPLAINED

To meet the needs of the optoelectronics industry,NIST offers measurement services for the calibration ofoptical fiber power meters. A new paper from NISTexplains these services and their traceability to primarystandards. The services consist of absolute powercalibrations using either parallel-beam or optical fiber/connector configurations. In addition, NIST providesmeasurements of non-linearity, spectral responsivity(based both on tunable lasers and white-light sources)and uniformity. Calibrations are available at the threeprincipal wavelength regions used by the optical fiber

telecommunications industry—850 nm, 1300 nm, and1550 nm. Other optical power meter users, such ascompact-disc player manufacturers and users of erbium-doped fiber amplifiers, are interested in wavelengths at670 nm, 780 nm, and 980 nm. These wavelengths havebeen incorporated into NIST’s absolute power calibra-tion program as well.

The paper discusses a new laser power and energymeasurement system based on a commercial cryogenicradiometer designated the Laser Optimized CryogenicRadiometer. It provides laser power measurements witha relative combined standard uncertainty of 0.02 % orless.

Copies of paper No. 55-99, “Optical Fiber PowerMeasurements,” are available from Sarabeth Harris,NIST, MC 104, Boulder, CO 80303-3337; (303) 497-3237; [email protected] Contact: Fred McGehan, (303) 497-3246;[email protected].

ON-LINE INSPECTION OF BARSDuring the past 2 years NIST staff members havebeen issued patents on noncontacting ultrasonic trans-ducers that induce resonant vibrations in cylindricalobjects such as found in tubes and bars. By changing theshape of the coils and permanent magnets used to con-struct these transducers, specific radial, torsional orflexural modes can be excited and detected. Further-more, the vibrations can be made independent of themechanical constraints that support the cylinder andthey can be made to subject the cylinder to differentdisplacement distributions. Because the supports do notaffect the frequency of the resonance, it is possible tomake a very sensitive load cell that has a larger thannormal dynamic range, produces a digital output, andcan be made nearly independent of temperature.Because the displacement distributions are different fordifferent resonant modes, surface layers can be charac-terized and flaws on the surface of a bar can be distin-guished from internal defects during the high speedproduction of rods, bars and billets. A small businesslicensee has now incorporated these features intoan instrument package that is being used to performon-line inspections of aluminum bar produced by acontinuous extrusion process and to monitor the incom-ing steel rods at a stamping plant that produces automo-tive fasteners. The latter application prevents costlyproduction delays when a flaw in the starting materialcauses a partially formed fastener to shatter in thestamping die.CONTACT: Ward Johnson, (303) 497-5805; [email protected].

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ON-WAFER CALIBRATIONS APPLIED TO THECHARACTERIZATION OF HIGH-SPEED DIGI-TAL TRANSISTORSOver the past 2 years, a NIST scientist has collaboratedwith a private company to apply on-wafer calibrations tomeasurements of high-speed digital transistors. Aftermuch effort and several interlaboratory visits, the firstphase of the project has culminated in success. The newNIST developed methods provide the means to quantifydevice performance with a significant improvement inprecision.

The key technological hurdles addressed in this workwere the high RF losses encountered in commercialCMOS technology and the measurement of three portdevices when the three ports are connected in differentmetalization layers. To address the three port problem,the NIST scientist designed two sets of calibration stan-dards and devised a calibration sequence to acquirecalibrated data at the three ports of the devices. Theprivate company fabricated the coplanar waveguidestandards on three generations of transistor test wafersand worked with NIST in verifying the artifacts andmethods. This project also relied on new software writ-ten by a NIST scientist for removing contact pad effectsfrom characteristic impedance calculation. This signifi-cantly improved the accuracy of the extracted deviceparameters.CONTACT: Don DeGroot , (303) 497-7212;[email protected].

DIFFUSE REFLECTANCE SPECTROSCOPYIMPROVES TEMPERATURE ACCURACY FORSEMICONDUCTOR WAFERSNIST researchers have achieved a more accurate mea-sure of compound semiconductor wafer temperature byimplementing diffuse reflectance spectroscopy (DRS),a sensor that detects the absorption of light at thesurface and requires only fractions of a second for dataacquisition. With the new sensor, it is now possible toreach an uncertainty of 1 �C during the growth of ultra-thin layered films at high temperatures, compared with25 �C to 70 �C previously possible. Accurate growthcontrol is important to the industry, because it providesa direct way to improve the yield and process costreduction of advanced high-frequency circuits forwireless applications.

Measurement and control of temperature is a com-mon difficulty, particularly in the molecular beamepitaxy growth of multilayered heterostructures(pHEMTs). The conventional approach depends onreading thermocouple sensors placed in contact with theback surface of the wafer and must allow for timedelays for the back and front surfaces to equilibrate.

This may be several minutes or more, which is longerthan the time to grow the entire structure.

By comparison, DRS data can be acquired in less thana second, because it senses changes in the absorptionof light reflected from the wafers surface. Selectiveabsorption depends on the bandgap of the material, andthis in turn is related to temperature just at the outersurface where growth is taking place. DRS has made itpossible for the first time to realistically monitor thetemperature continuously and implement growth ratecorrections in a rapid response feedback mode.

The experiment revealed that temperature changes ashigh as 70 �C can occur during growth monitored bythermocouples and that such excursions often may goundetected. Preliminary data indicate that extremedifferences alter the conductance, as well as otherelectrical properties of the sample. Plans are to validatethese findings and quantify the effects of more accuratetemperature control on material properties such asphase segregation, desorption, dopant activation, and theparametrics of fabricated wireless devices.CONTACT: Thomas J. Shaffner, (301) 975-8009;[email protected].

NIST EXPANDS XML CONFORMANCE TEST-SUITE TO INCLUDE DOM TESTSWith the advancement of the Extensible MarkupLanguage (XML), a number of related technologies areemerging and their importance is impacting XMLtechnology, electronic commerce, and the web. Onesuch technology is the Document Object Model (DOM).The DOM is a W3C API (Application ProgrammingInterface) recommendation, approved in October 1998.Defining a set of APIs for both Java and JavaScript, theDOM is intended to dynamically manage and manipu-late XML and HTML documents.

In a continuing effort to develop conformance testsfor XML technologies and enable interoperability, NISTdeveloped an XML DOM test suite. The test suite com-plements the previously released XML ConformanceTest suite, developed by NIST in partnership with theOrganization for the Advancement of Structured Infor-mation Standards. The DOM and XML test suites areavailable at www.nist.gov/xml/.

The DOM test suite contains just over 800 tests forboth XML (Fundamental and Extended) and HTML.The testing approach focuses on defining XML andHTML conformant files and using the DOM to retrievespecific elements and/or attributes that are furtherevaluated in light of the DOM-defined behavior. Testsare available for the JavaScript and Java bindings. TheDOM test suite was introduced and demonstrated at the

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XML Conference in December 1999 and received highmarks from the XML community.CONTACT: Carmelo Montanez, (301) 975-2874;[email protected] or Mary Brady, (301) 975-4049; [email protected].

REFERENCE MATERIAL 8983 COMPLETEDFOR NITROGEN, OXYGEN, AND CARBONIN SILICON NITRIDE POWDERA new Reference Material intended primarily for use asan analytical standard for the determination of nitrogen,oxygen, and carbon in silicon nitride powders hasbeen completed. Silicon nitride is a widely used high-temperature ceramic for industrial applications requir-ing high fracture and wear resistance and is manufac-tured by compaction and sintering of powders. Anychemical impurities present in the starting powders willadversely affect the final properties of the material.Therefore, both metallic and non-metallic impuritiessuch as nitrogen, oxygen, and carbon in the powder mustbe controlled to within certain limits.

A review of analytical methods used in the determi-nation of these three elements was conducted and thehigh-temperature combustion method based on theASTM E 1019 test method was selected for analysis andcertification. However, it was necessary to modify thestandard test method originally developed for metalpowders before it could be applied to silicon nitride.

One unit of RM 8983 consists of a bottle of approxi-mately 4.5 g of silicon nitride powder. The referencemass fraction values in % for total nitrogen, oxygen,and carbon, with expanded uncertainties u at the 95%level of confidence, are 39.23 � 1.06, 1.20 � 0.14 and0.107 � 0.015 %, respectively.

The modified tests method has been submitted toASTM C28.05 (Advanced Ceramics) for approval as anew ASTM method dedicated to the analysis of ceramicpowders. The combination of this new RM and theASTM test method fulfill the industrial need for acalibration standard and measurement protocol foranalysis of impurities in silicon nitride.CONTACT: Patrick Pei, (301) 975-3681; [email protected].

HIGH PRECISION CAPACITANCE CELLDEVELOPED FOR THIN FILM OUT-OF-PLANEEXPANSIONTwo NIST researchers have developed a high-precisioncapacitance cell for measuring the expansion of dielec-tric, semiconducting, or conducting films between5 �m and 0.5 cm thick due to changes in temperatureand humidity. The new apparatus allows accuratemeasurements on semiconducting and conducting

materials that were not possible with a previous NISTdesign. The capacitance cell technique is expected toprovide researchers in the microelectronics industrywith a means of determining the coefficient of thermalexpansion of thin film interlevel dielectrics. This metrol-ogy was designed to measure films with thicknesses thatare between the measurement capabilities of thermo-mechanical analysis (lower limit of 2 mm) and x-rayreflectivity (upper limit of 0.1 m).

The previously reported design produced accuratevalues for the coefficient of thermal expansion of a0.5 mm thick single crystal �0001� oriented Al2O3

sample. The previous design also was shown to have theability to measure thin (14 �m) polymer films. Valuesdetermined for the thin polymer film were comparableto those obtained by a combination of in-plane ex-pansion meas-urements and volume dilatometry. Therelative expanded uncertainty in the thickness for theprevious and current designs is 0.1�10–6 upon thermalcycling under dry conditions (i.e., 0 % relative humid-ity). The limitation of the previous cell was that it wasunable to measure conducting or semiconductingsamples. Measurements with the previous design on sin-gle crystal silicon resulted in damage to the capacitancecell. This damage was due to the creation of a Schottkyjunction (silicon/nichrome interface) that functioned asa frequency multiplier and took the 1 kHz measurementfrequency into the ultrasonic region, thereby breakingthe conducting epoxy contacts. The new design electri-cally isolates the sample using a guard ring on the topand bottom electrodes. The bottom electrode wasdesigned so that its inner electrode diameter was halfthat of the top to minimize the problems associated withelectrode alignment. Measurements on single crystal�100� oriented silicon reproduced recommended literature values within the aforementioned experimentaluncertainty. This metrology has a variety of other appli-cations as an extremely sensitive displacement sensor.CONTACT: Chad Snyde r , (301 ) 975 -4526 ;[email protected].

GUIDE FOR THE SELECTION OF CHEMICALAGENT AND TOXIC INDUSTRIAL CHEMICALDETECTION EQUIPMENT FOR EMERGENCYRESPONDERSAs part of its work in support of the national domesticpreparedness against terrorism, NIST’s Office of LawEnforcement Standards, in collaboration with theDepartment of Defense’s Soldier Biological andChemical Command, completed work on a “Guidefor the Selection of Chemical Warfare Agent andToxic Industrial Chemical Detection Equipment forEmergency Responders.”

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This document is now out in circulation for reviewand comments. The primary purpose of this guide is toprovide emergency responders with information to aidthem in the selection and utilization of chemical agentand toxic industrial chemicals (TIC) detection equip-ment. The guide is thus more practical than technical,emphasizing advice about the capabilities of differenttechnologies and what technologies are likely to workbest in various applications. A wide variety of factorsare considered that may be important to purchasers ofdetection equipment, including cost, sensitivity,portability, ease of use.

Due to the high number of chemical agent and TICdetectors identified, the guide is separated into twovolumes. Volume I represents the actual guide whileVolume II serves as a supplement to Volume I since itcontains the detector/instrument information sheetsonly. This guide contains information that should aidemergency responders in the selection and utilization ofchemical agent and TIC detection equipment. Sometechnical information is included in sections describinghow the various detection technologies work. For eachtechnology, a short description is provided along withphotographs of specific equipment that fall within thetechnology discussed. The guide also discusses variouscharacteristics and performance parameters used toevaluate chemical agent and TIC detection equipment.These characteristics and performance parametersare referred to as evaluation criteria. Twenty-twoevaluation criteria have been identified. These criteriaare grouped and discussed within four categories:operational, physical, logistical, and special. Weightsfor each of the criteria also are provided. Finally,the guide presents the assessment process and corre-sponding results of assessing each device against theevaluation criteria.CONTACT: Al Fatah, (301) 975-2753; [email protected].

UNCERTAINTY ANALYSIS OF FOURTERMINAL-PAIR (4TP) CAPACITANCE ANDDISSIPATION FACTOR MEASUREMENTSYSTEM COMPLETED; SPECIAL TESTSERVICE OFFEREDNIST staff have completed the uncertainty analysis onan impedance measurement system that has been underdevelopment for making accurate measurements of 4TPcapacitance and dissipation factor. A NIST Special Testservice now will be offered to the public for these typesof measurements. Two papers describing the results ofthese efforts were presented at the Instrumentation andMeasurement Technology Conference in Venice, Italy,in May 1999.

The capacitor industry ($9 billion worldwide) hasrequested measurement services in the megahertzfrequency range; however, there are no impedancestandards in this range (the NIST Calculable Capacitoroperates at 1592 Hz and the NIST Calculable Air Linesoperate above 1 GHz). NIST has taken the lead amongnational metrological institutes in offering this servicefor 4TP capacitance and dissipation factor to supportLCR meter calibrations and chip capacitor testing.

This new service covers the characterization of capac-itance and dissipation factor for standard 4TP air-dielec-tric capacitors with nominal values of 1 pF, 10 pF,100 pF, and 1000 pF, in the frequency range from 1 kHzto 10 MHz. First, three-terminal capacitance measure-ments are taken at 1 kHz for each capacitor under test,thus linking these values to the NIST Calculable Capac-itor. Single-port complex impedance measurementsthen are taken at frequencies in the 100 MHz range,linking these values to the NIST Air Line Standard.Next, a mathematical extrapolation algorithm is used topredict the 4TP resistance and inductance at the inter-mediate frequency of interest, and finally the 4TP ca-pacitance and dissipation factor of the capacitor undertest is then computed at the test frequencies.CONTACT: Barry A. Bell, (301) 975-2419; [email protected].

MODIFIABLE INPUT CAPACITANCE ANDSENSITIVITY DISCOVERED IN SETTRANSISTORSSET devices are based on nanoelectronic devices oper-ated at low temperatures, in which the motion of singleelectrons are sensed or controlled. They are of interest toNIST for standards of capacitance or electrical current,and to the electronics industry as design rules continueto shrink. One of the classes of applications often citedfor SET transistors is that of ultrasensitive charge elec-tro-meters. Nominally, such a transistor can sense achange in charge of about 10–3 e ; this is about 105 timesbetter than the best conventional microelectronic FET-type transistors, operating at room temperature. How-ever, this sensitivity is often drastically reduced by thestray capacitance to ground between the charge sourceand the SET transistor; this stray capacitance is typicallyat least one order of magnitude bigger than the inputcapacitance of the transistor (which must be kept belowabout 1 fF to observe SET behavior). For instance, in theelectron-counting capacitance standard which NIST ispursuing using SET pumps and transistors, the sensitiv-ity of the SET transistor used as a null detector is de-creased by about 104 due to the stray capacitance effect.

Recently, NIST scientists have shown theoreticallythat the input capacitance of the SET transistor is not a

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constant but in fact changes with the gate and biasvoltages applied to the transistor. These changes meanthat the sensitivity of the transistor as a null detectorvaries by the same amount. The effect varies with deviceparameters and can in some cases enhance the sensi-tivity by a factor up to one third. In addition, it turns outthat if one uses applied voltages that are only slightly offfrom the optimum values, the input capacitance (and thesensitivity) may be degraded by a much larger factor(up to 100). This work may have subtle implications forthe electron-counting capacitance standard beingpursued by NIST, in terms of the optimum choice ofapplied voltages for the SET null detector.

This work has been submitted for publication in theJournal of Applied Physics.CONTACT: Michael H. Kelley, (301) 975-3722;[email protected].

WIDEBAND MEASUREMENTS APPLIED TOEMISSION AND IMMUNITY CHAMBERSNIST researchers used a NIST-developed ultra wide-band measurement system to perform measurements ofa precompliance emissions and immunity chamber at awell-known manufacturer of chemical analysis equip-ment. The data obtained will be highly useful for devel-oping rapid techniques for evaluating chambers forelectromagnetic compatibility (EMC) testing—a keyrequirement for both domestic and foreign commerce inall electronic products. In addition, the data obtainedwill assist compliance engineers at the manufacturingcompany in performing a future retrofit of theirEMC facility. The NIST scientists also advised theengineers regarding basic enhancements of the chamberto improve its performance. Chamber performancemeasurements were performed before and after thetreatments.CONTACT: Bob Johnk, (303) 497-3737; [email protected].

NIST’S CRYPTOGRAPHIC MODULEVALIDATION PROGRAM ADDS FOURTHTESTING LABORATORYThe Cryptographic Module Validation Program(CMVP) of the U.S. and Canadian governmentsachieved another milestone by adding a fourth NationalVoluntary Laboratory Accreditation Program (NVLAP)accredited laboratory. The addition of COACT Inc. CAFLaboratory is the first new laboratory added to theprogram in five years. The four CMVP laboratories testcryptographic modules to the requirements of Federal

Information Processing Standard (FIPS) 140-1,Security Require-ments for Cryptographic Modules. Inaddition, the CMVP continues its exponential growth byissuing the programs 86th certificate, which increasedthe total number of validated modules by 26 sinceSeptember 1999.

The FIPS 140-1 Validated Modules List has becomea “Whos Who” of cryptographic and informationtechnology vendors and developers from the UnitedStates, Canada, and abroad. The list contains a completerange of security levels and a broad spectrum of producttypes including secure radios, Internet browsers, VPNdevices, PC Postage equipment, cryptographic accelera-tors, secure tokens, and others. Federal agencies nowhave greater choices of tested and validated crypto-graphic products for use in securing sensitive informa-tion. The CMVP is a joint effort between NIST and theCanadian Security Establishment (CSE).

For more information on FIPS 140-1, validatedmodules, and the accredited laboratories, see http://csrc.nist.gov/cryptval.CONTACT: Ray Snouffer, (301) 975-4436; [email protected].

WWVB UPGRADE COMPLETEDNIST’s multiyear program to upgrade and increase theoutput power of WWVB from 10 kW to 50 kW wascompleted in December 1999. The station has beenoperating at the new broadcast power of since October1999, but complete auto tuning of the transmitters to theantenna systems was implemented only recently. Amajor portion of this upgrade was done by the stationsstaff, however, some design and component-fabricationwork was done by U.S. Navy staff and Navy contractors,which retains the best U.S. expertise in low-frequencybroadcast systems.

WWVB broadcasts are now delivered at full powerusing two separate in-phase transmitter-antennasystems; a third backup transmitter can be switched intoservice should either of the primary transmitters fail.The transmitters were obtained several years ago fromthe Navy at no cost. The final phase of work thatbrought this upgrade to completion involved rebuildingthe networks that match the antennas to the transmitters,installing safeguards to protect staff from high voltages,and implementing auto tuning of the antenna impedancematching network. A new generator capable of assuringcontinuity of operation at full power has been deliveredto the site, but is not yet installed. Until that installationis complete, the available backup power is not sufficientto allow operation at full power.CONTACT: Wayne Hanson, (303) 497-5233; [email protected].

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NIST MEASUREMENTS AID INDEVELOPMENT OF NEW RADIATIONTHERAPY DEVICEA private company is developing a new radiation treat-ment technique to prevent the recurrence of aggressivebrain tumors after surgical resection. The AmericanCancer Society projects 18 000 U.S. patients will bediagnosed each year with malignant brain tumors, andnearly all experience tumor re-growth after initialtreatment. Most tumors recur within a short period oftime. This new treatment modality involves the implan-tation of a small balloon device, named the “GliaSite,”in the cavity that remains after the tumor is removed.The balloon is subsequently filled with a solutioncontaining radioactive 125I, which is marketed under atrade name. Treatment planning for brachytherapy ofresected brain tumors with the GliaSite and iodinesolution requires dosimetry estimates based on accurate125 I activity measurements using commerciallyavailable dose calibrators.

The iodine solution is shipped to the hospital in2 mL conical vials and assayed/administered in 5 mLsyringes. A correct calibration factor is required for eachsource geometry and dose calibrator model. NIST hasexperimentally analyzed the response of severalcommercial dose calibrators to NIST-calibrated iodinesolutions. New calibration factors and dial settingswere determined from these data, which significantlyimprove the accuracy of iodine assays. The resultsindicate that the use of the dose-calibrator manufactur-ers previously recommended dial setting may produceerrors in the activity assay of up to +16 % and –55 % forthe syringes and vials, respectively. Furthermore, thesedata constitute an important part of the documentationthat must be submitted in order to receive FDA approvalfor the device.CONTACT: Brian Zimmerman, (301) 975-5191; [email protected] or Jeffrey Cessna, (301) 975-5539; [email protected].

NIST HOSTS FIRST ANNUAL OPTICALPROPERTIES OF MATERIALS CONSORTIUMWORKSHOPThe first annual Optical Properties of MaterialsConsortium Workshop was held at NIST in December1999. The consortium was established as a CooperativeResearch and Development Agreement (CRADA)through NIST. The consortium partners have the optionto actively participate in projects at NIST involving thedevelopment of Standard Reference Materials andspecific calibration services. The development ofStandard Reference Materials suitable for use in thewavelength range of 193 nm to 30 �m, in accordance

with U.S. regulatory protocols and accepted standardprotocols, is an integral part of the consortiums mission.Representative industries participating in the consor-tium include manufacturers and processors of pharma-ceuticals, consumer health products, food and bever-ages, cosmetics, paper, textiles, chemicals, opticaldevices and instruments, and lasers. Key optical materi-als issues in diverse applications, such as color standardsfor color film and printer paper, lens index of refractionfor ultraviolet photolithography, and low-level absorp-tion in infrared sensor windows, were discussed.CONTACT: Leonard Hanssen, (301) 975-2344; [email protected].

NIST METROLOGISTS WORK WITH THEAMERICAN PETROLEUM INSTITUTEON TRACEABILITY ISSUESNIST has been working closely with the AmericanPetroleum Institute (API) to improve procedures forestablishing traceability of API gages to the NIST/APIgrand master gages. As a first step and at API’s request,NIST metrologists reviewed and updated a history of thetesting and certification of API regional master gages.This review was finished in December.

API, a trade association representing the entirepetroleum industry, works with NIST to ensure unifor-mity in fittings used worldwide for oil drilling opera-tions. NIST is the custodian of the API grand mastergages, which are the pinnacle of the traceabilitychainthe standard to which all fittings are indirectlycompared to ensure uniformity. Regional master gagesare sent to NIST for comparison to the grand masters.CONTACT: Bryon Faust, (301) 975-4351; [email protected].

NIST LEADS THE WAY IN OPTICAL FIBERMEASUREMENTSPersons interested in the metrology of optical fibers willwant to get a new technical paper from NIST thatexplains the variety of artifact standards that NISToffers to industry. The NIST standards, known asStandard Reference Materials (SRMs), fall into twocategories for optical fibersgeometrical properties andpropagation characteristics. These standards allow afiber to be described based either on its physical dimen-sions or the way in which light propagates within it.In the area of physical dimensions, NIST offers SRMsfor fiber cladding diameter, fiber coating diameter,connector ferrule (both inner and outer diameter),and mode-field diameter. In the field of propagationcharacteristics, NIST offers SRMs for chromatic disper-sion, polarization-mode dispersion, and polarization-

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dependent loss. NIST’s web site, www.nist.gov,provides information on other SRMs and calibrationservices that support the optical communicationsindustry.

Copies of the paper, “NIST Artifact Standards forFiber Optic Metrology,” (03-00) can be obtainedfrom Sarabeth Harris, MS 104, NIST, Boulder,CO 80303-3337; (303) 497-3237; [email protected].

For more information on the optical fiber artifactsand other SRMs, contact Lee Best, 100 Bureau Dr.,Stop 2320, NIST, Gaithersburg, MD 20899-2320;(301) 975- 2027; [email protected] Contact: Fred McGehan, (303) 497-3246;[email protected].

WHAT’S UP, DOCS? FIND OUT ATCONFERENCEExactly what is a document? And what is an electronicdocument? A conference at NIST’s Gaithersburg, MD,headquarters in March 2000, examined what standardsare needed to encourage the smooth exchange of thedocuments of the future.

Among the topics discussed were the generation andtransmission of trans-media documents, such as e-mailmessages converted to voice mail.

Other kinds of “documents” examined included:

• three-dimensional content expressed as software,such as DNA structures and other moleculardesigns, holographs and computer-aided designfiles;

• video and multimedia objects; and

• audio documents such as voice mail messages.

Media Contact Philip Bulman, (301) 975-5661;[email protected].

NEW REGISTRY SEEKS END TO NAMINGCONFLICTSImagine two software developers in different parts ofthe country who both need to come up with a filenameextension for a program. Since such tags are generallyabbreviations or acronyms (.glo for glossary or .pwl forpassword list, for example), the programmers couldselect the same name and never know it—that is, untilthe duplication causes both softwares to run ineffec-tively or crash after reaching the market.

Avoiding such conflicts when choosing identifiers—the entities that distinguish filename extensions, HTMLtags, Java top-level packages, Dynamic Link Libraries,

variables, port numbers and the like in programminglanguages—is the main purpose for the NIST IdentifierCollaboration Service (NICS), a free, online registry.Users can browse the database for identifiers in 22domain types, determine that theirs is original and thenadd it to the repository.

Unlike simple lists of identifiers, the NICS registryhas the additional benefit of allowing other developersto peer review new names and warn the owner aboutpotential problems. And if a conflict does occur, boththe person trying to register the name and the authors ofits already registered twin are automatically contactedso that negotiations toward an agreement cancommence.

The NICS was created by NIST after encounteringidentifier naming difficulties during the development ofSTEP (now known as ISO 10303), the global Standardfor the Exchange of Product model data. The registryproved so valuable that its natural expansion to otherprogramming languages was inevitable. NIST, as aneutral party, is the perfect sponsor for the service sincethe agency has no vested interest in the success orfailure of any specific users.

To access the NICS, go to http//pitch.nist.gov/nics onthe World Wide Web. For technical information, contactDon Libes, (301) 975-3535, [email protected] Contact: Michael E. Newman, (301) 975-3025;[email protected].

2000 CRITERIA NOW AVAILABLE; NEWCOMPETITION BEGINSYour organization should have a copy of the newlyupdated Baldrige Criteria for Performance Excellence.One of the nation’s most popular and influential organi-zational improvement publications, the criteria aretailored for three different audiencesfor-profit busi-nesses, health care providers, and education organiza-tions.

The 2000 criteria booklet is easy to use and includesa series of questions covering seven key areasleadership,strategic planning, customer and market focus, informa-tion and analysis, human resource focus, processmanagement, and results. Over the years, NIST hasrevised and streamlined the criteria to focus moresharply on overall performance excellence and results asintegral parts of today’s management practice.

Thousands of U.S. organizations use the criteria toassess and improve their overall performance. Since1988, almost 2 million copies of the Baldrige Criteriafor Performance Excellence have been distributed, andwide-scale reproduction by companies and electronicaccess add to that number significantly.

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Single copies of the Baldrige Criteria for Perfor-mance Excellence are available from NIST by calling(301) 975-2036; faxing a request to (301) 948-3716;sending e-mail to [email protected]; or by downloadingfrom the World Wide Web at www.quality.nist.gov.Packets of 10 or more copies, as well as other Baldrige-related materials (such as case studies and videos onBaldrige Award recipients) may be ordered for a feefrom the American Society for Quality, (800) 248-1946; www.asq.org.Media Contact: Jan Kosko, (301) 975-2767; [email protected].

UPGRADED SYSTEM MEANS BETTER DATA,LOWER COSTS FOR BUILDINGSComparing how much it costs to build and maintaindifferent buildings allows developers and owners tomake a host of improved decisions—especially the cost-effective selection of building designs and materials.However, making accurate and reliable comparisons ofdata collected during a building’s life cycle is impossi-ble unless everyone uses the same system to defineelements. Elements are the major components commonto most buildings that usually perform a given functionwhatever the design specification, construction methodor materials used. Examples include foundations,exterior walls, sprinkler systems and lighting.

NIST has refined and expanded its UNIFORMAT IIsystem for standardizing these building-related classifi-cations. A new report (NIST Interim Report 6389)describes the improvements to the 1992 NIST systemadopted as a standard by the American Society forTesting and Materials (ASTM).

The proposed changes in UNIFORMAT II—designedto be implemented in the near future as a revised ASTMstandard—would enable the development of moredetailed comparisons among buildings. They advancethe use of the UNIFORMAT II classification system inthree ways(1) adding a fourth level of elements to thecurrent ASTM standard; (2) describing applications forthe system that were not anticipated in earlier versions(such as life-cycle electronic tracking of project data);and (3) presenting a standard format for summarizing anelemental cost estimate.

Applying UNIFORMAT II at each step of the build-ing process provides significant saving to industry. Dataentered in a consistent format will not have to bereentered at different phases of the building life cycle.This means better, inexpensive information that is easilyaccessed and compared.

For technical questions or to request the report, con-tact Harold Marshall at NIST, 100 Bureau Dr., Stop8603, Gaithersburg, MD 20899-8603; (301) 975-6131;

[email protected]. NIST IR 6389 also is avail-able in Adobe Acrobat format from the World WideWeb at www.bfrl.nist.gov/oae/publications/nistirs/6389.html.Media Contact: John Blair, (301) 975-4261; [email protected].

EFFECTIVE USE OF COMMON CRITERIAThe 3 day First International Common Criteria Confer-ence took place at the Baltimore Convention Center inMay 2000. Executives from information technologycompanies learned about the international computersecurity arrangement that makes it easier for Americancompanies to sell their products in other countries.

The International Common Criteria Mutual Recogni-tion Arrangement is a pact that establishes a concise butcommon language specifying security requirements ininformation technology products and systems. Sevennations, including some of the world’s largest markets,now participate in the Common Criteria (also known asISO/IEC 15408). They are Australia, Canada, France,Germany, New Zealand, the United Kingdom, and theUnited States.

In the United States the evaluation and validationprogram is managed jointly by NIST and the NationalSecurity Agency.

The signatory nations recognize the results ofsecurity evaluations conducted by each other’s accred-ited testing laboratories. This eliminates the need forcostly and time-consuming testing by different coun-tries. As the arrangement creates a standardized evalua-tion process across borders, it fosters a barrier-free,worldwide market for IT security products.

While private-sector laboratories do the testing ofcomputer security products, the governments involvedaccredit the participating laboratories and certify orvalidate the resulting tests. For more information, or toregister electronically, go to the World Wide Web athttp//niap.nist.gov/cc-scheme/iccc.Media Contact: Philip Bulman, (301) 975-5661; [email protected].

NBS-DEVELOPED METHOD NAMED“ALGORITHM OF THE CENTURY”A mathematical algorithm developed at NBS (theNational Bureau of Standards, now NIST) during the1950s has been identified as one of the “Top TenAlgorithms of the Century” by Computing in Science &Engineering (CS&E) magazine. Actually a class ofmethods, the algorithm known today as Krylov sub-space iteration saw its genesis in work done by twoNIST mathematicians and a Swiss mathematician at the

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Institute for Numerical Analysis operated by NBS atUCLA in the late 1940s and early 1950s.

Krylov methods can be used to solve very largesystems of linear equations. Early Krylov methods werecalled the conjugate gradient method. These methodshave the advantage of not requiring an array of matrixelements to be stored and are of great interest in solvingvery large, sparse systems. The first reports on thesemethods were published in the Journal of Research ofthe National Bureau of Standards in 1952. Since then,many thousands of papers have been published on thistopic, and Kyrlov methods remain the most popular andeffective techniques for solving such problems today.

The January/February 2000 issue of CS&E in whichthis algorithm was cited set out to identify the “tenalgorithms with the greatest influence on the develop-ment and practice of science and engineering in the 20thcentury.”CONTACT: Ronald Boisvert, (301) 975-3812; [email protected].

NIST MEASUREMENT METHOD ADAPTED TOINDUSTRIAL PROCESSIn collaboration with a private company, a NIST-devel-oped method for noncontact measurement of tempera-ture has been adapted to processing reactive polymerresins. The measurements showed the resin temperaturevariation across the exit die of a reactive extruder thatrevealed new information about the process. Thenoncontact temperature measurements made on theDow reactive extruder revealed that the temperature ofthe resin at certain locations was much higher than thatmeasured by conventional thermometry. Temperature isa critical processing parameter that in reactive extrusionis affected not only by shear heating, common to otherextrusion processes, but also by the exothermic chemi-cal reactions. The temperature must be maintained in acertain range to optimize proc-essing without degradingthe polymer by exposure to excessive temperatures.

The noncontact temperature method was developed atNIST to address industry’s need for a way to measuretemperature of a hot resin as a function of its positionin the processing equipment. The method is based onfluorescence measurements of a fluorescent dye that isadded to the resin in minute amounts. The spectralcharacteristics of the fluorescence changes with temper-ature in a manner that can be determined in separateexperiments. Another advantage of the temperaturesensor is that no special modifications of the processingequipment are required. The confocal optical devicethreads into existing extruder ports that accommodateother types of sensors.

CONTACT: Anthony Bur, (301) 975-6748; [email protected].

MAGNETIZATION CONTROLFor a large class of magnetic devices, including readheads in hard drives and magnetic random accessmemory (MRAM) cells, it is important to control thedirection of the magnetization in thin films of magneticmetals such as cobalt and Permalloy (Ni80Fe20). NISTresearchers have come up with an alternative to thecommon practice of using antiferromagnetic materialsfor this purpose. The new method provides an an-isotropy (directional magnetization) that is very strongand very homogeneous and that is expected to show highthermal stability. The large anisotropy is found in thinmagnetic films deposited on top of obliquely depositedtantalum underlayers. The oblique deposition of thetantalum produces a corrugated tantalum surface asripples running perpendicular to the atom flux areamplified through shadowing effects. The cobalt,nickel, or iron atoms, deposited at normal incidence, aremore mobile than the tantalum atoms, so they fill the5 nm wide grooves in the tantalum surface and thenform a relatively smooth upper surface, resulting in amagnetic film which carries the corrugated imprint ofthe underlayer.

The low energy states of this structure have themagnetization lying in either direction along the corru-gations, parallel to the wavy surface, for the same reasonthat it easy to magnetize an iron needle parallel to itslength: magnetostatic energy is minimized when themagnetization lies parallel to an interface. Cobalt films30 nm thick have been deposited on a corrugatedtantalum surface and found to take as much as 0.16 T torotate the magnetization perpendicular to the corruga-tions. A second cobalt film, separated from the firstcobalt layer by 4 nm of copper, required only 13 mT.The anisotropy generated by the obliquely depositedtantalum underlayers is very uniform, with localanisotropy axis directions varying less than 2�, andanisotropy fields varying by less than 5 mT. Since theanisotropy field is magnetostatic in origin, it is expectedto be as thermally stable as the magnetization itself.CONTACT: Robert D. McMichael, (301) 975-5121;[email protected].

NEUTRON STUDIES OF NOVELFERROELECTRIC MATERIALS SHEDLIGHT ON ORIGIN OF REMARKABLEPIEZOELECTRIC PROPERTIESPiezoelectric materials expand in the presence of anelectric field. Conversely they generate an electric field.

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Conversely they generate an electric field when com-pressed. This property forms the basis of operation insolid state transducers that convert mechanical energyinto electrical energy, and vice versa. The present daymaterial of choice for the fabrication of high-perfor-mance electromechanical actuators is the ceramicPb(Zr1–x Tix )O3 (PZT).

Recently scientists at the NIST Center for NeutronResearch (NCNR) and Penn State University have devel-oped a program to study single crystals of the ferro-electric relaxor-based materials Pb(Zn1/3Nb2/3)1–x Tix O3

(PZN-xPT) and PMN-xPT (M=Mg) that exhibit re-markably large piezoelectric coefficients (>2500 pC/N).Strain levels as high as 1.7 % have been achieved, withlittle dielectric loss, that are an order of magnitudelarger than those presently achievable with PZT. Suchexceptional piezoelectric properties make these materi-als leading candidates in the next generation of solidstate transducers that are crucial for industrial anddefense applications.

Neutron scattering measurements at the NCNR haverevealed information about the nature of the atomicvibrations in these novel materials that are related totheir unusual piezoelectric properties. In particular, akey vibrational mode is found to be largely inhibited dueto an underlying structure of nanometer-sized polarizeddomains, unlike in normal ferroelectric materials.Future neutron measurements are planned to probethese vibrations in the presence of an applied electricfield to further elucidate the microscopic origin of theseenhanced piezoelectric properties.CONTACT: Peter M. Gehring, (301) 975-3946;[email protected].

FERRITE STANDARDS ENTER NISTINVENTORYNIST has completed certification of a new batch ofSecondary Ferrite Standards, RM 8480 and RM 8481.The reference materials are intended for the calibrationof instruments used to measure weld metal ferritecontent in accordance with ANSI/AWS Standard A4.2and ISO Standard 8249. These standards are designedfor use in welding construction and repair applicationswhere the ferrite content of austenitic stainless steelwelds must be controlled in tight ferrite number (FN)ranges. RM 8480 consists of a low range (eight speci-mens distributed in the range of 0 FN to 30 FN) andRM 8481 is the corresponding high range (eight speci-mens distributed in the range of 30 FN to 120 FN). Thecertification process required the development of anadvanced calibration procedure and included over25 000 individual magnetic measurements, before thedata could be reduced into statistical summaries. The

calibration procedure and statistical summaries areincluded in the RM certificates and in NIST SP260-141“Secondary Ferrite Reference Materials: Gage Calibra-tion and Assignment of Values.”CONTACT: Tom Siewert, (303) 497-3523; [email protected].

NIST COMMISSIONS NEW X-RAYINSTRUMENT AT ADVANCED PHOTONSOURCE FOR CHARACTERIZATION OFANISOTROPIC MATERIALSAs part of a collaboration, known as UNICAT, with theUniversity of Illinois, Oak Ridge National Laboratory,and a private company, NIST researchers have devel-oped novel small-angle x-ray scattering (SAXS)methods at the Advanced Photon Source (APS) tocharacterize anisotropic alloy and ceramic microstruc-tures such as found in coatings, laminates and highlytextured materials. While pinhole-geometry SAXS andsmall angle neutron scattering (SANS) instruments,with their two-dimensional detectors, can characterizeanisotropic microstructures in the nanometer to0.1 micrometer scale regime, this range is not easilyextended to larger sizes unless multiple scattering meth-ods are used. Double-crystal Bonse-Hart ultrasmall-an-gle x-ray scattering (USAXS) instruments can extendthe scale regime to several micrometers, but the data areintrinsically slit-smeared, and the standard USAXS con-figuration is not suitable for anisotropic studies.

To remove this limitation, transverse crystal reflec-tions orthogonal to the plane of the main USAXSmonochromator/collimator and analyzer crystal reflec-tions were introduced. While the data in a single scanare still associated with one azimuthal direction in theplane of the sample, the transverse crystal reflectionsremove the slit-smearing and effectively restore apinhole geometry. To study an anisotropic microstruc-ture, the sample must be measured repeatedly for differ-ent azimuthal orientations with respect to the incidentbeam. However, this is not a disadvantage for highlyanisotropic microstructures because the resolution ofthe azimuthal rotation increments can be made almostvanishingly fine. Indeed, the anisotropic resolution ofthe new instrument can surpass that of conventionalSAXS or SANS instruments with a two-dimensionaldetector.

The anisotropic USAXS configuration also takesadvantage of innovations previously introduced intoNIST’s standard USAXS design, including a continu-ously tunable x-ray wavelength, and a photodiode detec-tor with a 10-decade linear dynamic range that enablesa primary absolute intensity calibration to be made withrespect to the incident beam. Early anisotropic studies

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have focused on the microstructural characterization ofplasma-sprayed coatings and of cracking in highly tex-tured brittle ceramics. However, it is envisaged that theanisotropic USAXS capability could open up a poten-tially wide field of quantitative microstructure charac-terization in thin films and coatings on substrates, usinga glancing-angle reflection geometry.CONTACT: Andrew J. Allen, (301) 975-5982; [email protected].

IMAGED AUDIO TAPES USING SCANNINGMAGNETO-RESISTIVE MICROSCOPYNIST researchers in collaboration with a scientist fromthe Institute of Telecommunication Sciences, haveimaged audio tapes using scanning magneto-resistive(MR) microscopy and reconstructed the audio signalsfrom the images. Four test tracks were produced,imaged, and reconstructed. Two of the test tracks weresine wave tones of 500 Hz and 700 Hz and the other twohad test phrases such as “NIST” and “FBI.” This workaddresses the need of forensics analysts to searchfor traces of tampering and/or characteristic sounds(gunshots, etc.) in recorded evidence. The microscope isbased on commercial MR heads from computer harddrives, and has a resolution of �20 nm downtrack and�1 �m track width. The required sample rate for thesereconstructions was only 5.9 �m; however, the higherresolution available with the MR heads is needed formedia such as digital audio tapes and other computerstorage media.CONTACT: David P. Pappas, (303) 497-3374; [email protected].

JOSEPHSON ARBITRARY WAVEFORMSYNTHESIZER DEMONSTRATEDNIST researchers have demonstrated 127 mV peak-to-peak voltage and operating margins for ac waveformswith a Josephson Arbitrary Waveform Synthesizer. Thisdevice is capable of digitally synthesizing any waveformfrom dc to 10 MHz. This is the first demonstration of thedevice as an ac voltage standard source with operatingmargins. The output voltage, frequency, and relativephase between synthesized tones are stable and preciselycalculable as a result of digital synthesis using perfectlyquantized voltage pulses from superconductingJosephson junctions. The recent improvements in oper-ating margins (previously zero for ac waveforms) andoutput voltage (previously 52 mV peak-to-peak) are aresult of improved broadband 60 MHz to 20 GHzon-chip filters and larger arrays of 4096 Josephsonjunctions. The device has synthesized 127 mV peak-to-peak voltage waveforms with harmonic distortion

better than –75 dB below the fundamental. Demonstra-tion of the potential –140 dB theoretical harmonicdistortion is presently limited by existing instrumenta-tion.CONTACT: Sam Benz, (303) 497-5258; [email protected].

OPTICAL PROPERTIES OF MATERIALS FORDEEP ULTRAVIOLET LITHOGRAPHYThe single most significant productivity improvementfactor in semiconductor manufacturing has been thecontinuing reduction in feature size, enabling evergreater scales of integration, higher speed performance,and lower power consumption. To date this feat has beenaccomplished by using systems with shorter and shorterwavelength illumination. The “illumination” goesthrough a mask, exposing a photoresist on the integratedcircuit, in order to pattern the circuit. Lithography toolsoperating at 193 nm are currently being introduced intomanufacturing. The next generation tools need to oper-ate at 157 nm. A major unanswered question to date hasbeen whether or not refractive systems can be designedand built that have chromatic aberration correction,allowing the use of laser sources with enough opticalpower to permit economically useful wafer throughput.NIST has answered that question in the affirmative withrecent optical data on barium fluoride. This work hasshown that the index and dispersion properties ofbarium fluoride near 157 nm are such that the materialcan be used in combination with calcium fluoride forthe optics of refractive lithography tools with sufficientchromatic aberration correction for operation at 157 nm.Two-material, all-refractive lithography tools are nowbeing designed by the major lithography tool manufac-turers based on these results.CONTACT: John Burnett, (301) 975-2679; [email protected].

NIST IMPROVES TRACEABILITY OFEXPOSURES FROM MAMMOGRAMSMEASURED AROUND THE WORLDNIST recently calibrated a secondary-standard ioniza-tion chamber for the International Atomic EnergyAgency (IAEA), Dosimetry and Medical RadiationPhysics Section. This section serves as the centralmeasurement and administrative laboratory of theIAEA/WHO network of Secondary Standard DosimetryLaboratories (SSDLs) and provides traceable calibra-tions, free of charge, to all SSDLs in the 76-membernetwork. The chamber will be used to improve thequality of mammograms taken worldwide. Memberlaboratories have been established in countries from

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Algeria to Yugoslavia and include many in South andCentral America, Scandinavia, Eastern Europe, Africa,and the Near, Middle and Far East.

The calibrations were performed at the NISTMammography Calibration Facility, and were conductedfor 17 NIST mammography x-ray beam qualities, sincethe IAEA laboratory has modeled their availablemammography beam qualities after the NIST facility.The calibrations will allow the IAEA to transfer theNIST standards for exposure (air-kerma) to the IAEA/WHO SSDL network.CONTACT: Michelle O’Brien, (301) 975-2014; [email protected].

NEW MEASUREMENT SYSTEM WILLIMPROVE RADIOMETRIC SCALESNIST metrologists have developed a new laser-basedcalibration facility designed to reduce the uncertaintiesin measurements of power, irradiance, and radianceresponsivity for optical detectors. The facility forSpectral Irradiance and Radiance Responsivity Calibra-tions using Uniform Sources (SIRCUS) was used, forexample, to reduce the relative uncertainty in irradianceresponsivity calibrations from 0.5 % to 0.1 % in thevisible wavelength range. As NIST continues to movefrom source-based to detector-based radiometry andphotometry, reducing the uncertainties in the responsiv-ities of filter radiometers will directly impact NIST’sradiometric and photometric scales.

Recently, these metrologists used SIRCUS to cali-brate a photoelectric pyrometer (PEP). The PEP is usedto determine radiance temperatures of blackbodies andtungsten filament lamps by comparison against the goldfixed-point blackbody. Smaller wavelength uncertaintiesand the larger dynamic range of measurements onSIRCUS contribute to a reduction in the combinedstandard uncertainty in the relative response of the PEP.In addition, because measurements on SIRCUS areinherently “narrow-band,” deconvolution of the respon-sivity to eliminate finite-bandwidth effects associatedwith conventional lamp-monochromator systems is nolonger necessary. Such measurements will reduce theuncertainty in NIST radiance temperature measure-ments and will similarly impact other detector-basedradiometric and photometric scales maintained at NIST.CONTACT: Steven Brown, (301) 975-5167; [email protected] or George Eppeldauer, (301) 975-2338; [email protected].

NEW OPTICAL MEASUREMENT TECHNIQUEFOR THE CALIBRATION OF CCD CAMERASDigital cameras presently are used for a wide varietyof applications including astronomical observations,geological and earth-resource management, machineand inspection processes, archeology, and imagingcollection and dissemination in the television and movieindustries. A common type of detector used in digitalcameras is a two-dimensional array of charge-coupleddevice (CCD) elements. The CCD elements arelithographically fabricated on a silicon wafer, and thenumber of individual elements in the array can begreater than 1 million.

NIST metrologists recently calibrated a commercialphotometric digital camera used to measure the perfor-mance of lamps and light-emitting diodes as well as toquantify material-appearance characteristics such asreflectance and haze. The calibration of CCD cameras isa difficult endeavor, however, since the response ofindividual detector elements can vary, and is oftennonlinear. Utilizing the unique capabilities of thefacility for Spectral Irradiance and Radiance Responsiv-ity Calibrations using Uniform Sources (SIRCUS),NIST scientists have simultaneously calibrated the morethan 300 000 individual elements in the camera’s640 pixel by 480 pixel CCD array. The camera’s pixel-to-pixel uniformity, nonlinearity, and absolute spectralresponsivity were measured on SIRCUS over the visiblespectral region with a relative combined standard uncer-tainty of 3 %. Commercial cameras that are calibratedagainst broadband incandescent sources typically haveuncertainties on the order of 5 %.CONTACT: Steven Brown, (301) 975-5167; [email protected].

A SILICON TUNNEL-TRAP TRANSFERSTANDARD FOR SPECTRAL POWER ANDIRRADIANCE RESPONSIVITY DEVELOPEDNIST physicists have developed a high-accuracy light-trap radiometer in cooperation with a private company.This new six-element device will be used as a high-leveltransfer standard to reduce NISTs measurement uncer-tainties for spectral irradiance and spectral responsivi-ties. The heart of the device contains two medium- andfour large-size silicon photo-diodes that were packedtightly to obtain a minimum field-of-view of 6�. Thedevice features a precision input aperture whose areawas measured with high accuracy in NIST’s Optical

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Area Measurement Facility. The radiometer can becalibrated for spectral power responsivity against theprimary standard high accuracy cryogenic radiometerwhen both measure the same total power in stabilizedlaser beams. A second light trap is attached to the outputof the device to collect the transmitted light and tominimize pickup of ambient light. The expected com-bined standard uncertainties of the radiometer in thepower measurement mode and irradiance measurementmode are 0.03 % and 0.05 %, respectively.CONTACT: George Eppeldauer, (301) 975-2338;[email protected].

NIST CONSULTS ON COORDINATEMEASURING MACHINE INTENDED FORLARGE MILLIMETER TELESCOPEThe University of Massachusetts went to the expertswhen they recently needed help evaluating the metrol-ogy capability of a very large coordinate measuringmachine (CMM) being developed by the Mexicanresearch institute Instituto Nacional de Astrofisica,Optica, y Electronica (INAOE), Tonantzinla, Puebla,Mexico. Recognized for their experience and expertisein CMM technology, NIST scientists were contractedby the University of Massachusetts to perform a techni-cal evaluation of this CMM in January 2000. TheINAOE CMM is intended to measure the 3 m � 5 mpanels of the Large Millimeter Telescope (LMT), a50 m diameter radio telescope being constructed inMexico. This radio telescope is being developed as ajoint venture of the University of Massachusetts, thenational government of Mexico, and the DefenseAdvanced Research Projects Agency of the UnitedStates.CONTACT: W. Tyler Estler, (301) 975-3483;[email protected] or Steven D. Phillips, (301) 975-3565; [email protected].

FIPS 186-2, DIGITAL SIGNATURE STANDARD(DSS), ADOPTEDThe Secretary of Commerce accepted NIST’s recom-mendation and approved Federal Information Process-ing Standard (FIPS) 186-2, Digital Signature Standard(DSS), which supersedes FIPS 186-1, DSS. FIPS 186-2expands the Digital Signature Standard by specifyingtwo voluntary industry standards for generating andverifying digital signatures. This action will enablefederal agencies to use the Digital Signature Algorithm(DSA), which was originally the single approvedtechnique for digital signatures, as well as twoAmerican National Standards Intsitute (ANSI) thatwere developed by the financial community. These

latter standards are ANSI X9.31, Digital SignaturesUsing Reversible Public Key Cryptography, and ANSIX9.62, Elliptic Curve Digital Signature Algorithm(ECDSA). FIPS 186-2 specifies an 18 month transitionperiod, during which agencies may continue to use theirexisting digital signature systems and acquire additionalequipment that may be needed to interoperate with theselegacy digital signature systems. In addition, FIPS 186-2specifies recommended elliptic curves for use by thefederal government when using X9.62 Digital Signaturetechniques. See http://csrc.nist.gov/cryptval and selectFIPS 186-2.CONTACT: Elaine Barker, (301) 975-2911; [email protected].

NIST ANALYZES VENTILATION IN U.S.MANUFACTURED HOMESNIST has completed a project for the U.S. Departmentof Housing and Urban Development (HUD) to addressissues related to the ventilation of manufactured hous-ing. The HUD Manufactured Home Construction andSafety Standards contain requirements intended toprovide adequate levels of outdoor air ventilation inmanufactured homes. However, in the implementationof these standards, questions have arisen regarding theactual ventilation rates in homes built to the standardsand the approaches being employed to meet the rates inhomes built to the standards and the approaches beingemployed to meet the requirements of the standards.Other questions have arisen as to how specific ventila-tion system components such as duct leakage, localexhaust fans and ventilation inlets affect ventilationrates, air movement patterns, and building pressures.

In order to obtain some insight into these issues,NIST’s multizone airflow and indoor air quality programCONTAM was used to simulate a double-wide unitunder several different ventilation scenarios. Simula-tions were performed to predict outdoor air ventilationrates into the house due to infiltration and mechanicalventilation, interzone airflow rates between the rooms,building air pressures, and ventilation air distribution.Annual simulations were performed in three cities toassess ventilation rates and energy consumption associ-ated with these scenarios. The results show that despitethe assumption in the HUD standards that infiltrationcontributes 0.25 h–1 (air changes per hour), thepredicted infiltration rates are lower than this value formany hours of the year. The supplemental ventilationsystems investigated in this study provide ventilationrates that meet or exceed the total ventilation require-ment of 0.35 h–1, but the impacts of such systems aredependent on their operating schedules. In addition, inthese simulations, the impacts of a whole house exhaust

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fan are independent of whether this fan is located in themain living area or in a bathroom off the main livingarea. Also, for the case of ventilation with a whole houseexhaust fan, the inclusion of passive inlet vents is notcritical given the level of envelope airtightness used inthese simulations. The results of these simulations arepresented and discussed and recommendations aremade for changes to the HUD standards and for futureresearch. The results are described in detail in the finalreport (NISTIR 6455).CONTACT: Andrew Persily, (301) 975-6418; [email protected].

FIRE DYNAMICS SIMULATORIn cooperation with industry, a numerical fire model,Fire Dynamics Simulator, is being developed at NIST toevaluate the performance of fire protection systems inbuildings. The model has been used to generatepredictions of fires in industrial facilities protectedentirely or in part by automatic fire sprinklers. Becausethe model provides far more detailed simulations thanzone models can, it requires more detailed informationabout the fuels, building materials and fire protectionsystems. NIST has supported efforts, both internally andthrough its grants program, to develop measurementtechniques to generate this information. These measure-ments include droplet size distributions, spray patterns,droplet trajectories, and heat transfer coefficients.

NIST recently has released version 1.0 of the FireDynamics Simulator (FDS). Previous versions of themodel were referred to as LES, LES3D, and mostrecently IFS (Industrial Fire Simulator). More informa-tion about the model and its applications can be found athttp://fire.nist.CONTACT: Kevin McGrattan, (301) 975-2712; [email protected].

LARGE SCALE COORDINATEMETROLOGY GROUP HAS MAJOREFFECT ON ISO MEETINGSA NIST scientist participated in the ISO TechnicalCommittee 213 (TC213) Dimensional & GeometricalProduct Specifications, Working Group 10 (WG10)Coordinate Measuring Machines (CMMs) meetingsfrom Jan. 12-17, 2000, in Clearwater, Fla. This group isattempting to define calculational techniques andmethodologies affecting CMM uncertainty. As the U.S.subject matter expert, the NIST scientist presented theU.S. and its allies position that successfully delayed theadoption of the flawed concepts in ISO WD 17450-2from infecting WG10. Additionally, the United States

was assigned the important job of chairing the long-term revision of 10360-2, a project that the UnitedStates has been trying to organize for 5 years. Assign-ments for completing the 15530 series were allotted; theUnited States picks up three of the six sections of thisseries. Finally, the United States was assigned the taskof developing the “metrological characteristics” ofCMMs as assigned by TC213.CONTACT: Steven D. Phillips, (301) 975-3565; [email protected].

INTERNET SITE INITIATED FOR HALLMEASUREMENT TECHNIQUETo address an identified gap in the metrology ofsemiconductor materials, NIST has prepared an Internetsite to describe Hall measurement techniques andpractices. It projects a simple tutorial style, with funda-mental equations and concepts relevant to the practicingindustrial engineer, and includes worksheets and refer-ences for data acquisition and reduction. To encourageuser participation and to increase awareness of thetechnique, an electronic bulletin board is also included,where those interested in the methodology can exchangeideas and information.

Over a century ago, Edwin Hall discovered thata small transverse voltage appears across a current-carrying thin metal strip in an applied magnetic field.Today, this effect bears his name (the Hall effect), andhas since evolved in the form of an indispensable charac-terization tool, capable of determining the density andmobility of free carrier electrons and holes in semicon-ductor materials and devices. The broad acceptance ofthe technique in both academic and industrial laborato-ries is attributed to its simplicity, low cost, and minimaltime required for analysis. In spite of such a key role,only a single ASTM document (ASTM F-76) was previ-ously available for outlining standard procedures andpractices for the Hall measurement of semiconductingmaterials.

The appearance of modern equipment and newengineering graduates in industrial laboratories hasopened this opportunity for a more readily available anduser-friendly presentation of the Hall effect, whichencompass simple theory, modern equipment, andmeasurement practices. This was one of the majorfindings of recent survey of industrial users and wasidentified as an important gap in the industrial metrol-ogy roadmap formulated for the SED project incompound semiconductor materials.CONTACT: Thomas J. Shaffner, (301) 975-8009;[email protected].

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NIST HOSTS WORKSHOP ON MEASUREMENTAND STANDARDS NEEDS OF ADEREGULATED ELECTRIC POWERINDUSTRYNIST researchers organized and hosted the “Workshopon Challenges for Measurements and Standards in aDeregulated Electric Power Industry” in Arlington, VAin December 1999. The purpose of the workshop was tobring together world experts to discuss the impact ofderegulation on the electric power industrys measure-ment and standards infrastructure. The workshop wasopened by the deputy under secretary for technology,U.S. Department of Commerce, who presented a call toindustry members to become involved in the interna-tional standards-making process. The workshop enjoyedsignificant industrial support with technical co-sponsor-ship by the Electric Power Research Institute, theNational Electrical Manufacturers Association PowerEquipment Division, the IEEE Power EngineeringSociety, the National Science Foundation, and the U.S.Department of Energy.

Significant conclusions from the workshop included(1) that new standards are needed for nearly every aspectof the industry (control, pricing, access, security,distributed generation, brokering, etc.) as multipleplayers become involved in the production, distribution,and selling of power; (2) that there is a significant riskthat emerging international standards will not reflect theneeds or situation of the U.S. electric power industry;(3) that additional low-uncertainty measurements areneeded to ensure the accurate sale of power; and (4) thatthe electric power industry may become, in the nearfuture, the largest e-commerce industry in the world. Areport of the impact of these conclusions on researchprograms at NIST is forthcoming. Many of the speakerspresentations are available on the workshop web site(www.eeel.nist.gov/deregulation-workshop).CONTACT: James K. Olthoff, (301) 975-2431; [email protected].

NIST’S PROTOCOL MODELING OFBLUETOOTH SPECIFICATION PAYS OFFFollowing a year of review, comment, and modeling thespecifications of the Bluetooth Special Interest Group(SIG) as a non-SIG member, the group asked a NISTscientist to collaborate on further development of theSpecification and Description Language (SDL) modelsfor the Bluetooth specification. When the SIG submit-ted its specification for consideration as a standard to theIEEE 802.15, the NIST scientist, with help from a guestscientist, quickly developed SDL models. These proto-col models clearly showed the problems that need to beaddressed in the Bluetooth specification before the

IEEE 802 can adopt it as a standard. Currently, theBluetooth Specification is under consideration forstandardization within the IEEE 802.15 expert groupworking on Wireless Personal Area Networks.

The NIST scientist’s work stems from the Networkingfor Smart Spaces project, which examines the mostrecent and future developments on networking technolo-gies (e.g., wireless) that provide access to resources.These resources can be printers, personal computers,cellular telephones, and network access points. TheBluetooth SIG (www.bluetooth.com) is an internationalconsortium developing specifications for pico-cellularnetwork systems. The specification addresses wireless,network, self-discovery, and application areas.CONTACT: David Cypher, (301) 975-4855; [email protected].

NIST SPONSORS PERVASIVE COMPUTING2000 CONFERENCEIn January 2000, NIST sponsored the PervasiveComputing 2000 Conference in Gaithersburg, MD. Thepurpose of the conference was to explore the directionsthat industry is taking in the emerging area of pervasivecomputing and smart spaces. Topics discussed includedhuman-computer interaction in pervasive computing,pico-cellular wireless communication, informationaccess and management for smart spaces, dynamicservice discovery in networking, integration and inter-operability of human-centered technologies, program-ming pervasive computing applications, and innovativepervasive computing hardware.

Pervasive computing refers to the emerging trendtoward numerous, easily accessible computing devicesconnected to an increasingly ubiquitous network in-frastructure. This trend likely will create new opportuni-ties and challenges for the information technologymarketplace, placing high-performance computers andsensors in virtually every device, appliance, and pieceof equipment; in buildings, homes, workplaces, andfactories; and even in clothing. Pervasive computing willrequire inno-vative approaches to human-computerinteraction and information access technologies, as therewill be a shift toward interacting with small, distributed,and often invisible devices.

This conference supported a new pervasive comput-ing initiative at NIST. As a first step in this initiative,several experimental smart spaces are currently beingprototyped. These are focusing on advanced forms ofhuman-computer-interaction, integrating pico-cellularwireless networks with dynamic service discovery, auto-matic device configuration, and software infrastructuresrequired to successfully program pervasive computingapplications.

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CONTACT: Alden Dima, (301) 975-2450; [email protected] or Marty Herman, (301) 975-4495; [email protected] or Kevin Mills, (301) 975-3643;[email protected].

OPEN ELECTRONIC BOOK FORUM FORMEDTO DEVELOP STANDARDS FOR e-BOOKSRepresentatives from more than 30 companies and non-profit organizations met recently with members of theOpen Electronic Book (OEB) Standards InitiativeAuthoring Group to facilitate the next step forward inpromoting the growth of the electronic book industry.Held in December 1999 in San Francisco, the meetingresulted in the formation of the Open Electronic BookForum (OEBF). A preliminary charter for the newlyformed organization was composed and ratified. Thepurpose of the OEBF is to create and maintain standardsto promote the successful adoption of electronic books.

Charter members elected an Interim Board to guidethe organization in its nascent stages; a NIST staffmember chairs the board.

Formation of the OEBF continues the yearlong effortof the Open e-Book Authoring Group. Its purpose wasto develop a specification for electronic content, basedon existing standards, that allows such content to beviewed over reading systems on various devices andplatforms, while still guaranteeing fidelity and accessi-bility of that content. The Open e-Book PublicationStructure is a specification that enables contentproviders to convert once and publish anywhere. TheAuthoring Group at Electronic Book 99 introduced thisspecification at the second NIST-sponsored workshopin September 1999.CONTACT: Victor McCrary, (301) 975-4321; [email protected].

NIST HOSTS KEY MANAGEMENT STANDARDWORKSHOPNIST hosted a workshop in February 2000, to examinepublic key-based management techniques as specifiedin several private industry standards under develop-ment. Approximately 90 people from government andprivate industry participated in the workshop. Thefederal government currently has no public key-basedstandard for the establishment of cryptographic keys forunclassified applications. Since the government reliesheavily on commercial off-the-shelf products, federalagencies need to understand the options that will beavailable in industry standards. Agencies must decidewhich techniques are suitable for protecting sensitivefederal information and promoting interoperabilityamong government agencies, between the government

and the private sector, and between the U.S. governmentand the governments of other countries. The work-shop reviewed the options and techniques contained indraft standards and discussed related issues. Seehttp://www.nist.gov/kms.CONTACT: Elaine Barker, (301) 975-2911; [email protected].

STEP AND OMG PRODUCT DATAMANAGEMENT SPECIFICATION: A GUIDEFOR DECISION MAKERSOn Nov. 12, 1999, the standards group ISO TC184 onIndustrial Automation Systems and Integration, SC4 onIndustrial Data (TC184/SC4) unanimously adopted aresolution identifying the white paper “STEP and OMGProduct Data Management Specifications: A Guide forDecision Makers,” as a guideline for the complemen-tary use of the two international standards for ProductData Management (PDM) interfaces. These interfacesare the STEP (STandard for the Exchange of Productmodel data) PDM Schema and the OMG (ObjectManagement Group) PDM Enablers. On Nov. 19, 1999,the Domain Technical Committee of the ObjectManagement Group unanimously adopted the samewhite paper. This white paper identifies the twostandards, shows how the same major PDM concernsare reflected in the two standards, identifies conceptualdifferences, and describes common manufacturingscenarios for which the use of each standard is appropri-ate. The white paper was developed by a joint activityof the developers of the STEP PDM Schema and thedevelopers of the OMG PDM Enablers Metaphase.NIST experts contributed about 25 % of the text of thewhite paper. This is seen as the first successful effortin a program for harmonization of several standardsactivities for interfaces between product data manage-ment systems and other engineering software systems.CONTACT: Ed Barkmeyer , (301) 975-3528;[email protected].

NIST CRAFTSMAN CO-AUTHORS ARTICLEA NIST fabrication craftsman prepared information foran article in Fusion: The Journal for the AmericanScientific Glassblowers Society. The article reports onan octagonal glass vacuum chamber for Bose-Einsteincondensates that he made. This very complicated glassassembly involved making 14 different quartz parts thatthen were fused together to make an octagonal cell withfour quartz tubes projecting from the sides. The tubesare 32 mm diameter by 100 mm long. All the octagonparts are made from 2 mm thick quartz. This cell in-volved optically fusing the components together at an

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elevated temperature to produce the complete vacuumtight cell. This cell is being used by a group of physicistsat NIST to experiment with laser cooling and trapping ofatoms.CONTACT: Jack Fuller, (301) 975-6514; [email protected].

Standard Reference Materials

LOW-LEVEL RADIONUCLIDE ASHED BONESTANDARD REFERENCE MATERIALBone tissue is one of the most important biological sinksfor a number of long-lived radionuclides. Accuratedetermination of the radionuclides in bone specimens isessential for improving biokinetics modeling and assess-ing occupational and public internal radiation dose.However, lack of a bone standard for method validationand quality control in analytical measurements limitsthe reliability of the current analytical results and thedata comparability among national and internationallaboratories. In collaboration with the InternationalCommittee on Radionuclide Metrology, NIST led aninternational group of experienced laboratories todevelop a unique ashed bone Standard ReferenceMaterial (SRM 4356) for low-level radionuclides inbone. The SRM is a composite material containing 4 %occupationally contaminated human bone and 96 %bovine bone.

The massic activities of 90Sr, 226Ra, 230Th, 232Th, 234U,238U, 238Pu, (239+240)Pu, and (243+244)Cm were certifiedusing a variety of radiochemical procedures and detec-tion methods, and the analytical results were evaluatedusing several statistical techniques. The data analysisindicates that heterogeneities of the certified radio-nuclides are undetectable down to a sample size of 5 g.A unique character of this SRM material is the dis-equilibrium of U and Th decay chains, which is theresult of mixing occupationally contaminated humanbone with natural bovine bone, and results fromfractionation during internal biological processes.Radionuclide disequilibria prevented the certification ofthe U and Th daughters, 210Pb and 228Th.CONTACT: Zhichao Lin, (301) 975-5645; [email protected] or James Filliben, (301) 975-2855; [email protected].

NIST ISSUES NEW STANDARD FORMITOCHONDRIAL DNA SEQUENCINGSince its development, medical researchers and lawenforcement agencies have embraced DNA testing as akey tool in diagnosing diseases, pinpointing criminalsuspects, and identifying the remains of soldiers andaccident victims undistinguishable by other means.While current DNA typing requires a sample of theDNA found in the nucleus of nearly every living cell,a newer procedure makes use of a different kind—mitochondrial DNA.

Mitochondrial DNA, inherited only from yourmother, is a small circular strand of genetic materiallocated within a cell’s mitochondria, a sausage-shapedorganelle that converts nutrients into energy. Since asingle cell can have thousands of these structures, mito-chondrial DNA persists long after the DNA that makesup chromosomes has degraded. This makes it an attrac-tive target for genetic sleuths examining old evidence.Certain diseases, such as Alzheimer’s, Parkinson’s,neuromuscular dis-orders and some forms of blindness,are associated with mutations in mitochondrial DNA,making it a potential source of valuable data for medicalresearchers.

In order to ensure accuracy of mitochondrial DNAtesting and sequencing, NIST has just issued StandardReference Material 2392, Mitochondrial DNASequencing. Designed to help labs verify their mito-chondrial DNA results, SRM 2392 also can be used asa control when sequencing any DNA.

The SRM contains DNA extracted from two cell linesplus cloned DNA from a region that is difficult tosequence. It is accompanied by a certificate detailingthe base pair sequences of the DNA, so labs can checktheir own results against the values determined by NIST.The certificate also provides the sequences of 58 uniqueprimer sets which permit the amplification and sequenc-ing of any specific area or all of the mitochondrialDNA.

The new Mitochondrial DNA Sequencing SRM isavailable from the NIST Standard Reference MaterialsProgram for $766. For ordering information, call(301) 975-6776; fax (301) 948-3730; or send e-mail [email protected] Contact: Linda Joy, (301) 975-4403; [email protected].

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NEW NIST STANDARD FOR REFRACTOMETRYISSUEDRefractometry is used in the food and chemical indus-tries as a rapid and simple technique for the measure-ment of solute concentrations. The most common appli-cations of refractometry are for measurements ofsucrose in corn syrups and beverages, and ethyleneand propylene glycol in antifreeze solutions. These twoapplications alone have a large industrial impact, assmall variations in sucrose concentration control themarket price of corn syrup, and small variations in theconcentrations of ethylene and propylene glycol affectthe deicing capabilities of a solution. SRM 1922 wasissued recently as a mineral oil with a certified refractiveindex comparable to sucrose and ethylene or propyleneglycol solutions. The standard was characterizedusing the minimum deviation technique, which is thepreferred method for refractive index measurement as itdepends only on angular measurements and does notrequire reference to a material of known refractiveindex. A goniometer capable of angular measurementsof 1 second of arc or better is required for precisemeasurements, and it also must be coupled with aspectrometer. NIST fortunately maintained an instru-ment of this type, as they are now quite rare and expen-sive. A specially designed hollow glass prism enclosedin a temperature-controlled housing was used for themeasurement of the mineral oil. The choice of a liquidas the standard limited the uncertainty of the certifiedvalues to a few � 105 times the refractive index, but stillan order of magnitude better than most commercialrefractometers can achieve. A liquid was chosen for thestandard for comparability with sucrose and ethylene orpropylene glycol solutions. For solid materials NIST isable to make refractive index measurements at an uncer-tainty level that competes with the best in the world.CONTACT: Jennifer Verkouteren, (301) 975-2168;[email protected].

Standard Reference Data

NEW DATABASE OF ELECTRON INELASTICMEAN FREE PATHS RELEASEDA new NIST database (SRD 71) containing data for theinelastic mean free paths (IMFPs) of electrons withenergies between 50 eV and 10 000 eV in solids hasbeen recently released. This database includes IMFPscalculated from experimental optical data and IMFPsmeas-ured by elastic-peak electron spectroscopy. If no

calculated or measured IMFPs are available for a mate-rial of interest, values can be estimated from predictiveformulae. A user can select data from different sourcesand can display this information graphically (i.e., a plotof IMFP versus electron energy) or as values for one ormore user-specified electron energies. IMFP data fromdifferent sources or for different materials can becompared graphically.

The IMFP is a key parameter in the widely usedtechniques of Auger-electron spectroscopy and x-rayphotoelectron spectroscopy for surface analysis. Forthese applications, IMFPs are needed for quantitativesurface analyses (to correct elemental sensitivity factorsfor variations of IMFP with chemical state), for determi-nation of effective attenuation lengths (to measure filmthicknesses), for determination of mean escape depths(to find the average depth of analysis), and for simula-tions of the transport of signal electrons (to correct forthe effects of elastic-electron scattering and to deter-mine surface compositions in specimens with complexmorphologies). The IMFPs also are needed for definingthe surface sensitivity of other surface-characterizationmethods in which electron beams are employed(e.g., low-energy electron diffraction and appearance-potential spectroscopy).CONTACT: Cedric Powell, (301) 975-2534; [email protected].

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The International System of Units (SI)The Modern Metric System

Uncertain about the InternationalSystem of Units (universally abbreviatedSI), the modern metric system usedthroughout the world? Do you need toknow the proper way to express the resultsof measurements and the values of quanti-ties in units of the SI? Do you need to knowthe NIST policy on the use of the SI? Thenyou need the 1995 edition of the NationalInstitute of Standards and TechnologySpecial Publication 811, Guide for the Useof the International System of Units (SI) .

The 1995 edition of the National Institute of Standards and Technology Special Publication 811,Guide for the Use of the International System of Units (SI) , by Barry N. Taylor, is now available.

The 1995 edition of SP 811 corrects a number of misprints in the 1991 edition, incorporates asignificant amount of additional material intended to answer frequently asked questions concerningthe SI and SI usage, and updates the bibliography. The added material includes a check list forreviewing the consistency of written documents with the SI. Some changes in format have alsobeen made in an attempt to improve the ease of use of SP 811.

The topics covered by SP 811 include:• NIST policy on the use of the SI in NIST publications.• Classes of SI units, those SI derived units that have special names and symbols, and the SI

prefixes that are used to form decimal multiples and submultiples of SI units.• Those units outside the SI that may be used with the SI and those that may not.• Rules and style conventions for printing and using quantity symbols, unit symbols, and prefix

symbols, and for spelling unit names.• Rules and style conventions for expressing the results of measurements and the values of quan-

tities.• Definitions of the SI base units.• Conversion factors for converting values of quantities expressed in units that are mainly unac-

ceptable for use with the SI to values expressed mainly in units of the SI.• Rounding numbers and rounding converted numerical values of quantities.

Single copies of the 84-page SP 811 may be obtained from the NIST Calibration Program,100 Bureau Dr., Building 820, Room 236, Stop 2330, Gaithersburg, MD 20899-2330, telephone:301-975-2002, fax: 301-869-3548.

Special Publication 811

1995 Edition

Guide for the Use of the International

System of Units (SI)

Barry N. Taylor

United States Department of Commerce

Technology Administration

National Institute of Standards and Technology

Evaluating and Expressing the Uncertaintyof Measurement Results

Uncertain about expressing measure-ment uncertainty? Do you need to knowhow NIST states the uncertainty of its mea-surement results and how you can imple-ment their internationally accepted methodin your own laboratory? Then you need thenewly available 1994 edition of theNational Institute of Standards and Tech-nology Technical Note 1297, Guidelinesfor Evaluating and Expressing the Uncer-tainty of NIST Measurement Results.

The 1994 edition of the National Institute of Standards and Technology Technical Note 1297,Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results , by BarryN. Taylor and Chris E. Kuyatt is now available.

The 1994 edition of TN 1297 includes a new appendix—Appendix D—which clarifies and givesadditional guidance on a number of topics related to measurement uncertainty, including the useof certain terms such as accuracy and precision. Very minor word changes have also been madein a few portions of the text of the 1993 edition in order to recognize the official publication inOctober 1993 by the International Organization for Standardization (ISO) of the Guide to theExpression of Uncertainty in Measurement on which TN 1297 is based. However, the NIST policyon measurement uncertainty, Statements of Uncertainty Associated with Measurement Results,which is reproduced as Appendix C of TN 1297, is unchanged.

It is expected that the 1994 edition of TN 1297 will be even more useful than its immediatepredecessor, the 1993 edition, of which 10 000 copies were distributed worldwide.

Those United States readers who wish to delve into the subject of measurement uncertainty ingreater depth may purchase a copy of the 100-page ISO Guide from the Sales Department of theAmerican National Standards Institute (ANSI), 105-111 South State Street, Hackensack,NJ 07601. Copies may also be purchased from the ISO Central Secretariat, 1 rue de Varembe,Case postale 56, CH-1211 Geneve 20, Switzerland.

Single copies of the 20-page TN 1297 may be obtained from the NIST Calibration Program,100 Bureau Dr., Building 820, Room 236, Stop 2330, Gaithersburg, MD 20899-2330, telephone:301-975-2002, fax: 301-869-3548.

NIST Technical Note 1297

1994 Edition

Guidelines for Evaluating and Expressing

the Uncertainty of NIST Measurement Results

Barry N. Taylor and Chris E. Kuyatt

United States Department of Commerce

Technology Administration

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 the basic 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 the following 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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