new journal of research of the national institute of standards and … · 2000. 7. 23. ·...

Volume 105, Number 3, May–June 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.

INFORMATION ON WELD FERRITESTANDARDS NOW AVAILABLEAustenitic weld metals usually contain a small butcontrolled amount of ferrite to reduce the tendency forcracking during solidification. Ferrite is a magneticcomponent that has an important effect on propertiessuch as weld toughness and corrosion resistance.Stainless steel welds contain a balance of austenitic andferritic phases to optimize their mechanical properties.Measurement of the ferrite content is an importantcommercial issue because content ranges are commonlyspecified in contracts and production standards. In theUnited States, the amount of ferrite is usually measuredmagnetically according to the American WeldingSociety AWS A4.2 standard.

The AWS standard specifies procedures for bothprimary and secondary calibration of the instruments.Primary calibration is based on reference materials ofcoating thickness, such as NIST Standard ReferenceMaterials 1361 to 1364. Secondary calibration is basedon certified specimens of stainless steel and is the onlyway of calibrating instruments for which no primarycalibration method exists. It is also the most appropriatestandard for in-process checks and is much moredurable than the primary reference materials.

NIST recently acquired the responsibility forcalibrating and distributing secondary standards forboth national and international markets, and has justpublished a guide to these calibrations titled SecondaryFerrite Number Reference Materials: Gage Calibrationand Assignment of Values (NIST Special Publication

News Briefs

260-141). The publication covers gage calibration,measurement of secondary reference materials, certifi-cation of secondary reference materials and discussionof errors, and microstructure. NIST also sells sets ofthese secondary ferrite standards, known as RM 8480and RM 8481 (RM stands for reference materials).

Copies of the calibration guide (ask for no. 10-00) areavailable from Sarabeth Harris, NIST, MC104, Boulder,CO 80303-3337; (303) 497-3237. The SRMs and RMscan be ordered from the Standard Reference MaterialsProgram, NIST, 100 Bureau Dr., Stop 2322, Gaithers-burg, MD 20899-2322; (301) 975-6776; fax: (301)948-3730; [email protected] Contact: Fred McGehan (303) 497-3246;[email protected].

COMMON TIME SCALE ESTABLISHED FORALL OF NORTH AMERICAThe official time scales of North America are co-ordinated through regular comparisons among theCanadian National Research Council (NRC), theMexican Centro Nacional de Metrologia (CENAM),and the U.S. National Institute of Standards andTechnology. After several years of internationalcomparisons and negotiations, NRC, CENAM, andNIST recently have declared that their respectiveversions of Coordinated Universal Time (known asUTC) are equivalent to within 5�10–6s for timemeasurements and within 1�10–12 for frequencymeasurements.

The common time scale defined by the declaration isknown as UTC North America, and within the stateduncertainties, the time supplied by any of the threenational laboratories UTC(NRC), UTC(CENAM) orUTC(NIST) can be used as UTC North Americawithout corrections or conversions.

This declaration supports trade and technology acrossthe region, especially through such things as timetags for financial transactions and scientific observa-tions. The three institutions hope that a common time

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eventually can be extended to include all members of theInteramerican Metrology System (abbreviated SIM forthe Spanish translation, Sistema Interamericano deMetrologia), an organization set up to harmonizemeasurement standards among its members, includingnearly all of the nations in North, Central and SouthAmerica, as well as the Caribbean.

To access the official time in any U.S. time zone, goto www.time.gov on the World Wide Web. For timesoutside the United States, the site offers links to a UTCdisplay and an international time zone web site (via the“About This Service” page).Media Contact: Collier Smith (303) 497-3198;[email protected].

OH, WHAT A TANGLED WEB THESEPARTICLES WEAVE!Researchers in the Time and Frequency Division ofNIST’s Boulder, CO, Laboratories have made the firstobservation of quantum entanglement of four particles.Featured as the cover story in the March 16, 2000, issueof Nature, the experiment is considered an essentialstep toward the future development of a quantum com-puter a device whose computing capabilities would bedefined by the laws of quantum physics, far surpassingany conventional computer in power and efficiencywhen applied to certain problems.

Entanglement is a form of linking between two ormore particles in which some of the quantum propertiesof those particles become “shared.” Subsequently,information about one particle’s properties is instantlyand “mysteriously” linked to the others, even when theparticles become widely separated. Albert Einsteintermed this phenomenon “spooky action-at-a-distance,”and it remains one of the most puzzling features ofquantum mechanics.

To achieve the entanglement, NIST researchersconfined four singly ionized beryllium atoms in anelectromagnetic trap so that they were spaced along aline. They then used lasers to cool the atoms to nearabsolute zero and forced them all to be in the same spinstate (atoms can be in one of two states: spin-up orspin-down). Suitably tuned laser light then entangledthe atoms by exploiting their mutual electrical repul-sion, creating a superposition of all four atoms beingboth spin-up and spin-down simultaneously.

Quantum superpositions are often explained in termsof the famous cat postulated in 1935 by physicist ErwinSchroedinger. Schroedinger considered the possibilitythat a cat could be made to be both dead and alive at thesame time when the rules of quantum mechanics arefollowed to an extreme. “Schroedinger’s cat” soon

became a shorthand way to refer to a whole class ofsuperposed quantum states.

Although the NIST result represents the largest entan-gled superposition ever achieved, four atoms is still farremoved from the complexity of a cat. However, as aNIST researcher explains, “Our technique is scalable toa lot more atoms. If we get to that level, we’ll not onlybring the strangest feature of quantum mechanics closerto the macroscopic world, but we also may have aquantum computer.”

Scientists predict that such a computer could store andprocess superpositions of numbers in parallel, using theextra linkage afforded by entanglement. A quantumcomputer would quickly solve problems such as thefactoring of extremely large numbers and the handlingof huge arrays of data tasks requiring so much memorythat conventional computers cannot handle them.

For technical information, contact ChristopherMonroe at (303) 497-7415, [email protected] Contact: Collier Smith (303) 497-3198; [email protected].

NIST HELPS DEVELOP SOME OF WORLD’SCOLDEST REFRIGERATORSFor most people, refrigeration means a large box wheremilk is kept cool and ice cream is kept frozen. But thereare some people for whom refrigeration means coolingthings down to just a few degrees above absolute zero.Now, that’s really cold! NIST has been a pioneer in thedevelopment of these extremely low temperature refrig-erators, called cryocoolers.

Since 1950, about 100 000 cryocoolers have beenmanufactured in the United States for military applica-tions such as cooling infrared sensors in tanks, airplanesand missiles. However, the past decade saw the marketfor cryocoolers move to the civilian side—a trend thatappears to be growing strong. For example, cryopumpsfor the semiconductor fabrication industry have been theprimary application of the technology since 1990, withthe devices being produced at a rate of about 20 000 peryear. And as semiconductor components continue toshrink, companies will need cryocoolers with less vibra-tion and that can reach temperatures as low as 10 K to15 K above absolute zero. At the other end of the scale,large cryocoolers are being developed for liquefyingnatural gas and methane-rich gas emitted from largelandfills. Perhaps the application most familiar to thepublic is the use of cryocoolers in superconductingmagnets for magnetic resonance imaging systems wheretemperatures can get down to 4 K above absolute zero.

A new paper from NIST reviews the history and de-velopment of cryocoolers, focusing on one type called a

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pulse-tube refrigerator. Because these refrigerators haveno moving parts at the cold end, they provide less vibra-tion, higher reliability and lower cost. They also have alonger lifespan from 3 to 10 years—and are desirable forapplications in outer space. Other potential uses forpulse-tube refrigerators include industrial gas lique-faction and power applications of superconductors.

For a copy of the paper, “Development of the PulseTube Refrigerator as an Efficient and ReliableCryocooler” (no. 11-00), contact Sarabeth Harris,MC104, NIST, Boulder, CO 80303-3337; (303)497-3237; [email protected] Contact: Fred McGehan (303) 497-3246;[email protected].

FINANCIAL STANDARDS COMMUNITY TOUSE NIST CRYPTOGRAPHY GUIDELINE ASA MODELAt the most recent meeting of ANSI X9F3, a sub-committee of Accredited Standards Committee X9F,which is responsible for developing informationsecurity standards and guidelines for the financialcommunity, members expressed significant interestin the new NIST Special Publication (SP) 800-21,Guideline for Implementing Cryptography in theFederal Government. Members of the financialcommunity proposed the development of a new ANSIdocument based heavily on the guideline, which wasauthored by a NIST staff member. The ANSI documentwill be written for the financial sector, rather than thefederal government, and will guide developers, integra-tors, managers, technical specialists, procurementspecialists, and auditors of financial informationsecurity systems. X9F3 will submit a New Work Itemproposal for this document to ANSI X9F for ballotingthis spring.

SP 800-21 provides guidance to federal agencies onhow to select cryptographic controls for protectingsensitive unclassified information. It presents athorough overview of the current suite of federalstandards used to provide numerous security services,such as confidentiality, authentication, integrity, etc.Federal employees who are responsible for designingsystems and procuring, installing, and operatingsecurity products to meet identified security require-ments comprise the intended audience of SP 800-21.The document does not provide a technical discussionof the mathematics that underlies cryptographicsecurity. Rather, it provides managers, technicalspecialists (not necessarily experienced with cryptogra-phy), and procurement specialists with sufficient

information to select appropriate cryptographicmethods to protect sensitive data.

SP 800-21 is available at http://csrc.nist.gov/nistpubs/.For more information on NISTs cryptographicstandards, see http://csrc.nist.gov/cryptval.CONTACT: Annabelle Lee, (301) 975-2941; [email protected].

COORDINATE MEASURING MACHINEUTILIZED FOR PRECISION MEASUREMENTSA commercial, state-of-the-art coordinate measuringmachine (CMM), which was error mapped at NIST lastyear to improve its accuracy, is now being utilized byNIST staff for many demanding measurement needs.Most recently, the machine was used to measure a set ofball bars that serve as critical length standards for a newmeasurement of the universal gravitational constant Gbeing carried out by a team of researchers at the Univer-sity of Washington. Ball bars up to 460 mm in lengthwere measured with uncertainties below 0.5 �m. As aconsistency check, the ball bars also were measured onanother NIST CMM; these values agreed with thefirst values at the submicrometer level, which is withinthe combined uncertainties expected for the twomachines. CONTACT: Dennis Everett, (301) 975-5272; [email protected].

TRANSMITTAL PAGE OF U.S. CONSTITUTIONSEALED IN NEW ENCASEMENTResulting from the outstanding effort by a large numberof NIST staff, the transmittal page of the U.S. Constitu-tion has been sealed in the first of the new encasementsfor the Charters of Freedom documents (i.e., Constitu-tion, Declaration of Independence, and Bill of Rights).Several NIST staff members were present on Feb. 23 toclose the valves to complete the gas filling and sealingof the first encasement. The encasement is filled withhumidified argon (40 % relative humidity at the displaytemperature) with very low levels of residual oxygen.This accomplishment represents the end of the begin-ning for the project team. Next, the project team mustbuild the second prototype (of a smaller size) and thencomplete the production run of seven more encase-ments. The ability to draw on the diverse expertise of somany NIST staff has enabled this project to meet theextremely challenging performance and schedulesdemanded by the National Archives and RecordsAdministration.CONTACT: Christopher Evans, (301) 975-3484;[email protected] or Dick Rhorer, (301) 975-6506; [email protected].

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METROLOGY FOR DEVELOPMENT OFEMBEDDED CAPACITANCE TECHNOLOGYFOR HIGH-SPEED ELECTRONICSNIST scientists, in collaboration with industry andacademia, are developing test methodology for embed-ded capacitance technology. There is a widespread needfor power-ground decoupling in todays electroniccircuits to assure signal integrity and to reduce electro-magnetic noise. Currently used discrete capacitors poseseveral drawbacks, such as the significant manufactur-ing costs and the amount of surface area they occupy onthe electronic assembly. In addition, discrete capacitorsdo not perform adequately at frequencies above 1 GHz,the frequency regime for todays wireless communica-tion and other high-speed electronics. In looking for atechnical solution the National Center for Manufactur-ing Science, NIST, and more than a dozen industrypartners formed a consortium to develop and advanceembedded-decoupling-capacitance (EDC) technology.The embedded-decoupling capacitance appears to bethe most efficient way to achieve low noise in the voltagedriving device, and thus, the highest possible data-speedthat otherwise is unobtainable by any other known pack-aging solution.

Through this multidisciplinary effort over the past2 years, the EDC Consortium has identified polymer-ferroelectric-composite materials as one of the primarycandidates for this new technology need. The NIST ef-fort focused on design of test vehicles and proceduresfor dielectric testing these polymer composite films.Progress on this effort was reviewed at a recent work-shop organized by the EDC Consortium that attractedover 100 researchers from materials suppliers, circuitmanufacturers, original equipment manufacturers, anduniversities. During the workshop, experts from theconsortium members, including NIST, discussed newdesign guidelines and measurement aspects of the EDCtest methodology that led to agreement on furtheractions towards developing a new standard test proce-dure for EDC technology.CONTACT: Jan Obrzut, (301) 975-6845;[email protected].

COMPUTATIONAL STUDIES ADVANCEATOMISTIC UNDERSTANDING OFELECTRONIC CERAMICSRecent computational studies by NIST researchers havemade significant advances in elucidating the micro-scopic origins of the behaviors of two types of elec-tronic ceramics. The first type, lead-containing per-ovskite ceramics, PbB1/3B'2/3O3 (B and B' are metal ionssuch as Mg2+, Ti4+, and Nb5+), are currently used inactuators and sonar/medical imaging transducers. The

electrical properties of these materials are sensitivefunctions of the precise arrangements of the metal ionsin the crystal structure; hence, carefully controlledprocessing is required to achieve optimized properties.First-principles total energy calculations have revealed acomplex many-body interaction between lead and cer-tain oxygens that explains atomistically why the Bcations disorder at much lower temperatures when theceramics contain Pb instead of Ba. Typically, Pb–Obonds are stronger and more covalent than Ba–O bondsbecause Pb has a lone-pair of 6 sp electrons—thistype of interaction results in technically importantproperties such as ferroelectricity in PbTiO3. Thecomputational results showed that this Pb–O interactionis further enhanced when the oxygen is “underbonded”;i.e., when the other cations bonded to that oxygen arerelatively low in charge. For example, the oxygen ina Mg2+–O–Mg2+ environment is underbonded and reactsmore strongly with Pb than an oxygen in a Ti4+–O–Ti4+

environment. These results explain why, how, and underwhat conditions metal ions order and/or disorder, andare immediately useful for property optimization.

The second electronic ceramic, CaTiO3, is used inbase station filters and resonators for wireless communi-cations. The dielectric constant of CaTiO3 is nearly 200,which is unusually high for a non-ferroelectric material.First-principles calculations reveal the microscopicorigin of these unusual electrical properties. Computedphonon spectra and dielectric constant indicated thatinteratomic forces in CaTiO3 are characterized by adelicate balance between electrostatic attraction andshort-range repulsion, which results in a set of low-frequency phonons that have large amplitudes in anapplied electric fieldthese phonons are the direct causeof the high dielectric constant. The results also revealedthe nature of these critical phonons as modes in whichthe Ca2+ and Ti4+ cations move together in a directionopposite that of the negatively charged oxygens—thisexplains chemically why the polarization associatedwith these modes is maximized, and the very highdielectric constant is observed. These results providefundamental knowledge useful for the rational designand prediction of materials with controlled properties.CONTACT: Ben Burton, (301) 975-6043; [email protected].

THERMODYNAMIC DATA PREDICTSCONDITIONS FOR ALLOYELECTRODEPOSITIONThe electrodeposition of metallic alloys has been centralto the growth of the electronics and magnetic recordingindustries. This is largely due to the exceptional proper-ties exhibited by electrodeposited material as well as

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the favorable economy of scale associated with electro-deposition processes. Most often, alloy depositionproceeds at potentials well below the reversible poten-tials of the alloy constituents. Composition andmicrostructure are generally controlled by electrolytecomposition, solution hydrodynamics and electrodepotential. In some cases, alloys can be formed at poten-tials that are positive of the reversible potential of theless noble species (underpotential deposition, UPD)due to the favorable free energy associated with alloyformation.

A technology important to electronics manufacturingin which UPD plays a vital role in determining depositproperties is the electrodeposition of gold. For gold thinfilm growth, electrodeposition proceeds in the UPDregion of an impurity metal which promotes nucleationand grain refinement. The impurity metal is incorpo-rated only at trace levels in the deposit. It is likely thatUPD alloy deposition will be seriously examined forcopper metallization for future generations of on-chipinterconnects requiring copper alloys. NISTs researchobjective is to develop the underlying theory and metrol-ogy necessary to gain a better understanding of UPD asit relates to the bulk formation of alloys. In collaborationwith a University of Mississippi scientist, NISTresearchers have examined the electrodeposition ofaluminum-transition metal alloys from an aluminumchloride/1-methyl-3-ethylimidazolium chloride ambienttemperature molten salt. This non-aqueous electrolytewas chosen so that surface oxides and hydrogenevolution could be avoided. Using the alloy free energydata that appear in the phase diagram literature, theresearchers have accurately predicted that Cu-Al, Ni-Al,Co-Al, and Fe-Al alloys can be electro-deposited atpotentials positive of the aluminum reversible potential;i.e., these alloys co-deposit by a UPD mechanism.Further, the researchers can predict the potential atwhich alloy deposition is initiated. The alloy free energytreatment also accurately predicts that Zn-Al and Sb-Alalloys will not form by UPD. Future work will focus onthe development of electrode potential—alloy composi-tion relationships based on alloy free energy.CONTACT: Gery R. Stafford, (301) 975-6412; [email protected].

CROSSLINKED MICELLAR GEL FORENVIRONMENTAL CLEANUPSurfactants are commonly used in detergency applica-tions where several hundred surfactant molecules aggre-gate to form a micelle consisting of a hydrophobiccore that is shielded from its aqueous environment.Unwanted (often oily) solutes are spontaneously solubi-

lized in the hydrophobic cores of the micelles, providinga homo-geneous dispersion of oil in water where the oilis effectively concentrated inside the micelle. Unfortu-nately, the oil-containing micelles are typically toosmall (ca. 5 nm) to be removed from the water byconventional methods such as filtration or centrifuga-tion. Stabilized “macro-micelles” would provide amethod for not only concentrating contaminants, butalso removing them from solution.

Recently, a NIST chemical engineer in the NISTCenter for Neutron Research (NCNR), succeeded insynthesizing a surfactant-based material that retainsfeatures and functionality of surfactant micelles andbenefits from the structural stability of a crosslinkedpolymer matrix. The material, a crosslinked micellargel, is prepared by a simple one-step aqueous polymer-ization of the surfactant cetyltrimethylammonium4-vinylbenzoate to which a small quantity of acrosslinker, divinyl benzene, has been added. Asprepared, the surfactant mass fraction of the gel is 1 %and its water mass fraction is 99 %, but it can easily behandled and cut to a desired shape.

Physical characterization of the micellar gel at theNCNR by small-angle neutron scattering has confirmedthat the structure of the gel is that of cylindrical micellesbetween crosslinks. The micelles have a circular cross-section of 4 nm, and an average pore size of 40 nm. Thepore size is adjustable by controlling the initial surfac-tant concentration. The micellar gel is capable of solubi-lizing common hydrocarbons and other hydrophobicsolutes. The most significant advantage of the micellargel is that once oily material has been solubilized andconcentrated in the gel, the gel (and the contaminant)can simply be lifted from the solution. This materialclearly has promise in use for wastewater cleanup(gasoline, for example). Other possible applicationsinclude a controlled release matrix for drug delivery, aporous matrix for gel electrophoresis, or a selectivefilter membrane. A patent is pending on the material andwork is continuing toward defining a class of crosslink-able micellar materials.CONTACT: Steve Kline, (301) 975-6243; [email protected].

QUANTUM ENTANGLEMENT OF FOURPARTICLES FEATURED IN NATUREIn the cover story of the March 16, 2000, issue ofNature, NIST staff members describe the first success-ful quantum entanglement of four particles. This break-through represents an important step in demonstrating aquantum-logic system that possesses the requisitecharacteristics for scaling to larger computing systems.

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Such entangled states explicitly demonstrate the non-local character of quantum theory, and have beensuggested for use in quantum communication, crypto-graphy, computation, and high-resolution spectroscopy.

The entanglement used a recently proposed techniqueapplicable to trapped ions. Coupling between the ions isprovided by the Coulomb interaction through theircollective motional degrees of freedom, but actualmotional excitation is minimized. Entanglement wasachieved using a single laser pulse, and this same one-step method can in principle be applied to any numberof ions.CONTACT: David J. Wineland, (303) 497-5286;[email protected].

SCATMECH C++ LIBRARY MAKESPOLARIZATION CALCULATIONS AVAILABLETO EVERYONENIST Scientists perform measurements of the angulardistribution and polarization of laser light that has beenscattered elastically from smooth surfaces possessingvarious types of defects. They have found that scatter-ing from each type of defect or particulate contamina-tion on the surface exhibits a characteristic scatteringpattern, and the experimental results are in excellentagreement with theoretical predictions. Hence, bycomparing observed and theoretical scattering patterns,researchers can identify the particular defects present ina sample. These results are being used by the semicon-ductor industry to improve its ability to locate and iden-tify contamination on silicon wafers. Other industries,such as the display, storage, and optical industries,which also require high-quality surfaces, are expectedto follow.

Calculations of scattered light intensity and theanalysis of its polarization, however, are not typicallywithin the capabilities of any but the leading specialists.Accordingly, NIST has developed an object-orientedsoftware library, the SCATMECH Polarized LightScattering C++ Object Class Library, which imple-ments various models and allows researchers to analyzepolarizations readily. The SCATMECH librarycontains object classes that allow researchers to manip-ulate objects describing the polarization state of light, topredict the intensity and polarization of light scatteredusing various approximations, and to readily add newmodels to the library. The library enables researchers totry models for their own applications, allows softwaredevelopers to expand ray-tracing programs, and acts asa platform to allow other researchers to expand thelibrary. Anticipated users include wafer inspection tool-makers, optics companies, manufacturers of datastorage media and devices, com-panies interested in the

appearance and surface finish of products, andacademic researchers. The SCATMECH Libraryis being distributed on the World Wide Web athttp://physics.nist.gov/scatmech.CONTACT: Thomas A. Germer, (301) 975-2876;[email protected].

A NEW THEORY FOR TRANSVERSE COOLINGIN FOUNTAIN FREQUENCY STANDARDSREDUCES UNCERTAINTIESIn a collaborative effort with Russian scientists, a NISTresearcher has developed a new concept for two-dimen-sional sideband Raman cooling and Zeeman state prepa-ration in an optical lattice. The development of thisconcept was driven by the need to reduce transversevelocities of laser-cooled atoms in primary cesium-fountain frequency standards, and will provide forsignificant reduction in the uncertainty of NIST-F1,NIST’s new primary frequency standard.

This new approach for transverse cooling appears tobe both simpler and more effective than previouslyproposed methods and has two significant advan-tages: the method only requires laser beams transverseto that atomic fountain direction, and the coolingprocess simultaneously pumps atoms into the desiredground-state energy level. An experimental apparatusdesigned to test the effectiveness of this cooling methodis now under development at NIST.

The largest uncertainty in cesium-fountain frequencystandards is the so-called spin-exchange frequency shift,the magnitude of which depends on the density of atomsaveraged over the fountain trajectory. In NIST-F1, themagnitude of the transverse velocities of the launchedatoms (cooled to about 1.5 �K) results in a loss ofapproximately 90 % of the atoms before they reach thedetection region. This means that most of the atomscontribute to an increased spin-exchange frequencyshift without contributing to the output signal. Withbetter transverse cooling, a larger fraction of the atomswill reach the detection region and the launch densitycan be decreased leading to a lower spin-exchange shiftwhile retaining a good signal-to-noise ratio. The newtheory predicts that 95 % of the atoms can be cooled totransverse temperatures of about 100 nK.CONTACT: Leo Hollberg, (303) 497-5770; [email protected].

METALLIC XENON OBSERVEDA NIST scientist, in collaboration with workers atthe Carnegie Institution of Washington, has investi-gated the electrical conductivity of Xenon at highpressures.

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Rare gases such as Xe are expected to metallize onlyat very high pressures because the atoms have com-pletely filled electronic energy shells. Xe has beenpredicted to have the lowest metallization pressure.Various optical measurements have suggested a transi-tion to metallic-like behavior between 135 GPa and150 GPa.

In this work, direct measurements of the temperaturedependence of the conductivity from 0.03 K to 90 K, ata variety of pressures between 121 GPa and 155 GPa,have clearly shown a transition from semiconducting tometallic conductivity for pressures above 121 GPa. Asearch for pressure-induced superconductivity (whichsome theoretical work has predicted) yielded a nullresult, even at the highest pressure and lowest tempera-tures. This search will be continued when a newpressure cell capable of reaching higher pressures isfinished.CONTACT: Michael H. Kelley, (301) 975-3722;[email protected].

SUPPORT PROVIDED FOR NEWOSCILLOSCOPE CALIBRATORSAs the frequency response rolloff performance (or 3 dBbandwidth) of newer real-time analog and digital oscil-loscopes has increased, verifying the specification forthis important performance parameter has becomeincreasingly difficult. Recent offerings of popularbrands of real-time sampling scopes offer 3 dBbandwidth specifications as high as 3 GHz.

The capability at NIST of measuring the parametersof fast pulse sources has continued to improve. Equiva-lent-time sampling oscilloscopes having effective 3 dBbandwidths of 50 GHz are now used at NIST to supportcalibrating the parameters of fast pulse generators (edgerise times as short as 15 ps). Also, a precision waveformsampling system based on a custom-made, strobedanalog comparator integrated circuit has been devel-oped having an effective 3 dB bandwidth of 2.5 GHz.

Therefore, when two U.S. instrument manufacturersdecided to develop new oscilloscope calibrators havingfast edge pulse generators for 3 dB bandwidth testing,NIST was prepared to characterize the prototype unitsthat both companies sent in for special calibration(formal NIST reports issued). Besides testing for theedge rise time (or transition duration), the NIST pulsetesting systems were able to make accurate determina-tions of the waveform aberrations (deviations from flat-ness in settling) that were desired by the two companies.New product catalog entries and marketing literature byboth companies describe the specifications and features

that are now offered in the new calibrators, related to theunique measurement support capabilities provided byNIST.CONTACT: Barry A. Bell, (301) 975-2419; [email protected].

QUANTUM MECHANICAL SIMULATORSEVALUATED TO EXPEDITE DESIGN OF DEEPSUBMICROMETER TRANSISTORSResearchers at NIST initiated a study to compare, for thefirst time, quantum mechanical simulators and analysissoftware suites that are critical to the continued shrink-ing of silicon complementary metal oxide semiconduc-tor (CMOS) transistor structures. The significance andindustry need for this study is accentuated by a privatecompany’s recent announcement of the production of a2 nm gate oxide film, which is equivalent to about6 atoms stacked end-to-end. At this thickness, reliabilityof the transistor becomes a serious issue, becauseatomic-scale defects can result in charge leakage andlead to device failures. Even for a defect-free oxide,quantum mechanical tunneling leads to predictable, butunwanted currents.

Today, industrial determinations of gate oxide thick-ness are based on consistency between electrical meas-urements (capacitance-voltage, or C-V curves) andquantum mechanical simulations. The simulations takeinto account electron tunneling, quantization of states inthe gate channel, and depletion of charge in the poly-silicon gate electrode, all with different levels of sophis-tication. In spite of the importance of the models, therehave been no reported comparative investigations ofdifferences resulting from the different simulations untilnow.

In addressing this need with a first-ever benchmark-ing study, NIST researchers acquired and installed thesimulators and analysis software suites that are availablefrom university, corporate, and commercial researchgroups. A capacitor test structure was designed, repre-senting different levels of electrode doping, and oxidethickness ranging from 1 nm to 10 nm. Qualitativetrends of the C-V curves were found to be similar for allsimulators; however, quantitative analysis revealed bothdepletion and accumulation capacitance differences,which become larger as the film thickness approaches2 nm.

NIST researchers presented invited summaries ofthese findings to the SEMATECH Gate Stack Engineer-ing Working Group and the International MetrologyCouncil.CONTACT: Curt A. Richter, (301) 975-2082; [email protected].

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COAXIAL NOISE-TEMPERATUREMEASUREMENT SERVICE REOPENEDWITH NEW, FASTER RADIOMETERSNIST staff have completed construction and testing oftwo new radiometers for measuring coaxial noisesources. The two new radiometers cover the frequencies4 GHz to 8 GHz and 8 GHz to 12 GHz, respectively.Their completion has permitted the reopening of the4 GHz to 12 GHz coaxial noise-temperature measure-ment service, which had been suspended due to waterdamage to the previous radiometers. Careful mechani-cal, thermal, and electronic design and construction haveresulted in major improvements in stability, repeatabil-ity, and speed over the previous generation of NISTradiometers. These improvements are all required for ameasurement service for noise parameters of amplifiers,which is currently under development. The newradiometers also pay an immediate dividend in greatlyincreased speed of traditional noise-temperaturecalibrations. On the new system, it is possible tocalibrate a noise source at 10 or more frequencies in thetime required for one frequency on the old system. Thisgreatly increased speed has permitted a correspondingreduction in the fee charged to customers for themeasurement service. The cost for each additional fre-quency point (after the first) has been reduced by afactor of 10, i.e., to $210 per point. The new system isdocumented in a NIST Technical Note and a paperpresented at the 55th Conference of the AutomatedRadio Frequency Techniques Group (ARFTG) held inBoston in June 2000.CONTACT: Robert Judish, (301) 975-3380; [email protected].

NEW EFFICIENT APPROACH TO BLINDDECONVOLUTION OF IMAGES DISCOVEREDA NISTmathematician has developed a powerful newtechnique for blind deconvolution of images. Blinddeconvolution seeks to deblur an image without know-ing the cause of the blur. This is of considerable interestin numerous medical, industrial, scientific, and militaryapplications. The mathematical problem is very difficultand not fully understood. So far, most approaches toblind deconvolution have been iterative in nature. How-ever, the iterative approach is generally ill behaved,often developing stagnation points or diverging alto-gether. When the iterative process is stable, a largenumber of iterations and several hours of computationmay be necessary to resolve fine detail.

In a recently completed research paper, the mathe-matician has developed a novel approach to the problemthat is non-iterative in nature. The method does notattempt to solve the blind deconvolution problem in full

generality. Instead, attention is focused on a wide classof blurs that includes and generalizes Gaussian andLorentzian distributions, and has significant applica-tions. This is the class G. Likewise, a large class of sharpimages is exhibited and characterized in terms of itsbehavior in the Fourier domain. This is the class W. Itis shown how 1-D Fourier analysis of blurred image datacan be used to detect class G point spread functionsacting on class W images. This approach is based onempirical observations about the class W that have notpreviously been exploited in the literature. A separateimage deblurring technique uses this detected pointspread function to deblur the image. Each of these stepsuses direct (non-iterative) methods. Although the newtechnique does require interactive adjustment of para-meters, it still enables blind deblurring of 512 � 512images in only minutes of CPU time on current desktopworkstations.

Analysis of the blind deconvolution problem withinthe class G already has produced a number of interest-ing and unexpected results. Current research seeks toextend this approach to a wider class of blurs, in partic-ular, out-of-focus blurs.CONTACT: Alfred Carasso, (301) 975-2705; [email protected].

THE EFFECTS OF GAS SPECIE ON METERINGPERFORMANCE OF CRITICAL FLOWVENTURISNIST researchers have identified a new mechanism thataffects the mass flow of certain gases (e.g., CO2)flowing through small-scale critical flow venturis(CFVs). In small-scale CFVs, rapid flow accelerationprocesses occur over small distances (i.e., 1 mm)leading to short residence times (about 10–6 s). Thisleaves insufficient time for the vibrational energy of theflowing gas molecules to equilibrate with the changingthermodynamic environment. For gases that relaxslowly and have sufficient levels of vibrational energy,vibrational relaxation phenomena has been shown toincrease the discharge coefficient by as much as 2 %relative to gases unaffected by this mechanism.

A first principle mathematical model has been devel-oped that predicts mass flow for gases affected by non-equilibrium states (e.g., CO2) as well as gases unaf-fected by non-equilibrium states (e.g., N2, H2, O2, Ar).The model uses molecular theory to determine the rateof relaxation of vibrational energy modes due to non-equilibrium processes. The solution of the non-equilibrium flow field is obtained by globally iteratingbetween the gas dynamic equations and the vibrationalenergy rate equation so that both are simultaneouslysatisfied. This model yields a reduction in uncertainty

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by a factor of 5 compared to existing models for CO2 gasflow, and predicts the discharge coefficient for all gasesto within 0.4 % of experimental data. The good agree-ment between the model and experiment could helpalleviate the need for experimental calibration in manyapplications and even enable the use of these sensors asprimary standards at mid-range uncertainties.CONTACT: Aaron Johnson, (301) 975-5954; [email protected].

NIST HELPS ASME PRODUCE NEW STEAMTABLES BOOKThe American Society of Mechanical Engineers(ASME), through its Research and TechnologyCommittee on Water and Steam in Thermal Systems,Subcommittee on Properties of Steam, has issued a newreference book: ASME International Steam Tables forIndustrial Use (ASME Press, New York, 2000). Theauthors include two NIST staff members and NISTpersonnel produced several chapters and all of thetables.

Water and steam are important in many fields ofengineering, notably the power industry where thethermodynamic properties are central to the design andevaluation of steam power generation equipment.Standardized properties are essential to provide a levelplaying field for all parties in the industry. Standardproperty formulations are set by the InternationalAssociation for the Properties of Water and Steam(IAPWS). The book is based on the standard for indus-trial use adopted by IAPWS in 1997. The previousstandard, adopted in 1967, was the basis for the widelyused ASME Steam Tables book. The new formulationis a significant improvement in accuracy, internalconsistency, and computational speed. The book wasredesigned and rewritten to reflect the needs of currentengineers. Tables and charts are given in both SI andU.S. customary units, and are less extensive than in the1967 book in recognition that they are now mainly a toolfor rough estimates, with computers being used for mostdesign calculations.

This book is based on the IAPWS standard “forindustrial use,” which is tailored to the needs of thesteam power industry. This should not be confused withthe separate standard IAPWS maintains “for general andscientific use,” which is a more precise and comprehen-sive (but also more complex) formulation. Softwareimplementing this latter standard is distributed by NISTsStandard Reference Data office. Software implementingthe standard for industrial use, and thereforeconsistent with the new book, is available from ASME.

Copies of the steam tables handbook may be obtainedby contacting the American Society of Machanical

Engineers, Customer Service, 22 Law Dr., P.O. Box2900, Fairfield, NJ 07007-2900; (800) 843-2763;www.asme.org. The cost is $60 for ASME members and$75 for non-members.CONTACT: Allan Harvey, (303) 497-3555; [email protected].

NVLAP OFFERS NEW ACCREDITATIONPROGRAMSThe National Voluntary Laboratory AccreditationProgram (NVLAP) is now offering accreditation forcertifiers of spectrophotomet-ric filter NIST TraceableReference Materials (NTRMs) in the chemical calibra-tion field of its Calibration Laboratories AccreditationProgram. NIST Special Publication SP 260-140:Technical Specifications for Certification of Spectro-photometric NTRMs, describes an NTRM as “a com-mercially produced reference material with a welldefined traceability linkage to existing NIST chemicalmeasurement standards.”

In addition, under the terms of an agreement betweenNIST and the U.S. Environmental Protection Agency(EPA), NVLAP now accredits laboratories that arecompetent to characterize samples and to conductproficiency test programs to support EPA requirementsfor environmental laboratories. Technical oversight ofthe program and the evaluation process is provided byNIST.

NVLAP accreditation is offered in areas necessary tosupport environmental laboratory testing of drinkingwater and waste water. Testing is currently divided intothree major areas: inorganic chemical analysis; organicchemical analysis; and biological and microbiologicaltesting. A fourth group, radiological testing and analysis,will be added in the near future. To date, 11 providershave been accredited for various program codes withinthe three groups. The Directory of AccreditationLaboratories on the NVLAP web site at http://ts.nist.gov/nvlap provides details.CONTACT: Doug Faison, (301) 975-5304; [email protected].

NIST VALIDATES PREDICTIONS OF AIRCLEANER PERFORMANCENIST has completed the first phase of an experimentalevaluation of the ability of the CONTAM program topredict the impact of residential indoor air qualitycontrol technologies. CONTAM is a multizone airflowand pollutant transport model developed at NIST. In thisfirst phase of testing, the air cleaning ability of severalmechanical air filters and electronic air cleaners wasdetermined in a single-zone test house. Measurements

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were made of other airflow and particle transportparameters such as the envelope airtightness, particledeposition rates, and particle penetration factors. Theseparameters then were used as input data to a CONTAMmodel of the test house. CONTAM predictions of build-ing air change rates and particle concentrations werecompared to measurements for two different air cleanersto assess the ability of CONTAM to predict the impactof these devices. For both tests, CONTAM was able topredict air change rates within 5 % of measured valuesand average particle concentrations within 30 % ofmeasurements for particle sizes between 0.3 �m and5 �m. The results are described in detail in the finalreport (NISTIR 6461). This work is continuing witha second phase being conducted in an occupiedtownhouse.CONTACT: Steven J. Emmerich, (301) 975-6459;[email protected].

FIRE DYNAMICS SIMULATOR (FDS)RELEASED BY NISTNIST publicly released its fire model, Fire DynamicsSimulator (FDS), plus the companion visualizationprogram, Smokeview.

The model has previously been called LES3D (LargeEddy Simulation) and IFS (Industrial Fire Simulator).The new name was chosen to distinguish the releasedversion from internal research versions. An article inThe New York Times Science section (March 7, 2000)highlighted the capabilities and past applications of themodel. The software and references can be downloadedfrom http://fire.nist.gov.CONTACT: Kevin McGratten, (301) 975-2712; [email protected].

NIST CO-HOSTS WORKSHOP ON OPENARCHITECTURE CONTROL FOR ROBOTICSNIST and the Robotic Industries Association (RIA)hosted a workshop on Open Architecture Control for theRobotics Industry, in February 2000, in Orlando, FL.The workshop included presentations from end users,vendors, and systems integrators, followed by three par-allel breakout sessions in which the attendees discussedkey items of interest that could form the basis of ongoingwork. Key topics covered include the use of existingstandards to reduce system integration costs that canreach six times the purchase cost of the robot itself.Over 50 participants attended the workshop, andproceedings are available.CONTACT: Fred Proctor, (301) 975-3425; [email protected].

NEW NIST PROGRAM THE “SHOP FLOOR ASNATIONAL MEASUREMENT INSTITUTE”INTRODUCED AT CONFERENCEThe new NIST program, “The Shop Floor as NationalMeasurement Institute,” has been introduced publicly ata corporate conference on Large Scale Optical Metrol-ogy in an invited presentation by a NIST staff member.

The conference, held in Long Beach, CA, in February2000, was an ideal venue for this introduction becausethe audience was composed of metrology managers andpractitioners. The presentation described how U.S.manufacturers could meet the requirements of the “newtraceability” defined in an emerging suite of inter-national standards. These ISO standards, called the“Global Product Specification,” deal with measure-ments made to determine whether part dimensionsconform to the tolerances specified by a customer.

A primary concern of these standards is that meas-urements be linked to the Systeme InternationaledUnites (SI) unit of length and described by a statementof uncertainty. The uncertainty is to conform to theISO Guide to the Expression of Uncertainty in Measure-ments (GUM). A combination of GUM and shop floorinterferometers will allow industry to assert such trace-ability without use of national measurement institute(NMI)-calibrated dimensional standards. However, newmethods, procedures, instruments, and standards willneed to be developed. Therefore, a primary goal of thisnew program is to aid U.S. manufacturers to realize the“new traceability” on the shop floor through develop-ment of these needed measurements and standards.

The program will focus on three areas:

• compensating for the effect of shop-floor atmo-sphere on interferometric measurements;

• compensating for the effect of non-standard temper-atures on parts, gages, and measuring machines; and

• establishing an uncertainty statement for measure-ments made on the shop floor.

CONTACT: Dennis Swyt, (301) 975-3463; [email protected].

NIST STAGES AN ACROSS-THE-OCEANISO PROJECT TEAM MEETINGIn February 2000, NIST staff held a Tele-Conference/NetMeeting of the ISO Project Team developing Appli-cation Protocol (AP) 219 on Dimensional InspectionInformation Exchange. This specification is currently aPreliminary Work Item of Subcommittee 4 (SC4)on Industrial Data under ISO Technical Committee 184,Industrial Automation Systems and Integration. SC4

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has the main responsibility for the development of theset of industrial information standards known as STEP,the Standard for the Exchange of Product Data.

The special Tele-Conference/NetMeeting was heldduring the February SC4 Meeting in Melbourne,Australia. Together, the group discussed the harmoni-zation of the dimensional measurement concepts in thedeveloping AP219 with similar information concepts inexisting Application Protocols, AP214 for automotivemanufacturing and AP224 for machining features. Theteleconference setup included voice communications bytelephone and interactive editing of the EXPRESSschema for AP219. The meeting format enabled a gooddeal of technical work to be accomplished without theneed for all participants to travel to the Melbournevenue.CONTACT: Ted Vorburger, (301) 975-3493; [email protected] or Larry Welsch, (301) 975-3198;[email protected] or Simon Frechette, (301)975-3335; [email protected].

FOUR INVITED PAPERS PUBLISHEDIN METROLOGIAFour invited papers by NIST authors have beenpublished in Metrologia, the international journal ofpure and applied metrology (Vol. 36, No. 4, 1999). Thisvolume consists of a special issue to commemorate theformation of the Consultative Committee for Acoustics,Ultrasound, and Vibration (CCAUV) by the Inter-national Committee of Weights and Measures (CIPM).Articles in this issue recognize the substantial world-wide effort in the fields of acoustics, ultrasound, andvibration. The CCAUV is actively coordinating inter-national key comparisons that will be essential to thesuccess of the Mutual Recognition Arrangement signedlast year by over 30 national metrology institutedirectors. The titles of the papers are:

• Brief review of primary methods applicable to keycomparisons in acoustics;

• Ultrasonic continuous-wave beam-power measure-ments: 1978-1980 international comparison;

• Ultrasound power measurement by pulsed radiationpressure; and

• Comparison of results of calibrating the magnitudeof the sensitivity of accelerometers by laser interfer-ometry and reciprocity.

CONTACT: Victor Nedzelnitsky, (301) 975-6638;[email protected].

NIST HOLDS FIRST JOINT INDUSTRYMEETING ON QUANTUM INFORMATIONTECHNOLOGYNIST scientists recently held a meeting with industrialrepresentatives from leading communication andcomputer companies interested in quantum information.The meeting was held in March 2000. NIST has estab-lished worldwide leadership in the implementation ofquantum information using trapped ions. NIST hasrecently embarked on a larger, coordinated effort topursue experimental approaches using ultracold neutralatoms, and to evaluate other implementation schemes. ANIST scientist described the potential use of entangledquantum-bits (or qubits) to improve time and frequencystandards as one important near-term application.

Industry representatives described their currentefforts and interests in this potentially revolutionarytechnology, and commented on NIST’s planned activi-ties. The industry representatives are especially inter-ested in identifying “killer apps” involving a few qubitswith an emphasis on applications that can not be doneclassically. These companies sense that quantum infor-mation technology may have enormous economic bene-fit, but have adopted a wait and see approachpending the discovery of appropriate applications.CONTACT: Carl Williams, (301) 975-3531; [email protected].

NIST CO-SPONSORS ELECTRONICDOCUMENTS CONFERENCEIn March 2000, NIST and the Federal CIO Council’sInteroperability Committee co-sponsored the ElectronicDocuments Conference for e-gov designers and imple-menters throughout the federal government and industry.

The objective of the conference was to get a broadcross-industry/cross-applications look at where we are,where were going, what we want, and how to try to getit, for electronic document interoperability over the nextseveral years. Software product vendors, document userenterprises, government agencies, and standards organi-zations shared their views and interacted on the issues.

Presentations were given by various standards organi-zations, including the Association for Information andImage Management, the World Wide Web ConsortiumDocument Object Model Working Group, and theDocument Management Platform Special InterestGroup of the Object Management Group. The federalgovernment was represented through presentations givenby representatives from the U.S. Courts, the Patent andTrademark Office, the Department of Defense, andNASA.

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The conference established six working groupsto discuss and report back on the following topicareas: multimedia documents in which text/data issecondary; revisable documents-in-progress; businesstransaction documents of record; engineering andscientific/laboratory documents; negotiable bearerinstruments; and general “knowledge” documents.Conference presentations and working-group results areavailable at www.nist.gov/e-docs/conf.CONTACT: Bruce Rosen, (301) 975-3299; [email protected].

NIST HOSTS SECURITY EDUCATORSCONFERENCENIST hosted the 13th annual Federal InformationSystems Security Educators Association (FISSEA)Conference in March 2000. Nearly 120 informationsystems security practitioners and managers attended,primarily from federal agencies, college and universityfaculty and staff, and industry representatives fromfirms that support federal information systems andsecurity programs.

Presentations during the three-day conference cov-ered the spectrum of information systems securityawareness, training, and education. Several paneldiscussions addressed federal agency use of ComputerSecurity Day and other techniques to “reach themasses.” Numerous presenters discussed existing train-ing courses and techniques, from classroom settings toCD-ROM-based material, Web-based courses, and otherdistance-learning programs.

The annual conference continues to be a valuedforum in which federal information systems securityprofessionals can learn of ongoing and planned trainingand education programs and initiatives. It provides NISTthe opportunity to provide assistance to agencies asdirected by the Computer Security Act of 1987.CONTACT: Mark Wilson, (301) 975-3870; [email protected].

1998 NTTAA ANNUAL REPORT NOW ONWEB SITENIST is required to collect data on standards and con-formity assessment activities from federal agencies andsubmit an annual report to Congress through the Officeof Management and Budget. The 1998 Annual Reporton fulfillment of responsibilities under OMB CircularA-119 and the National Technology Transfer andAdvancement Act (Public Law 104-113) is now avail-able on the TS Office of Standards Services web site athttp//ts.nist.gov/icsp. The report includes informationon the progress that federal agencies have made toward

using voluntary standards instead of agency-uniquestandards. It also discusses NIST efforts to coordinateagencie’s use of voluntary standards and their participa-tion in voluntary standards activities. This report showsa continuing decline in the number of agency personnelparticipating in standards activities. Several possibleexplanations for the decline include retirements of keytechnical staff, increased strategic planning andmanagement of standards activities, and improvedreporting accuracy.CONTACT: Belinda Collins, (301) 975-4000; [email protected].

U.S.-CHINA AUTOMOTIVE STANDARDSWORKSHOPIn March 2000, NIST sponsored a 3 day workshop forrepresentatives of the Chinese automotive sector. TheNIST workshop was a component of a 2 week programorganized by the Society of Automotive EngineersInternational. The purpose of the program was to en-hance opportunities for harmonized standards andpromote Chinas recognition of U.S. standards andconformity assessment practices.

The 27 workshop participants from the Chinesegovernment and private sector were introduced to theU.S. agencies and organizations involved in automotivestandards development and conformity assessment.They heard about the public and private-sector responsi-bilities regarding automobile quality and safety, as wellas various aspects of the U.S. system, including adescription of the U.S. automotive industry and regula-tory approach. Participants also toured several NISTlaboratories where they were exposed to the researchbeing done at NIST related to the automotive sector. TheNIST visit concluded with a lively discussion amongU.S. industry representatives and the members of theChinese delegation about future trends in the auto-motive industry.CONTACT: Libby Parker, (301) 975-3089; [email protected].

BROCHURE CAN GET YOUR QUALITYJOURNEY ON THE ROADThousands of organizations use the Baldrige Criteria forPerformance Excellence to help assess and improve theirorganization. Vicki Spagnol, principal, Management In-sights, New York, N.Y., says, “The Baldrige criteriaprovide a proven road map for performance improve-ment—one that will enable your organization to be moresuccessful than you ever imagined.”

But, say you’ve looked at the criteria and are stilluncertain about how to begin. To help you get started,

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NIST’s Baldrige National Quality Program has devel-oped a new brochure, Getting Started-A Guide to Self-Assessment and Action. The guide will walk youthrough a 10-step approach to assessing your organiza-tion’s strengths and developing and implementing a planfor improvement.

For a free copy of the new brochure and the BaldrigeCriteria for Performance Excellence, contact theBaldrige National Quality Program, (301) 975-2036;fax, (301) 948-3716; [email protected]. Both publicationsalso are available on the Baldrige web site atwww.quality.nist.gov.Media Contact: Jan Kosko, (301) 975-2767; [email protected].

NEW VIDEO, CD SPOTLIGHT STRATEGIES OF1999 BALDRIGE RECIPIENTSNIST has released a new set of audiovisual materialsshowcasing the 1999 recipients of the Malcolm BaldrigeNational Quality Award and the Baldrige NationalQuality Program. A VHS videocassette contains twoversions of a program (short at 11:45 minutes and longat 47:50 minutes) that features the successful strategiesof the award’s 1999 recipients: STMicroelectronicsInc.-Region Americas; BI; The Ritz-Carlton HotelCompany L.L.C.; and Sunny Fresh Foods. Also in-cluded on the videocassette are “A Journey WorthBeginning,” encouraging organizations to apply for theBaldrige Award, and “A Uniquely Rewarding Experi-ence,” explaining the role of the examiners who evaluateaward applications. A CD-ROM package includes allfour video programs, as well as the Baldrige Perfor-mance Excellence Criteria for 2000, presentations givenby the 1999 award recipients at the Quest for ExcellenceXII conference in March 2000, and other information.

The audiovisual materials are available from theAmerican Society for Quality, 611 E. Wisconsin Ave.,Milwaukee, Wis. 53202-4606, (800) 248-1946. ItemT1089 is the VHS videocassette and CD-ROM for$49.95. Item T1087 is the CD ROM alone for $35.00.Item T1086 is the videocassette alone for $20.00.

For more information on the Baldrige NationalQuality Program or the Baldrige Award recipients, con-tact the Baldrige National Quality Program, (301) 975-2036, [email protected], or see the BNQP web site atwww.quality.nist.gov.Media Contact: Jan Kosko, (301) 975-2767; [email protected].

CONFERENCE OPENS NATIONAL DIALOGUEON COMBINATORIAL METHODSResearch scientists, process engineers, R&D managers,representatives from federal funding agencies, andacademics participated in a broad, open dialogue ontheir roles in forging the future of chemical and materi-als sciences through combinatorial methods. A widevariety of exciting technology platforms were discussed,and opportunities for networking with technologists andbusiness people were available. The workshop was heldat NIST in Gaithersburg, MD, May 31 to June 1, 2000.

Combinatorial methodology is a set of tools andtechniques the chemical and materials science commu-nities will use in the future to accelerate discovery anddevelopment of new materials to meet 21st centuryneeds. Combinatorial methods, which use a largenumber of carefully designed, multi-dimensional exper-iments that may be performed rapidly or in parallel ona miniaturized scale with automated instrumentation,have revolutionized the R&D process in drug develop-ment. Most major chemical manufacturers and severalstart-up companies have initiated programs within thepast two years to exploit combinatorial methodsand accelerate the discovery of advanced materials(catalysts, electronic and optical materials, polymers,metal alloys and ceramics) and process optimization.Media Contacts: Linda Joy, (301) 975-4403; [email protected].

WEIGHTS AND MEASURES DOCUMENTSNOW AVAILABLE ON THE INTERNETThe codes and specifications that form the basis of theU.S. system of weights and measures are now availablefrom NIST on the Internet. Manufacturers, as well asinternational weights and measures organizations, cannow easily access accepted specifications and tolerancesfor scales and other measuring devices in NISTHandbook 44. They also can view model weights andmeasures laws and regulations, which have beenadopted by most states, in NIST Handbook 130. NIST’sOffice of Weights and Measures posted these documentsto increase their dissemination and availability, therebypromoting uniformity of weights and measures inthe marketplace. Uniformity protects consumers andbenefits businesses by ensuring fair competition.

Handbook 44, Specifications, Tolerances, and OtherTechnical Requirements for Weighing and MeasuringDevices, contains information needed to design or test

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weighing and measuring devices for use in commerce.Its codes cover a wide variety of devices such as thoseused to dispense home heating oil and gasoline, foodstore scales, taxi meters, odometers and fabric measur-ing devices.

Handbook 130, Uniform Laws and Regulations in theAreas of Legal Metrology and Engine Fuel Quality,encourages standardization in weights and measureslaws within the United States. The handbook contains10 different model laws and regulations, plus the recom-mended procedure for verifying the accuracy of retailpricing. It includes regulations prescribing the methodof sale for commodities and packaging and labelingrequirements.

Both NIST Handbook 44 and NIST Handbook 130are published by NIST and have been adopted by theNational Conference on Weights and Measures, a volun-tary standards organization that works closely withNIST to ensure uniform weights and measures in theUnited States.

The two handbooks are now available on the WorldWide Web at www.nist.gov/owm under “General Infor-mation.” Both are in Adobe Acrobat and Word Perfectformats.Media Contact: Linda Joy, (301) 975-4403; [email protected].

LOOKING FOR CERAMICS INFO? CLICKOPEN THE NIST CERAMICS WEBBOOKMaterials scientists wanting easy access to ceramicsdata on the World Wide Web should point their Internetbrowsers to a new resource: the NIST CeramicsWebBook at www.ceramics.nist.gov/webbook/web-book.htm. This WebBook contains evaluated data, aguide to data centers and sources, as well as softwaretools and other resources useful for materials research.

The Ceramics WebBook has a link to three NIST-developed materials databases: the NIST High Tem-perature Superconducting Materials Database, theNIST Structural Ceramics Database and the NISTProperty Data Summaries for Advanced Materials. Thesuperconducting materials database offers evaluatedthermal, mechanical, structural and superconductingproperty data for oxide and borocarbide superconduc-tors. The structural ceramics database contains evalu-ated thermal, mechanical, structural and chemicalproperties for a wide range of engineering ceramics.The property data summaries contain topical collectionsof materials property data, each focused on a particularmaterial or a particular property.

In addition to the NIST databases, the CeramicsWebBook links to 22 other government and academicdata centers and web resources devoted to biomaterials,

ceramics, metals and composites, as well as chemicaland physical data. Another page of tools and resourcesprovides links to software tools, a ceramics virtuallibrary, a discussion forum and educational sites.

For more on ceramics research at NIST, visit theCeramics Division homepage at www.ceramics.nist.gov.Media Contact: Linda Joy , (301) 975-4403; [email protected].

NIST PARTICIPATES IN SECURE ELECTRONICMESSAGING DEMONSTRATIONIn April 2000 in Boston, MA, NIST participated withother federal agencies and industry partners in a demon-stration of the Federal Bridge Certificate Authority(FBCA) using secure electronic mail applications.

Attended by 2500 people, the meeting focused ontechnologies that enable electronic commerce. TheFBCA supports interoperability among federal agencyPublic Key Infrastructure (PKI) domains in a peer-to-peer fashion and identifies four policies that representfour different assurance levels (rudimentary, basic,medium, and high) for agency-issued public key digitalcertificates. For this demonstration, the FBCA consistedof two Certification Authorities (CA). It is expected thatmore internal CAs provided by different vendors will beadded to the FBCA in the future.

The internal CA nodes of the FBCA were cross-certified with each other. This resulted in certificate orcertificate status information issued by either CA to beaccepted by the other CA. In addition, each organizationchained an X.500 directory to the X.500 directorysystem provided by the FBCA. Each organization’se-mail client used a plugin that implemented S/MIMEversion 3 for encryption and decryption of messages andapplication and verification of message digital signa-tures. During the demonstration, digital signatures onthe e-mail messages sent between different domainswere successfully validated through the PKI. Thesesignature validations demonstrated the most complexmultivendor PKI built to date anywhere in the world.

The success of the FBCA demonstration illustrateshow electronic commerce can be securely enabledacross different governmental domains by providing thesecurity services of authentication and technical non-re-pudiation by leveraging cryptographic digital signa-tures. The basic FBCA concept is not limited to elec-tronic commerce between government domains but willenable electronic commerce between government andthe industrial and business domains.

More information on NIST’s PKI effort can be foundat http://csrc.nist.gov/pki.CONTACT: Kathy Lyons-Burke, (301) 975-4611;[email protected].

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NIST-SPONSORED REQUIREMENTS GROUPFOR REAL-TIME EXTENSIONS TO THE JAVAPLATFORM PUBLISHES FUNCTIONALITYREQUIREMENTSJava is being deployed in many information technol-ogy (IT) areas, far beyond the jazzy web page applets.There are few IT industries where Java is not beingmentioned. Real-time applications and embeddedsystems are two areas that are being addressed morerecently in the Java development arena.

The NIST-sponsored Requirements Group for Real-time Extensions to the Java Platform has completed itswork by finalizing NIST Special Publication 500-243,Requirements for Real-time Extensions for the Java Plat-form: Report from the Requirement Group for Real-timeExtensions for the Java Platform. The goal of theRequirements Group was the development of a consen-sus-based set of real-time functionality requirements forthe Java technologies. These requirements are currentlyserving as input to the Java real-time specificationprocess. Industry participants invited NIST to sponsorand coordinate the requirements effort. Participantsincluded organizations from the embedded, manufactur-ing, academia, development tool provider, and applica-tion developer communities. The group was open to allparties interested in developing requirements for real-time Java extensions. Currently, those interested in real-time extensions for Java are actively specifying thoseextensions in consortia. As such, the RequirementsGroup is no longer active.CONTACT: Lisa Carnahan, (301) 975-3362; [email protected].

NIST SOFTWARE ENABLES CRITICALMETROLOGY FOR TRANSISTOR SHALLOWJUNCTIONSNIST has released a beta version of software on CD-ROM to 40 semiconductor industry laboratories, whichrequire accurate measurement of the level and distribu-tion of dopant atoms within nanometer-scale transistorstructures. The software provides an essential linkbetween qualitative images measured by a scanningcapacitance microscope (SCM) and quantitative datarequired in the fundamental design of the transistor. TheInternational Technology Roadmap for Semiconductorsidentified SCM as a critical-path metrology for contin-ued miniaturization of integrated circuits, and thissoftware fanout highlights the success of a systematiceffort at NIST since the mid-1990s to address theshallow junction profiling problem.

The structure addressed by SCM is the doped junc-tion of the transistor, which is particularly difficult tomeasure, because it contains mole fractions of only 10–6

of electrically active elements such as B or As (dopants)in a highly localized region. In the microscope, capaci-tance is sensed between the doped region and an ultra-sharp tip positioned close to the surface of a cross sec-tion cut through the structure. Modern circuits requireprecise description of the dopant distribution with aspatial resolution better than 10 nm, to enable preciseelectric field-control of electrons flowing through thedevice.

The software makes it possible to transform pixeldata from an SCM image into an accurate quantitativedopant atom distribution map. The underlying theorywas developed at NIST and later reformatted into apackage suitable for engineers in the manufacturingenvironment. The approach was to be (1) user friendly,by employing a graphical interface on a desktop PC, (2)extremely fast, requiring only a few seconds for calcula-tion, and (3) highly accurate, by condensing a first-principles, full three dimensional Poisson solver solutionto the problem.

The beta code was made available to all members ofthe SEMATECH 2-D Profile Working Group when itmet at NIST last December. Members of the group arecurrently conducting round robin measurements oftwo-dimensional carrier profiles on a series of state-of-the-art circuits (MOSFETS, with channels of 0.5 �m,0.25 �m and 0.18 �m). Results of the round robin werediscussed when the working group reconvened at NISTin June.CONTACT: Joseph J. Kopanski, (301) 975-2089;[email protected].

EXPERIMENTAL MEASUREMENTSDEMONSTRATE ADVANTAGES OF USINGSUPERCRITICAL FLUIDS IN HEATEXCHANGERSFor the first time, NIST researchers have measured thethermal performance of a type of process heat ex-changer that has been proposed for a carbon dioxide-based alternative refrigeration cycle. This cycle could beused on a variety of heat pumps or air conditioningsystems that contain supercritical carbon dioxide(7.38 MPa critical pressure, 31.1 �C critical tempera-ture), a fluid potentially much less harmful to theenvironment than conventional refrigerants. Because theproperties of a fluid vary considerably near the criticalpoint with small changes in temperature or pressure,flow behavior and the transport of heat potentially arevery different in this regime and must be studiedcarefully to develop accurate predictive methods for pro-cess design. The system tested was prototypical of thewidely used shell-in-tube heat exchanger. Specifically,it was a horizontal tube 2.74 m long and inside diameter

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10.9 mm, with cold water flowing countercurrent on theoutside of the tube. Measurements were made at operat-ing pressures from 7.4 MPa to 13.0 MPa, fluid flowrates from 1.0 kg/min to 5.0 kg/min, cooling rates from1780 W to 6220 W, inlet temperatures from 31.6 �C to88.6 �C, and outlet temperatures from 23.2 �C to55.5 �C. The results showed significant improvement inthermal performance for the supercritical fluid whencompared to a constant property fluid. This observationcontrasts with what was found previously on the sametube when the carbon dioxide was heated instead ofcooled; for that condition, excessive heating or low flowrates caused the supercritical fluid to perform morepoorly than a constant property fluid. The presentresults also showed that existing engineering correla-tions could predict the measurements when the operat-ing temperatures were above the critical, but not whenthey were below the critical. These experimental datawill be valuable in developing predictive methods fordesign of heat exchangers in alternative refrigerationcycles or other modern technologies utilizing supercrit-ical fluids.CONTACT: Douglas Olson, (301) 975-2956; [email protected].

NIST DEVELOPS A NEW TECHNIQUE FORMEASURING THE TEMPERATURES OFWEAKLY IONIZED GASESA new diagnostic technique using non-linear variationof frequency-resolved Rayleigh scattering has beendeveloped by NIST for probing neutral and ion temper-atures in weakly ionized gases, such as occur in theshock waves of aircraft at high altitudes. The instrumentconsists of two frequency-doubled Nd:YAG lasersystems, one running on a single longitudinal mode andthe other running on several longitudinal modes. Thebeam from the multimode laser is split into two compo-nents, which counter propagate through the sample at anangle of approximately 175�. These beams interfere,creating a superposition of traveling-wave and stationaryfringe patterns. The laser electric field works against therandom thermal motion of the gas to compress thepolarizable gas atoms or molecules into regions of highelectric-field intensity. This compression leads tospatially periodic density perturbations that Rayleighscatter the single-mode probe beam. The travelingcomponents introduce Doppler shifts into the scatteredlight as well. By measuring the Doppler profile of theRayleigh scattering, the underlying temperature of thegas is obtained. Initial tests indicate a greatly enhancedsensitivity over spontaneous Rayleigh scattering at lowpressures.

CONTACT: Jay Grinstead, (301) 975-4253; [email protected].

SURF III BOOSTS OPERATING ENERGY ANDINCREASES CALIBRATION RANGEIn March 2000, the SURF III electron storage ringachieved a record electron beam operating energy of387 MeV, with an injection current of 300 mA. Routineoperation at SURF is now maintained at 362 MeV, withinjected beam currents exceeding 250 mA. Since thehigh-energy end of SURF’s optical radiation spectrumincreases as the third power of the electron energy, theseimprovements provide a doubling of the photon energyrange for which SURF can provide calibration services.The “water window” region (wavelength of 3 nmto 4 nm), which is important for biological x-raymicroscopy, was previously outside SURF’s practicaloperating range. SURF III now produces more usefulradiation in the water window than did its predecessormachine, SURF II, which operated at 288 MeV.CONTACT: Mitchell Furst, (301) 975-6378; [email protected] or Lanny Hughey, (301) 975-3724;[email protected].

MILESTONES ACHIEVED FOR NIJ STANDARD0115.00, STAB RESISTANCE OF PERSONALBODY ARMORSignificant milestones were reached in the developmentof National Institute of Justice (NIJ) Standard 0115.00,Stab Resistance of Personal Body Armor. The draftstandard was distributed to members of the NationalArmor Advisory Board and the Law Enforcement andCorrections Technology Advisory Council for commentand review. A formal solicitation for potential testlaboratories that wish to become certified to conductcompliance testing was issued in the CommerceBusiness Daily. Work will continue over the next couplemonths to address comments and concerns receivedfrom members of the body armor community on thestandard and to identify test laboratories for the compli-ance test program.CONTACT: Kirk Rice, (301) 975-8071; [email protected].

NIST 100 A CURRENT SHUNTS SUPPORTCOMMERCIAL VERSIONSA wideband (100 kHz), high-current (100 A rms) shunt,designed and developed by NIST, has been convertedinto a commercial version that is now available. Thedevelopment of this shunt has been driven by the interest

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in supporting a commercially available 100 A, 100 kHztransconductance amplifier that was also designed anddeveloped earlier by NIST.

Under contract with the Air Force Primary StandardsLaboratory, four of the commercial shunts were pur-chased by NIST and compared to the NIST-designedand fabricated shunts. These consisted of a 10 A to 30 Ashunt, 30 A to 50 A shunt, 50 A to 80 A shunt, and 80 Ato 100 A shunt. A current build-up from a 20 A NISTreference to the 100 A commercial shunt was per-formed; preliminary data indicate that the build-upmeasurements differ from direct comparisons to theNIST 100 A reference standard by only about 1 mA/A.

To support the NIST reference shunts, comparisonswere made with a set of NIST-made two-stage, ampli-fier-aided current transformers (CTs) out to 100 kHz.The frequency coefficients of these CTs were character-ized by direct comparison to NIST working standardthermal converters using an automated currentcomparator system, based on 50 Hz as the referencefrequency.

The effort to develop these CT and shunt standardsnow permits NIST to offer measurement services forhigh-current ac shunts up to 100 A, the only nationalmeasurement institute with this capability.CONTACT: Barry A. Bel l , (301) 975-2419;[email protected].

1�8 ARRAYS OF HIGH SENSITIVITYSUPERCONDUCTING TRANSITION-EDGEBOLOMETERSNIST researchers, in collaboration with researchers atGoddard Spaceflight Center (GSFC), have fabricatedand characterized, both electrically and radiometrically,several 1�8 arrays of superconducting transition-edgebolometers for NASA and European Space Agency(ESA) applications. These arrays are prototypes of anew generation of detector arrays for low background,far-infrared astronomy and were spotlighted in a recentarticle in Superconductor Week.

The NIST fabricated bolometer elements are com-prised of Al-Ag bilayers; similar GSFC-fabricatedelements are Mo-Au bilayers. The 1�8 arrays arefabricated on micromachined Si structures that enableconstruction of closely packed two-dimensional arrays(by folding the “legs” back out of the focal plane). Thebolometers are operated in a voltage-biased mode,resulting in an electrical-substitution measurement ofradiant power, similar to measurements performed bystandards-grade, cryogenic radiometers even thoughthere is no separate heater incorporated into the system.Readout is performed by a 1�8 SQUID multiplexercircuit previously developed by the NIST team (Appl.

Phys. Lett., June 1999), which greatly reduces the low-temperature wire count for large arrays. Typical operat-ing parameters for the arrays are: Tc = 450 mK,Tbase = 300 mK, saturation power is 5 pW, and time con-stant is 2 ms. Electrical noise-equivalent power (NEP),the basic measure of sensitivity, is roughly 2�10–17

W/Hz1/2, the best ever reported for an IR bolometeroperating with 3He refrigeration (i.e., at 300 mK), andwithin a factor of 6 of the best reported for any IRbolometer. Radiometric efficiency is presently 30 %,limited chiefly by diffraction losses inherent to the mea-surement configuration. Shortly two of the Al-Ag arraysand two of the Mo-Au arrays, along with four of the1�8 MUX chips and GSFC room-temperature elec-tronics, will be assembled into a multiplexed 4�8demonstration system and delivered to an ESA team atQueen Mary College, London. A field test of a single1�8 array is planned for the California Institute ofTechnology Submillimeter Observatory later this winter.CONTACT: Erich Grossman, (303) 497-5102; [email protected].

DIGITAL ELECTRONICS ENABLES NEWASTRONOMY INSTRUMENTNIST’s Nanoscale Cryoelectronics Project has devel-oped new digital electronics for reading out supercon-ducting transition-edge sensor (TES) detectors for x-rayand optical photons. The electronics use a high-speedand high-performance analog-to-digital converter(ADC), a field-programmable gate array (FPGA), and adigital-to-analog converter (DAC) to form a feedbackloop for sensor readout. The FPGA also has the capabil-ity to perform digital pulse processing on the feedbacksignal in real time. Parameters for the pulse processingand feedback control can be programmed via an opticalfiber link with a computer; this can even be performedremotely over the Internet. For a collaboration withStanford University, a set of electronics was built andused with a small array (2�2) of optical TES detectors(built by Stanford). Because of their relatively highquantum efficiency, reasonable energy resolution, andfast response, TES detectors appear very promisingfor astronomical observations of faint quasi-periodicobjects such as pulsars, nebulae, and possible blackholes. In early February, NIST researchers performedthe first astonomical observations with this instrument atthe 2.7 m Harlan J. Smith telescope at the McDonaldObservatory. By using the new electronics, they wereable to acquire data in real-time and at rates previouslynot achievable on objects like the Crab pulsar.CONTACT: David Rudman, (303) 497-5081; [email protected].

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INFRARED RECTIFICATION WITHNANOSCALE, ANTENNA-COUPLED,METAL-INSULATOR-METAL (MIM) DIODESNIST scientists have fabricated and characterized a setof fully kithographic MIM diodes coupled to infraredantennas. Antenna-coupled MIMdiodes, in the form ofelectrochemically sharpened whiskers contactingmacroscopic metallic surfaces, have been used for manyyears for infrared frequency metrology. The new, fullylithographic diodes have areas as low as (30�30) nm2

and are fabricated by angled evaporation through a free-standing PMMA resist bridge defined by electron-beamlithography. (Small areas are required to minimize diodecapacitance.) The diodes are coupled to planar dipoleantennas, also defined by electron-beam lithography,and designed for resonance at 10 m wavelength. Diodeshave been successfully fabricated and tested fromAl-AlOx -Al, Al-AlOx -Pd, and Nb-NbOx -Ag materials.Non-linearity in the current-voltage characteristics ismeasured in all cases. The Brinkman-Dynes-Rowellanalysis of tunneling through trapezoidal barriers accu-rately fits the nanoMIM I-V characteristics, as well asthose of separate, micrometer-sized Nb-NbOx -Ag MIMdiodes. Optical response on the nanoMIM diodes wasmeasured using a few mW of 10 �m CO2 laser radia-tion, coupled through the substrate via a Ge hemispher-ical lens. Previous attempts to fabricate fully litho-graphic MIM diodes have all foundered on the difficultyof separating optical signals due to rectification fromthose due to thermal mechanisms.

In the recent NIST experiments, two key observationsrule out thermal mechanisms. Firstly, the bias depen-dence of the detected signal from IR illumination isaccurately proportional to the second derivative of thedc current-voltage characteristic, a signature of classicalrectification. Secondly, at 0 bias, there is substantialoptical signal, the sign of which varies between devices,but always remaining the same as the sign of the 0-biascurvature in the I-V curve. The non-linearity observed inthe large area diodes is, according to theory, sufficient toenable observation of photon-assisted tunneling steps atroom temperature. These diodes are being developedunder a cooperative research and development agree-ment with a thin film solar cell manufacturer, as part ofa Defense Advanced Research Projects Agency-sponsored program to develop solar cells based on directrectification of sunlight.CONTACT: Carl Reintsema, (303) 497-5052;[email protected].

MICROMECHANICAL DETECTION OFENERGY AND ANGULAR MOMENTUMTRANSFER IN FERROMAGNETIC RESONANCEA spinning top in a gravitational field undergoes preces-sion. Since magnetic moments have angular momentumjust like a spinning top, the magnetization of a ferro-magnet precesses in a magnetic field. For the precessionto persist, it must be driven with microwaves at theferromagnetic resonance (FMR) frequency.

Natural damping of the precessional motion of mag-netic spins in FMR results in a transfer of both energyand angular momentum to the crystal lattice of theferromagnetic specimen. Absorption of the energyresults in heating of the material, whereas transfer of theangular momentum results in a torque on the material.The source of the energy and angular momentum can betraced back to the energy and angular momentum of themicrowave photons that induce the resonance.

NIST scientists have used silicon micro-cantileversto detect both the heating and torsion of a thin filmspecimen when the ferromagnetic resonance conditionis met. These new measurement techniques are applica-ble to the characterization of magnetic properties ofvery small samples as well as detection in magneticresonance force microscopy. This is one example ofnew micro-cantilever based magnetic metrologymethods developed at NIST and the first demonstrationof torque detection from angular momentum transfer inFMR.CONTACT: John Moreland, (303) 497-3641; [email protected].

SOUNDS RECONSTRUCTED FROMAUDIO TAPESNIST researchers, in collaboration with the Institute forTelecommunication Sciences, have imaged audio tapesusing scanning magneto-resistive (MR) microscopy andreconstructed the audio signals from the images. Fourtest tracks were produced, imaged, and reconstructed.Two of the test tracks were sine wave tones of 500 Hzand 700 Hz and the other two had test phrases such as“NIST” and “FBI.” This work addresses the need offorensics analysts to search for traces of tampering and/or characteristic sounds (gunshots, etc.) in recordedevidence. The microscope is based on commercial MRheads from computer hard drives and has a resolution of�20 nm downtrack and �1 �m track width. The re-quired sample rate for these reconstructions was only

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5.9 �m; however, the higher resolution available withthe MR heads is needed for media such as digital audiotapes and other computer storage media.CONTACT: David P. Pappas, (303) 497-3374; [email protected].

OPTICAL FIBER BRAGG GRATINGROUND ROBINAt the request of industry, NIST has administered around robin for the measurement of optical fiber Bragggrating (FBG) characteristics. Fiber Bragg gratings area relatively new component—a wavelength-selectivereflector that can be written into the core of opticalfiber. These components are extremely important fortelecommunication and sensor applications. They arevery useful as wavelength filters and dispersion compen-sators in the new wavelength division multiplexed(WDM) optical fiber communication systems, and alsomake excellent strain sensors that can be networked toobtain distributed strain measurements of large struc-tures, such as bridges and ships. In spite of the numer-ous and growing commercial applications of fiber Bragggratings, there are no standard measurement proceduresand a variety of definitions are being used for importantparameters.

The NIST-facilitated round robin began at an infor-mal meeting during the Optical Fiber CommunicationConference in February 1999. A quorum of industryrepresentatives recommended measuring specific spec-tral and relative group delay (rgd) properties of FBGs.(The derivative of rgd versus wavelength gives ameasure of dispersion in an optical component. Disper-sion in optical fiber spreads optical pulses in time andlimits the fiber link data rate.) In June 1999, NISTlaunched the round robin among two industry groups.One group, named “telecom,” measured spectral prop-erties and rgd for their gratings. The other industrygroup, named “sensors,” measured only the spectralproperties of their gratings. Raw data from the partici-pants were sent to NIST because no formal methods foranalyzing the spectral or rgd data existed.

To assist industry in this evaluation, NIST has devel-oped high-sensitivity, state-of-the-art techniques tomeasure the spectral and rgd values of FBGs. Forspectral quantities, a grating-tuned diode laser filteredby a tunable fiber Fabry-Perot interferometer was usedto achieve a dynamic range of 68 dB, a wavelength res-olution of �0.1 pm, and wavelength uncertainty of0.2 pm. NIST used two systems to measure the rgd ofthe gratings, an rf-modulated phase-delay method,which had an uncertainty of about 0.3 ps and a wave-length uncertainty of about 30 pm, and a low-coherenceinterferometer. The uncertainty analysis on a newlydeveloped low-coherence interferometer method is stillin progress.

The results of the round robin showed that measure-ments of the central wavelength of a FBG appear to beadequate for telecom systems. However, current metrol-ogy is clearly inadequate for bandwidth, minimumtransmittance, and rgd linear slope. For a rgd linearslope of about –6.8 ps/nm the range in measured valueswas 1.1 ps/nm. The participants’ minimum transmit-tance values were about 5 dB above the true valuebecause of inadequate filtering of source spectral noise.The bandwidth of a FBG, determined from relativereflectance data, depends on the criteria used to deter-mine the band-edge. When two different popular crite-ria (–3 dB and –0.5 dB) were used to determine thebandwidth of a 50 GHz grating, the bandwidth differedby about 11 GHz. Also, sensor applications need betterabsolute wavelength calibration. The spread in values forthe center wavelength of the sensor grating (27 pm) willnot meet the needs of long-term structural monitoring.Data analysis methods developed by NIST during thisstudy have now been incorporated into a draft Telecom-munications Industry Association (TIA) standard testprocedure document. NIST plans to continue workingwith the TIA to develop standard test procedures andevaluate measurement capabilities.CONTACT: Sarah L. Gilbert, (303) 497-3120; [email protected].

KEY COMPARISON OF LONG END STANDARDSNIST researchers just completed measurements for akey international comparison of long end standards. Thisis one of a series of comparisons that will help to estab-lish the degree of equivalence between length measure-ments made by various national measurement institutesthroughout the world.

The end standards, gage blocks ranging in lengthfrom 175 mm to 900 mm, were measured by NISTmetrologists using several different techniques. All butthe longest (900 mm) block were measured both bystatic interferometry and by mechanical comparison;the 900 mm standard was measured on a linescale inter-ferometer. As a check, all of the blocks also were mea-sured on a coordinate measuring machine. In all cases,measurement results obtained on different instrumentsfor a given block did not differ from each other by morethan 135 nm, well within expected uncertainties. Theexcellent agreement between differing methods givesgood confidence in the NIST results.

NIST is the second of 16 laboratories spread through-out all regions of the world that will participate inthis comparison.This is one of a number of measure-ment comparisons sponsored by the CIPM (ComiteInternational des Poids et Mesures) that will form thetechnical underpinning of the recently signed Mutual

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Recognition Arrangement. This agreement is intended toreduce barriers to trade by establishing mutual recogni-tion of measurements and tests between trading nations.CONTACT: John Stoup, (301) 975-3476; [email protected] or Bill Penzes, (301) 975-3477;[email protected].

FLUCTUATIONS IN THERMAL SPRAYPROCESS MEASUREDThermal spray is a relatively low cost, but difficult tocontrol, process for applying protective coatings tomaterial surfaces. These coatings are often of metals orceramics, and are used for a variety of purposes such asthermal, wear, or corrosion protection. The use of ther-mal spray technology is often limited, however, by thedifficulty of obtaining reproducible coating quality.NIST has therefore instituted a program to use advancedsensors to study and control the spray plume, and corre-late process parameters to spray characteristics andcoating properties.

Using a novel two-color imaging pyrometer, NISTresearchers are obtaining time-resolved spray particletemperature and velocity data in thermal spray plumesand correlating these to the selectable process para-meters of the thermal spray torch control system.Combining this with a thermodynamic model of thespray torch is providing information on strategiesfor independent control of particle temperatures andvelocities.

Other sensors are being used to analyze time-depen-dent fluctuations in the thermal spray plume. Suchfluctuations recently have been studied by severallaboratories, but their exact origin and their possibleeffects on the quality of the deposits have not beendetermined. The NIST program is using a high-speedschlieren method to visualize the hot thermal sprayplume, revealing some significant low-frequencyprocesses in addition to the higher frequency fluctua-tions which other investigations have revealed.CONTACT: Steven P. Mates, (301) 975-8114;[email protected].

FANS-I COMMISSIONED AT THE NCNR, WITH20 TIMES THE INTENSITY OF INELASTICNEUTRON SCATTERINGThe increasing complexity of new materials andprocesses is an important factor driving the develop-ment of new characterization tools. The traditionalvibrational spectroscopies, infrared absorption andRaman scattering, have long played a central role.Neutrons are a more versatile dynamical probe thanphotons, but inelastic neutron scattering long has

suffered from the comparatively low intensity. Toaddress this, a new, high-intensity filter-analyzerneutron spectrometer (FANS) is being constructed intwo phases at the NIST Center for Neutron Research(NCNR) by a consortium of scientists from NISTacademe, and industry. The first phase of FANS recentlyhas been commissioned. The measured intensityexceeds that of the previous instrument by a factor of�20, providing significant new measurement opportu-nities for the U.S. scientific community. For instance,FANS will be used to study intra- and intermolecularvibrations in molecular crystals; polymers; and guest-host systems including hydrogen in metals, hydrocar-bons in zeolite catalysts, sorbed gases on surfaces andclathrates for fine chemical separation. It also will beused to characterize novel forms of carbon includingfullerenes, nanotubes, foams and aerogels, amorphouscarbons, and fibers as well as environmentally accept-able refrigerants, gas separation materials, and thehydration reaction of cements.CONTACT: Dan Neumann, (301) 975-5252; [email protected] or Terrence Udovic, (301) 975-6241; [email protected].

COMBINATORIAL CHARACTERIZATION OFPOLYMERIC THIN FILMS AND COATINGSRecently, NIST scientists have developed methods forrapid measurements of the properties of polymercoatings. Polymeric coatings play an important role inmany industrial applications, such as automotive,electrical, and aerospace industries where their stabilityand integrity is of fundamental importance. The NISTresearchers adapted the concept of combinatorial andhigh-throughput analysis for rapid acquisition of proper-ties data on polymer coatings that would be useful infundamental studies, validation of physical models, orexploration of industrial applications. Combinatorialmethods of drug discovery in pharmaceuticals researchare well known, and more recent applications of themethodology have led to the discovery and synthesisof new inorganic materials, catalysts, and organicpolymers.

The material properties of polymeric coatings aresensitive to a variety of factors, including composition,temperature, and thickness. Most polymeric coatingsare also multicomponent blend materials and the misci-bility of the blend components is an important issue thataffects ultimate properties. To acquire data covering arange of variables is both time consuming and expensivewhen done by traditional methods. The novel approachdeveloped included methods for depositing polymericcoating libraries that employ continuous gradientsin thickness, composition, and temperature. Each

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“library,” which is the size of a standard microscopeslide, contains as many as 1500 differentiable conditionssuch as film thickness, composition, and temperature.Analysis of these libraries provides characterization offundamental properties and thin-film phenomena occur-ring in such coatings. By automating ellipsometry andoptical microscopy for high-throughput screening, thedewetting and polymer blend phase separation behaviorwere characterized in orders of magnitude less time thanwith conventional methods. The high-throughput tech-niques produce a large amount of data over a broadrange of parameter values, so that novel regimes ofkinetic and thermodynamic behavior can be observed.CONTACT: Alamgir Karim, (301) 975-6588; [email protected].

NIST BURNS TOWNHOUSES IN ARIZONANIST’s Large Fire Research Group conducted 24 full-scale fire experiments in a two-story, six-unit townhousestructure provided by Pinal County, AZ, during a2 week period in March 2000. The townhouses were inexcellent condition, which provided a great opportunityto collect “real world data for five different differentNIST research projects.”

In addition, the experiments were used as a basis forthe International Association of Arson Investigators’seminar on fire dynamics and burn pattern analysisbeing conducted during the same time period. Fourengineers from the NIST Large Fire Research Groupmade presentations to more than 135 student and localfire officials during the course of the seminar. Studentswitnessed several of the fire experiments conducted inthe townhouses. NIST measurements provided thestudents with additional useful information about thefires.CONTACT: Dan Madrzykowski, (301) 975-6677;[email protected] or David Stroup,(301) 975-6564; [email protected] or NelsonBryner, (301) 975-6868; [email protected].

WORKSHOP ON TELECOMMUNICATIONSSYNCHRONIZATION HELD AT NIST BOULDERIn cooperation with Technical Sub-Committee T1X1 ofthe American National Standards Institute (ANSI),Standards Committee on Telecommunications, NISTco-sponsored and hosted the “Workshop on Synchro-nization in Telecommunications Systems.” The work-shop was held in Boulder in March 2000, immediatelyfollowing the meeting of the T1X1 Sub-Committee, forwhich NIST also served as host.

This workshop series, which started as a NISTtutorial workshop dealing with noise-measurementmetrics, has grown to be the major U.S. forum fordiscussion of industry synchronization issues. It is aunique forum on this topic, since no similar meetingexists anywhere else in the world. Total participationfor the 3 day workshop was 104 people, including repre-sentatives of major telecommunications carriers andsynchronization-equipment manufacturers. Twenty-fourspeakers from 13 different companies and NIST pre-sented ideas on a wide range of topics affecting networksynchronization. For the first time, the workshop in-cluded equipment exhibits, giving the equipment manu-facturers a forum for discussing the merits of theirrespective products.CONTACT: Marc A. Weiss, (303) 497-3261; [email protected].

NIST COLLABORATES WITH CARNEGIEMELLON UNIVERSITY ON LARGE-SCALECOMPUTATION IN MATERIALS SIMULATIONA NIST researcher, along with a staff member fromCarnegie Mellon University, organized a successfulmeeting entitled “Large-Scale Computations in theSimulations of Materials” on March 30-April 1, 2000,at Carnegie Mellon University in Pittsburgh. The meet-ing was hosted by the university’s Center for NonlinearAnalysis, a National Science Foundation (NSF)-sponsored research and training center concentrating innon-linear analysis, mechanics, scientific computation,and mathematical finance. NSF and the Army ResearchOffice funded the event. The highly interdisciplinarymeeting brought together about 120 scientists from awide spectrum of academic, government, and industriallaboratories where contemporary challenges imposedby advances in industry, technology, and biomedicalsciences are being confronted with state-of-the-artmathematical and computational tools. The topicscovered were wide-ranging, from the simulation ofmicromagnetic materials to prediction of nerve trans-missions and blood flow.CONTACT: Anthony Kearsley, (301) 975-6103;[email protected].

NIST SPONSORS THIRD ADVANCEDENCRYPTION STANDARD CANDIDATECONFERENCEIn April 2000, NIST sponsored the Third AdvancedEncryption Standard (AES) Conference in New YorkCity. The purpose of the international conference wasto help answer the question: “Which algorithm(s)should NIST include in the AES Federal Information

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Processing Standard (FIPS) and why?” Conferenceparticipants included more than 200 cryptographers andother parties interested in participating in the evaluationand analysis of the five finalist candidate algorithmsbeing considered for the AES. Announced in August1999, the finalists are MARS, RC6TM, Rijndael,Serpent, and Twofish. Conference attendees heardthe results of experts who have analyzed the finalistalgorithms for security, efficiency, and other algorithmcharacteristics, as well as recommendations for theselection of the winner(s). Representatives from theteams of submitters for each of the finalists had anopportunity to make final arguments as to why theiralgorithm should be selected. Following the close of theRound 2 public analysis period in May 2000, NIST willstudy all available information and propose the AES(hopefully by late summer), which will incorporate oneor more of the AES algorithms selected from the final-ists. NIST will then request public comments on thedraft AES. The web site for the AES project is http://www.nist.gov/aes.ONTACT: Edward Roback, (301) 975-3696; edward.

[email protected].

NIST ADVANCES SOFTWARE USABILITYAt the International Human-Computer InterfaceConference (CHI 2000) in The Hague, The Netherlands,in April 2000, a NIST staff member conducted a SpecialInterest Group (SIG) entitled “Common IndustryFormat for Usability Test Reports.” The session wasbased on the Industry USability Reporting (IUSR)Project, which is led by NIST and includes membersfrom industry. The primary goal of the project is to raisethe visibility of usability as a factor when buying soft-ware. The key idea is that software purchases are costly,but the more usable a piece of software is, the lower thepost-purchase maintenance costs will be. More informa-tion about the IUSR project can be found athttp://www.nist.gov/iusr.CONTACT: Sharon Laskowski, (301) 975-4535;[email protected].

NIST CO-SPONSORS BioAPI USERS’ ANDDEVELOPERS’ SEMINARIn April 2000, NIST, the National Security Agency, andthe BioAPI Consortium co-sponsored the BioAPI Usersand Developers Seminar in Pentagon City, VA.

The seminar focused on the recent release of theBioAPI Specification Version 1.0. A common specifica-tion will accelerate adoption of biometric technologiesand biometric-based identification and verification

solutions in multiple markets. At the meeting, NISTannounced the BioAPI Interoperability Test Bed beingdeveloped at NIST’s Biometrics and Smart Cardslaboratory in support of the BioAPI Consortium, thebiometric industry at large, and users of these technolo-gies. NIST and the Financial Management Service ofthe Department of the Treasury will collaborate in thiseffort.

The release of the BioAPI Specification Version 1.0 isan important step for the biometrics industry, systemdevelopers, and end-users. It is significant that a numberof organizations are working together to develop andsupport biometrics common standards. The BioAPIConsortium (www.bioapi.org) was founded to develop amulti-leveled biometric Application Programming Inter-face (API) that brings platform and device indepen-dence to application programmers and biometricsservice providers. Seminar presentations are at the website www.nist.gov/bioapi-seminar.CONTACT: Fernando Podio, (301) 975-2947;[email protected].

NIST HOSTS SIXTH IEC MEETING ONSUPERCONDUCTIVITYNIST researchers organized, hosted, and participated inthe sixth meeting of International ElectrotechnicalCommission (IEC) Technical Committee 90 (TC 90) onsuperconductivity in Boulder, CO, in March 2000. Themeeting allowed experts from around the world to cometogether and work to advance the draft internationalstandards in six working groups (WGs). In addition,results from pre-standards research and interlaboratorycomparisons were presented on four new working draftsand on six future drafts. To date, two IEC measurementstandards have been published and a third standard isbeing published that covers the terms and definitionsused in superconductor technology. As a result of thismeeting, three more draft standards are now ready forthe final voting stage.

One key technical breakthrough during these meet-ings occurred in the WG on electronic characteristicmeasurements, specifically the microwave surface resis-tance of a superconducting thin film. Such films noware being demonstrated on-line for large-scale introduc-tion as filters for the cellular telephone industry. Thedraft standard as written contained a procedure for thedetermination of the loss in a dielectric that has beenshown to be problematic, and the U.S. members hadrecommended significant and potentially controversialchanges. During the course of discussion and consensusbuilding, a new technical approach to the problemswas invented through concerted work by the U.S. and

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foreign experts. This new approach will be adopted inthe next draft and represents a significant success of theprocess for writing international standards.CONTACT: Loren Goodrich, (303) 497-3143;[email protected].

NEOLITHOGRAPHY CONSORTIUM FORMEDFive major companies in semiconductor manufactureand process modeling agreed to form the nucleus of theNIST-conceived Neolithography Consortium. Theiragreement followed a presentation on the subject and apre-inception meeting at the SPIE Annual Symposiumon Microlithography in March 2000. More companiesare expected to join before the next meeting atSEMICON West.

The Neolithography Consortium’s goal is to realizethe virtual semiconductor wafer fabrication process(“the virtual fab”) on the process designer’s desktop.This means a process engineer will be able to assemblesimulation software products from diverse manufactur-ers into an integrated computer application that cansimulate and optimize the entire microlithography pro-cess, from the wafer pattern specifications to the finalwafer etch. This will require development of interoper-ability standards, development of missing simulationcomponents, development of a global optimizationprogram, and removal of any other impediments torealizing the “virtual fab” that may be identified by theconsortium members. The potential benefits of the“virtual fab” are impressive and the costs minimal. Withthis tool the wafer patterning process engineer canoptimize, globally and automatically, both the photo-mask pattern design and all of the adjustable processparameters. The engineer then can print virtual wafersin his computer and compare the sizes and placementsof the virtual features with their specifications and toler-ances. In contrast to the expensive printing and metrol-ogy of real test wafers, virtual wafers are free andrequire no metrology. After the real photomask is fabri-cated to the specifications derived in the “virtual fab,”mask metrology data from the emulated exposure aerialimage can be inserted into the simulation at the appro-priate point. The resulting emulated virtual waferfeatures include the effects of any errors and defects inthis specific mask and can again be compared with theirspecifications to qualify the mask or re-optimize theprocess parameters. This consortium is open to allinterested parties. Members benefit because a membersproduct is more valuable to customers because it iseasier to use and it forms an essential part of an inte-grated simulation package; members can influencestandards development; common file formats, user inter-faces, etc. reduce software product design workload.

The integrated circuit industry benefits because thevirtual fab reduces design-to-product time and lowersproduction costs, and open standards encourage new andinnovative simulation products.CONTACT: James Potzick, (301) 975-3481; [email protected].

METROLOGY TERMS AND DEFINITIONSBECOME SEMICONDUCTOR INDUSTRYSTANDARDThe work of the Semiconductor and Materials Interna-tional (SEMI) Standards task force on metrology termsand definitions has become the industry standard SEMIP35-0200, “Terminology for Microlithography Metrol-ogy.” This is the first edition of an ongoing accumula-tion of metrology definitions appropriate to semicon-ductor manufacture. To better coordinate semiconductormetrology terms with usage in other industries,this standard contains definitions from the ISO“International Vocabulary of Basic and General Termsin Metrology,” reference to the ISO “Guide to theExpression of Uncertainty in Measurement,” and termsdescribing some new concepts in the measurement ofmicroscopic feature size or linewidth. This SEMIStandards task force, the NIST project on the interna-tional comparison of linewidth measurements for theBureau International des Poids et Mesures (BIPM), andthe calibration of NIST Photomask Linewidth StandardReference Materials all have to deal with the difficultissue of measurement uncertainty of imperfect micro-scopic objects. The synergy between these projects hasbeen helpful to all.CONTACT: James Potzick, (301) 975-3481; [email protected].

NIST/INDUSTRY INTERLABORATORYCOMPARISON COMPLETEDManufacturers of thermal insulation in the United Statesand Canada require reliable thermal resistance measure-ments to market their products effectively. An importantcomponent of their measurement process is the determi-nation of the level of uncertainty attainable with currentcommercial equipment. In collaboration with AmericanSociety for Testing and Materials (ASTM) CommitteeC-16 on thermal Insulation, NIST has completed a“round-robin” laboratory comparison of small heat flowmeter apparatus. This apparatus is a popular instrumentused by industry for checking the quality assurance ofinsulation products. Twelve industry laboratories in theUnited States and Canada participated by circulatingspecimens of NIST high-density fibrous-glass boardamong the participants. Using NIST’s 1 m guarded-hot-

495


plate apparatus, the specimens were characterized at24 �C providing accepted reference values of thermalresistance. From the test results, the 95 % repeatability(within-laboratory) and reproducibility (between-laboratory) imprecision indexes were 1.1 % and 4.0 %,respectively. Bias, characterized by the difference of thetest results and the NIST accepted reference values, wasdetermined to be statistically insignificant at the 95 %confidence level for these materials. The results havebeen documented in the ASTM Journal of Testing andEvaluation and will be included in futurerevisions of ASTM Test Method C 518 on heat-flow-meter apparatus.CONTACT: Robert R. Zarr, (301) 975-6436;[email protected].

CONFERENCE EXPLORES IT APPLICATIONSAND INTEGRATIONA practical review of the challenges that manufacturersface when striving to integrate their information tech-nology—from in-house engineering to supply chain ex-ecution—and, then laboring to make it all work togetherwas the purpose of a conference sponsored by NIST inJune 2000, at its Gaithersburg, MD, headquarters.

Information Technology for Engineering and Manu-facturing 2000 addressed the interests of a wide range oIT users, from manufacturing managers and engineersto systems integrators and software developers. In fiveconference sessions, NIST scientists and engineers,joined by experts from industry and universities, exam-ined key issues in five major areas of IT applica-tions: product data management, manufacturing simu-lation, knowledge-aided engineering, processrepresentation and electronic commerce. A sixth ses-sion evaluated the potential of XML—the eXtensibleMarkup Language—to overcome today’s obstacles tointegration and interoperability.Media Contact: Michael E. Newman, (301) 975-3025;[email protected].

Standard Reference Materials

SRM 2100: FIRST IN THE WORLD FORCERAMIC FRACTURE TOUGHNESSAccurate fracture toughness measurements are impor-tant for new materials development and materialsspecifications. Standard Reference Material (SRM)2100 is the first reference material in the world for theproperty fracture toughness. This ceramic SRM may beused to verify fracture toughness testing procedures. Itcomplements the new ASTM Standard Test Method C1421-99 as well as two International Organization forStandardization (ISO) draft standards now under devel-opment. This SRM, for which the fracture toughness(KIc = 4.57�0.23 MN/m1.5) is known with a high accu-racy and precision, should dramatically improvefracture toughness testing procedures for brittlematerials.

SRM 2100 consists of five hot-pressed silicon nitrideflexure specimens cut from a single master billet. TheSRM may be used with any credible fracture toughnesstest method, but has been optimized for beam bendingtype tests. ASTM C 1421 features three such tests: thesurface crack in flexure (SCF), precracked beam (PB)[also known as single-edged precracked beam (SEPB)],and chevron notch in bending (CNB) methods. TheSRM specimens are common 3 mm�4 mm�47 mmbeams which must be precracked by the users.CONTACT: George Quinn, (301) 975-5765;[email protected].

496

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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

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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