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General DevelopmentsInquiries about News Briefs, where no contact personis identified, should be referred to the Managing Editor,Journal of Research, National Institute of Standardsand Technology, Building 101, Room E215, Gaithers-burg, MD 20899-2500; telephone: (301) 975-3577.

NIST REPORTS MEASURABLE SUCCESS OFADVANCED ENCRYPTION STANDARDAn independent study confirms industrys early adoptionand implementation of NIST’s Federal InformationProcessing Standard (FIPS) 197, Advanced EncryptionStandard (AES).

The number of products worldwide that implementedthe NIST Data Encryption Standard (DES), includingTriple DES, grew rapidly from 1999 through June 2001,but leveled off by December 2001. The slowdown in theannouncement of new DES products apparently was dueto the impending adoption of FIPS 197, AES, whichwas approved by the Secretary of Commerce on Dec. 6,2001. In December 2001, a private survey found atotal of 74 products had already implemented the AES,indicating very rapid acceptance and adoption ofthe AES algorithm, with companies already offeringproducts in anticipation of final approval of thestandard.

The early adoption of AES is perhaps more remark-able because, prior to the approval of FIPS 197, AESalgorithm testing was not available through NIST’sCryptographic Module Validation Program (CMVP), aprogram for assurance testing of cryptographic modulesjointly operated by NIST and the Canadian GovernmentCommunications Security Establishment. NIST hasnow released an updated algorithm test tool to theCMVP laboratories that includes AES algorithm testingand expects to see many more AES implementationsnow that validation testing is available.CONTACT: Bill Burr, (301) 975-2914; william.burr@nist.gov.

News Briefs

NIST DATA UNDERPINS NEW REFERENCEWORKA group of 17 scientists at Kobe University, Japan, havepublished an extensive set of data entitled Doppler-FreeHigh Resolution Spectral Atlas of Iodine Molecule,15000 to 19000 cm –1. The set consists of four volumes,each having more than 1000 pages. The spectral plotsand numerical data in these volumes are to be used as asource of precision reference wavelengths for re-searchers working with very-narrow-band tunable lasersin the green and red regions of the spectrum. The workwas carried out under the auspices of the JapaneseResearch Promotion Committee of Photoscience.

Calibration of the absolute wavelength scale forthis work was based on precision measurements ofwavelengths for the iodine molecule by a NIST scientistpublished in the Journal of the Optical Society ofAmerica in 1997. In recognition of this contribution, theproject leader at Kobe University has presented NISTwith a set of these volumes together with a laudatoryletter about the value the NIST measurements to theirlarge project.CONTACT: Craig Sansonetti, (301) 975-3223; craig.sansonetti@nist.gov.

NIST’S IMPROVED INVERSE SOLUTIONMETHOD PRESSES DOPANT PROFILINGTOWARDS INDUSTRY GOALSNIST has demonstrated a higher accuracy and higherspatial resolution inverse solution method for determin-ing dopant profiles from scanning capacitance micro-scope (SCM) images of silicon transistors. Dopantprofiles are a major factor controlling the functionaloperation of deep sub-micrometer transistors. Highaccuracy measurements of dopant profiles are needed toimprove the predictive quality of transistor models anddesign. The breakthrough is embodied in computercode that makes a large step towards meeting theaggressive spatial resolution goals set out in the Inter-national Technology Roadmap for Semiconductors(ITRS).

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In the mid-1990s, SED launched a systematic effortto address the so-called shallow-junction-profilingproblem and has since developed the SCM as a practicaltool for imaging the two-dimensional dopant concen-tration distribution in transistor junctions near theirgates. An essential element for quantifying the measure-ment is a detailed model of how the microscope inter-acts with the junction during imaging. Up to this point,models treated each data point of an SCM image inde-pendently. A forward solution (calculation of SCMsignal from a dopant profile) was used to calculate acalibration curve, which could then be used to deducedopant profiles with spatial resolution of about 20 nm.The spatial resolution of this model was still far short ofthe current goal of 4 nm (increasing to 1 nm by 2016)defined by ITRS.

Recent breakthroughs in the NIST modeling ap-proach now allow for a better inverse solution of thedopant profile, in which the dopant concentration ateach measurement point is calculated considering theeffects of the neighboring points. The regression proce-dure makes use of both coarse and fine grid meshes, sothat only a few iterations are needed to reach conver-gence. Preliminary demonstrations with one-dimen-sional model data indicate the resulting spatialresolution could meet current and future ITRS goals.The recent NIST National Research Council panelrecognized that the inverse solution of SCM data couldpotentially overcome one of the key roadblocksexpressed in the ITRS.CONTACT: Jay Marchiando, (301) 975-2088;jay.marchiando@nist.gov.

NIST COLLABORATION TO INCREASEMACHINING PRODUCTIVITY FOR U.S. NAVYNIST has been collaborating with the Naval SurfaceWarfare Center, Carderock, MD, and the Naval Foundryand Propeller Center, Philadelphia, PA, since 1999.

This collaboration resulted in significant advance-ments in the understanding of process dynamics duringhigh speed machining and the optimization of machin-ing process parameters for cutting the nickel-aluminum-bronze material of interest to the Navy. Submarinepropellers are roughly 6 meters in diameter and 2 metersdeep. Currently, production costs for a single propellerare about $1.6 million and the production takes about 12months. The goal of the joint effort is to decrease theproduction time for a propeller down to 4 months.

NIST results to date have achieved a 10 fold increasein material removal rate during the machining opera-tions of the propeller—a significant improvement inmachining productivity for the U.S. Navy. NIST results

also form much of the technical basis for the procure-ment and expected operation of the new Navy system. Inaddition, a NIST scientist completed dynamic measure-ments of a representative high-speed spindle to be usedwith a NIST-developed algorithm, called receptancecoupling substructure analysis, to select the appropriatetooling and machining parameters prior to delivery ofthe machine. This result will reduce the developmenttime typically required when manufacturing a new parton a newly installed machine.CONTACT: Tony Schmitz, (301) 975-8346; tony.schmitz@nist.gov.

INITIAL TESTS SHOW HIGH PERFORMANCEOF NIST RM 8240 STANDARD BULLETSThe fabrication of 20 standard bullets (ReferenceMaterial 8240) was completed on Jan. 7, 2002, by ateam composed of NIST researchers. Based on com-ments received from bullet examiners on prototypestandard bullets developed at NIST in 1998, these refer-ence material bullets were designed with six signaturesfrom six master bullets of the ATF and FBI nationallaboratories, and with material, color, and shape similarto real bullets. In February, NIST researchers visited aprivate company in Canada, the principal manufacturerof optical instruments used to link suspect weapons tobullets and casings recovered from crime scenes. Thepurpose of the visit was to test the reproducibility of theNIST bullets and to discuss procedures for their use andopportunities for dissemination.

The instrument manufactured by the private com-pany is the Integrated Ballistics Identification System(IBIS). Six NIST bullets were tested there using one oftheir IBIS systems. The initial test results showed thatthe reproducibility of the manufactured bullet signa-tures on the different bullets is close to the measurementreproducibility of the IBIS system itself. That suggeststhat when these bullets are distributed nationwide forIBIS calibrations, they can virtually play the samefunction as a single standard bullet.

Scientists and engineers at the company also agreedto investigate the use of a NIST developed parameterbased on autocorrelation functions, combined with theuse of NIST standard bullets, for establishment of trace-ability and quality control for ballistics measurements.A NIST workshop is planned for bullet examinersbefore the delivery of these bullets to government andlaw enforcement agencies. The NIST RM 8240/8250standard bullets and casings project will support theATF and FBI, as well as homeland security.CONTACT: John Song, (301) 975-3799; song@nist.gov.

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W3C AND NIST RELEASE DOMCONFORMANCE TEST SUITEThe World Wide Web Consortium (W3C), in partner-ship with NIST, released the first version of theDocument Object Model (DOM) Conformance TestSuite, Level 1 Core. The DOM Test Suite aims to helpimplementers test their implementations conformancewith the W3C DOM Level 1 specification. This work,launched by W3C and NIST, is a publicly developedand open framework to test the DOM Level 1 Coreimplementations.

The DOM is a platform- and language-neutral inter-face that allows programs and scripts to dynamicallyaccess and update the content, structure, and style ofdocuments. The DOM test suite consists of over 600tests for the DOM Java and ECMA Script bindings. Anadditional set of more than 1000 tests for the HTMLmodule and HTML-compatible core will be releasedsoon. The test suite was developed using XML technol-ogy and automated test generation techniques. The testsare represented in an XML grammar (i.e., in XMLschema and in DTD form) that was automaticallygenerated from the DOM specification using an XSLTtransform. These tests, which are language-neutral, areused together with XSLT style sheets to generate theJava and ECMA Script bindings of the tests. Thismethod of generating tests ensures traceability to thespecification as well as a consistent set of executabletests across language bindings.CONTACT: Rick Rivello, (301) 975-3519; richard.rivello@nist.gov.

SEVENTH NIAP COMMON CRITERIATESTING LABORATORY APPROVED FORIT SECURITY TESTINGThe National Information Assurance Partnership(NIAP), a U.S. Government collaboration betweenNIST and the National Security Agency, announcedapproval of the seventh information technology securitytesting laboratory under the Common CriteriaEvaluation and Validation Scheme (CCEVS). The newCommon Criteria Testing Laboratory (CCTL), a privatecompany in Linthicum, MD, successfully completed therigorous National Voluntary Laboratory AccreditationProgram process and has been accredited to conductevaluations of commercial products against theCommon Criteria for Information Technology SecurityEvaluation (ISO/IEC15408) standard. This processincluded an in-depth analysis of the laboratory’s qualitysystem and procedures, the administration of a compre-hensive proficiency test covering the application of the

Common Criteria and the Common EvaluationMethodology, and an on-site assessment of thelaboratory facilities.

The Common Criteria evaluation technical reportsproduced by testing laboratories and validated by theNIAP CCEVS Validation Body are recognized by 14other countries currently participating with the UnitedStates in the Arrangement on the Recognitionof Common Criteria Certificates in the Field ofInformation Technology Security, signed during theFirst International Common Criteria Conferencein May 2000. In order for the Validation Body toissue an internationally recognized common criteriacertificate, the evaluation must have been conducted byan independent third party, laboratory in accordancewith the requirements of the NIAP CCEVS.CONTACT: Arnold Johnson, (301) 975-3247; l.johnson@nist.gov.

INDEPENDENT TESTING FORCONFORMANCE TO BACnet BEGINSFor many years, the building industry struggled with theproblem of integrating control devices made by differentmanufacturers in order to optimize operations,improve safety, and reduce maintenance costs. NISTresearchers worked with industry to develop a commu-nication protocol standard for building automation andcontrol systems known as BACnet that was adopted inthe mid-1990s.

A marketplace barrier to BACnet products has beenthe lack of an independent testing program to verify thatproducts correctly implement the standard. Conse-quently, NIST created a BACnet Interoperability TestingConsortium with 22 private sector companies. NISTresearchers and the consortium partners workedtogether to develop test procedures that are nowincorporated in a draft American national standard.NIST also developed software tools that can be used toimplement the BACnet tests. The results of these effortshave now resulted in the creation of the BACnetManufacturers Association (BMA), a private sectorBACnet Testing Laboratory (BTL), and the completionof the first set of tests on commercial products.

The BMA will issue a BTL mark and publish a list ofproducts that have passed the tests. The goal is for theBTL mark and listing program to play a role in thebuilding automation and control industry much like themore well know Underwriters Laboratory mark and list-ing program for product safety.CONTACT: Steven Bushby, (301) 975-5873; steven.bushby@nist.gov.

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PARCS ADVANCES THROUGH NASAREVIEWSThe NIST-led program entitled Primary AtomicReference Clock in Space (PARCS) has successfullycompleted its second NASA review, the requirementsdefinition review. This review, which included both ascience panel and an engineering panel, considered boththe scientific merits of the mission and the technicalfeasibility of the proposed experiments. This was thefinal review of the science. A series of additionalreviews also address engineering issues of the flightsystems.

In its report to NASA, the review panel recommendedthat “the PARCS project should proceed with allpossible speed and deliberation toward the preliminarydesign review.” The complete preliminary design of thesystem will be considered in the next review, which isscheduled for late summer.

This NASA-funded mission, which is a collaborationof NIST, the Jet Propulsion Laboratory, the Universityof Colorado, the Harvard-Smithsonian Center forAstrophysics, and the Politecnico di Torino, is currentlyscheduled to fly in 2005. The objectives are to testcertain aspects of relativity theory, to improve upon therealization of the second, to study the performance ofGPS clocks, and to study the dynamics of atoms inmicrogravity.CONTACT: Don Sullivan, (303) 497-3772; dbs@boulder.nist.gov.

QUENCHED NARROW-LINE COOLINGOF CALCIUMSince their invention, atomic clocks have operatedin the microwave portion of the spectrum, where theiroutput frequencies have been amenable to electronicsystems. However, the precision of such standards hasbeen limited by their spectral linewidths (relative to thereference frequencies themselves). Substantial progressin this field can be achieved by using very narrowoptical transitions instead, in part because the referencefrequencies are orders of magnitude higher.

NIST has achieved a technical milestone in its push todevelop optical atomic frequency standards and clocks.The objective is to improve upon the accuracy andstability of the calcium optical standard, which is theonly optical standard for which high-accuracy inter-national comparisons have been made. The bestcomparison to date is between NIST and PTB where adifference of only 30 Hz was measured for the 456 THz(657 nm) transition. This was well within the uncertain-ties of the individual measurements.

The 26 Hz uncertainty in recent measurements atNIST arose from the limitations of the laser-cooling

method that was then available. In calcium, normallyonly Doppler cooling is possible. However, the Dopplerlimit is large, of the order of 1 mK.

NIST has recently achieved sub-Doppler cooling of40Ca to near the recoil limit using a quenched narrow-line laser-cooling method. A laser operating justbelow 657 nm (on the clock reference transition)provides a cooling force while a second, co-linear laser(at 552 nm) provides both additional cooling andoptical pumping required for the process to work. Usingthis method, calcium atoms were cooled in onedimension to < 2 �K and in three dimensions to below10 �K. Further improvements will include furtherreduction in temperature and increased coolingefficiency.CONTACT: Chris Oates, (303) 497-7654; oates@boulder.nist.gov, Anne Curtis, (303) 497-7969; curtisa@boulder.nist.gov, or Leo Hollberg, (303) 497-5770;hollberg@boulder.nist.gov.

EXTREME ULTRAVIOLET REFLECTIVITYINTERCOMPARISONIn the microelectronics industry, the number of transis-tors on an integrated-circuit chip doubles about every 18months (Moore’s Law). This accomplishment has beenmade possible by utilizing shorter and shorter wave-lengths of radiation for photolithography. Today, leadingmanufacturers are pushing deeper into the ultravioletspectrum. However, the end is in sight for further incre-mental changes. Very different technology will be re-quired for wavelengths shorter than 157 nm.

A number of leading chip companies have formedthe EUV LLC research consortium to develop next-generation manufacturing technology. Extreme ultra-violet (EUV) radiation at 13.4 nm holds promisebecause of the fortuitous high reflectivity of Mo/Simultilayer mirrors at this wavelength.

The NIST/DARPA Reflectometry Facility at NIST’sSynchrotron Ultraviolet Radiation Facility (SURF) wasestablished in anticipation of these needs. It is the onlyfacility in the world capable of making a completemeasurement of reflectivity on the large mirrors beingused by EUV LLC in their engineering test stand, aninstrument intended to provide the foundation for theultimate design of an EUV lithographic tool.

A just-completed international intercomparisonconfirmed NISTs capabilities. Seven test samples werestudied by NIST, PTB, Lawrence Berkeley Laboratory,ASET (a Japanese consortium), and the HimejiiInstitute of Technology (Japan).CONTACT: Thomas Lucatorto, (301) 975-3734;thomas.lucatorto@nist.gov.

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ROTATING CONDENSATES PUT NEW SPINON SUPERFLUIDITYScientists at NIST have been studying the behavior ofBose-Einstein condensates subject to rotation of thetrap, which is a key issue in the phenomenon of super-fluidity. When the trap is subject to a low rate of rota-tion, the condensate does not exhibit any net circulation,unlike a classical fluid that will circulate with the trap.Nevertheless, the condensate does acquire some angularmomentum, which results in an anisotropic densitydistribution.

NIST scientists had the simple theoretical insight thatwhen a condensate is released from a rotating trap itflies apart under conditions in which angular momen-tum is conserved, preserving the anisotropy in thedensity distribution. This effect is simple to observe andpossible to test with considerable quantitative accuracy.An experimental group at Oxford University, havingreceived a preprint of the NIST paper, performed theexperiment and confirmed the theoretical predictions.The theoretical and experimental papers were publishedsimultaneously in the February 11, 2002, issue ofPhysical Review Letters.CONTACT: Charles Clark, (301) 975-3709; charles.clark@nist.gov.

THERMAL-INFRARED TRANSFERRADIOMETER VALIDATES RADIANCESCALES USED ON LAND, AT SEA,AND IN SPACEThe Thermal-Infrared Transfer Radiometer (TXR) wasdesigned at NIST to permit NIST staff to perform fieldcalibrations of critical instruments used for environmen-tal remote sensing. As word spread through the remote-sensing calibration community about this unique andvaluable measurement capability, the TXR was de-ployed on three critical missions during thesummer of 2001.

In May, NIST in collaboration with NASAs GoddardSpace Flight Center deployed the TXR at an infraredradiometry workshop at the University of Miami(Florida) Rosenstiel School of Marine and AtmosphericScience. The TXR checked the radiance scales of black-body sources used by the sea-surface remote sensingcommunity to calibrate ship-based radiometersthat validate satellite measurements of sea-surfacetemperature.

In July, the TXR was deployed to the NOAAGeostationary Operational Environmental Satellites(GOES) Imager calibration chamber at a privatecompany in Ft. Wayne, IN. NIST staff, in collaboration

with this company, performed measurements of theradiance of two calibration targets used for GOESImagers during pre-flight calibration. These data willenable radiometric calibration models used by theGOES program to be checked against the NIST infraredradiance scale.

Finally, in August, the TXR was deployed toLos Alamos National Laboratory (LANL). NIST andLANL collaborated to measure in a cryogenic vacuumchamber, the radiance of blackbody sources which wereused previously to calibrate a DOE satellite-basedinfrared sensor. These data will enable a comparisonbetween the scale used for calibration of the DOEsensor and the NIST infrared radiance scale.

Presently, the TXR is back at NIST undergoing post-deployment recalibration and even more thoroughcharacterization. Reports will soon be issued on theresults of the 2001 measurement campaigns.CONTACT: Joe Rice, (301) 975-2133; joseph.rice@nist.gov.

PHOTOASSOCIATION IN A BOSE-EINSTEINCONDENSATETwo colliding atoms can absorb a photon and be photo-associated into an excited, diatomic molecule. NISTresearchers investigated the fundamental rate at whichthis process can take place in a Bose-Einstein conden-sate (BEC) and demonstrated that simple classicalsaturation arguments do not work when applied to thissituation.

While the photoassociation reaction has been well-studied in a thermal gas, one can argue that the sameprocess will run into limitations under the conditionspresent in a BEC. A simple classical argument says thata pair of atoms has a narrow range of internuclearseparations at which the photoassociation process canbe driven to take place. Once atoms with this range ofseparations are depleted, the population must be replen-ished by the movement of atoms, and that this is limitedby their thermal velocity (about 0.5 mm/s in this case).On the other hand, a quantum mechanical description ofthe BEC has a single wavefunction for all the atoms;each atom is extended across the entire region where theexperiment is performed. The measured rate coefficientfor the reaction is in good agreement with results froma quantum mechanical two-body scattering theory forall the intensities that were achievable experimentally,and can exceed the classical limit by more than fourorders of magnitude.CONTACT: Paul Lett, (301) 975-6559; paul.lett@nist.gov.

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BROADBAND FERROMAGNETICRESONANCE SPECTROMETERNIST researchers have constructed a broadband spec-trometer for measurements of ferromagnetic resonance(FMR) in magnetic thin films from 1 GHz to 26 GHz.Like electron paramagnetic resonance and nuclearmagnetic resonance, FMR involves precession of themagnetization around an equilibrium direction, butmotion of the magnetization is heavily influenced by thelarge magnetization that is characteristic of ferromag-nets. Measurements of the resonance condition as afunction of applied field direction are valuable fordetermining magnetic anisotropy energies and couplingbetween magnetic layers in multilayer structures such asthe spin valves that are used as the active elements ofread heads in modern disk drives.

The resonance line width includes the effects of bothinhomogeneities and intrinsic damping. The extrinsicline width is an important indicator of film quality, andthe intrinsic damping, which governs the magneticrelaxation rate, is projected to become increasinglyimportant for the development of fast magnetic memory(MRAM) and GHz-rate disk drives. In disk drives, therelaxation rate is important for high data rate operationof the read head and for writing, both in the writer andin the media. In addition, the damping mechanisms thatcouple the magnetism to the thermal bath also drive themagnetic fluctuations that characterize the superpara-magnetic limit of storage density.

The broad frequency range and the angular controlprovided by this new spectrometer allows thorough test-ing of line width and damping models that are needed toseparate the inhomogeneous and intrinsic contri-butions to the measured resonance line width. Initialmeasurements using the new spectrometer have beenmade on films with intentionally created defects andnominally uniform films.CONTACT: Bob McMichael, (301) 975-5121; robert.mcmichael@nist.gov.

BRILLOUIN LIGHT SCATTERINGNIST scientists have recently implemented a Brillouinlight scattering facility for characterizing acoustic andmagnetic waves in thin-film and bulk materials. Thissystem is capable of measurements in the 3 GHz to300 GHz range with sampling volumes less than 50 �min diameter and a few hundred nanometers in depth,thus enabling detailed measurements on micron-scalepatterned thin-film structures.

Because it can selectively detect both acoustic andmagnetic waves, Brillouin light scattering can provideunique information on the coupling between magnetic

states and thermal phonons. The initial research usingthis system is focused on measurements of ferro-magnetic thin films with the goal of providing informa-tion on damping mechanisms that limit the switchingtimes of magnetic memory elements, a project partlyfunded under the NIST Nanotechnology Initiative.CONTACT: Donna Hurley, (303) 497-3081; hurley@boulder.nist.gov.

NEW METHOD TO MEASURE MASSDISTRIBUTION OF POLYOLEFINSA new technique for measuring the molecular massdistribution of polyolefins has been developed byresearchers at NIST. The new method is based on massspectrometry, a long-standing technique for characteriz-ing low mass substances, but one that is difficult to useon high mass polymers owing to the requirement ofproducing intact charged molecules in the vapor state. Inthe past decade a variation of mass spectrometry,termed matrix assisted laser desorption/ionization(MALDI), has become a powerful tool to characterizebiopolymers, such as proteins and nucleic acids. Most-biopolymers and some types of synthetic polymers arereadily charged. However, polyolefins lack the chemicalcomposition for charging by the usual methods. NISTresearchers have developed a method of chemicallymodifying polyethylene to a readily ionized molecule.The method has been demonstrated on polyethylene ofmasses to 15 ku, a mass limit that far exceeds what hadbeen previously reported in the scientific literature. Thefirst report of the NIST accomplishment appeared in thejournal Polymer. A manuscript describing optimizationof the method has been accepted by Macromolecules.

The method addresses a major need of polymerproducers and users for rapid and reliable methods ofmeasuring the molecular mass distribution of polymers.The need is especially urgent for polyolefins, examplesare polyethylene and polypropylene that dominate thecommercial market, where advances in catalysis haveled to a plethora of new molecular variations. Owing tothe way synthetic polymers are synthesized they possessa range of molecular masses. The distribution of themass is critical to how the resins are processed intouseful objects as well as the resultant properties. Themethods currently used yield only averages of the massdistribution; chromatographic methods produce themass distribution, if calibrated properly with polymermass standards. All these methods require dissolution ofthe polymer in a solvent, for polyolefins this usuallymeans using aggressive solvents at elevated temperature.This is one reason why few mass standards areavailable for polyolefins. The innovative mass spectro-

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metric method provides a powerful direct approach formeasuring mass distribution in polyethylene at a time ofaccelerated introduction of new molecular architectures.CONTACT: William Wallace, (301) 975-5886; william.wallace@nist.gov.

NIST PERFORMS ELECTROMAGNETICSHIELDING EFFECTIVENESS TESTS ONA COMMERCIAL AIRCRAFTNIST recently performed electromagnetic shieldingeffectiveness tests on a commercial aircraft using NISTdesigned broadband horn antennas and specialized timedomain measurement methodology. The informationgained in this effort is being used to develop low-costand efficient measurement techniques for in situ testingof aircraft.

Shielding effectiveness measurements are performedto quantify the electromagnetic fields coupled into anaircraft from an external source, or conversely, internalto external coupling. It is best is to measure an aircraftat an open area test site. However, taking an aircraft outof the production chain is extremely costly for theaircraft industry. Continuous wave measurements madein a hanger or production facility suffer from unwantedreflections that make data interpretation difficult.Thus, the aircraft industry is interested in timedomain methods that enable extraneous reflectionsdue to hanger walls to be windowed out using gatingtechniques.

NIST engineers used time domain methodologydeveloped at NIST to measure an aircraft in a painthanger along the production line. In addition, NIST hasdeveloped a joint time-frequency analysis tool that willbe used to extract critical cavity decay characteristicsuseful in aircraft shielding studies. The Naval SurfaceWeapons Center and a private company sponsor thiseffort.CONTACT: Robert Johnk, (303) 497-3737; johnk@boulder.nist.gov.

NIST OPENS NEW SPECIAL TESTMEASUREMENT SERVICE FOR2.92 mm COAXIAL POWER DETECTORSStaff at NIST recently opened a new Special TestService for 2.92 mm coaxial power detectors. This newservice measures the effective efficiency and calibrationfactor of thermistor, thin-film, and thermoelectricpower detectors over a frequency range of 0.01 GHz to40 GHz. Power measurements are basic to all measure-ments in the microwave and electronics industry.

In recent years, the instrument manufacturers havebeen moving to coaxial line sizes that operate atfrequencies up to 40 GHz and beyond. A number ofelectronic instruments are now commercially availablethat have 2.92 mm coaxial connectors and that operateat frequencies up to 40 GHz. The new service willprovide power measurement traceability for thosedevices. The power calibrations are made on the NISTdirect comparison system. This system is calibratedusing 2.4 mm thin-film detectors, and characterized 2.4/2.92 mm adapters. The new service was developed incooperation with the Air Force, Army, and NavyPrimary Standards Laboratories.CONTACT: John Juroshek, (301) 975-5362; john.juroshek@nist.gov.

NIST STUDY ACCELERATESUNDERSTANDING OF OXIDATIONMECHANISMS IMPORTANT TO LASERMANUFACTURERSResearchers at NIST have shown that the oxidationkinetics of AlGaAs are independent of semiconductorgrowth method and edge preparation conditions. Nativesemiconductor oxide layers are critical components ofoptoelectronic devices, such as vertical-cavity surface-emitting lasers (VCSEL) used in high-speed datacommunication, in which they provide optical andelectrical confinement. VCSEL manufacturers havereported difficulties with the repeatability of theiroxidation process.

NIST researchers conducted a study of oxidation rateas a function of relevant semiconductor growth andprocessing variables for initial AlGaAs layers having Almole fractions from 0.9 to 1.0. They found that, contraryto the expectations of some device manufacturers, theoxidation rate did not depend on whether the initiallayers were grown by molecular beam epitaxy ormetalorganic chemical vapor deposition (MOCVD), thetwo methods most commonly used by the industry.The oxidation was independent of the V/III ratio ofthe growth, impurity level in the initial epilayer, andspecimen edge preparation, whether wet etched, ionmilled, chemically-assisted ion-beam etched, or cleaved.As expected, the oxidation reaction kinetics were asensitive function of semiconductor composition,oxidation temperature, and time. The study did reveal, inone sample set grown by MOCVD by an outside labora-tory, unintentional fluctuations in the epilayer composi-tion during growth (as confirmed by SIMS analysis),which increased the oxidation rate.

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The results of the NIST study are providing VCSELmanufacturers valuable insight into the tolerances oftheir native oxide fabrication process. They are alsoimportant input to a broader investigation of the impactof strain on device reliability. More details can be foundin the paper “Comparison of AlGaAs Oxidation in MBEand MOCVD Grown Samples,” by Y. Chen et al., Mat.Res. Soc. Symp. Proc. (2002) p. H6.11.1.CONTACT: Alexana Roshko, (303) 497-5420; roshko@boulder.nist.gov.

NIST RESEARCHERS MEASUREWAVELENGTH-DEPENDENT GAIN OFRAMAN FIBER OPTICAL AMPLIFIERSStaff at NIST recently completed measurements of thedependence of Raman gain in optical fiber on both thedifference between the pump and signal wavelengthsand the absolute pump wavelength. These measure-ments, made on four standard telecommunication fibers,represent the first direct measurements of the pump-wavelength dependence. The pump-wavelengthdependence was measured using two complimentarytechniques; a brute-force comparison of the Ramangain at different pump wavelengths and a simpler,more elegant comparison of the asymmetry in theStokes and anti-Stokes Raman gain at a fixed pumpwavelength.

Fiber Raman amplifiers are becoming increasinglyimportant in optical fiber communication systems sincethey provide both lower noise performance and a widerwavelength coverage than conventional optical amplifi-ers. In fiber Raman amplifiers, a strong pump laserprovides gain to signals at longer wavelengths throughstimulated Raman scattering within the optical trans-mission fiber. The Raman gain will depend strongly onthe wavelength difference between the pump and signalbeams and weakly on the absolute pump wavelength.Previous measurements of the Raman gain have focusedon its strong dependence on the wavelength differencebetween the pump and signal beams and have ignoredthe weaker pump-wavelength dependence. With thegrowing potential for widespread use of fiber Ramanamplifiers in deployed systems, more completemeasurements of the Raman gain are needed to provideinput for system simulations.CONTACT: Nathan Newbury, (303)497-4227; nnewbury@boulder.nist.gov.

NIST DEVELOPS ACCURATE MODEL FOR IONBOMBARDMENT ENERGIES IN PLASMAETCHERSNIST scientists have recently developed and validated amodel for predicting the kinetic energy of ions inplasma etching reactors used by the semiconductor in-dustry. During plasma etching, substrates are bom-barded by reactive chemical species and energetic ionsgenerated in the plasma, resulting in selective removalof material from exposed areas of the substrate. Theenergy of ions striking the substrate surface plays animportant role in determining the etching rate and theprofile of etched features. To control ion energies, radio-frequency (rf) power is applied to the substrate elec-trode, but the effect of the rf power on ion energies isquite complicated. Models describing the relation be-tween rf power and ion energy have been developed, butthey often involve simplifying assumptions that havenever been rigorously tested. Consequently, it is difficultto predict and to optimize ion energy distributions.

At NIST, a plasma model has recently been developedto predict ion energy distributions. This model includesa complete treatment of the time-dependent ion kineticsin the plasma sheath, the thin region between the plasmaand the substrate surface. Unlike previous models, nosimplifying assumptions are made regarding the timescale of ion motion or the frequency of the rf powerapplied to the substrate.

The new model has recently been validated by acomprehensive set of experiments performed in aninductively coupled plasma reactor. Measurements ofion energy distribution made by a mass spectrometerwere combined with capacitive probe measurements ofthe time-dependent plasma potential and Faraday cupmeasurements of the total ion flux. Together, thesemeasurements completely determine all the inputparameters of the model, allowing a direct comparisonof model results and measurements. Ion energydistributions predicted by the model were in goodagreement with measured distributions over the entirerange of frequencies investigated. The model was foundto accurately predict the dependence of ion energydistributions on rf frequency, rf amplitude, total ionflux, and ion mass. The validated model can be adaptedfor use in commercial plasma simulations. It alsoenables new, model-based methods for in situ monitor-ing of ion energies during plasma etching.CONTACT: Mark Sobolewski, (301) 975-2980;mark.sobolewski@nist.gov.

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EXPORT ALERT! SERVICE HELPS INDUSTRYThe free Export Alert! web-based system operated byNIST automatically provides early warning of changesin trade-related technical regulations proposed by mem-bers of the World Trade Organization (WTO). The OSSNational Center for Standards and Certification Infor-mation (NCSCI) is the U.S. inquiry point for the WTOand is responsible for distributing notifications to U.S.industry of proposed foreign technical regulations forreview and comment as appropriate. The WTO requiresits members to give notice of proposed regulations thatmight significantly affect trade. Using Export Alert!improves U.S. companies’ awareness of proposals thatmight affect their business.

Subscribers can select specific industry sectors and/or countries in order to receive relevant e-mail messages.NCSCI can provide full-text copies of proposed regula-tions and will transmit comments to appropriate foreignministries. When necessary, an extension of the com-ment period will be requested. Information on ExportAlert! can be found at http://ts.nist.gov/ncsci.

Since its inception, over 1000 U.S. private and publicorganizations have registered for the service, and morethan 1000 requests for copies of the full text of proposedregulations have been received by NCSCI staff. Manycompanies request two or more proposed regulations.CONTACT: Ellen Trager, (301) 975-4038; ellen.trager@nist.gov.

PUBLIC RELEASE OF THE NIST FIREDYNAMICS SIMULATOR 2.0Official release versions of NISTs computer programsfor modeling and visualizing fire and smoke flow, FireDynamics Simulator 2.0 and Smokeview 2.0, are nowavailable for download at http://fire.nist.gov/fds/. TheNIST Fire Dynamics Simulator predicts smoke and/orair flow movement caused by fire, wind, ventilationsystems, etc. Smokeview visualizes the predictionsgenerated by the Fire Dyanamics Simulator.

The Fire Dynamics Simulator is a computationalfluid dynamics model which solves a form of theNavier-Stokes equations appropriate for low-speed,thermally-driven flows of smoke and hot gasesgenerated in a fire. Version 2.0 of the Fire DynamicsSimulator includes improved combustion and radiationalgorithms. Details of the numerical methods maybe found in the Fire Dynamics Simulator TechnicalReference Guide (NISTIR 6783). Smokeview visualizesthe Fire Dynamics Simulator computed data by ani-mating time dependent particle flow, two-dimensionalslice contours and surface boundary contours. Detailsabout Smokeview may be found in the Smokeview

User’s Guide (NISTIR 6761). Version 2.0 of Smokeviewincludes new visualization techniques such as animatedisosurfaces and animated flow vectors. Instructionson how to use the Fire Dynamics Simulator andSmokeview can be found in the Fire Dynamics Simula-tor Users Guide (NISTIR 6784).CONTACT: Glenn Forney, (301) 975-2313; glenn.forney@nist.gov or Kevin McGrattan, (301) 975-2712;kevin.mcgrattan@nist.gov.

PROTOTYPE OF FLEXIBLE BALL STEPGAUGE ARTIFACTAs part of the program to maintain quality control oncoordinate measuring machines (CMMs) for the AirForce, NIST completed a prototype ball step gaugeartifact. The gauge is the first of a series to be usedthroughout the Air Force as a new calibration procedurefor CMMs. The use of a ball step gauge will allowCMMs to be calibrated quickly and easily accordingto an established protocol. The system is capableof positioning to eight azimuthal positions, at fivedifferent vertical incliniations. Each position isrepeatable, so that CMM calibration can occur with aminimal of operator interaction. The data obtainedfrom the calibrated gauge will be used to establishpart-specific measurement uncertainty using themethod of simulation by constraints developed at NIST.CONTACT: Steve Phillips, (301) 975-3565; steven.phillips@nist.gov.

NIST RESEARCHERS DEVELOPREVOLUTIONARY DETECTOR FORQUANTUM COMMUNICATION SYSTEMNIST, in collaboration with Stanford University andBoston University, has demonstrated the first quantum-communications detector system that not only indicateswhen a photon arrives, but also determines how manyphotons arrive simultaneously. As a result, this new sys-tem can extract far more information from quantum-en-tangled photons than conventional detectors.

The new detectors are based on superconductingtransition-edge sensor (TES) microcalorimeter technol-ogy, similar to that developed by EEEL for high-effi-ciency x-ray spectroscopy. The new TES photon coun-ters have a very broad spectral response, from thenear-infrared (3000 nm) through the visible and into thedeep-ultraviolet (100 nm) with a quantum efficiency ofabout 50 %. Unlike traditional semiconductor-basedphoton counters, these TES photon counters do not suf-fer from dark counts, nor do they have a gap-limitedinfrared cut-off.

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Even more exciting is the ability of the TES photoncounter to provide the energy of the incoming photon.For broadband sources, this resolution capability allowsspectral information to be determined from eachphoton. For monochromatic sources, such as quantum-entangled photon sources, the energy resolution capabil-ity allows the elimination of the multiphoton confusionproblem of conventional detectors. A four-channelsystem designed around TES devices is under construc-tion as a full Bell-state analyzer and may be very usefulas a broadband detector calibration instrument basedentirely on quantum standards. A demonstration of thefour-channel instrument is underway using a correlatedphoton source at Boston University.CONTACT: Aaron Miller, (303) 497-4212; ajmiller@boulder.nist.gov.

HELPING THE POSTAL SERVICE ADD “ZAP”TO THE MAILAs a member of the Mail Security Task Force of theWhite House Office of Science and Technology Policy(OSTP), NIST has been working on sanitizing lettermail contaminated or possibly cross-contaminated bythe anthrax bioterror actions of last October. However,parcel packages present a different problem. Theelectron irradiation process that so effectively sanitizesletter mail is not penetrating enough to be used on thenearly 200 000 larger-volume packages that have beensitting in limbo at the Brentwood and Trenton postalfacilities.

It has been decided that 5 MeV x-ray irradiation is thebest tool for decontaminating parcel mail. NIST trace-able dosimetry was used in phantom tests and spore-killtests to provide quality assurance of the correct dose asrequired by the bacillus anthracis radiation-kill curvesgenerated by the Armed Forces Radiobiology ResearchInstitute (AFRRI).

On April 11, NIST and AFRRI researchers briefedWhite House staff and other federal agencies in theIndian Treaty Room of the Eisenhower ExecutiveOffice Building. The results of NIST-designed experi-ments were presented, including the survivabilityof biological spore indicators as a function of absorbeddose, an analysis of volatile organic compoundemissions, and decontamination efforts using ethyleneoxide. As a result, the Postal Service qualified a privatecompany in Bridgeport, NJ, to begin irradiation of itsbacklog of suspect parcel mail. Anonymous mailwith destination ZIP codes 202xx through 205xx (toGovernment offices) will be irradiated by electron orx-ray beams on an ongoing basis.CONTACT: Larry Hudson, (301) 975-2537; lawrence.hudson@nist.gov.

NEWEST CRITICAL DIMENSION SCANNINGELECTRON MICROSCOPES USE NISTTECHNOLOGYScanning electron microscopes (SEM) are usedextensively in the semiconductor production environ-ment. NIST scientists are helping to improve SEMperformance with an objective diagnostic procedure toensure data fidelity by looking at the sharpnessmeasurements.

The concept of continuous or periodic sharpnessmonitoring has been incorporated into a new commer-cial critical dimension (CD) SEM. This CD-SEMincorporates a “beam condition” monitor that providesnumerical and graphical descriptions of the condition ofthe instrument and documents the instruments conditionover time.CONTACT: Michael Postek, (301) 975-2299; michael.postek@nist.gov.

SPUR-FREE, DISTORTION-FREEREFERENCE CLOCKNew generations of high-resolution Doppler radar relyon advanced digital-imaging and object-identificationtechniques. To test high data rate, high-fidelity digitalsignal processors in this application, the reference clockmust have extremely low random noise and no spurioussignals or half-period distortions.

NIST in Boulder has designed and built ultra-low-phase-noise reference clocks operating at 10 MHzand 100 MHz in which periodic and quasi-periodicspurious signals and half-period distortions are lowerthan any other reference source ever demonstrated. Theperformance of these clocks approaches the broadbandphase-noise level set by thermal noise.

Jitter on a reference clock degrades conversion ofradio signals to the digital-code domain. Small spurioussignals and clock distortions cause spurious coderesponses and distortions in the conversion process,which can be far more problematic than random noise.We have recently shown how discrete lines due to exter-nal influences, such as electromagnetic interference,vibration, and power-supply ripple, translate to jitter.These low-frequency lines, rather than broadband phasenoise, can be the dominant contributor to jitter, even foroperations involving very high-rate (microwave-band-width) digital signals, where low-frequency modulationnoise traditionally has been ignored as a concern.

We have demonstrated that jitter analyzers cannot sortout these lines, while phase-noise measurements can.Through a contract with industry, new filters weredeveloped to reduce reference-frequency harmonicdistortions, and these have been primarily responsiblefor the improved performance. However, further

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improvement was achieved through powering thesystems from separate isolated batteries, from a morecompact design that reduces pickup of external signals,and from the addition of electromagnetic interferenceshields.CONTACT: David Howe, (303) 497-3277; dhowe@boulder.nist.gov.

Standard Reference Materials

NIST RELEASES TWO NEW CALIBRATIONSTANDARDS FOR OPTICAL FIBERCOMMUNICATIONSNIST is releasing two artifact calibration standardsrelating to polarization dependent measurements inoptical fiber telecommunications applications.

NIST will provide traceable measurements for polar-ization dependent loss (PDL) in optical fiber and fibercomponents, using an artifact standard made available tocustomers through a Measurement AssuranceProgram (MAP). A NIST scientist developed theartifact and will conduct the MAP. When PDL iscombined with polarization-mode dispersion in acommunication channel, the bit error rate is degraded.Therefore accurate measurements are necessary toenable high data rate communication systems. The MAPartifact consists of a short section of polarizing fiberspliced to a single mode input fiber and a step-indexmultimode output, and its PDL is certified over the1535 nm to 1560 nm wavelength range. The artifact isimplemented as a MAP [rather than a StandardReference Material (SRM)] to mitigate the degradationto uncertainty that is caused by exposure of the artifactto unpredictable temperatures. The MAP implementa-tion includes a recording thermometer to indicate thetemperature exposure of the device during trans-portation and the customer measurement process.

An additional SRM for polarization mode dispersion(PMD) will expand NIST traceability in this area. Inan optical fiber communication system, propagationvelocity depends on the polarization state of the light.The resulting PMD can broaden optical pulses and limitbit rate. The new SRM, developed by another NISTscientist, is SRM 2538, Polarization-Mode Dispersion,Non-Mode-Coupled. It is the second SRM for PMD.The first, SRM 2518, emulates the differential groupdelay in a long length of optical fiber. The new artifact,SRM 2538, is a fiber-pigtailed quartz plate, designed to

emulate the PMD typically found in telecommunica-tions components. This new SRM is certified for meandifferential group delay over a wavelength range ofapproximately 1250 nm to 1650 nm. SRM 2538 iscertified for measurement by all PMD techniques(subject to instructions in the documentation). Due totechnical constraints, SRM 2518 is certified for only aparticular class of PMD measurement techniques.CONTACT: Paul Williams, (303) 497-3805; pwilliam@boulder.nist.gov.

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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 Institute of Physics (AIP). Subscription orders and renewals areavailable from AIP, P.O. Box 503284, St. Louis, MO 63150-3284.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 or Internal Reports (NISTIR)—The series includes interim or final reports on workperformed by NIST for outside sponsors (both government and nongovernment). In general, initialdistribution is handled by the sponsor; public distribution is handled by sales through the National TechnicalInformation Service, Springfield, VA 22161, in hard copy, electronic media, or microfiche form. NISTIR’smay also report results of NIST projects of transitory or limited interest, including those that will bepublished subsequently in more comprehensive form.

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