5
Physics Laboratory



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 5 Physics Laboratory

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 PANEL MEMBERS Janet S.Fender, Air Force Research Laboratory, Chair Neville V.Smith, Lawrence Berkeley National Laboratory, Vice Chair Patricia A.Baisden, Lawrence Livermore National Laboratory Anthony J.Berejka, Consultant, Huntington, New York Gary C.Bjorklund, Bjorklund Consulting, Inc. D.Keith Bowen, Bede Scientific Incorporated Leonard S.Cutler, Agilent Laboratories Ronald O.Daubach, OSRAM SYLVANIA Development, Inc. Paul M.DeLuca, Jr., University of Wisconsin Medical School Jay M.Eastman, Lucid, Inc. Stephen D.Fantone, Optikos Corporation Thomas F.Gallagher, University of Virginia Tony F.Heinz, Columbia University Jan F.Herbst, General Motors Research and Development Center Franz J.Himpsel, University of Wisconsin Daniel J.Larson, Pennsylvania State University David S.Leckrone, NASA Goddard Space Flight Center Thad G.Walker, University of Wisconsin Frank W.Wise, Cornell University Submitted for the panel by its Chair, Janet S.Fender, and its Vice Chair, Neville V.Smith, this assessment of the fiscal year 2001 activities of the Physics Laboratory is based on site visits by individual panel members, a formal meeting of the panel on March 8–9, 2001, in Gaithersburg, Md., and documents provided by the laboratory.1 1   U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology, Physics Laboratory: Technical Activities 2000, NISTIR 6590, National Institute of Standards and Technology, Gaithersburg, Md., February 2001, and U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology, Physics Laboratory: Annual Report 2000, National Institute of Standards and Technology, Gaithersburg, Md., February 2001.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 LABORATORY-LEVEL REVIEW Technical Merit The NIST Physics Laboratory (PL) states its mission as supporting U.S. industry, government, and the scientific community by providing measurement services and research for electronic, optical, and ionizing-radiation technology. The laboratory carries out this mission via programs ongoing in six divisions: Electron and Optical Physics, Atomic Physics, Optical Technology, Ionizing Radiation, Time and Frequency, and Quantum Physics (see Figure 5.1). Of these six divisions, five are reviewed below under “Divisional Reviews.” The sixth, Quantum Physics, operates within JILA, a joint institute with the University of Colorado at Boulder, and will be reviewed by a special subpanel in 2002. Based on its collective experience and expertise, the panel finds the programs ongoing in the laboratory to be of an extraordinarily high technical quality. This continues a long tradition of technical excellence at the laboratory. The Physics Laboratory is an indispensable national asset in terms of the technical capability that it maintains for the nation. Many of its capabilities are unique in the nation; FIGURE 5.1 Organizational structure of the Physics Laboratory. Listed under each division are the division’s groups.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 some are unique in the world. Its world-class research aims at long-term goals in fundamental standards and metrology. The panel spent a considerable amount of time at its meeting with laboratory management discussing four areas of science and technology that the laboratory has determined to be target areas for increases in investment. The four areas are nanotechnology, biophysics, medical physics, and quantum information. The panel had heard briefings on these areas at its 2000 meeting. The most recent discussions were intended to gauge Physics Laboratory progress in the last year toward building programs in these areas. At this point the panel comments briefly on the technical strength of the Physics Laboratory in the four areas. It comments in the next section, “Divisional Reports,” on the relevance and effectiveness of the laboratory’s work in these areas. The laboratory has a strong capability in nanotechnology. Several laboratory researchers are considered by their peers as among the world’s leaders in fabricating and characterizing structures on the nanoscale. The laboratory recently completed assembly of specialized instrumentation, the Nanoscale Physics Laboratory, which integrates fabrication and characterization of nanostructured materials into one instrument and allows their characterization under conditions of low temperature and both fixed and variably oriented magnetic field. This gives the laboratory a unique technical capability. The panel anticipates that the next several years will bring continued outstanding results from the PL in nanotechnology. The Physics Laboratory does not have a notable capability in biophysics. To have an impact in this area, it would need access to substantial expertise in the biological aspects of the relevant problems. The laboratory currently has a strong technical capability in the medical use of radiation, one aspect of medical physics. It has been successful in developing new measurement capabilities and dosage standards to keep pace with the growing numbers and types of radiation therapies delivered to patients each year in the United States. The laboratory has access to unique facilities, one of which is the NIST Center for Neutron Research, that enable its capabilities in this area. The laboratory is clearly well positioned technically to lead the country in attempts to use trapped atoms and ions and exotic states of matter such as the Bose-Einstein condensate to develop information storage systems based on the quantum properties of atoms. Of the dozen or so people in the world who are considered the experts in this rapidly developing area, NIST counts three on its staff, one a Nobel laureate. The technical knowledge and skills required to succeed in this area are well established in the laboratory, and groundbreaking work, such as the demonstration of a four-atom entangled state, or four “qubit” system, has already come out of this group. The team has set an extraordinarily challenging goal of a 10-qubit system by 2005, but its strength is so outstanding that it stands a very reasonable chance of achieving it. Detailed comments on other technical programs ongoing in the Physics Laboratory are given below in “Divisional Reports.” Program Relevance and Effectiveness Many programs in the Physics Laboratory are clearly reaching their customers in industry and the scientific community. For example, the laboratory’s programs in optical radiation measurements (including derived photometric and radiometric units, the radiation temperature scale, spectral source and detector scales, and optical properties of materials such as reflectance and transmittance) are utilized by the aerospace, biotechnology, photographic, lighting, display, automotive, pharmaceutical, semiconductor, and scientific and optical instrumentation industries, among others. The laboratory’s measure-

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 ment services support important niche sectors of the economy—for example, its highly accurate measurements of the spectra of rare-earth elements have value to the commercial lighting industry. Although many technical programs were clearly targeted at current or anticipated industry needs, not all programs have such a clear focus. Assessing program relevance and effectiveness was difficult, since the panel did not hear a clearly articulated overall strategic vision for the laboratory’s impact. Clearly, articulating specific overall strategic goals for the laboratory would help improve alignment of individual programs with the laboratory mission and allow NIST stakeholders to better understand the value and effectiveness of the programs. The panel strongly supports the laboratory’s planned emphasis on nanotechnology. Experts in science and technology predict that nanotechnology will lead the next industrial revolution. Advances are being made much more rapidly than had been anticipated when the field emerged. In the United States, Congress funded the National Nanotechnology Initiative to stimulate research by leading universities and industry in this important emerging area. The European Union is very well organized and intent on leading the world in the invention, development, production, and sales of nanobased technologies and devices. Standards and measurement capabilities are already needed in some key areas and will certainly be required as these technologies move closer to implementation. The laboratory has a strong technical base in place to begin such work. However, the panel did not find an articulated overall vision for the work, whose ultimate goals were not clear to it. The panel supports near-term development of a NIST program in nanotechnology and high-level sponsorship by NIST management. First and foremost, the NIST program in nanotechnology needs to be defined. To develop the scope of its niche area, the NIST team should identify critical parameters and methods for measuring fabrication quality, performance, interfaces, and other aspects of nanotechnology devices. Since nano devices are atomic and molecular constructions, measuring bulk properties may not adequately characterize their performance. Interactions among individual atoms and molecules may produce effects that are not observed when properties of bulk materials are measured. Understanding what properties need to be measured will require a multidisciplinary team at NIST. A clear statement of vision and the niche that NIST will fill should be communicated to U.S. industry and all other stakeholders in the field. The panel was unable to divine the role that the Physics Laboratory believes it can fill in biophysics. For the laboratory to have an impact, its role must be determined early and driven toward. A solid base of technical expertise does not yet exist in the laboratory in biophysics, so the laboratory must consider carefully whether the role it can play merits diverting the resources necessary to establish such a base in the current flat budget situation. As noted above, NIST already has a strong presence in medical radiation dosimetry, one aspect of medical physics. It was not clear to the panel what the NIST goals were for broader expansion into medical physics. A long-range vision is needed to guide the effort and to engage both staff scientists and stakeholders. The panel was very impressed with laboratory plans in the Quantum Information Program. While this is a highly speculative effort, it is critical to both U.S. commerce and defense that the United States be the leader when and if this technology comes to fruition. The laboratory already has on its staff many of the world’s leading experts in science relevant to this area and is extraordinarily well-positioned to succeed in this effort. Despite the long-term, high-risk nature of the program, the team has set very specific, definable goals (10 qubits by 2005) for its work, and it communicated these goals effectively to the panel. These clearly defined goals and vision, coupled with the tremendous laboratory expertise in this area, bode well for the future success of the program. This program is a model of clear vision and organization that can be followed as PL defines its programs in other emerging areas.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 TABLE 5.1 Sources of Funding for the Physics Laboratory (in millions of dollars), FY 1998 to FY 2001 Source of Funding Fiscal Year 1998 (actual) Fiscal Year 1999 (actual) Fiscal Year 2000 (actual) Fiscal Year 2001 (estimated) NIST-STRS, excluding Competence 31.2 33.0 33.0 33.9 Competence 1.9 1.6 1.8 2.2 ATP 1.8 1.9 1.9 2.3 Measurement Services (SRM production) 0.2 0.2 0.1 0.1 OA/NFG/CRADA 9.5 10.1 10.6 12.5 Other Reimbursable 3.5 3.6 4.2 4.0 Total 48.1 50.4 51.6 55.0 Full-time permanent staff (total)a 207 204 200 205 NOTE: Funding for the NIST Measurement and Standards Laboratories comes from a variety of sources. The laboratories receive appropriations from Congress, known as Scientific and Technical Research and Services (STRS) funding. Competence funding also comes from NIST’s congressional appropriations but is allocated by the NIST director’s office in multiyear grants for projects that advance NIST’s capabilities in new and emerging areas of measurement science. Advanced Technology Program (ATP) funding reflects support from NIST’s ATP for work done at the NIST laboratories in collaboration with or in support of ATP projects. Funding to support production of Standard Reference Materials (SRMs) is tied to the use of such products and is classified as Measurement Services. NIST laboratories also receive funding through grants or contracts from other government agencies (OA), from nonfederal government (NFG) agencies, and from industry in the form of Cooperative Research and Development Agreements (CRADAs). All other laboratory funding, including that for Calibration Services, is grouped under “Other Reimbursable.” aThe number of full-time permanent staff is as of January of that fiscal year. Laboratory Resources Funding sources for the Physics Laboratory are shown in Table 5.1. As of January 2001, staffing for the Physics Laboratory included 205 full-time permanent positions, of which 170 were for technical professionals. There were also 51 nonpermanent or supplemental personnel, such as postdoctoral research associates and temporary or part-time workers. The onset of construction of the NIST Advanced Measurement Laboratory is a positive sign and should significantly alleviate the facilities deficiencies that the panel has noted for a number of years. In general, the laboratory has adequate capital equipment, although specific needs in both capital equipment and facilities are noted in some of the divisional reports below. The greatest resource of the Physics Laboratory is its staff. The panel takes great pleasure in once again noting that the assembled scientific talent constitutes a world-class team that any institution would be hard pressed to rival. It is a pleasure and an honor for the panel to interact with this staff during its assessment process. The laboratory has been operating under a basically level budget for several years, and when mandatory cost of living increases for staff are taken into account, the budget has actually been in

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 gradual decline. This situation is reducing the laboratory’s capability to renew staff skills by replacement hiring and is of great concern to the panel since the staff is the laboratory’s most valuable asset. The laboratory must focus its programs even more tightly and articulate its vision and goals even more clearly. The panel reiterates that such articulation is key to bringing and keeping key stakeholders on board as the laboratory seeks to maintain the vitality of its programs and move into important new areas. DIVISIONAL REVIEWS Electron and Optical Physics Division Technical Merit The Electron and Optical Physics Division states that its mission is to develop measurement capabilities needed by emerging electronic and optical technologies, particularly those required for submicrometer fabrication and analysis. The division is organized into three groups: Photon Physics, Electron Physics, and Far UV Physics. Photon Physics. The Photon Physics Group’s research in extreme ultraviolet (EUV) physics and measurement technology is high-quality, state-of-the-art work that clearly supports important national goals in the emerging technology of EUV lithography. The group is also carrying out important and highly innovative work in EUV and x-ray microscopy. In EUV lithography, the group maintains several strong programs. It has constructed a laser-produced plasma source of pulsed EUV radiation. This source, which generates plasma by the laser irradiation of inert gas clusters produced by supersonic expansion, provides superior repeatability, and, compared with commonly used solid-state laser plasma sources, is relatively free from degradation and contamination after multiple irradiations. The group is currently using this source to characterize optical components. The group has also upgraded its EUV reflectometry facility with a larger sample chamber. This enlarged chamber is capable of holding EUV mirrors as large as 40 cm in diameter and weighing 50 kg. A large mirror from the Sandia-developed engineering test stand, the C-1 mirror, has been sent to the NIST facility for characterization. This new instrument is the only one in the world that can make reflectometry measurements on such large mirrors. The first sample EUV mirrors for calibration in this facility were to arrive shortly after the panel met. The panel looks forward to reviewing the results of these new calibration capabilities in its next report. The group has in place several capabilities that position it to study the contamination that degrades the EUV mirrors used in lithographic processes because: It can produce high-quality, sputter-deposited EUV multilayer mirrors. Its Synchrotron Ultraviolet Radiation Facility, SURF III, can provide high fluences over extended times at the lithographically relevant 13-nm wavelength. It also has the reflectometery capabilities to measure mirror reflectivities before and after exposure to this radiation. The three processes that limit the lifetime of EUV mirrors are deposition of debris from the laser plasma source, EUV-induced oxidation, and EUV-induced carbonization. The group could conduct

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 long-term studies of these contamination problems and of the cleaning phenomena that have been proposed as solutions. In the area of EUV and x-ray microscopy, the Photon Physics Group has performed x-ray nanotomography of integrated circuits using the Advanced Photon Source at Argonne National Laboratory. Using 1800-eV photons, the first three-dimensional reconstruction of an integrated circuit interconnect (aluminum/tungsten technology) was achieved, with 400-nm resolution. The group is following up on this success with an experiment on the Advanced Light Source at Lawrence Berkeley National Laboratory, which will provide even greater image resolution. The group will have full access to a beam line dedicated to tomography experiments and anticipates beginning experiments using 4000-eV photons and hollow-cone illumination by the end of 2001. Images with a resolution of 80 nm should be obtained. An interesting possibility for another application of the x-ray nanotomography technique is the study of the three-dimensional structure of photonic devices such as integrated optical circuits. In many cases significant amounts of dopants are used to modify the index of refraction to define channel waveguides. These dopants might provide sufficient contrast to be imaged, provided that the x-ray wavelength is properly chosen at the appropriate absorption edges. Electron Physics. The research programs pursued by the members of the Electron Physics Group are in all cases state of the art and in some cases unique. The group has been a longtime leader in the area of magnetic microscopy, and its current projects bode well for extending that leadership into the future. The group has upgraded its capabilities in scanning electron microscopy with polarization analysis (SEMPA) by installing a new, ultrahighvacuum, field-emission scanning electron microscope in the facility. This new microscope provides a higher-intensity field-emission electron source and state-of-the-art optics compared with the units it is replacing. This upgrade has improved the resolution of magnetic images obtained from the SEMPA apparatus from 50 nm to 20 nm. The group plans to couple this new instrument with its polarized detection system. This system, based on the detection of circularly polarized light emitted by polarized electrons tunneling from a ferromagnetic sample into a GaAs tip, gives a well-defined, quantitative signal compared with other spin detection schemes. When this detection system is in place, the group hopes to achieve 10-nm resolution of its images, which would be the best of any SEMPA system in the world. This instrument has been of great interest to industrial customers such as Seagate and IBM, since the width of a bit in state-of-the-art hard disks is 50 nm and the size of a magnetic storage particle is about 10 nm. The SEMPA facility also has capabilities for in situ thin-film growth and nanoscale compositional and structural analysis. Structures such as trilayer wedges can be grown and characterized with techniques such as reflection high-energy electron diffraction. The completion of the Nanoscale Physics Laboratory was discussed in the panel’s previous report. Its centerpiece is a cryogenic, ultrahigh-vacuum scanning tunneling microscope (STM) capable of operating at temperatures as low as 2.3 K in a fixed-orientation applied magnetic field of 10 T or a variable-orientation field as large as 1.5 T. With its two molecular beam epitaxy chambers, field-ion microscopy apparatus, and integrated design, the system is truly unique. The first results from this facility were presented to the panel this year. Initial experimental results include an STM image and measurement of the tunneling conductance for a single-atom Kondo system comprising an isolated Co atom on a Cu (111) substrate. These atomic-level images were obtained at temperatures as low as 2.3 K and in magnetic fields as high as 10 T. This new facility positions the group to be a leader in the fabrication and characterization of nanoscale magnetic materials.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 Room-temperature STM was used to study the growth and morphology of epitaxial Mn films grown on Fe (100) single-crystal whiskers, enabling elucidation of interlayer exchange coupling mechanisms. In Fe/Mn/Fe (100) trilayers an interesting spiral spin structure was found that is connected with a 90° magnetic coupling different from the 0°, 180° coupling through antiferromagnetic Cr in Fe/Cr/Fe (100) wedges. In a fascinating extension of the work on laser-focused deposition, the concept of “atom on demand” is beginning to be explored. The idea is to capture a single atom in a trap, creating a source of individual atoms that might be used to build a precise microstructure. An important contributor to the overall success of the group is its strong theoretical contingent. The theorists interact with the experimentalists in the group and with other researchers within and outside of NIST. The presence of theoretical expertise in the group provides an enhanced opportunity for cross-fertilization of ideas and brings a second perspective to problem solving. Recent theoretical activities include work on exchange-bias bilayers, calculation of spin-dependent interface resistance, and investigation of magnetization reversal in ultrathin films. Far UV Physics. The Far UV Physics Group operates SURF III. This recently upgraded facility has provided its users with improved capabilities, such as an increase in beam current from 200 mA to 700 mA, a remarkable achievement given the low energy of the synchrotron ring. This capability, coupled with its available instrumentation for absolute optical and radiation measurements makes SURF III unique in the United States. The facility has a well-defined customer base that requires high-precision radiometry and optical measurements in the near and extended ultraviolet frequencies. Customers include NASA (characterization of space-based probes), Lawrence Livermore National Laboratory (as part of its activities for the EUV LLC consortium2), and industrial firms examining the use of UV radiation to cure organic compounds with less release of VOCs. Further enhancements to the facility are under way, including the addition of a beam line for UV Fourier transform interferometry. Other areas for possible expansion include infrared microscopy and photoemission microscopy. The low energy of SURF III is uniquely suited for producing tunable near-UV photons (3 to 6 eV) that are used for obtaining work function contrast in photoemission microscopy. Both potential options are well matched to the qualities of the SURF III light source. For full implementation of infrared microscopy, an improved beam stability at higher frequencies needs to be pursued. For successful development of photoelectron microscopy, a clear tie into a specific scientific application is essential to motivate and guide the work. The facility is well managed, and the panel noted pride and enthusiasm among the small but competent staff. Program Relevance and Effectiveness As feature sizes in semiconductors shrink, optical lithography moves toward shorter and shorter wavelengths of light. EUV lithography at around 13 nm is a leading candidate technology for future semiconductor manufacturing. The division holds regular technical meetings with representatives of EUV LLC. The consortium has requested NIST assistance in nine areas, including EUV source, mirror, and detector calibrations. This collaboration has involved no funding, and the division has tried to offer 2   A consortium founded by Intel, Motorola, and Advanced Micro Devices in 1997 and now including many additional industrial firms and three DOE national laboratories.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 assistance using its limited resources and staff. Additional staff in this area would allow the division to provide a more timely response and have a greater impact. X-ray nanotomography of integrated circuits is another area with potentially significant impact. Clearly, the ability to form three-dimensional, element-specific images of conducting pathways in integrated circuits with 100-nm resolution is of great interest to the semiconductor industry. This technique could have some importance for the field of photonics if three-dimensional dopant-specific images could be formed of optical integrated circuits. The frontier research of the Electron Physics Group in nanoscale science and technology assures its relevance to a broad customer base spanning the industrial, governmental, and academic communities. With its wide-ranging capability for fabricating nanostructures atom by atom and for investigating their electronic and magnetic properties, the Nanoscale Physics Laboratory will interest a broad spectrum of customers, ranging from those concerned with atom manipulation in specific nanostructures to those studying the intrinsic physics of atom-solid interactions. As noted, the anticipated extension of the SEMPA capability to 10-nm resolution is attracting interest from the magnetic data storage industry, with manufacturers already sending samples for evaluation. The NIST MEL is utilizing laser-deposited nanoscale Cr line structures on Si substrates prepared in this facility as a standard for nanoscale length measurements. The division’s results are communicated to customers through a variety of methods. Most significant is the substantial number of high-quality papers published in refereed external scientific literature. Division Resources Funding sources for the Electron and Optical Physics Division are shown in Table 5.2. As of January 2001, staffing for the Electron and Optical Physics Division included 24 full-time permanent TABLE 5.2 Sources of Funding for the Electron and Optical Physics Division (in millions of dollars), FY 1998 to FY 2001 Source of Funding Fiscal Year 1998 (actual) Fiscal Year 1999 (actual) Fiscal Year 2000 (actual) Fiscal Year 2001 (estimated) NIST-STRS, excluding Competence 4.6 5.0 5.4 5.4 Competence 0.0 0.0 0.0 0.2 ATP 0.2 0.2 0.1 0.2 OA/NFG/CRADA 0.5 0.6 0.5 0.8 Other Reimbursable 0.1 0.1 0.1 0.1 Total 5.4 5.9 6.1 6.7 Full-time permanent staff (total)a 27 23 23 24 NOTE: Sources of funding are as described in the note accompanying Table 5.1. aThe number of full-time permanent staff is as of January of that fiscal year.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 positions, of which 21 were for technical professionals. There were also 4 nonpermanent or supplemental personnel, such as postdoctoral research associates and temporary or part-time workers. The division staff is of high quality, and the panel observed generally good morale among its members. However the division appears to be understaffed relative to customer needs in key areas such as EUV lithography and EUV and x-ray microscopy. In a situation of flat budgets, there is little opportunity to hire new staff. The division chief perceives the NIST overhead rate as unusually high and believes that it impacts his budget sufficiently to inhibit his ability to maintain adequate staffing for existing projects. In addition, staff are concerned that the federal salary scale does not allow them to compete on a level playing field for the best researchers and postdoctoral fellows. Equipment funding for the Electron and Optical Physics Division appears to be adequate. Atomic Physics Division Technical Merit The Atomic Physics Division states its mission as carrying out a broad range of experimental and theoretical research in atomic physics in support of emerging technologies, industrial needs, and national science programs. It is organized into five groups: Plasma Radiation, Quantum Processes, Laser Cooling and Trapping, Atomic Spectroscopy, and Quantum Metrology. Plasma Radiation. The Plasma Radiation Group is responsible for maintaining and operating the laboratory’s electron beam ion trap (EBIT), which produces and traps ions in charge states up to 70+. About 10 EBIT facilities are in operation around the world. These facilities use ion-trapping techniques to enable studies in atomic physics and nanoscale surface science. For most facilities, no data are available on the spatial distribution and dynamical motion of ions inside the trap. The NIST group has used a charged coupled device camera and modeling to determine the thermal distribution within its EBIT and more accurately describe ion behavior within the trap. For this reason, the NIST EBIT is probably the best characterized in the world. As a consequence, the Plasma Radiation Group is in a good position to make quantitative collision measurements of highly charged atomic species. The NIST EBIT is also equipped with a variety of spectrometers that enable measurement of transition wavelengths of highly charged ionic species from the visible to the x-ray region. This capability, coupled with the spectroscopic capability afforded by the new detectors that are being installed, should make the apparatus unique. Furthermore, the panel believes that it is the only EBIT that is coupled to a microscope to allow careful in situ analysis of the effects of high-energy ions impinging on surfaces, which resolves ambiguities in such measurements due to exposure to air. The group is fitting the GEC Inductively Coupled Plasma (GEC-ICP) plasma source apparatus with a new type of optical-fiber-based tomographic detection system. This will enable three-dimensional imaging of the plasma constituents. This is of potential importance in semiconductor manufacturing, since as the wafer diameters used in semiconductor etching increase, the ability to monitor and control plasma uniformity during the etching process becomes increasingly necessary. There are roughly 30 plasma cells of this type in the country, three of them at NIST. The group’s ability to perform high-accuracy UV index of refraction measurements has been used to help solve a key materials issue in 157-nm optical lithography. Calcium fluoride, the candidate material for such optical systems, suffers from chromatic aberrations at the 157-nm wavelength that limit its usability. Based on index of refraction measurements made by the group, barium fluoride has been

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 the development of an apparatus with a trapping volume four times greater than that of the previous apparatus. Further improvements in the signal-to-noise ratio are planned using a new 9-Å monochromator. This could lead to a 100-fold reduction in signal-to-noise ratio. Previous work in this area was reported in Nature.5 A separate, NIST-led neutron lifetime experiment utilizes a Penning trap for decay protons. The success of this experiment may rest on a complete understanding and analysis of the complex decay data and the neutron flux. While considerable data were acquired during 2000, their analysis remains to be completed. The program on developing polarized 3He neutron spin filters continues to sustain NIST’s leadership in this area. Using spectrally narrow diode lasers, a neutron-compatible spin exchange cell was developed that can function at low pressure (1 bar) in contrast to the heretofore higher pressure cells (3.5 bar). This has extended relaxation times to about 400 h, which may be a world record. Such low-pressure cells would allow for quite stable polarization. The Neutron Interferometry and Optics Facility (NIOF) continues to generate significant industrial interest. Prior work on the characterization of fuel cell membranes has spurred interest in the DOE Office of Transportation Technologies Fuel Cell Program. This could lead to sustained support for the use of neutron tomography in the characterization and development of fuel cell technologies. NIOF is also starting to study the migration of Li ions in batteries. The goal is to resolve long-standing discrepancies between theory and experimental results for these systems. Phase contrast radiographs of very small objects were developed at the NIOF and reported in Nature.6 Phase-contrast radiography is novel in providing a means of extracting phase information in an image without the use of an interferometer. This technique will be applied to phase-contrast tomography. The Neutron Interactions and Dosimetry Group’s activities in the area of neutron dosimetry continue to provide much-needed calibrations for industry and government. A significant development was an accelerated test for neutron-induced soft failures in static random access memory (SRAM) and dynamic random access memory (DRAM) computer chips. This work showed that soft neutrons from cosmic rays can induce failures in certain borosilicate glasses used in chip manufacture, which was of major importance to a leading U.S. chip manufacturer. In the past the group played a leading role in establishing international neutron cross-section standards, but the retirement of a key individual means this effort will now be largely curtailed. However, a recent hire in computational physics has greatly strengthened the group’s computational abilities related to transport phenomena. In fact, recent theoretical work on Compton scattering may lead to new dosimetry capabilities at a microscopic level. Radiation Interactions and Dosimetry. The Radiation Interactions and Dosimetry Group is also involved in four scientific and technical activities: (1) theoretical dosimetry, (2) industrial dosimetry, (3) medical dosimetry, and (4) protection and accident dosimetry. The group provides NIST-traceable dosimetry to the medical and industrial communities and engages in the development of innovative dosimetry methods and techniques. In support of these uses, the group works on models and codes that assist in the interpretation of dose penetration. The group’s capabilities in theoretical dosimetry were greatly strengthened by the hiring of a 5   Huffman, P.R., et al., “Magnetic Trapping of Neutrons,” Nature 403:62–64 (2000). 6   Allman, B.E., et al., “Quantitative Phase Radiography with Neutrons,” Nature 408:158–159 (2000).

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 research physicist to focus on this area. Substantial theoretical advances have been made in electron scattering cross-section evaluations and in understanding Compton scattering. Such efforts are fundamental to the understanding of the detailed detector response. An appropriate extension of current work on particle interactions would begin to address such interactions with DNA itself. This may be a long-term endeavor that ultimately underlies all bioresponses. Codes and theoretical calculations have been used to aid in the understanding of dose distributions from brachytherapy sources. Fundamental theoretical work is addressing concerns in both the industrial and medical communities. The group has disseminated notice of the e-calibration service that it is developing to large industrial users of electron beam and gamma processing. NIST will be able to remotely read dosimeters and to evaluate the response of a customer’s instrument via the Internet. This computer-controlled system can then issue temporary certificates of calibration. It relies on the use of electron paramagnetic resonance (EPR) measurements from alanine-based dosimeters. In an extension of this work, the division has developed thin-film, alanine-coated strips and complementary EPR instrumentation. Two major users of low-voltage electron beam processing are now engaged in an evaluation of these alanine-coated, thin-film dosimeters. Acquiring an EPR instrument capable of handling these thin films was crucial to this project. While the division has done considerable work to restore a 1930s accelerator to use in this program, industrial credibility will suffer for want of a state-of-the-art high-current electron beam. Dose rate effects that are significant in some industrial applications cannot be appraised using this very antiquated equipment. Both industrial and medical users rely on the Radiation Interactions and Dosimetry Group for calibrations to a national reference 60Co beam. It is crucial that this beam be cross-calibrated with an older, weaker 60Co source that had been used as a reference. All industrial and radiotherapy calibrations (there are more than 5000 installations nationally) are linked to this 60Co reference beam. It is therefore imperative that the source calibration be transferred from the old to the new source in a timely and comprehensive manner. The group should consider this a high priority and complete work on it during this calendar year. To keep up with the needs of the medical community, NIST needs to move quickly to water-based dosimetry from its current air kerma system. This should first be carried out with the new 60Co source using water calorimetry. The next step should be to establish the water-based calibration on a modern high x-ray beam. In this regard, the existing Medical/Industrial Radiation Facility accelerator falls short of providing the quality and similarity to conventional radiotherapy electron linac needed for this calibration. A state-of-the-art 6- to 8-MeV linac is needed if NIST is to play a leadership role in this area. With respect to low-energy photon calibrations, some concern emerged over the divergence of air kerma measurements from calibrations performed using the wide-angle free-air chambers and the well counters. While these discrepancies seem to have been resolved, it would benefit the medical community that relies upon these source calibrations to have a comprehensive report on them. A workshop in this area for involving brachytherapy seed manufacturers and the Accredited Dosimetry Calibration Laboratories might also be considered. The Radiation Interactions and Dosimetry Group is engaged in commendable programs involving mammography proficiency testing, improved international dose traceability for mammography testing, and comparisons of mammography quality. These involve collaborations with international organizations, such as the International Atomic Energy Agency (IAEA) and the World Heath Organization, and with national laboratories in the United Kingdom and Germany.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 Program Relevance and Effectiveness The division maintains a significant presence in national standards organizations, such as the American Society for Testing and Materials, the American National Standards Institute, and the Institute of Electrical and Electronics Engineers. It is also active in the international standards community through bodies such as the International Commission on Radiation Units and Measurements, the International Electrotechnical Commission, and the International Committee for Radionuclide Metrology. Division personnel are members of key professional associations, such as the American Association of Physicists in Medicine and the Health Physics Society, and of national bodies such as the National Council on Radiation Protection and Measurements and the Council on Ionizing Radiation Measurements and Standards (CIRMS). The division has been attentive to national needs as spelled out by CIRMS, an independent, nonprofit coordinating council that draws its constituents from industry, academia, and government. It is through these organizations and its direct contact with the scientific and industrial communities that the division demonstrates leadership in establishing appropriate standards and in identifying critical measurement issues in its fields of expertise. The division’s SRM program provides industry, government agencies, and the scientific community with well-characterized materials certified for radiochemical and/or isotopic composition. These SRMs are used to calibrate measuring instruments, to evaluate methods and systems, and to produce scientific data that can be readily referenced to a common base that is traceable to national standards. To ensure that the division is in touch with the needs of the communities it serves, members participate in a number of user organizations, such as the Nuclear Energy Institute (NEI), and in measurement assurance programs for radioactivity measurement traceability. Through NEI, the division provides traceability services in two areas: (1) for suppliers of radiochemical and radiopharmaceuticals, dose calibrators, and nuclear pharmacy services and (2) to the nuclear power industry for utilities, source suppliers, and services laboratories. For the radiopharmaceutical industry, which comprises about 10 participating companies or organizations, the division provides 10 different SRMs on a one-per-month schedule. With the exception of 99mTc, the SRMs are provided each month in two activity levels, high (tens to hundreds of millicuries) and low (tens to hundreds of microcuries). During the other 2 months of the year, NEI member organizations interact with the division to address traceability issues related to new diagnostic or therapeutic techniques under development involving radionuclides not yet available as SRMs or to resolve measurement problems they might be experiencing with existing products. A similar but low-activity-level SRM program is also administered to support environmental and bioassay analyses. Interactions with organizations such as CIRMS, the National Voluntary Laboratory Accreditation Program, and the DOE’s National Analytical Management Program provide the division with guidance on the radioisotopes that require measurements. Division staff often take leadership roles with such organizations and sponsor workshops to address methods and procedures for detecting, measuring, and analyzing radioactive materials found in a wide variety of environmental and biological matrices. This division also completed the fourth year of the NIST Radiochemistry Intercomparison Program to provide measurement traceability for low-level environmental measurements in accordance with the acceptance criteria as defined in ANSI-N42.22, “Traceability of Radioactive Sources to NIST and Associated Instruments Quality Control.” The division also enjoys excellent industrial and academic collaboration predicated on having a world-class facility, the ultracold neutron (UCN) source, and on the outstanding nondestructive analytical capabilities of the NIOF. These tools have enabled the division to engage in projects on the cutting edge of small-scale power generation: analysis of fuel cell membranes and investigations into ion transport in Li batteries. The division also has excellent rapport with the nuclear power industry.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 The Neutron Interactions and Dosimetry Group does an outstanding job of balancing industrial concerns with fundamental research. However, the fundamental research projects are complex, and a more complete perspective, as provided by an overview of these projects, milestones passed, and milestones expected, would be helpful. More frequent updates are needed to keep the medical and industrial communities abreast of developments and issues involving calibrations and dosimetry determinations. For example, concerns about variances in air kerma calibrations could be put to rest by more frequent updates on results for the user community. Quarterly updating of relevant information, perhaps on the NIST Web site, would be useful. The panel commends the division for its response to the suggestion that it engage in issues involving nuclear waste and waste disposal. In April 2000, in collaboration with CIRMS, the division hosted the workshop “Radiation Measurements in Support of Nuclear Material and International Security.” How the outcome of this workshop fits into the division’s agenda remains to be determined. In 2000, the division hosted seven such workshops in conjunction with CIRMS covering a broad spectrum of division and CIRMS interests. Division Resources Funding sources for the Ionizing Radiation Division are shown in Table 5.5. As of January 2001, staffing for the Ionizing Radiation Division included 38 full-time permanent positions, of which 34 were for technical professionals. There were also 3 nonpermanent or supplemental personnel, such as postdoctoral research associates and temporary or part-time workers. Division staff have demonstrated a notable esprit de corps. This may be attributable to improvements in facilities—for example, better lighting and fresh paint—to an invigorated scientific mission, and to solid divisional leadership. The division had 45 refereed articles published in a variety of journals in the past year, a figure that speaks to the quality of the staff. TABLE 5.5 Sources of Funding for the Ionizing Radiation Division (in millions of dollars), FY 1998 to FY 2001 Source of Funding Fiscal Year 1998 (actual) Fiscal Year 1999 (actual) Fiscal Year 2000 (actual) Fiscal Year 2001 (estimated) NIST-STRS, excluding Competence 4.3 4.5 4.3 4.3 ATP 0.2 0.2 0.2 0.1 Measurement Services (SRM production) 0.1 0.1 0.1 0.1 OA/NFG/CRADA 1.5 1.6 1.5 2.0 Other Reimbursable 0.8 0.9 1.2 1.1 Total 6.9 7.3 7.3 7.6 Full-time permanent staff (total)a 35 36 33 38 NOTE: Sources of funding are as described in the note accompanying Table 5.1. aThe number of full-time permanent staff is as of January of that fiscal year.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 However, the division’s group leaders are at times overextended, taking on project responsibilities in addition to their managerial functions such as the training of new personnel and maintaining a division presence at international and national measurement forums. A strategic hire to enhance computational capabilities in the Radiation Interactions and Dosimetry Group is unfortunately offset by the loss of a key person in nuclear data in the Neutron Interactions and Dosimetry Group. The division’s essentially flat budget (taking into consideration cost-of-living increases, it is, in effect, declining 2 to 5 percent every year) will eventually erode the division’s ability to pursue its mission and damage the above noted esprit de corps. Of particular concern are crucial areas in which division projects are dependent on cofunding from other federal departments or agencies, including the traceability program to bring agencies into compliance with ANSI N42.22 and commitments to develop a regulatory guide for the Nuclear Regulatory Commission. CIRMS has expressed concerns about division staffing. It believes that growing demands in the medical applications and emerging issues such as food irradiation will require increased NIST efforts in these areas. It also recommends increasing the level of effort for occupational radiation protection. The division derives some revenues from its SRMs, calibration and traceability services. This income is prone to vary from year to year and should not be counted upon for planning purposes. This customer-based source of revenue is at best able to support two to three staff professionals. The panel has noted in previous reviews the need for the division to develop a capital plan. To date the panel has not seen such a plan. Four specific items that the panel suggests the division considered in such a plan are (1) a state-of-the-art TIMS that would put the Radioactivity Group ahead of the current state of measurements in terms of resolution and sensitivity; (2) an upgrade in neutron imaging capabilities to improve resolution down to 10 μ and significantly reduce the time to generate an image (as use of neutron imaging increases, the time factors involved in image generation must be addressed); (3) a state-of-the-art, high-current, low-voltage laboratory electron beam accelerator (a number of leading industrial firms recently obtained an innovative high-current, low-voltage self-contained solid state and computer-controlled laboratory unit for less than $150,000); and (4) a 6- to 8-MeV medical linac that will have sufficient beam intensity to also serve as a bremsstrahlung source and be used for standards and reference purposes. Time and Frequency Division Technical Merit The Time and Frequency Division states its mission is to support U.S. industry and science through provision of measurement services and research in time and frequency and related technology. The division is organized into six technical groups: Time and Frequency Services, Network Synchronization, Atomic Standards, Ion Storage, Phase Noise Measurements, and Optical Frequency Measurements. There are strong connections and interactions between the groups, so this assessment is not organized by group. The Time and Frequency Division is experiencing extraordinary success and productivity. Long-range research is flourishing. Research results obtained over the last 20 years are bearing fruit in improved techniques, including the connection of optical and microwave frequencies and the use of trapped ions for significantly improved stability of frequency standards, and real improvements in standards and services are being realized. Morale in the division is high. Staff members have a real sense of advancing the state of the art, enjoying the fruits of many years’ worth of discovery and development, and of exploiting recently developed techniques and opportunities.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 As planned, the NIST cesium fountain frequency standard, NIST-F1, has replaced the cesium beam standard, NIST-7, as the nation’s primary frequency standard. The current evaluation of NIST-F1 indicates a frequency uncertainty of 1.7×10–15, a threefold improvement over the performance of NIST-7. NIST-F1’s frequency agrees, within stated uncertainties, with a number of international standards, including two other fountain standards. Agreement with NIST-7 is also within the uncertainties. A report on the evaluation has been submitted to Metrología and three formal evaluations have been submitted to the International Bureau of Weights and Measures (BIPM), as is required for NIST-F1 to be included in the determination of Coordinated Universal Time (UTC). The present performance of NIST-F1 certainly ranks it among the best cesium standards in the world, and it perhaps is the best. The Time and Frequency Division continues to further refine and improve NIST-F1. The team is trying to implement transverse cooling of the cesium in the fountain standard. This is important in reducing the uncertainty in the density shift, presently the largest uncertainty in the measurement. In addition, the uncertainty in the gravitational shift of NIST-F1 at its current location has been further reduced, to 2×10–17. The Time and Frequency Division has developed a special time scale, AT1E, for comparing primary frequency standards. AT1E involves the use of five hydrogen masers with cavity autotuning, which, in combination with frequency comparison data attained through satellite-based methods, provides for absolute comparisons of the frequencies of NIST standards against those of other countries without the need for simultaneous operation of those standards. This has allowed quick measurements aimed at refining the atom density frequency shift in NIST-F1 and intercomparisons between NIST’s UTC and other countries’ time scales. The division continues to improve the stability of the NIST UTC time scale with respect to the UTC disseminated by BIPM. Improvements in comparison of time scales have been achieved by the application of two-way time transfer and carrier phase common-view techniques. AT 1E has enabled comparing frequency standards at very high precision over extended periods of time. Division staff also added a new comparison and measurement system at 100 MHz to enable better measurements of local high-performance frequency standards. The Time and Frequency Division continues its development of an optical frequency standard based on the locking of an ultrastable laser to an ultraviolet transition in a single Hg+ ion. The Q (ratio of the transition frequency to the line width) achieved in this system exceeds 1014, four orders of magnitude larger than that achieved for the microwave transitions currently used in frequency standards. This standard has the potential to reach an accuracy of 1×10–18, well beyond that of the best microwave frequency standards and even beyond other optical standards. This work is defining the state of the art. Substantial developments in the measurement of the Hg+ frequency using frequency combs, as described below, are also essential for the characterization and eventual use of this and other optical frequency standards. Substantial progress has also been made on a calcium optical frequency standard. This standard, based on a narrow resonance in calcium atoms that are laser cooled and trapped in a magneto-optical trap, has very good short-term stability (currently 4×10–15 at one second), as well as other attractive characteristics (low sensitivity to external fields, cooling, trapping, and probing done with diode lasers). The standard serves as a useful companion to the mercury ion standard; however, owing to its lower Q (by two orders of magnitude), it does not appear to be a serious competitor for use as the eventual primary standard. In the past year, the division moved quickly to capitalize on German developments in frequency comb generation and measurement techniques. In collaboration with German colleagues, the division has demonstrated an optical frequency comb produced by injecting femtosecond pulses from a mode-

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 locked laser into a microstructure fiber. After emerging from the fiber, the periodically spaced, phase-coherent modes span an octave of frequency. The modes of the comb are phase-locked to a reference, such as a hydrogen maser. The frequency of every line in the comb is then known with the precision of the frequency of the reference. Such a system allows any frequency in the spectral range of the comb to be measured with the uncertainty of a primary frequency standard. One of the significant applications of the femtosecond comb to measurements of atomic frequencies was measuring the 282-nm transition of a single Hg+ ion relative to the optical transition in calcium. The uncertainty in the measured Hg+ frequency is 1000 times lower than that in previous results and is limited by the uncertainty of the calcium frequency. Just recently, the frequency comb was used to measure the absolute frequencies of the Hg+ and Ca optical-clock transitions with unprecedented precision. Such a connection between microwave and optical frequencies has been a long-sought goal of the frequency-measurement community. This connection allows a system to benefit from both the high Q of an optical transition and the cycle-counting capabilities that exist at lower frequencies, and thereby from the translation of the high performance of optical standards to microwave frequencies. In a demonstration of the generation of a microwave output from an optical standard, a line in the comb was locked to the Hg+ optical frequency standard. The stability of the resulting microwave output exceeded that of the best quartz oscillators. Given these new techniques, the path is clear for optical standards to replace microwave standards such as the cesium fountain clock. The division’s continuing work on correlated states of trapped ions plays a major role in the Physics Laboratory’s quantum computing initiative and is relevant to reducing noise in trapped-ion frequency standards. In the past year, the division published news of the first successful quantum entanglement of four particles, performed using beryllium ions. This achievement was heralded widely and is setting the pace for the division’s competitors. The division recently demonstrated operation of a decoherence-free quantum memory. An experiment with a pair of ions showed a clear violation of Bell’s inequality while avoiding a problem with detection efficiencies present in previous experiments using other systems. The Time and Frequency Division is continuing its work on a small gas-cell frequency standard using coherent population trapping. The gas cell is irradiated with 852-nm light from a vertical-cavity surface-emitting laser, which is frequency modulated at 4.596-GHz, half the hyperfine frequency of cesium. This gives two coherent laser emission frequencies corresponding to the frequencies of transitions from the ground state hyperfine levels to an excited state. When the frequency difference is equal to the hyperfine level separation, there is reduced absorption by the atoms, leading to an increase in the transmitted light through (or a reduction in the fluorescent light from) the gas cell. An 85-Hz line width at 4.596 GHz has been obtained. The narrow line is used to stabilize the frequency of the 4.596-GHz modulation. Since there is no microwave excitation of the gas cell, no microwave cavity is needed and the device can be made very small, perhaps 2000 mm3. Power consumption is also expected to be low, perhaps 100 mW. The performance of such a standard should be similar to that of rubidium gas-cell devices. In view of its potentially small size, low power, and moderately good performance, this gas-cell standard could have many military and commercial applications, particularly in telecommunications. The Time and Frequency Division continues high-quality work on phase and amplitude noise measurements and standards and on electronics for the primary frequency standards. It has made several copies of a flexible microwave synthesizer for frequency standards that it developed. These have low phase noise and very high phase stability with ambient temperature changes. High efficiency and low noise power supply design is critical in these units. It is particularly noteworthy that these standards are made completely from commercially available parts. Phase and amplitude noise measurement capability has been extended to 110 GHz. The phase noise measurement technique for microwave

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 pulse amplifiers has been further improved. This technique uses the cross correlation method and provides tens of decibels improvement over previously available measurements. As a first step toward assessing the performance of frequency standards delivered over optical fibers, a 3.5-km fiber link between NIST Boulder and the University of Colorado was established in the past year. Network lines were assigned, and the first experiments in transmission of a frequency standard over these lines were encouraging. Light of 1.3-μ wavelength, modulated at 2.36 GHz and locked to a hydrogen maser, was launched into the fiber, and its stability was measured after one round-trip through the link. The observed stability is better than 10–12 τ–1/2, limited by the noise floor of the measurement system. Program Relevance and Effectiveness In addition to producing outstanding work on basic science and technology and the related development of enhanced primary standards, the Time and Frequency Division carries out development work and provides services that are directly relevant to a large number of customers. At the time the panel met, the division’s network time service was receiving 40 million hits per day compared with 25 million a year previously. New servers are being installed to meet the increasing demand, which will bring the total of servers to 14. The division is in discussion with commercial firms that have expressed interest in taking over this authenticated time service and hopes to transition its activity to the private sector. The division also has a new Web site, time.gov. This site, intended for the nontechnical user, provides official United States time with an uncertainty of less than 1 second and is traceable to both the U.S. Naval Observatory and NIST. In October 2000, the site received 3.7 million hits. Many of the Time and Frequency Division’s results on phase and amplitude noise measurement capability and microwave frequency synthesizers for frequency standards have direct and important applications in industry. The division even provides systems for measurements of phase noise in pulsed radar amplifiers. It also performs many calibrations for industry, receiving about $2000 per month for its services. The division is also working on issues of timing for code division multiple access cell phone technology. In case the Global Positioning System’s (GPS’s) reference signal is lost, these cells must be able to maintain accurate time (holdover) to within 3 μs for 24 hours. Better estimates than those produced by the current smart clock technique of the raw oscillator noise and drift performance are desired, and wavelet analysis is being considered for this purpose. The Frequency Measurement Service has been enhanced in terms of both measurement uncertainty and flexibility. Uncertainty has been reduced to 2×10–13 for 24-hour averaging, and the system can measure any frequency from 1 Hz to 120 MHz in 1-Hz increments. The upgrade of NIST frequency broadcast station WWVB is complete. While the station now radiates 35 to 40 kW rather than the 50 kW originally planned, the simultaneous use of both available antennas improves the received signals by about 5 dB within the continental United States. The division has now turned its attention to replacing the high-frequency antennas for station WWVH in Kauai. The 30-year-old antennas have been corroded by the saltwater environment and are being replaced with fiberglass whip antennas designed for marine environments. The Time and Frequency Division is in the process of surveying customers about its time and frequency services, an exercise it carries out approximately every 10 years. The survey will soon be posted on the Internet and published in professional journals. Based on past experience, approximately

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 5000 responses are anticipated. The results of the survey will be used to make decisions about the broadcast and Internet time services and their formats. The primary customers for these services are in the transportation, telecommunications, and financial industries. The division is currently working with four industry customers who are current or potential providers of time signals. These companies are considering taking over some part of the distribution of time signals in the United States and Japan, where NIST is currently setting itself up to provide time services. Reports on the progress with the small gas cell standard have provoked interest in an ultraminiature standard—a clock on a chip. A meeting will be held soon with government and industry participants to consider the possibility of developing such a device for use in GPS receivers for telecommunications and military purposes. As noted above, the low-power, small gas-cell Cs standard should have many applications, both military and commercial, particularly in telecommunications. With its 54 publications of good to extremely high quality in the last year and its impact and substantial participation at conferences and workshops, the Time and Frequency Division’s dissemination of results to the primary scientific community has been excellent. This community includes academic scientists and scientists and engineers working in industry. Division Resources Funding sources for the Time and Frequency Division are shown in Table 5.6. As of January 2001, staffing for the Time and Frequency Division included 39 full-time permanent positions, of which 34 were for technical professionals. There were also 6 nonpermanent or supplemental personnel, such as postdoctoral research associates and temporary or part-time workers. The division continues to attract and retain high-quality personnel. One of its strengths is its management system, in which group leaders are primarily scientific and technical leaders rather than administrators. Leadership is distributed, with group leaders involved in major decisions. The division experienced a 20 percent staff turnover in the last 3 years, with half of the departures due to retirements. TABLE 5.6 Sources of Funding for the Time and Frequency Division (in millions of dollars), FY 1998 to FY 2001 Source of Funding Fiscal Year 1998 (actual) Fiscal Year 1999 (actual) Fiscal Year 2000 (actual) Fiscal Year 2001 (estimated) NIST-STRS, excluding Competence 5.9 6.0 6.0 5.9 Competence 0.3 0.0 0.1 0.4 ATP 0.0 0.1 0.1 0.2 OA/NFG/CRADA 1.9 2.6 2.5 3.3 Other Reimbursable 0.7 0.6 0.9 1.0 Total 8.8 9.3 9.6 10.8 Full-time permanent staff (total)a 38 40 39 39 NOTE: Sources of funding are as described in the note accompanying Table 5.1. aThe number of full-time permanent staff is as of January of that fiscal year.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 It is currently staffed at a level sufficient to continue good progress on all ongoing scientific and technical projects. While the division is reasonably well supported, division staff have enough outstanding ideas to keep a significantly larger staff very productively engaged. The division has done a very good job of managing its resources and, because of the high quality of its work, has been able to bring in enough funding from other agencies. However, with level budgets and increasing overhead and other costs, division leadership may need to reduce total staff levels in the future. The quality and quantity of laboratory space has been a problem for the division. Construction of new laboratory space for the ion storage group is under way. This is a much-needed step forward. Other laboratory improvements presumably must wait for the major infrastructure and renovation projects being considered for all of the labs in Boulder. MAJOR OBSERVATIONS The ongoing programs in the Physics Laboratory are of extraordinarily high technical merit. The laboratory is an indispensable national asset in terms of the technical capability that it maintains for the nation. While many programs in the Physics Laboratory are clearly reaching their customers in industry and the scientific community, others did not have a clear focus. Clearly articulated overall strategic goals for the Physics Laboratory would improve the alignment of individual programs with the laboratory mission and improve communication of the value and effectiveness of programs to NIST stakeholders. The laboratory’s planned emphasis on nanotechnology is based on a strong existing competency and addresses an area of clear future importance. Clearer program goals would improve stakeholder support of this program. The laboratory’s initiative in quantum computing is a model of vision, organization, and technical excellence. It is based on a strong existing competency in an area in which the laboratory leads the world. Despite the long-term, high-risk nature of the project, the Physics Laboratory has very specific goals that bode well for program success. The panel is concerned that gradually declining real budgets will impact the laboratory’s ability to renew staff skills by replacement hiring. Such a scenario would devastate the technical quality of the laboratory’s work over the long term.

OCR for page 129
An Assessment of the National Institute of Standards and Technology Measurement and Standards Laboratories: Fiscal Year 2001 This page in the original is blank.