An Assessment of the National Institute of Standards and Technology Programs Fiscal Year 1993 (1994) / Chapter Skim
Currently Skimming:
7 PHYSICS LABORATORY
7 PHYSICS LABORATORY
Pages 113-152
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 113... ...
LABORATORY OVERVI EW Functions and Mission The Physics Laboratory conducts long-term research in measurement science; develops new physical standards, measurement methods, and reference data; and promulgates these standards, methods, and data by providing measurement services, conducting workshops, publishing research results, and collaborating with industry, universities, and other agencies of government. Specifically, the Physics Laboratory establishes spectroscopic methods and standards for infrared, visible, ultraviolet, x-ray, gamma-ray, and neutron radiation; investigates the structure and dynamics of atoms and molecules, singly and in aggregate; and develops and disseminates national standards of time and frequency and for the measurement of optical and ionizing radiation by means of calibrations, measurement quality assurance, and standard reference materials.
|
From page 114... ...
The reorganization of NIST in fiscal years 1990 and 1991 resulted in the creation of the Physics Laboratory, which is organized into eight divisions -- electron and optical physics, atomic physics, molecular physics, radiometric physics, quantum metrology, ionizing radiation, time and frequency, and quantum physics (Figure 7.1~. (The Quantum Physics Division, which consists mainly of researchers at the Joint Institute for Laboratory Astrophysics at Boulder, Colorado, is assessed biennially and is not included in this assessment.)
|
From page 115... ...
~,, ~ Quantum Ionizing Time and Metrology Radiation Frequency Division ~ ~ Division ~ ~ Division Precision X-Rays and y-Rays Theoretical Studies Synchrotron Radiation I Electron and | | Atomic Physics | || Molecular l Optical Physics Division Physics L Dlvlslon I I I I L Dlvlslon High-Resolution Spectroscopy Atomic Radiation Data Plasma Radiation Laser Cooling Molecular Dynamics Molecular Theory Radiometric Physics Division Thermal Radiometry Infrared Radiometry Detector Metrology Quantum Physics .
|
From page 116... ...
The Laser Polarization of Neutrons Program will make the Advanced Neutron Source (a $2.5 billion Department of Energy program scheduled to come on-line in the early part of the next century at Oak Ridge National Laboratory) much more useful in the study of magnetic materials, biological materials, and polymers.
|
From page 117... ...
The laboratory proposed an exciting "umbrella" initiative on advanced optical technology, involving staff from many of its divisions. NIST is the only laboratory in the United States where the broad range of necessary expertise exists in optical measurement and instrumentation techniques to pursue the proposed advances in optical technology.
|
From page 118... ...
This issue is discussed further in the panel's assessment of the Time and Frequency Division. With regard to career development and personnel matters of its technical staff, the Physics Laboratory is strengthening its diversity.
|
From page 119... ...
SURF's comparative advantage over more recently constructed synchrotron radiation sources is its broad spectrum of wavelengths of light suited for research and calibrations. SURF is more than competitive in its absolute flux reference capabilities.
|
From page 120... ...
; · Scanning tunneling microscopy (STM) studies of the electronic properties of cesium structures -- one-, two-, and three-dimensional -- deposited on indium antimonide surfaces; · STM studies of the initial stages of film growth, in particular, iron on iron and chromium on iron; · Initial stages of the development of a scanning tunneling microscope with magnetic sensitivity; · Studies of polarized electron-atom scattering, in particular, scattering from sodium atoms that were spin polarized by optical pumping; · Theoretical studies of exchange coupling in magnetic heterostructures, in particular, magnetic layers separated by a nonmagnetic spacer; and · Theoretical studies of the isotope effect in hightemperature superconductivity and the constraints it imposes on the various theoretical models.
|
From page 121... ...
The panel supports future plans that call for measurements to analyze buried interfaces, with more emphasis on the solid-state physics phenomena. A similar spectrometer is being constructed for one of the beamlines at the new Advanced Light Source at the University of California, Berkeley.
|
From page 122... ...
This novel ion source, which is discussed further in the assessment of the Plasma Radiation Group, will provide new opportunities to obtain high-resolution spectra of highly charged ions in an environment free of plasma effects. The productivity of the Atomic Spectroscopy Group is reflected in its number of high-quality publications and the receipt of the 1992 William F
|
From page 123... ...
This effort is parallel to the networking of the Atomic Physics Division's critically evaluated spectroscopic data to NASA's Astrophysical Data System. The Atomic Radiation Group shared in the development of an interdivisional proposal for the federal HPCC initiative.
|
From page 124... ...
The Plasma Radiation Group is refining radio frequency plasma measurement techniques by reproducing and checking diagnostic measurements in independent laboratories. The well-defined, well-diagnosed plasma in the GEC reference reactor is providing benchmark data for comparisons with models of complex low-temperature plasmas.
|
From page 125... ...
Molecular Physics Division The Molecular Physics Division continues to do outstanding scientific work, as demonstrated by the number of honors that have accrued to its members. The most recent include a fellowship in the American Association for the Advancement of Science and the 1992 Sigma Xi Young Scientist Award.
|
From page 126... ...
Equipment purchased and built over the past 2 years will allow this outstanding group to continue its forefront scientific work. The Molecular Dynamics Group focuses on the most significant topics in chemical dynamics, including the following: (1)
|
From page 127... ...
Because the time scale and the transition states that characterize these kinds of solvent insertion reactions are currently unknown, this work constitutes another scientific breakthrough and unique contribution, typical of the group's work over the past few years. The overlap of the scientific concepts relevant to different programs in the Molecular Dynamics Group, whether in the gas phase, in clusters, in liquids, or on surfaces, is impressive.
|
From page 128... ...
The group is also continuing its long-term effort in high-resolution spectroscopy using both diode lasers and a unique laser difference frequency spectrometer. The problems under study are related to a number of questions in atmospheric chemistry, including acid rain formation and ozone destruction.
|
From page 129... ...
Finally, the High-Resolution Spectroscopy Group continues to provide a significant service to both the scientific and the industrial communities by producing a number of critically edited data compilations. The most recent of these include a compilation of visible and infrared spectra of free radicals, a completed volume of critically evaluated molecular spectra (the third volume in a series)
|
From page 130... ...
It is crucial to understand the collisions of laser-cooled atoms for two reasons: first, such collisions affect the properties of beams and other sources of cold atoms for intended applications and, second, the collisions themselves can be controlled using optical laser light. The Molecular Theory Group has carried out pioneering work in this area by developing new ideas and techniques required to predict and interpret the collision rates of extremely cold atoms at temperatures below 0.001 K
|
From page 131... ...
The panel notes that the addition of another staff scientist to the group would greatly enhance its effectiveness and ability to contribute to the NIST mission, especially in the areas of high-performance computing and new technology development. Radiometric Physics Division The Radiometric Physics Division promotes accurate and useful optical radiation measurements in the ultravioJ et, visible, and infrared spectral regions.
|
From page 132... ...
facility is developing into a first-rate infrared spectral detector calibration facility by the extension of its range from 1.8 to 25 ~m. New possibilities for measurements of optical properties of materials using the hemiellipsoidal diffuse reflectance apparatus are evident.
|
From page 133... ...
In order to extend the power levels of the radiometer operating at liquid helium temperature below 20 no, a superconducting kinetic-inductance absolute cryogenic radiometer (AKACR) has been constructed within the Advanced Concepts of Radiometry Program.
|
From page 134... ...
The development of a low-temperature graphite blackbody is under way while the high-temperature unit, which is to operate at up to 3000°C, is being refined. These blackbodies will become the basis for an expanded capability in the Radiometric Physics Division's thermal imaging radiometry work.
|
From page 135... ...
The Radiometric Physics Division is seeking to better align its programs with customer needs through closer coordination with customers. Detector Metrology Group A wide variety of programs is under way in the Detector Metrology Group; highlights are discussed below.
|
From page 136... ...
In the Detector Applications Program, the single-detectorelement radiometer used for high-accuracy radiometry has been improved by redesigning the electronics section and using modular construction techniques. The Radiometric Physics Division has several contracts to provide improved radiometers to primary calibration laboratories within the Department of Defense.
|
From page 137... ...
The uncertainty of such funding puts not only the division's personnel but also the nation's standards and measurement services in jeopardy. Many scientifically exciting programs are under way or are being planned in the Radiometric Physics Division, with emphasis on continuing research on the optical properties of materials and microelectronics.
|
From page 138... ...
The Physics Laboratory's 1993 Competence Building Program proposals, "Fabrication and Characterization of Nanostructures" and "Optical Properties of Novel Materials," are excellent complementary studies. Quantum Metrology Division The Quantum Metrology Division conducts a wide range of activities with a small number (eight)
|
From page 139... ...
The staff of the Synchrotron Radiation Group and the Precision X-Rays and Gamma-Rays Group, in collaboration with the staff from the Ionizing Radiation Division, devised a practical means for voltage measurement and calibration in x-ray tubes used for mammography. Relatively hard x-rays (20 to 50 keV)
|
From page 140... ...
The timely installation of the new Gammacell 220 60Co Irradiation Facility, completed in fiscal year 1992, will support the growing needs of the nation's rapidly developing radiation processing industry. A collateral development is the installation of the 32-MeV Sagittairc linear accelerator in the group's medical and industrial irradiation facility (MIRF)
|
From page 141... ...
The office disseminates standards and techniques required for reliable measurement of ionizing radiation to government, industrial, medical, and defense communities. It ~ responsible for the national system of secondary standards laboratories for improving the accuracy of field measurements (Measurement Quality Assurance, or MQA)
|
From page 142... ...
Other fast-neutron-related programs involve neutron transport through iron shells, a fast neutron calibration spectrometer of interest to the Defense Nuclear Agency, and calculations related to correction factors for fast neutron measuring instruments due to neutron reflections from the walls, floor, and ceiling surrounding the instrument. Calibration work on detection of fast neutron radiation is difficult, important (especially at research reactors and neutron spallation sources)
|
From page 143... ...
The Laser Polarization of Neutrons Program takes advantage of the high flux of neutrons from NIST's research reactor and NIST's high level of laser expertise to polarize the nuclei of 3He gas by optical pumping. This program polarizes the 3He gas by spin exchange; i.e., anoptica1ly polarized rubidium vapor sample polarizes the dense 3He gas by collisions.
|
From page 144... ...
Al though the Council on Ionizing Radiation Measurements and Standards was set up in 1992, it has yet to assist the Ionizing Radiation Division in program planning and priority setting. More workshops like the Ionizing Radiation Division's March 1992 "National Voluntary Laboratory Accreditation Program (NVLAP)
|
From page 145... ...
This improvement in stability will benefit the telecommunications industry. The Time and Frequency Division has an excellent record of dissemination and transfer of time standards, as evidenced by the following: 1.
|
From page 146... ...
There are many applications for tunable diode lasers of high stability, e.g., in laser manipulation of atoms on surfaces in nanostructures, optical pumping for frequency standards, a transferable standard for length, and in spectroscopy for chemical analysis,analysis of pollutants, and similar applications. Development of high-stability tunable diode lasers is an important new technological development at NIST based on cooperation with U.S.
|
From page 147... ...
The Time and Frequency Division, with its laser expertise, could be assigned responsibility for developing and implementing a unified time-length standard. The essential aspect of this standard would be a laser-generated light source at a frequency directly related to the NIST primary frequency standard.
|
From page 148... ...
Division-level Recommendations Electron and Optical Physics Division · The panel recommends additional emphasis on making the toroidal gradient monochromator operational. · As new synchrotron radiation facilities come on-line, the panel recommends that managers of the Synchrotron Ultraviolet Radiation Facility (SURF)
|
From page 149... ...
· The panel recommends that the Radiometric Physics Division examine all of the scales to be integrated with the high-accuracy cryogenic radiometer (HACR) and prepare a master plan to address the tasks required to achieve this objective, associated funding required, and the proposed time line for completion.
|
From page 150... ...
goals and document plans. · The Radiometric Physics Division should increase its emphasis on dissemination of information regarding optical calibration techniques and measurement techniques and the dissemination of routine measurement techniques.
|
From page 151... ...
· The panel recommends that NIST formalize, in some useful way, a new definition of the meter in terms of the velocity of light.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.