NAT'L INST. OF STAND & TECH NBSIR 87-3587 Center for Basic Standards QC October 1987 100 .U56 U.S. DEPARTMENT OF COMMERCE National Bureau of Standards //87-35S7 1987 NBSIR 87-3587 jCdmical Activities 1987 Center for Basic Standards Peter L. M. Heydemann U.S. DEPARTMENT OF COMMERCE National Bureau of Standards National Measurement Laboratory Center for Basic Standards Gaithersburg, MD 20899 October 1987 U.S. DEPARTMENT OF COMMERCE, Clarence J. Brown, Acting Secretary National Bureau of Standards, Ernest Ambler, Director ABSTRACT This report summarizes the research and technical activities of the Center for Basic Standards during the Fiscal Year 1987. These activities include work in the areas of electricity, temperature and pressure, mass and length, time and frequency, quantum metrology, and quantum physics. Keywords: Astrophysics; atomic and molecular physics; chemical physics; electrical standards; fundamental constants; gravity measurements; laser physics; length standards; mass standards; pressure and vacuum standards; temperature standards; time and frequency standards; X-ray and gamma- ray wavelength standards. INTRODUCTION This report is a summary of the technical activities of the NBS Center for Basic Standards (CBS) for the period October 1, 1986 to September 30, 1987. The Center is one of the four centers and operating units in the National Measurement Laboratory. The summary of activities is organized in six sections, one for the technical activities of the Quantum Metrology Group, and one each for the five divisions of the Center. Each division or group tells its own story in its own way. In general, there is an overview followed by a series of short reports on current projects. Then the publications, invited, talks, committee participation and professional interactions during the year are listed. More information about particular work may be desired. To obtain this, the reader should address the individual scientists or their division, c/o Center for Basic Standards, B160 Physics Building, National Bureau of Standards, Gaithersburg, Maryland 20899. IV TABLE OF CONTENTS Abstract iii Introduction iv Electricity Division (521) 1 Temperature and Pressure Division (522) 45 Length and Mass Division (523) 93 Time and Frequency Division (524) 105 Quantum Physics Division (525) 155 Quantum Metrology Group (520.06, 526) 261 V . TECHNICAL ACTIVITIES: ELECTRICITY DIVISION FISCAL YEAR 1987 INTRODUCTION AND OVERVIEW The Electricity Division (ED) concerns itself with fundamental electrical quantities such as current, voltage, and impedance at DC and low frequencies (to roughly 100 kHz) over many orders of magnitude and at the highest possible levels of accuracy. Its primary mission is to provide the central basis for a reliable and consistent system of electrical measurement throughout the U.S., including the Nation's scientific and defense communities as well as industry and commerce; and to ensure that the U.S. system is consistent with those of other countries and the internationally accepted system (i.e,, the International System of Units or SI). The justification for all of the ED's work comes directly from the Bureau's Organic Act, as amended, and is in its primary mission areas, that is, the areas of responsibility for which the Bureau was originally founded in 1901. The major technical areas which benefit from the ED's work include fundamental physical theory; high technology-based R&D; electrical power revenue metering, transmission, and distribution; industrial process control; quality control in the manufacture of electronic components and products; testing and maintenance of electronic systems, which includes civilian contract suppliers of defense and aerospace programs; and national defense requirements directly under the Department of Defense. End user groups include scientists in universities; electric power utilities, both public and private; electric equipment manufacturers; process engineers who design, build and use industrial process control systems; manufacturers of electronic components and consumer products; high technology civilian companies and government agencies involved with communications, computers, aerospace, transportation, health, and defense; and finally the armed seirvices It is probably not an overstatement to say that the Nation's electric power system, the cost-effective manufacture of reliable consiamer goods, the economic production of industrial materials, a viable national defense, and R6cD at the cutting edge of science and technology, would not be possible without adequate electrical measurements; and that the basis for ail such measurements within the U.S. is the fundamental electrical units the ED maintains and disseminates through its various services; the measurement methods and instrumentation it develops; and the tests and calibrations of standards and instruments it performs. For example, each year well over one thousand calibrations are carried out on primary electrical standards of voltage, resistance, capacitance, inductance, and AC-DG difference that belong to some of the Nation's most important corporations, utilities, universities and government organizations, including Hewlett-Packard, General Motors, IBM, General Electric, Pacific Gas and Electric, Rockwell, McDonnell-Douglas Boeing, TRW, the TVA, the , FAA, and the DoD. These standards are used in turn to calibrate and 1 . otherwise support a wide range of work-horse electrical measuring instruments and systems numbering literally in the hundreds of thousands, such as digital voltmeters (DVMs) programmable voltage and current , sources, analog- to-digital and digital-to analog converters, resistance/inductance/capacitance (RLC) meters, impedance bridges, electrometers, oscilloscopes, data recorders, component and printed circuit board testers, automatic test equipment (ATE) for weapons systems, etc. Without reliable measurement results from such equipment, a technologically sophisticated society like that of the U.S. could not even exist, let alone advance To fulfill its main responsibility of providing the central basis for the U.S. electrical measurement system, the ED carries out work in eight distinct but related areas with the following objectives: 1. Realize the SI definitions of basic electrical measurement units such as the ampere, volt, ohm, and farad, thereby ensuring that the U.S. legal electrical units are consistent with the internationally accepted system. 2. Develop and maintain U.S. Legal or National Reference Standards for the basic electrical units and related quantities, thus providing a central basis for the U.S. system of electrical measurement. 3. Disseminate the basic electrical measurement units to users within the U.S. via a variety of measurement and calibration services, and develop new means for doing so, thereby ensuring the traceability of electrical measurements made throughout the country to National Reference Standards. 4. Develop new methodologies and the required instrumentation and standards which will lead to advances in the state-of-the-art of electrical measurement, thus ensuring the availability to the technical community of adequate measurement techniques. 5. Determine fundamental physical constants closely related to the electrical units in order to provide the scientific community the means to test basic physical theory. 6. Initiate and participate in international comparisons of the basic electrical units, thus ensuring that the U.S. system of electrical measurement is consistent with those of other countries. 7. Participate in voluntary national and international standardizing activities related to the electrical units, and the fundamental physical constants, in order to foster international compatibility of electrical measurements, eliminate and prevent non- tariff barriers to trade, and contribute to internationally acceptable data compilations. 8. Provide training for personnel active in the field of electrical measurements and standards, including the presentation of seminars and 2 workshops, and the generation of tutorial written material, thereby elevating the overall level of competence in the field. In practice, the Division's work falls within two major categories: (1) electrical dissemination services; and (2) fundamental electrical measurements. The focus of the former is the maintenance and dissemination of the basic electrical quantities such as voltage, resistance, and capacitance; that of the latter the realization of the SI electrical units and the development of standards based on phenomena such as the quantum Hall effect. An introduction and overview to electrical dissemination services immediately follows this introduction and overview of the Division. The principal projects in the fundamental electrical measurements category are Realization of the SI Ampere, Realization of the SI Farad and Ohm, Josephson Voltage Standards, Quantized Hall Resistance, Gamma-P and the Fine -Structure Constant, and Fundamental Constants Data Center. (Details of the objectives, current activities, FY 87 accomplishments, and future plans for these and two other projects in this category are given in individual reports following those for the electrical dissemination services projects.) The two principal goals of the above projects are (1) to deteirmine the best possible values in SI units for the Josephson frequency-voltage quotient 2e/h and the quantized Hall resistance Rg = to put h/e^ ; and (2) into place and bring to a highly efficient operational state improved and