Technical Highlights
- Guide for the Use of the SI-1995 Edition of NIST SP 811.
We prepared, published, and widely distributed a new edition of NIST Special
Publication (SP) 811, Guide for the Use of the International System of
Units (SI).
The 1995 edition of SP 811 corrects a number of misprints in the 1991
edition (prepared by A.O. McCoubrey), incorporates a significant amount of
additional material intended to answer frequently asked questions concerning
the SI and SI usage, and updates the bibliography. The added material includes
a check list for reviewing the consistency of written documents with the SI.
Some changes in format have also been made in an attempt to improve the ease
of use of SP 811.
The topics covered by SP 811 include:
- NIST policy on the use of the SI in NIST publications.
- Classes of SI units, those SI derived units that have special names and
symbols, and the SI prefixes that are used to form decimal multiples and
submultiples of SI units.
- Those units outside the SI that may be used with the SI and those that
may not.
- Rules and style conventions for printing and using quantity symbols, unit
symbols, and prefix symbols, and for spelling unit names.
- Rules and style conventions for expressing the results of measurements
and the values of quantities.
- Conversion factors for converting values of quantities expressed in
units that are mainly unacceptable for use with the SI to values expressed
mainly in units of the SI.
- Rounding numbers and rounding converted numerical values of quantities.
To date, over ten thousand copies have been distributed throughout the world.
These include copies to the NIST technical staff, to the members of the
National Conference of Standards Laboratories, to the Members and Corresponding
Members of the International Organization of Legal Metrology, to the Committee
Delegates, Rapporteurs, and Contact Persons of EUROMET (a European
collaboration in measurement standards) and of NORAMET (a North American
regional collaboration in national measurement standards and services), to the
members of the Council on Optical Radiation Measurements and of the Council on
Ionizing Radiation Measurements and Standards, and to numerous readers of many
different trade magazines, newsletters, technical journals, etc.
- Precision Measurement Grants. We awarded, on behalf of NIST, new
Precision Measurement Grants to Siu Au Lee of Colorado State
University and Jonathan Sapirstein of the University of Notre Dame. The grants
are in the amount of $50,000 per year, renewable for two additional years. NIST
sponsors these grants to promote fundamental research in measurement science in
U.S. colleges and universities and to foster contacts between NIST scientists
and researchers in the academic community actively engaged in such work.
The aim of Sui Au Lee's project is to directly measure, for the first
time, the birefrigence of light propagating in vacuum in a strong magnetic
field, and to conduct an improved laboratory search for axions, the prime
candidates for the dark matter in the universe. This work is based on the
prediction that when a beam of light travels in vacuum in a strong applied
magnetic field, the quantum electrodynamic (QED) vacuum polarization induces a
small change in the index of refraction of the vacuum.
The aim of Sapirstein's project is to improve the theory of the energy levels
of atomic helium. A second goal is to extend the existing calculations of the
helium fine structure to other states of helium. When combined with experiment,
these calculations will provide sensitive tests of radiative corrections in
helium.
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