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Radioactivity measurements on glazed ceramic surfaces
No full textA variety of commonly available household and industrial ceramic items and some specialty glass materials were assayed by alpha pulse counting and ion chamber voltage measurements for radioactivity concentrations. Identification of radionuclides in some of the items was performed by gamma spectroscopy. The samples included tableware, construction tiles and decorative tiles, figurines, and other products with a clay based composition. The concentrations of radioactivity ranged from near background to about four orders of magnitude higher. Almost every nuclide identification test demonstrated some radioactivity content from one or more of the naturally occurring radionuclide series of thorium or uranium. The glazes seemed to contribute most of the activity, although a sample of unglazed pottery greenware showed some activity. Samples of glazing paints and samples of deliberately doped glass from the World War II era were in, eluded in the test, as was a section of foam filled poster board. A glass disc with known Th-232 radioactivity concentration was cast for use as a calibration source. The results from the two assay methods are compared, and a projection of sensitivity from larger electret ion chamber devices is presented
Material properties of titanium diboride
No full textThe physical, mechanical, and thermal properties of polycrystalline TiB2 are examined with an emphasis on the significant dependence of the properties on the density and grain size of the material specimens. Using trend analysis, property relations, and interpolation methods, a coherent set of trend values for the properties of polycrystalline TiB2 is determined for a mass fraction of TiB2 greater than or equal to 98 %, a density of (4.5+/-0.1) g/cm(3), and a mean grain size of (9+/-1) micrometers
Coding and modulation for LMDS and analysis of the LMDS channel
No full textLocal Multipoint Distribution Service (LMDS) has the potential to become a viable alternative to coaxial cable, fiber and other wired and wireless technologies providing ""last mile"" communication services. A major obstacle, however, is the high equipment cost. While for example cable modems supporting two-way services are available for 300, LMDS modem providing similar services will cost over $1000. The major cost driver of LMDS equipment is the radio frequency (RF) unit, as Ka-band technology still is quite expensive. The modem design must minimize the overall architecture cost, and low-cost modems requiring an expensive architecture should not be used. The channel characteristics of LMDS systems are very different from those of fiber, coaxial cable, and lower frequency wireless links, major channel impairments being non-linear high power amplifier (HPA), high phase noise and high co-channel interference. Modems should therefore be developed specifically for LMDS systems. This report deals with the choice of coding and modulation schemes, the LMDS channel, and how the channel impairments should be overcome by digital signal processing algorithms
Alan P. Balutis (2000)
No full textAlan P. Balutis was director of NIST's Advanced Technology Program from 2000-2001. Image source: Alan P. Balutis biographical file
Johanna M.H. Levelt Sengers
No full textJOHANNA M.H. LEVELT SENGERS
Inducted: 2000
Citation:
For elucidation of the critical behavior and thermophysical properties of industrially important fluids and fluid mixtures
Tenure: 1963‑1995
Birth: 1929, Amsterdam, Netherlands
Education:
University of Amsterdam: BSc, 1950; MSc, 1954; PhD (Physics), 1958
Positions held:
Research Physicist
Group Leader, Thermophysics Division, National Engineering Laboratory
Senior NBS Fellow
Post‑retirement: Fellow Emeritus, Physical and Chemical Properties Division, Chemical Science and Technology Laboratory
Honors:
U.S. Department of Commerce: Silver Medal, 1972, Gold Medal, 1978
NBS Condon Award, 1975
Interagency Committee for Women in Science and Engineering WISE Lifetime Achievement Award, 1985
Federal Republic of Germany Alexander von Humboldt Research Award, 1991
Delft University of Technology, ScD (Honorary), 1992
Elected to National Academy of Sciences and National Academy of Engineering
Elected to Sigma Xi
Memberships:
American Physical Society (Fellow)
Netherlands Royal Academy of Sciences (Corresponding Member)
International Association for the Properties of Water and Steam (Honorary Fellow)
European Physical Society
American Society of Chemical Engineers
American Society of Mechanical Engineers
Publications:
Over 120 technical papers and a dozen book chapters in the fields of thermodynamic properties and critical phenomena in fluids, equation of state, and supercritical aqueous systems
GRID and multiphonon states
No full textThe development of the GRID technique for determining nuclear level lifetimes of excited low-spin states populated in thermal neutron capture reactions has resulted in the ability to perform detailed studies of proposed multiphonon excitations for the first time. This paper discusses the experimental evidence for multiphonon excitations determined using the GRID technique. In deformed nuclei several good examples of gamma gamma K-pi = 4(+) excitations have been established, whereas the experimental evidence gathered on K-pi=0(+) bands is contradictory, and any interpretations will likely involve the mixing of several differ ent configurations. In vibrational nuclei the GRID technique has helped to establish the existence of multiple quadrupole phonon excitations in Cd-114, and-an almost complete set of quadrupole-octupole coupled states in Nd-144
Application of GRID to foreign atom localization in single crystals
No full textThe application of GRID (Gamma Ray Induced Doppler broadening) spectroscopy to the localization of foreign atoms in single crystals is demonstrated on erbium in YAP. By the investigation of the Doppler broadened secondary gamma line for two crystalline directions, the Er was determined to be localized on the Y site. Conditions for the nuclear parameters of the impurity atoms used for the application of GRID spectroscopy are discussed
Nuclear resonance photon scattering studies of N-2 adsorbed on grafoil and of NaNO2 single crystal
No full textThe nuclear resonance photon scattering (NRPS) from N-15(2) adsorbed on graphite was investigated. The resonantly scattered intensities from the 6324 keV level of N-15 with the photon beam parallel and perpendicular to the adsorbing grafoil planes was measured at 140 K and coverages below 0.7 monolayers (ML), where the N-15(2) occur in the vapor phase. The data were used for deducing the out-of-plane tilt angle of adsorbed N-2 relative to the graphite surface and the results were compared with grand canonical Monte Carlo (GCMC) calculations. Using the same method, a single crystal of NaNO2 was studied by measuring the scattering intensities with the nitrite planes aligned parallel and perpendicular to the photon beam. At 80 K, a huge anisotropy (R approximate to 3.6) was observed, caused by the anisotropy in the zero-point motion of the internal modes of vibration of the NO2 ion. The variation of the scattering intensity from a powdered isotopic (NaNO2)-Na-15 sample versus T in the range 12 K to 297 K was also measured and explained by accounting for the internal, and external vibrational modes in NaNO2
Using impedance spectroscopy to assess the viability of the rapid chloride test for determining concrete conductivity
No full textThe suitability of using the initial current from the rapid chloride test (ASTM C 1202) to determine specimen conductivity is tested using impedance spectroscopy with a frequency spectrum of 10 Hz to 1 MHz. The specimen conductivity has an analytical relationship to specimen diffusivity and so is a useful quantity in service life prediction. Measurements made on specimens of different lengths indicate that the total charge passed during the six hour conduction test carried out according to ASTM C 1202 is not a direct measure of specimen conductivity. Further, ohmic heating during the 6 hour test makes it nearly impossible to directly measure any specimen transport property from the results. The total charge passed during the 6 hour conduction test is, therefore, not a reliable quantity for service life prediction. Results indicate that the direct current (dc) measurement of resistance using a voltage of 60 V is sufficient to overwhelm polarization effects, thereby yielding an accurate estimate of the true specimen conductivity. Impedance spectroscopy measurements also indicate that corrosion may form on the brass electrodes, adding bias to a conductivity estimate based upon a dc measurement
Equations for the magnetic field produced by one or more rectangular loops of wire in the same plane
No full textBeginning with expressions for the vector potential, the equations for calculating the magnetic flux density from up to three rectangular loops of wire in the same plane are derived. The geometry considered is the same as that found in some walk-through metal detectors and electronic article surveillance systems. Equations for more or fewer loops can be determined by inspection. A computer program for performing the magnetic field calculation is provided in an appendix