Critical evaluation and compilation of viscosity and diffusivity data Semiannual status report, May 1 - Oct. 31, 1967
Diffusion coefficient measurements for binary noble gas mixtures, silver chloride, and polymer diluent systems
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Effect of multispecies ionization on electrical conductivity calculations.
Multiple species ionization effect on electrical conductivity/current density of seeded noble gas plasmas
Kruger, C. H.↗
Numerical experiments on scattering of noble gases from single-crystal silver.
Noble gas atomic scattering from Ag single crystal surfaces, describing three dimensional numerical experimental method for interaction parameters
Oman, R. A.↗
Performance of a large scale, non-equilibrium MHD generator with rare gases. II
Noble gas mixture large shock tunnel driven linear MHD generator, examining electron density, operating characteristics and electrical properties
Tate, E.↗
Trapped solar wind noble gases, exposure age and K/Ar-age in Apollo 11 lunar fine material
Apollo 11 lunar fines trapped noble gas elemental and isotopic abundances, suggesting solar wind origin
Eberhardt, P.↗
Noble gases and radionuclides in Lost City and other recently fallen meteorites
Radionuclides and noble gas isotopic abundances in recently fallen meteorites for cosmic ray exposure ages estimates
Bogard, D. D.↗
Spectroscopy of dimers.
The method of Stogryn and Hirschfelder, which divides two-particle phase space into bound, metastable, and free particle parts, is applied to the statistical averages which determine the first three spectroscopic moments of 'collision-induced' far-infrared and Raman spectra. Numerical results are presented for a number of models of noble gas systems. It is shown that for some systems, but not all, dimers make important, although not necessarily well-separated, contributions to the spectrum.
Levine, H. B.↗
Monte Carlo Simulation of Nonlinear Radiation Induced Plasmas
A Monte Carlo simulation model for radiation induced plasmas with nonlinear properties due to recombination was, employing a piecewise linearized predict-correct iterative technique. Several important variance reduction techniques were developed and incorporated into the model, including an antithetic variates technique. This approach is especially efficient for plasma systems with inhomogeneous media, multidimensions, and irregular boundaries. The Monte Carlo code developed has been applied to the determination of the electron energy distribution function and related parameters for a noble gas plasma created by alpha-particle irradiation. The characteristics of the radiation induced plasma involved are given.
Wang, B. S.↗
Vanadium isotopic composition and concentrations of ferromagnesian elements in returned lunar samples
The effects are sought of an energetic charged particle irradiation of solar system material which is postulated as having taken place early in its history. A similar irradiation took place much more recently in the history of lunar samples and meteorites and this process is studied by means of a variety of monitors including highly sensitive noble gas nuclides, radionuclides, and tracks. Such monitors cannot be used to study the postulated early irradiation since it could have taken place under conditions such that these monitors were not retained or were subsequently lost. Accordingly, it is necessary that a nongaseous element be used to search for the effects of this irradiation, and one of the most sensitive of these is the vanadium isotopic composition. A comparative study is made of the 50 sub V/51 sub V ratios in 15 meteoritic, 5 terrestrial, and 11 lunar samples.
Lipschutz, M. E.↗
Chemical pump study
Sorption pumps applicable to the Pioneer Venus Mass Spectrometer Experiment were investigated. The pump requirements are discussed, and a survey of the existing pumps presented. Zirconium and zirconium graphite products were found to be the most promising among the getter materials surveyed. A preliminary pump design for the noble gas experiment is discussed.
Bergquist, L. E.↗
Solubilities of noble gases in magnetite - Implications for planetary gases in meteorites.
Solubilities of noble gases in magnetite were determined by growing magnetite in a noble-gas atmosphere between 450 and 700 K. Henry's law is obeyed at pressures up to .01 atm for He, Ne, Ar and up to .00001 atm for Kr, Xe, with the following distribution coefficients at 500 K: He 0.042, Ne 0.016, Ar 3.6, Kr 1.3, Xe 0.88, some 100 to 100,000 times higher than previous determinations on silicate and fluoride melts. Apparent heats of solution are in sharp contrast with earlier determinations on melts which were small and positive, but are comparable to the values for clathrates. Presumably the gases are held in anion vacancies.
Lancet, M. S.↗
Composition of the earth's atmosphere by shock-layer radiometry during the PAET entry probe experiment.
A determination of the composition of the earth's atmosphere obtained from onboard radiometer measurements of the spectra emitted from the bow shock layer of a high-speed entry probe is reported. The N2, O2, CO2, and noble gas concentrations in the earth's atmosphere were determined to good accuracy by this technique. The results demonstrate unequivocally the feasibility of determining the composition of an unknown planetary atmosphere by means of a multichannel radiometer viewing optical emission from the heated atmospheric gases in the region between the bow shock wave and the vehicle surface. The spectral locations in this experiment were preselected to enable the observation of CN violet, N2(+) first negative and atomic oxygen emission at 3870, 3910, and 7775 A, respectively. The atmospheric gases were heated and compressed by the shock wave to a peak temperature of about 6100 K and a corresponding pressure of 0.4 atm. Complete descriptions of the data analysis technique and the onboard radiometer and its calibration are given.
Whiting, E. E.↗
Carbon chemistry of the Apollo 15 and 16 deep drill cores
The carbon chemistry of the Apollo 15 and 16 deep drill cores is a function of the surface exposure plus the chemical and mineralogical composition of the individual samples. The depth profiles of carbide and methane yields in the Apollo 15 core show a general decline with depth and correlate with the solar wind noble gas content, percentage agglutinates, track densities, and metallic iron. All horizons examined were exposed for a considerable time on the lunar surface. The Apollo 16 core samples show that chemical and mineralogical composition plays an important role in determining the nature of carbide-like material present in the fines. The higher aluminum and calcium contents and lower iron contents of highlands material result in carbide-like material yielding less CD4 and more C2D2 (deuteroacetylene) upon DF acid dissolution.
Wszolek, P. C.↗
The unique cosmic-ray history of the Malakal chondrite
Cosmogenic radionuclides, including Na-22, Al-26, and Mn-54, were measured in a sample of the recently-fallen Malakal hypersthene chondrite. The high Al-26 activity, 79 plus or minus 2 dpm/kg, greatly exceeds the levels expected from elemental production rates, shielding considerations, or comparisons with other ordinary chondrites, and can only be explained by exposure to a uniquely high cosmic-ray flux. Calculations including noble gas, H-3, and Mn-53 data from other laboratories require a two-stage irradiation. Malakal's most probable history is: exposure in excess of 4 m.y. to an effective cosmic-ray flux approximately three times that experienced by other chondrites, an orbit change (very possibly caused by a collision), and a final period of about 2 m.y. during which it was exposed to a normal cosmic-ray flux.
Cressy, P. J., Jr.↗
Magnetospheric particle composition experiment
Thin foils of aluminum and platinum were mounted on the exterior of the Skylab spacecraft where they were bombarded by particles that penetrate to the 400-km spacecraft altitude, including auroral particles precipitating from the earth magnetosphere. These foils have a high trapping efficiency for both charged and neutral particles above 1 keV and a decreasing but appreciable efficiency below that energy. Some sections of the foils were double layered to obtain an estimate of the energy of the entrapped particles. The foils were retrieved and returned for analysis in an ultrahigh-vacuum mass spectrometer. So far, the noble gas components of the entrapped particles have been analyzed in selected sections of two foils. Helium-4, helium-3, neon-20, and neon-22 have been detected.
Geiss, J.↗
Variability of the Al-26 production rate in ordinary chondrites
Fifteen ordinary chondrites for which unusually high spallogenic Ne-22/Ne-21 or He-3/Ne-21 ratios had been reported and one meteorite with marked shock characteristics were selected in order to investigate the relations between Ne-22/Ne-21 ratios, Al-26 contents and depth. We report Al-26 and K contents of 13 samples from 11 of these and noble gas contents of 30 samples from all of these stones.
Herzog, G. F.↗
On the calculation of cosmic-ray exposure ages of stone meteorites
Abundances of cosmic ray-produced noble gases and Al-26, including some new measurements, have been compiled for some 23 stone meteorites with exposure ages less than 3,000,000 yr. Concentrations of cosmogenic He, Ne, and Ar in these meteorites have been corrected for differences in target element abundances by normalization to L-chondrite chemistry. Combined noble gas measurements in depth samples of the Keyes and St. Severin chondrites are utilized to derive equations for normalizing the production rates of cosmogenic He-3, Ne-21, and Ar-38 in chondrites to an adopted 'average' shielding. The measured unsaturated AL-26 concentrations and the calculated equilibrium Al-26 for these meteorites are combined to estimate exposure ages. These exposure ages are statistically compared with chemistry- and shielding-corrected concentrations of cosmogenic He, Ne, and Ar to derive absolute production rates for these nuclides, which are found to be roughly 25% higher than production rates used in the past. From these production rates and relative chemical correction factors, production rates for other classes of stone meteorites are derived.
Cressy, P. J., Jr.↗
The excess fission xenon problem in lunar samples
This paper presents noble-gas (neon, krypton, and xenon) data obtained in stepwise heating of five lunar breccias: 14063, 14082, 15205, 15405, and 15445. These data are discussed in terms of spallation gas content, cosmic-ray exposure ages, and content of fission xenon. None of these samples is rich in solar-wind gases, and none contains more fission xenon than would be expected for in situ fission of U-238 and Pu-244. The essential features of the excess-fission-xenon phenomenon seen in several Apollo 14 samples are reviewed, as are models which might account for this phenomenon and criteria by which these models may be evaluated. The lack of excess fission xenon in 14063 and 14082 eliminates models relying on microscale xenon redistribution. A model is proposed in which the excess fission xenon originates in local material and percolates through and is adsorbed on regolith material.
Drozd, R. J.↗