Anthony L. Turkevich

Uranium and barium in stone meteorites

Abstract The uranium and barium contents of some meteorites (4 chondrites and 1 achondrite), a basalt and a dunite have been determined by neutron activation. The isotopic composition of the uranium in the stone meteorites has been shown to be the same as that of terrestrial uranium to within 10 per cent. The uranium content of the chondrites is close to 1·1 × 10−8g/g; that of the achondrite (Nuevo Laredo) is about ten times higher. The barium contents are all about 350 times the uranium contents. The results are compared with previous determinations.

Chemical Analysis of the Moon at the Surveyor V Landing Site

The chemical composition of the lunar surface material at a maria landing site has been determined by the alpha-scattering technique. Oxygen, silicon, and aluminum have been identified in the preliminary evaluation of the data. The general chemical composition is similar to that of a silicate of a basaltic type.

Chemical Analysis of the Moon at the Surveyor VI Landing Site: Preliminary Results

The alpha-scattering experiment aboard Surveyor VII has provided a chemical analysis of the moon in the area of the crater Tycho. The preliminary results indicate a chemical composition similar to that already found at two mare sites, but with a lower concentration of elements of the iron group (titanium through copper).

Chemical Composition of the Lunar Surface in Mare Tranquillitatis

More precise and comprehensive analytical results have been derived for lunar material at the Surveyor V landing site from alpha-scattering data. The composition is, in general, basaltic; the low sodium and high titanium contents, however, are distinctly different from the abundances in meteorites or common terrestrial rocks.

Chemical Analysis of Surfaces by Use of Large-Angle Scattering of Heavy Charged Particles

The Rutherford scattering of carged particles from the heavier elements and nuclear scattering and (α,p) reactions from the light elements result in energy spectra that are characteristic of the nucleus being bombarded. A simple apparatus for analyzing surfaces based on these ideas can be made by using an alpha source such as Cm244, a solid state detector, and an electronic pulse height analyzer

Chemical Composition of the Lunar Surface in a Terra Region near the Crater Tycho

More precise and comprehensive analytical results for lunar surface material in a terra region have been derived from the data of the alpha-scattering experiment on Surveyor 7. The silicon content and the low sodium abundance are close to that of mare material. The abundances of titanium and iron are at least a factor of 2 lower, whereas the abundances of aluminum and calcium are significantly higher. The analytical results provide direct evidence for chemical differentiation in the moon and indicate a lunar crust of appreciably lower density than the whole moon and with lower density and higher albedo than lunar mare material.

Double beta decay of U-238

The half-life for the decay of {sup 238}U to {sup 238}Pu has been measured to be (2.0{plus minus}0.6){times}10{sup 21} yr by chemically isolating and measuring from the resultant alpha particles the amount of plutonium that had accumulated in 35 yr from 8.4 Kg of purified uranyl nitrate. Other sources of {sup 238}Pu have been studied and found negligible.

Chemical Composition of the Lunar Surface in Sinus Medii

More precise and comprehensive analytical results for lunar material in Sinus Medii have been derived from the alpha-scattering experiment on Surveyor VI. The amounts of the principal constituents at this mare are approximately the same as those of constituents at Mare Tranquillitatis. The sodium contents of both maria are lower than those of terrestrial basalts. The titanium content at Sinus Medii is lower than that at Mare Tranquillitatis; this suggests important differences in detailed chemical composition at different mare areas on the moon.

Heavy Methanes as Atmospheric Tracers

Methane-21 (13CD4) is potentially a useful nonradioactive tracer for testing atmospheric transport and diffusion models on a continental scale. In an experiment to demonstrate this long-range utility, the release of 84 grams of methane-21 was detected at distances of 1500 to about 2500 kilometers at concentrations of about 1 part in 2 x 1016 parts (by volume) in the air by a technique in which methane was separated and the methane-21 content was measured with a mass spectrometer.

Alpha Radioactivity of the Lunar Surface at the Landing Sites of Surveyors 5,6, and 7

Evidence has been obtained for a radioactive deposit on the lunar surface at Mare Tranquillitatis with a total intensity of 0.09 � 0.03 alpha disintegration per second per square centimeter. The presence of polonium-210 in amounts that are close to equilibrium indicates a continuous turnover rate of lunar material at this site of less than 0.1 micrometer per year. The lack of such a deposit at two other lunar sites suggests lower local concentrations of uranium there.