ArticlesOther Physical Properties

Determination of Manganese-53 by Neutron Activation and Other Miscellaneous Studies on Lunar Dust

Science  30 Jan 1970:
Vol. 167, Issue 3918, pp. 747-749
DOI: 10.1126/science.167.3918.747


A highly sensitive determination of spallogenic 53Mn (T = 2 x 106 yr) was accomplished in 0.99 g of lunar soil. The chemical yield of Mn is determined with "carrier-free" 52Mn tracer. During a 23-day reactor irradiation the 53Mn is transformed into 54Mn (T = 300 days). Appropriate chemical recycling was done by ion exchange and distillation. Interferences of the (n,p) and the (n,2n) nuclear reactions were carefully studied. A 53Mn disintegration rate of 30.3 ± 5.5 dpm/kg results. This extremely economic method is proposed for further detailed lunar profile measurements. The Re content, which is of possible cosmochemical interest, was determined to be 11 ppb. Appropriate separation techniques were used. The rather weak and complex thermoluminescence properties made a more basic study advisable. Thermogravimetric analysis, mass spectroscopy, and Moessbauer spectroscopy were applied. The presence of ilmenite, metallic Fe etc., and of an unidentified Fe2+-containing compound was deduced. Natural thermoluminescence could not be proved with certainty in our surface sample. However, the complexity of the artificial thermoluminescence demands better defined mineral fractions. The fission track method was used to measure U distribution in glass spherules etc.