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The total neutron cross section of radiogenic lead was studied as a function of neutron energy in the range from 15 to 750 kev, using energy resolutions of 3 to 10 kev. Several resonances were observed; these were interpreted as caused by energy levels in the compound nucleus Pb²⁰⁷. The level spacing found in Pb²⁰⁷ was of the order of 50 kev. Maxima previously found in the cross section of ordinary lead and attributed to resonance interactions of neutrons with Pb²⁰⁸ were re-investigated with better energy resolution. No resonances were observed when earlier measurements of the cross section of Bi were extended to higher energies.
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Peterson et al. (1950) studied this question.
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