Heavy Isotope Abundances in Mike Thermonuclear Device

The Nov. 1, 1952, thermonuclear explosion ( Mike'') /sup 240/,...U/sup 255/ through multiple neutron capture by U/sup 238/. The long-lived products of successive BETA decays from these isotopes were measured mass spectrometrically and radiometrically. The logarithms of the abundances decline smoothly with increasing mass number; the even-mass abundances slightly exceed the geometric mean of adjacent odd-mass abundances. Some nuclear properties of neutron-rich heavy nuclides, not subject to ordinary investigation, are inferred. (auth)