High-energy β's and γ's from long half-life fission debris products

Abstract

An examination of the decay scheme of Br87, Figure 1, [Evans, 1955], shows the potential existence of a relatively long‐lived source of high‐energy trapped radiation following a high‐altitude nuclear detonation. It is seen that ∼14% of the decays of Br87 are accompanied by the emission of 5.4‐Mev γ rays, while 30% of the decays produce 8 Mev β's. Since the half‐life of Br87 is 55.6 sec, this isotope is a source of high‐energy β's and γ's long after all the other high‐energy β decays have essentially terminated. A survey of the tabulated properties of fission debris products [Katcoff, 1960] indicates that (with one exception discussed below) Br87 is unique in producing such high‐energy radiation with such a long half‐life.