Reactions Produced by Neutrons in Heavy Elements^*

Abstract

THE nuclear reaction produced by neutron bombardment in heavy elements can be conveniently described, according to Bohr, with the assumption that, as soon as the bombarding neutron strikes the nucleus, it is incorporated into the nuclear structure with the formation of the so-called compound nucleus. This is a relatively stable system in the sense that its lifetime is very long compared with the frequencies of nuclear particles; in an absolute sense, however, the life-time is very short, being sometimes of the order of 10^-12 sec. and sometimes much less.