Gamma-ray spectrum of bovine thyroid during nuclear fallout

Following a nuclear explosion, the radioactive materials descend, to the earth. Most of the activity results from fission fragments. Therefore, new atoms created when heavy atoms such as uranium and plutonium are fissioned, Atoms made radioactive by neutron capture are also important. If the explosion is sufficiently high in the air, it takes months to years for most of the resulting finely dispersed particle to settle [1and 2]. By this time the greater part of the initial radioactivity has decayed away. This delayed fallout covers the entire world. Rain and snow help to bring it down. It tends to be greater in wet climate and seasons. In this article the data obtained during Russian nuclear air tests has been analysed [1961]