The Beta of 82As and Energy Levels in 82Se

Abstract

This thesis describes the detection and study of a new nuclide, 82As, produced by the fast neutron activiation of 82Se. The work presented in this thesis was carried out at the Institute of Nuclear Sciences (Department of Scientific and Industrial Research), Lower Hutt, during the period from mid-1966 to the beginning of 1969. The first seven months of this period was devoted to work associated with the installation of a 3-million volt accelerator (Model KN 3MV Van de Graaff positive ion accelerator manufactured by High Voltage Engineering Corporation, Mass., U.S.A.). The present investigation started with a survey of nuclides, the existence of which had not previously been reported, and which could be produced by neutron activiation of stable nuclei. Several such nuclei were considered namely, 7He, 36P, 48K, 70Cu, 73Zn, 79Ge, 82As, 150Pr and 204Au. Of these nuclei, 82As and 204Au were found to be the most promising since they could be produced by fast neutron activiation of 82Se and 204Hg respectively whose natural abundance (9% and 6.8%) were fairly high when compared with the others. To start with, an attempt was made to produce and detect 204Au. When natural mercury samples were bombarded with 14Ma neutrons a new gamma ray of energy 432 keV and half-life 4 sec was observed in the subsequent decay. Before further work could be done, the discovery of this nuclide (204Au) was reported by a group working at the University of Arkansas. It was then decided to attempt to produce 82As.