A “nuclear-spin spectrometer”: Theory and general characteristics of a 4 π gamma-ray multidetector system for investigations of nuclear structure and reactions at high angular momentum

Abstract

The theory and properties of a new type of spectrometer for studying the properties of high-spin states in nuclei and the mechanisms of heavy-ion induced nuclear reactions are presented in some detail. The spectrometer consists of a high efficiency 4π NaI multidetector system with individual tightly packed detector elements. This instrument is capable of recording on an event-by-event basis: (a) the γ-ray multiplicity; (b) the pulse heights and under certain conditions the energies of individual γ-transitions; (c) the total pulse height and the associated γ-ray multiplicity; (d) the associated neutron multiplicity; (e) the angular correlations among most of the γ-rays in the cascade; and (f) the time correlations among the various groups of γ-rays in each cascade. This information is obtained simultaneously thus permitting many correlations to be made among several relevant physical parameters that will enable us to learn more about the properties of nuclei at high-spin and about the role of angular momentum on the mechanism of many types of nuclear reaction.