Nuclear Structure of ⁷⁰Ga

Abstract

<p>The nuclear properties of ⁷⁰Ga have been investigated by several methods. High resolution studies of the reactions ⁶⁹Ga(d,p) ⁷⁰Ga and ⁷¹Ga(d,t) ⁷⁰Ga show that 7 levels exist below 1 MeV excitation, with a large gap of 508 keV separating the first two. Between 1 and 2 MeV, 42 additional levels are observed. Parities and spectroscopic factors for the low lying levels were extracted by DWBA analysis of the proton and triton angular distributions.</p> <p>Electromagnetic decay properties of the levels of ⁷⁰Ga were investigated by means of the ⁷⁰Zn (p,nϒ) ⁷⁰Ga reaction. Gamma ray angular distribution and linear polarization measurements were used to elucidate spins of low lying levels and mixing ratios of the transitions. Gamma-ray yields as a function of energy are shown to depend markedly on the spin of the level, in agreement with Hauser-Feshbach calculations for the (p,n) cross section. Analysis of the decay of the low lying levels indicates the existence of remarkably few E1 transitions.</p> <p>A theoretical calculation of the energy levels of ⁷⁰Ga is presented in the light of the shell model. Both the zero range and surface delta interactions were used as the residual interaction between the nucleons. The surface delta interaction is shown to reproduce the energy levels much better than the zero range force, but fails to predict the large energy gap between the first two levels.</p>