Systematics of Gamow-Teller beta decay 'Southeast' of Sn.

The energy centroids and integrated strengths of Gamow-Teller transitions in the $ \beta^{+}_{}$ and electron-capture decay are analyzed for nuclei whose proton number Z and neutron number N are restricted to 44 $ \leq$ Z $ \leq$ 50 and 50 $ \leq$ N $ \leq$ 58 . The analysis is based on data measured both with high-resolution $ \gamma$ -ray spectrometry and total $ \gamma$ -ray absorption techniques. The dependence of the considered quantities on the relative neutron excess are established after taking into account the effects due to the Coulomb interaction and mean-field level occupancies. An extrapolation of this dependence to the lightest known tin isotopes is used to estimate the decay characteristics of Sn and Sn . The values extrapolated for the half-lives of Sn and Sn agree with experimental data. Using the extrapolated values together with shell model predictions, the Q values for the electron-capture decay of Sn is evaluated. The quenching factor for $ \beta^{+}_{}$ and the electron-capture decay of the nuclei under consideration here is established to be 0.56(2) with a possible weak dependence on N - Z . [ABSTRACT FROM AUTHOR]