β decay of the exotic Tz=-2 nuclei Fe 48, Ni 52, and Zn 56

Abstract

The results of a study of the β decays of three proton-rich nuclei with Tz=-2, namely Fe48,Ni52, and Zn56, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total β-delayed proton emission branching ratios. We have measured the individual β-delayed protons and β-delayed γ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between β-delayed protons and γ rays is observed in the de-excitation of the T=2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case Zn56, where the exotic β-delayed γ-proton decay has been observed.