beta decays of the heaviest N = Z - l nuclei and proton instability of In-97

Abstract

We report on new or more precise half-lives, beta-decay endpoint energies, and beta-delayed proton emission branching ratios of(91) Pd, Cd-95,In-97, and Sn-99. The measured values are consistent with known mirror transitions in lighter T-z = -1/2 nuclei, shell-model calculations, and various mass models. In addition to the beta -decaying (9/2(+)) ground state, circumstantial evidence for a short-lived, proton-emitting isomer with spin (1 /2(-)) was found in(97)In. Based on the experimental data, a semiempirical theory on proton emission, and shell-model calculations, the proton separation energy of the In-97 ground state was determined to be -0.10 +/- 0.19 MeV. The existence of the short-lived, proton-unstable (1 /2(-)) isomer in In-97 establishes Cd-9S as an rp-process waiting point.