Tz = case12 β-delayed proton precursors: (II). The decays of 65Ge and 73Kr

Abstract The β-delayed proton decays of 65 Ge (t 1 2 = 30.8 ± 1.0 s ) and 73 Kr (t 1 2 = 28.4 ± 0.7 s ) have been studied in detail, proton spectra as well as p-γ and p-X coincidences being obtained. The fraction of 65 Ge β-decays populating proton-emitting states in 65 Ga is measured to be (1.3 ± 0.5) × 10 −4 , and the proton branch in the decay of 73 Kr that populates the first excited state in 72 Se is (18 ± 4)% of the total proton decay. Average γ-widths at 5.5 MeV excitation have been established to be 200±60 meV in 65 Ga and 320±60 meV in 73 Br. Values for Q EC − B P are measured to be 2300±100 keV for 65 Ge decay and 3700±150 keV for 73 Kr. The data for both decays have been subjected to statistical model analysis with considerable success. The back-shifted Fermi gas model gives better results for level densities than the Gilbert and Cameron formulas, although important numerical results extracted from the data are shown to be independent of the details of analysis. No evidence is found for local structure in the β-decay strength function. A J π assignment of 5 2 + ( or possibly 7 2 + ) for 73 Kr gives best agreement with the data.