Year: 1990
Type: article
Abstract: In a series of experiments, we have reinvestigated the decay of the doubly magic nucleus $^{56}\mathrm{Ni}$, which is believed to be copiously produced in supernovae. We have confirmed its previously known decay scheme and half-life, and have searched for several rare decay modes. We establish an upper limit of 5.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$ for the branching ratio of the second forbidden unique ${\mathrm{\ensuremath{\beta}}}^{+}$ decay to the 158-keV level in $^{56}\mathrm{Co}$, leading to a lower limit of 2.9\ifmmode\times\else\texttimes\fi{}${10}^{4}$ yr for the half-life of fully ionized $^{56}\mathrm{Ni}$ nuclei in cosmic rays. We also establish an upper limit of 5.0\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ for the branching ratio of the isospin forbidden Fermi electron capture transition to the 1451-keV level in $^{56}\mathrm{Co}$, which in turn leads to an upper limit of 124 keV for the isospin mixing Coulomb matrix element of the $^{56}\mathrm{Ni}$ ground state.
Source: Physical Review C
Institution: Lawrence Berkeley National Laboratory
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1398330795, G1643223109, G193590374
OpenAlex ID: W33201601