Mirrored one-nucleon knockout reactions to theTz=±32 A=53mirror nuclei

Abstract

Background: The study of excited states in mirror nuclei allows us to extract information on charge-dependent (i.e., isospin-nonconserving) interactions in nuclei.Purpose: To extend previous studies of mirror nuclei in the ${f}_{\frac{7}{2}}$ region, investigating charge symmetry breaking of the strong nuclear force.Methods: $\ensuremath{\gamma}$-ray spectroscopy has been performed for the mirror $({T}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{3}{2})$ pair $^{53}\text{Ni}$ and $^{53}\text{Mn}$, produced via mirrored one-nucleon knockout reactions.Results: Several new transitions have been identified in $^{53}\text{Ni}$ from which a new level scheme has been constructed. Cross sections for knockout have been analyzed and compared with reaction model calculations where evidence is found for knockout from high-spin isomeric states. Mirror energy differences between isobaric analog states have been computed, compared to large scale shell-model calculations, and interpreted in terms of isospin-nonconserving effects. In addition, lifetimes for the long-lived ${J}^{\ensuremath{\pi}}={\frac{5}{2}}_{1}^{\ensuremath{-}}$ analog states in both $^{53}\text{Mn}$ and $^{53}\text{Ni}$ have been extracted through lineshape analysis, giving half-lives of ${t}_{\frac{1}{2}}=120\phantom{\rule{0.16em}{0ex}}(14)$ ps and ${t}_{\frac{1}{2}}=198\phantom{\rule{0.16em}{0ex}}(12)$ ps, respectively.Conclusions: The inclusion of a set of isovector isospin-nonconserving matrix elements to the shell-model calculations gave the best agreement with the experimental data.