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

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 f7/2 region, investigating charge symmetry breaking of the strong nuclear force. Methods: γ-ray spectroscopy has been performed for the mirror (Tz= ±3/2) pair 53Ni and 53Mn, produced via mirrored one-nucleon knockout reactions. Results: Several new transitions have been identified in 53Ni 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 π = 5 /2 − 1 analog states in both 53Mn and 53Ni have been extracted through lineshape analysis, giving half-lives of t1/2 = 120 (14) ps and t1/2 = 198 (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.