Abstract
Background: Neutron-rich, even-mass chromium and iron isotopes approaching neutron number have been important benchmarks in the development of shell-model effective interactions incorporating the effects of shell evolution in the exotic regime. Odd-mass manganese nuclei have received less attention, but provide important and complementary sensitivity to these interactions.
Purpose: We report the observation of two new -ray transitions in , which establish the and levels on top of the previously known first-excited state. The lifetime for the and excited states were determined for the first time, while an upper limit could be established for the level.
Method: Excited states in have been populated in inelastic scattering from a target and in the fragmentation of . coincidence relationships were used to establish the decay level scheme. A Doppler line-shape analysis for the Doppler-broadened , and transitions was used to determine (limits for) the corresponding excited-state lifetimes.
Results: The low-lying level scheme and the excited-state lifetimes were compared with large-scale shell-model calculations using different model spaces and effective interactions in order to isolate important aspects of shell evolution in this region of structural change.
Conclusions: While the theoretical and excitation energies show little dependence on the model space, the calculated lifetime of the level and calculated energy of the level reveal the importance of including the neutron and orbitals in the model space. The LNPS effective shell-model interaction provides the best overall agreement with the new data.
- Received 24 March 2014
- Revised 1 December 2015
DOI:https://doi.org/10.1103/PhysRevC.93.014313
©2016 American Physical Society