Abstract
Background: Shell-model calculations crucially depend on the residual interaction used to approximate the nucleon-nucleon interaction. Recent improvements to the empirical universal interaction (USD) describing nuclei within the shell yielded two new interactions—USDA and USDB—causing changes in the theoretical description of these nuclei.
Purpose: Transition matrix elements between excited states provide an excellent probe to examine the underlying shell structure. These observables provide a stringent test for the newly derived interactions. The nucleus with 7 valence neutrons and 3 valence protons outside the doubly-magic core is used as a test case.
Method: A radioactive beam experiment with () was performed at the REX-ISOLDE facility (CERN) using Coulomb excitation at safe energies below the Coulomb barrier. Scattered particles were detected with an annular Si detector in coincidence with rays observed by the segmented MINIBALL array. Coulomb excitation cross sections of the beam have been obtained by normalization to the well known Coulomb excitation cross sections of the target.
Results: The observation of three -ray transitions in together with available spectroscopic data allows us to determine - and -transitional matrix elements. Results are compared to theoretical predictions.
Conclusion: The improved theoretical description of could be validated. Remaining discrepancies between experimental data and theoretical predictions indicate the need for future experiments and possibly further theoretical improvements.
- Received 28 October 2014
- Revised 12 December 2014
DOI:https://doi.org/10.1103/PhysRevC.91.014311
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Published by the American Physical Society