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Cross-shell excitation in two-proton knockout: Structure of $^{52}$Ca

A. Gade·R. V. F. Janssens·D. Bazin·R. Broda·B. A. Brown·C. M. Campbell·M. P. Carpenter·J. M. Cook·A. N. Deacon·D. -C. Dinca·B. Fornal·S. J. Freeman·T. Glasmacher·P. G. Hansen·B. P. Kay·P. F. Mantica·W. F. Mueller·J. R. Terry·J. A. Tostevin·S. Zhu
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Abstract

The two-proton knockout reaction $^9$Be($^{54}$Ti,$^{52}$Ca$ + γ$) has been studied at 72 MeV/nucleon. Besides the strong feeding of the $^{52}$Ca ground state, the only other sizeable cross section proceeds to a 3$^-$ level at 3.9 MeV. There is no measurable direct yield to the first excited 2$^+$ state at 2.6 MeV. The results illustrate the potential of such direct reactions for exploring cross-shell proton excitations in neutron-rich nuclei and confirms the doubly-magic nature of $^{52}$Ca.

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A. Gade, R. V. F. Janssens, D. Bazin, R. Broda, B. A. Brown, C. M. Campbell, M. P. Carpenter, J. M. Cook, A. N. Deacon, D. -C. Dinca, B. Fornal, S. J. Freeman, T. Glasmacher, P. G. Hansen, B. P. Kay, P. F. Mantica, W. F. Mueller, J. R. Terry, J. A. Tostevin, S. Zhu. 2006-06-26. Cross-shell excitation in two-proton knockout: Structure of $^{52}$Ca. https://doi.org/10.1103/physrevc.74.021302

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