The two-proton knockout reaction 9Be(54Ti,52Ca+γ) has been studied at 72 MeV/nucleon. Besides the strong feeding of the 52Ca 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 52Ca.
@article{arxiv.nucl-ex/0606033,
title = {Cross-shell excitation in two-proton knockout: Structure of $^{52}$Ca},
author = {A. Gade and R. V. F. Janssens and D. Bazin and R. Broda and B. A. Brown and C. M. Campbell and M. P. Carpenter and J. M. Cook and A. N. Deacon and D. -C. Dinca and B. Fornal and S. J. Freeman and T. Glasmacher and P. G. Hansen and B. P. Kay and P. F. Mantica and W. F. Mueller and J. R. Terry and J. A. Tostevin and S. Zhu},
journal= {arXiv preprint arXiv:nucl-ex/0606033},
year = {2008}
}