{"paper":{"title":"Cross-shell excitation in two-proton knockout: Structure of $^{52}$Ca","license":"","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"A. Gade, A. N. Deacon, B. A. Brown, B. Fornal, B. P. Kay, C. M. Campbell, D. Bazin, D.-C. Dinca, J. A. Tostevin, J. M. Cook, J. R. Terry, M. P. Carpenter, P. F. Mantica, P. G. Hansen, R. Broda, R. V. F. Janssens, S. J. Freeman, S. Zhu, T. Glasmacher, W. F. Mueller","submitted_at":"2006-06-26T17:52:34Z","abstract_excerpt":"The two-proton knockout reaction $^9$Be($^{54}$Ti,$^{52}$Ca$ + \\gamma$) 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."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"nucl-ex/0606033","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/nucl-ex/0606033/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}