Unexpected distribution of ν1f7/2 strength in Ca 49

Author(s): Crawford, HL; Macchiavelli, AO; Fallon, P; Albers, M; Bader, VM; Bazin, D; Campbell, CM; Clark, RM; Cromaz, M; Dilling, J; Gade, A; Gallant, A; Holt, JD; Janssens, RVF; Krucken, R; Langer, C; Lauritsen, T; Lee, IY; Menendez, J; Noji, S; Paschalis, S; Recchia, F; Rissanen, J; Schwenk, A; Scott, M; Simonis, J; Stroberg, SR; Tostevin, JA; Walz, C; Weisshaar, D; Wiens, A; Wimmer, K; Zhu, S | Abstract: © 2017 American Physical Society. The calcium isotopes have emerged as a critical testing ground for new microscopically derived shell-model interactions, and a great deal of experimental and theoretical focus has been directed toward this region. We investigate the relative spectroscopic strengths associated with 1f7/2 neutron hole states in Ca47,49 following one-neutron knockout reactions from Ca48,50. The observed reduction of strength populating the 7/21- state in Ca49, as compared to Ca47, is inconsistent with shell-model calculations using both phenomenological interactions such as GXPF1, and interactions derived from microscopically based two- and three-nucleon forces. The result suggests a fragmentation of the l=3 strength to higher-lying states as suggested by the microscopic calculations, but the observed magnitude of the reduction is not reproduced in any shell-model description.