학술논문
Level structures of 56,58Ca cast doubt on a doubly magic 60Ca
Document Type
article
Author
S. Chen; F. Browne; P. Doornenbal; J. Lee; A. Obertelli; Y. Tsunoda; T. Otsuka; Y. Chazono; G. Hagen; J.D. Holt; G.R. Jansen; K. Ogata; N. Shimizu; Y. Utsuno; K. Yoshida; N.L. Achouri; H. Baba; D. Calvet; F. Château; N. Chiga; A. Corsi; M.L. Cortés; A. Delbart; J.-M. Gheller; A. Giganon; A. Gillibert; C. Hilaire; T. Isobe; T. Kobayashi; Y. Kubota; V. Lapoux; H.N. Liu; T. Motobayashi; I. Murray; H. Otsu; V. Panin; N. Paul; W. Rodriguez; H. Sakurai; M. Sasano; D. Steppenbeck; L. Stuhl; Y.L. Sun; Y. Togano; T. Uesaka; K. Wimmer; K. Yoneda; O. Aktas; T. Aumann; L.X. Chung; F. Flavigny; S. Franchoo; I. Gasparic; R.-B. Gerst; J. Gibelin; K.I. Hahn; D. Kim; T. Koiwai; Y. Kondo; P. Koseoglou; C. Lehr; B.D. Linh; T. Lokotko; M. MacCormick; K. Moschner; T. Nakamura; S.Y. Park; D. Rossi; E. Sahin; P.-A. Söderström; D. Sohler; S. Takeuchi; H. Törnqvist; V. Vaquero; V. Wagner; S. Wang; V. Werner; X. Xu; H. Yamada; D. Yan; Z. Yang; M. Yasuda; L. Zanetti
Source
Physics Letters B, Vol 843, Iss , Pp 138025- (2023)
Subject
Language
English
ISSN
0370-2693
Abstract
Gamma decays were observed in 56Ca and 58Ca following quasi-free one-proton knockout reactions from 57,59Sc beams at ≈200 MeV/nucleon. For 56Ca, a γ ray transition was measured to be 1456(12) keV, while for 58Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the 21+→0gs+ decays, and were compared to results from ab initio and conventional shell-model approaches. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 21+ level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the 0f5/2 and 0g9/2 orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic 60Ca and potentially drives the dripline of Ca isotopes to 70Ca or even beyond.