DSpace at EWHA: How Robust is the N=34 Subshell Closure? First Spectroscopy of Ar 52

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How Robust is the N=34 Subshell Closure? First Spectroscopy of Ar 52

Authors: Liu H.N.; Obertelli A.; Doornenbal P.; Bertulani C.A.; Hagen G.; Holt J.D.; Jansen G.R.; Morris T.D.; Schwenk A.; Stroberg R.; Achouri N.; Baba H.; Browne F.; Calvet D.; Château F.; Chen S.; Chiga N.; Corsi A.; Cortés M.L.; Delbart A.; Gheller J.-M.; Giganon A.; Gillibert A.; Hilaire C.; Isobe T.; Kobayashi T.; Kubota Y.; Lapoux V.; Motobayashi T.; Murray I.; Otsu H.; Panin V.; Paul N.; Rodriguez W.; Sakurai H.; Sasano M.; Steppenbeck D.; Stuhl L.; Sun Y.L.; Togano Y.; Uesaka T.; Wimmer K.; Yoneda K.; Aktas O.; Aumann T.; Chung L.X.; Flavigny F.; Franchoo S.; Gašparić I.; Gerst R.-B.; Gibelin J.; Hahn K.I.; Kim D.; Koiwai T.; Kondo Y.; Koseoglou P.; Lee J.; Lehr C.; Linh B.D.; Lokotko T.; Maccormick M.; Moschner K.; Nakamura T.; Park S.Y.; Rossi D.; Sahin E.; Sohler D.; Söderström P.-A.; Takeuchi S.; Törnqvist H.; Vaquero V.; Wagner V.; Wang S.; Werner V.; Xu X.; Yamada H.; Yan D.; Yang Z.; Yasuda M.; Zanetti L.

Abstract: The first γ-ray spectroscopy of Ar52, with the neutron number N=34, was measured using the K53(p,2p) one-proton removal reaction at ∼210 MeV/u at the RIBF facility. The 21+ excitation energy is found at 1656(18) keV, the highest among the Ar isotopes with N>20. This result is the first experimental signature of the persistence of the N=34 subshell closure beyond Ca54, i.e., below the magic proton number Z=20. Shell-model calculations with phenomenological and chiral-effective-field-theory interactions both reproduce the measured 21+ systematics of neutron-rich Ar isotopes, and support a N=34 subshell closure in Ar52. © 2019 authors. Published by the American Physical Society.