학술논문
A First Glimpse at the Shell Structure beyond $^{54}$Ca: Spectroscopy of $^{55}$K, $^{55}$Ca, and $^{57}$Ca
Document Type
Working Paper
Author
Koiwai, T.; Wimmer, K.; Doornenbal, P.; Obertelli, A.; Barbieri, C.; Duguet, T.; Holt, J. D.; Miyagi, T.; Navrátil, P.; Ogata, K.; Shimizu, N.; Somà, V.; Utsuno, Y.; Yoshida, K.; Achouri, N. L.; Baba, H.; Browne, F.; f, D. Calvet; 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.; Liu, H. N.; 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.; Yoneda, K.; Aktas, O.; Aumann, T.; Chung, L. X.; Flavigny, F.; Franchoo v, S.; Gasparic, I.; Gerst, R. -B.; Gibelin, J.; Hahn, K. I.; Kim, D.; 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.; Söderström, P-A.; Sohler, D.; Takeuchi, S.; Toernqvist, H.; Vaquero, V.; Wagner, V.; Wang, S.; Werner, V.; Xu, X.; Yamada, H.; Yan, D.; Yang, Z.; Yasuda, M.; Zanetti, L.
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Abstract
States in the $N=35$ and 37 isotopes $^{55,57}$Ca have been populated by direct proton-induced nucleon removal reactions from $^{56,58}$Sc and $^{56}$Ca beams at the RIBF. In addition, the $(p,2p)$ quasi-free single-proton removal reaction from $^{56}$Ca was studied. Excited states in $^{55}$K, $^{55}$Ca, and $^{57}$Ca were established for the first time via in-beam $\gamma$-ray spectroscopy. Results for the proton and neutron removal reactions from $^{56}$Ca to states in $^{55}$K and $^{55}$Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in $^{57}$Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at $N=35$ to collective excitations at $N=37$.
Comment: accepted Phys. Lett. B
Comment: accepted Phys. Lett. B