학술논문
Extending the Southern Shore of the Island of Inversion to $^{28}$F
Document Type
Working Paper
Author
Revel, A.; Sorlin, O.; Marques, F. M.; Kondo, Y.; Kahlbow, J.; Nakamura, T.; Orr, N. A.; Nowacki, F.; Tostevin, J. A.; Yuan, C. X.; Achouri, N. L.; Falou, H. Al; Atar, L.; Aumann, T.; Baba, H.; Boretzky, K.; Caesar, C.; Calvet, D.; Chae, H.; Chiga, N.; Corsi, A.; Crawford, H. L.; Delaunay, F.; Delbart, A.; Deshayes, Q.; Dombradi, Z.; Douma, C. A.; Elekes, Z.; Fallon, P.; Gasparic, I.; Gheller, J. -M.; Gibelin, J.; Gillibert, A.; Harakeh, M. N.; He, W.; Hirayama, A.; Hoffman, C. R.; Holl, M.; Horvat, A.; Horvath, A.; Hwang, J. W.; Isobe, T.; Kalantar-Nayestanaki, N.; Kawase, S.; Kim, S.; Kisamori, K.; Kobayashi, T.; Korper, D.; Koyama, S.; Kuti, I.; Lapoux, V.; Lindberg, S.; Masuoka, S.; Mayer, J.; Miki, K.; Murakami, T.; Najafi, M.; Nakano, K.; Nakatsuka, N.; Nilsson, T.; Obertelli, A.; Santos, F. de Oliveira; Otsu, H.; Ozaki, T.; Panin, V.; Paschalis, S.; Rossi, D.; Saito, A. T.; Saito, T.; Sasano, M.; Sato, H.; Satou, Y.; Scheit, H.; Schindler, F.; Schrock, P.; Shikata, M.; Shimizu, Y.; Simon, H.; Sohler, D.; Stuhl, L.; Takeuchi, S.; Tanaka, M.; Thoennessen, M.; Tornqvist, H.; Togano, Y.; Tomai, T.; Tscheuschner, J.; Tsubota, J.; Uesaka, T.; Yang, Z.; Yasuda, M.; Yoneda, K.
Source
Subject
Language
Abstract
Detailed spectroscopy of the neutron-unbound nucleus $^{28}$F has been performed for the first time following proton/neutron removal from $^{29}$Ne/$^{29}$F beams at energies around 230 MeV/nucleon. The invariant-mass spectra were reconstructed for both the $^{27}$F$^{(*)}+n$ and $^{26}$F$^{(*)}+2n$ coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the $^{28}$F ground state, with $S_n(^{28}$F$)=-199(6)$ keV, while analysis of the $2n$ decay channel allowed a considerably improved $S_n(^{27}$F$)=1620(60)$ keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of $^{28}$F. Importantly, in the case of the ground state, the reconstructed $^{27}$F$+n$ momentum distribution following neutron removal from $^{29}$F indicates that it arises mainly from the $1p_{3/2}$ neutron intruder configuration. This demonstrates that the island of inversion around $N=20$ includes $^{28}$F, and most probably $^{29}$F, and suggests that $^{28}$O is not doubly magic.
Comment: 6 pages, 3 figures, Supplemental Material, accepted for publication in Physical Review Letters
Comment: 6 pages, 3 figures, Supplemental Material, accepted for publication in Physical Review Letters