论文标题

将反转岛的南岸扩展到$^{28} $ f

Extending the Southern Shore of the Island of Inversion to $^{28}$F

论文作者

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.

论文摘要

从$^{29} $ ne/$ ne/$ ne/$^{29} $ f梁左右的proton/neutron去除后,首次执行了中子核核$^{28} $ f的详细光谱。 $^{27} $ f $^{(*)}+n $和$^{26} $ f $^{(*)+2n $ cocisciscences均重建了不变的质量光谱。在这两种反应中都观察到了一个接近阈值的状态,并被确定为$^{28} $ f地面状态,具有$ s_n(^{28} $ f $)= - 199(6)$ keV,而对$ 2N $ decay渠道的分析允许$ s_n(^{27} $ f $ f $ f $ f $ f $ f $ f $ s_n = 1620(60)$ kev ded ded允许$ 2N $ decay频道。与壳模型预测和Eikonal模型反应计算的比较允许对某些$^{28} $ f的某些下层水平提出旋转式分配。重要的是,在基态的情况下,重建的$^{27} $ f $+n $动量分布从$^{29} $ f中删除后,表明它主要来自$ 1p_ {3/2} $中子入侵者的配置。这表明$ n = 20 $的反转岛包括$^{28} $ f,很可能$^{29} $ f,并暗示$^{28} $ o不是双重魔术。

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.

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