First Determination of the Level Structure of an sd-Shell Hypernucleus, _{Λ}^{19}F

• Published in: Physical review letters 2018-03, Vol.120 (13), p.132505-132505
• Main Authors: Yang, S B, Ahn, J K, Akazawa, Y, Aoki, K, Chiga, N, Ekawa, H, Evtoukhovitch, P, Feliciello, A, Fujita, M, Hasegawa, S, Hayakawa, S, Hayakawa, T, Honda, R, Hosomi, K, Hwang, S H, Ichige, N, Ichikawa, Y, Ikeda, M, Imai, K, Ishimoto, S, Kanatsuki, S, Kim, S H, Kinbara, S, Kobayashi, K, Koike, T, Lee, J Y, Miwa, K, Moon, T J, Nagae, T, Nakada, Y, Nakagawa, M, Ogura, Y, Sakaguchi, A, Sako, H, Sasaki, Y, Sato, S, Shirotori, K, Sugimura, H, Suto, S, Suzuki, S, Takahashi, T, Tamura, H, Tanida, K, Togawa, Y, Tsamalaidze, Z, Ukai, M, Wang, T F, Yamamoto, T O
• Format: Article
• Language: English
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.120.132505

We report on the first observation of γ rays emitted from an sd-shell hypernucleus, _{Λ}^{19}F. The energy spacing between the ground state doublet, 1/2^{+} and 3/2^{+} states, of _{Λ}^{19}F is determined to be 315.5±0.4(stat)_{-0.5}^{+0.6}(syst)  keV by measuring the γ-ray energy of the M1(3/2^{+}→1/2^{+}) transition. In addition, three γ-ray peaks are observed and assigned as E2(5/2^{+}→1/2^{+}), E1(1/2^{-}→1/2^{+}), and E1(1/2^{-}→3/2^{+}) transitions. The excitation energies of the 5/2^{+} and 1/2^{-} states are determined to be 895.2±0.3(stat)±0.5(syst) and 1265.6±1.2(stat)_{-0.5}^{+0.7}(syst)  keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s- and p-shell hypernuclear data.