-ray spectroscopy of hypernuclei; Recent results and prospect at J-PARC

ハイパー核の線分光; 最近の結果とJ-PARCでの展望

田村 裕和*; 江川 弘行; 長谷川 勝一   ; 早川 修平; 細見 健二  ; Hwang, S.; 市川 裕大   ; 今井 憲一; 佐甲 博之   ; 佐藤 進  ; 杉村 仁志; 谷田 聖   ; J-PARC E13 Collaboration*; 他42名*

Tamura, Hirokazu*; Ekawa, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Hwang, S.; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; Tanida, Kiyoshi; J-PARC E13 Collaboration*; 42 of others*

The present status and future prospects of precision -ray spectroscopy of hypernuclei are described. A new experiment (J-PARC E13) has been performed at the J-PARC K1.8 line employing a newly-developed germanium (Ge) detector array, Hyperball-J, via the reaction on He and F targets. This is the first study of -shell and -shell hypernuclei with Ge detectors. The He target spectrum exhibited a -ray peak of at MeV. Compared with the energy ( MeV) of the corresponding transition for the mirror hypernucleus, , the present result clearly indicates a large charge symmetry breaking (CSB) effect. This decisive data for CSB allows a stringent test of baryon-baryon interaction models. As for the F target run, a preliminary spectrum shows several -ray peaks assigned to transitions. Future plans of -ray spectroscopy are also discussed.