How different is the core of F from O ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro ; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; Inabe, Naoto*; Kameda, Daisuke*; Kawahara, Tomomi*; Kim, W.*; Kisamori, Keiichi*; Kobayashi, Motoki*; Kubo, Toshiyuki*; Kubota, Yuki*; Kusaka, Kensuke*; Lee, C. S.*; Maeda, Yukie*; Matsubara, Hiroaki*; Michimasa, Shinichiro*; Miya, Hiroyuki*; Noro, Tetsuo*; Obertelli, A.*; Ogata, Kazuyuki*; Ota, Shinsuke*; Padilla-Rodal, E.*; Sakaguchi, Satoshi*; Sakai, Hideyuki*; Sasano, Masaki*; Shimoura, Susumu*; Stepanyan, S. S.*; Suzuki, Hiroshi*; Takaki, Motonobu*; Takeda, Hiroyuki*; Tokieda, Hiroshi*; Wakasa, Tomotsugu*; Wakui, Takashi*; Yako, Kentaro*; Yanagisawa, Yoshiyuki*; Yasuda, Jumpei*; Yokoyama, Rin*; Yoshida, Koichi*; Yoshida, Kazuki   ; Zenihiro, Juzo*

The structure of a neutron-rich F nucleus is investigated by a quasifree () knockout reaction. The sum of spectroscopic factors of orbital is found to be 1.0 0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 35% O, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.