Anomaly of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>=</mo><mn>8</mn><mn></mn></math> shell closure in neutron-rich Be and B isotopes studied via delayed neutron emitting <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow></mrow><mrow><mn>14</mn></mrow></msup></mrow><mi mathvariant="normal">Be</mi></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>β</mi></math> decay

N. Aoi; K. Yoneda; E. Ideguchi; T. Kishida; T. Nakamura; M. Notani; H. Sakurai; T. Teranishi; Y. Watanabe; H. Wu; A. Yoshida; H. Miyatake; Y. Yamamoto; H. Ogawa; S. S. Yamamoto; M. Ishihara

doi:10.1103/PhysRevC.66.014301

Anomaly of $N = 8$ shell closure in neutron-rich Be and B isotopes studied via delayed neutron emitting $^{14} Be$ $β$ decay

N. Aoi, K. Yoneda, E. Ideguchi, T. Kishida, T. Nakamura, M. Notani, H. Sakurai, T. Teranishi, Y. Watanabe, H. Wu, A. Yoshida, H. Miyatake, Y. Yamamoto, H. Ogawa, S. S. Yamamoto, and M. Ishihara

Phys. Rev. C 66, 014301 – Published 26 June 2002

Abstract

We investigated the $β$ decay of the neutron drip line nucleus $^{14} Be$ by means of double and triple coincidence measurements of $β$ rays, delayed neutrons, and $γ$ rays. The decay sequences were established and new values of the half-life and branching ratios were obtained. The decay scheme obtained is characterized by a single dominant branch leading to a $1^{+}$ state in $^{14} B$ with a branching ratio of $(91 \pm 9) %,$ which subsequently emits a delayed neutron with an energy of $288 \pm 8 keV .$ The excitation energy and width of the $1^{+}$ state were determined to be $1.28 \pm 0.02 MeV$ and $49 \pm 2 keV,$ respectively. The excitation energy and width of this level as well as the $\log ft$ value were treated in terms of a simple shell model and found to be strongly related to the $N = 8$ shell gap quenching ${in}^{13, 14} B$ and $^{12} Be .$

Received 21 February 2002

DOI:https://doi.org/10.1103/PhysRevC.66.014301

Authors & Affiliations

N. Aoi^* and K. Yoneda^†

Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan

E. Ideguchi, T. Kishida, T. Nakamura^‡, M. Notani^§, H. Sakurai^∥, T. Teranishi^§, Y. Watanabe, H. Wu^¶, and A. Yoshida

RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

H. Miyatake^** and Y. Yamamoto

Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560, Japan

H. Ogawa

Department of Applied Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan

S. S. Yamamoto^†

Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102, Japan

M. Ishihara

Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

^*Electronic address: aoi@phys.s.u-tokyo.ac.jp
^†Present address: RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
^‡Present address: Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan.
^§Present address: Center for Nuclear Study (CNS), University of Tokyo, Wako, Saitama 351-0198, Japan.
^∥Present address: Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
^¶Present address: Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.
^**Present address: High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba Ibaraki 305-0801, Japan.

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Vol. 66, Iss. 1 — July 2002

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