Three-body model for nuclei near and beyond neutron drip line
▣ 제 목 : Three-body model for nuclei near and beyond neutron drip line
▣ 연 사 : Prof. Hiroyuki SAGAWA
(RIKEN and Univ. of Aizu)
▣ 일 시 : 2017년 4월 14일(금) 오후 2:50-3:20
▣ 장 소 : 제1과학관 201-4호실
◈요 약 :
In recent years, there has been a rapidly increasing interest in two-neutron correlations and two-neutron decays of unbound nuclei beyond the neutron drip line. Among the two-neutron emitters studied so far, the 26O nucleus has attracted a particular attention [1,2,3], owing partly to the problem of abrupt termination of neutron-drip line for the oxygen isotopes at the neutron number N=16. We studied the ground and excited resonance states of 26O by using a three-body model of 24O+n+n taking into account the coupling to the continuum [4,5,6,7]. Using the new experimental data for the invariant mass spectroscopy of the unbound 25O and 26O nuclei, we present an update three-body model calculations for the two-neutron decay of the 26O nucleus to extract di-neutron correlations and halo nature of this nucleus. With the new model inputs determined with the ground state decay of 26O, we achieve an excellent agreement with the experimental data for the energy of the 2+ state. We show that the 2+ state consists predominantly of the (d3=2)2 conguration, for which the pairing interaction between the valence neutrons slightly decreases its energy from the unperturbed one. We shall also investigate the two-neutron emission decay energy spectrum of the unbound nucleus 26O and the angular correlation of the two emitted neutrons. We will conclude that the back-to-back emission is enhanced due to the dineutron correlation in 26O.