학술논문
Neutron-hole states in 131Sn and spin-orbit splitting in neutron-rich nuclei
Document Type
article
Author
R. Orlandi; S.D. Pain; S. Ahn; A. Jungclaus; K.T. Schmitt; D.W. Bardayan; W.N. Catford; R. Chapman; K.A. Chipps; J.A. Cizewski; C.G. Gross; M.E. Howard; K.L. Jones; R.L. Kozub; B. Manning; M. Matos; K. Nishio; P.D. O' Malley; W.A. Peters; S.T. Pittman; A. Ratkiewicz; C. Shand; J.F. Smith; M.S. Smith; T. Fukui; J.A. Tostevin; Y. Utsuno
Source
Physics Letters B, Vol 785, Iss , Pp 615-620 (2018)
Subject
Language
English
ISSN
0370-2693
Abstract
In atomic nuclei, the spin-orbit interaction originates from the coupling of the orbital motion of a nucleon with its intrinsic spin. Recent experimental and theoretical works have suggested a weakening of the spin-orbit interaction in neutron-rich nuclei far from stability. To study this phenomenon, we have investigated the spin-orbit energy splittings of single-hole and single-particle valence neutron orbits of 132Sn. The spectroscopic strength of single-hole states in 131Sn was determined from the measured differential cross sections of the tritons from the neutron-removing 132Sn(d, t)131Sn reaction, which was studied in inverse kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The spectroscopic factors of the lowest 3/2+, 1/2+ and 5/2+ states were found to be consistent with their maximal values of (2j+1), confirming the robust N=82 shell closure at 132Sn. We compared the spin-orbit splitting of neutron single-hole states in 131Sn to those of single-particle states in 133Sn determined in a recent measurement of the 132Sn(d, p)133Sn reaction. We found a significant reduction of the energy splitting of the weakly bound 3p orbits compared to the well-bound 2d orbits, and that all the observed energy splittings can be reproduced remarkably well by calculations using a one-body spin-orbit interaction and a Woods–Saxon potential of standard radius and diffuseness. The observed reduction of spin-orbit splitting can be explained by the extended radial wavefunctions of the weakly bound orbits, without invoking a weakening of the spin-orbit strength. Keywords: Nuclear structure, Spin-orbit interaction, Transfer reactions, Doubly-magic nuclei, Shell model