Neutron-hole states in 131Sn and spin-orbit splitting in neutron-rich nuclei

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

Physics Letters B (Oct 2018)

Neutron-hole states in 131Sn and spin-orbit splitting in neutron-rich nuclei

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

Affiliations

R. Orlandi: Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan; Instituto de Estructura de la Materia (IEM), CSIC, Madrid, E-28006, Spain; School of Engineering and Computing, University of the West of Scotland, Paisley, PA1 2BE, UK; The Scottish Universities Physics Alliance (SUPA), UK; Corresponding author at: Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan.
S.D. Pain: Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
S. Ahn: Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
A. Jungclaus: Instituto de Estructura de la Materia (IEM), CSIC, Madrid, E-28006, Spain
K.T. Schmitt: Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
D.W. Bardayan: Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
W.N. Catford: Department of Physics, University of Surrey, Guildford, GU2 7XH, UK
R. Chapman: School of Engineering and Computing, University of the West of Scotland, Paisley, PA1 2BE, UK; The Scottish Universities Physics Alliance (SUPA), UK
K.A. Chipps: Physics Department, Colorado School of Mines, Golden, CO 80401, USA; Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
J.A. Cizewski: Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
C.G. Gross: Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
M.E. Howard: Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
K.L. Jones: Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
R.L. Kozub: Department of Physics, Tennessee Technological University, Cookeville, TN 38505, USA
B. Manning: Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
M. Matos: Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
K. Nishio: Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
P.D. O' Malley: Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
W.A. Peters: Oak Ridge Associated Universities, Oak Ridge, TN 37831, USA
S.T. Pittman: Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
A. Ratkiewicz: Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
C. Shand: Department of Physics, University of Surrey, Guildford, GU2 7XH, UK; Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903, USA
J.F. Smith: School of Engineering and Computing, University of the West of Scotland, Paisley, PA1 2BE, UK; The Scottish Universities Physics Alliance (SUPA), UK
M.S. Smith: Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
T. Fukui: Nuclear Data Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan; Istituto Nazionale di Fisica Nucleare, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy
J.A. Tostevin: Department of Physics, University of Surrey, Guildford, GU2 7XH, UK; Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan
Y. Utsuno: Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan

Journal volume & issue: Vol. 785
pp. 615 – 620

Abstract

Read online

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

Published in Physics Letters B

ISSN: 0370-2693 (Print); 1873-2445 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/physics-letters-b/

About the journal