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

Orlandi, R, Pain, SD, Ahn, S, Jungclaus, A, Schmitt, KT, Bardayan, DW, Catford, Wilton, Chapman, R, Chipps, KA, Cizewski, JA , Gross, CG, Howard, ME, Jones, KL, Kozub, RL, Manning, B, Matos, M, Nishio, K, O’ Malley, PD, Peters, WA, Pittman, ST, Ratkiewicz, A, Shand, Callum, Smith, JF, Smith, MS, Fukui, T, Tostevin, Jeffrey and Utsuno, Y (2018) Neutron-hole states in 131Sn and spin-orbit splitting in neutron-rich nuclei Physics Letters B, 785. pp. 615-620.

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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 (2 j+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 onebody 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.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Orlandi, R
Pain, SD
Ahn, S
Jungclaus, A
Schmitt, KT
Bardayan, DW
Chapman, R
Chipps, KA
Cizewski, JA
Gross, CG
Howard, ME
Jones, KL
Kozub, RL
Manning, B
Matos, M
Nishio, K
O’ Malley, PD
Peters, WA
Pittman, ST
Ratkiewicz, A
Smith, JF
Smith, MS
Fukui, T
Utsuno, Y
Date : 10 October 2018
Funders : STFC
DOI : 10.1016/j.physletb.2018.08.005
Copyright Disclaimer : © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (
Uncontrolled Keywords : Nuclear structure, spin-orbit interaction, transfer reactions, doubly-magic nuclei, shell model
Depositing User : Melanie Hughes
Date Deposited : 03 Aug 2018 14:44
Last Modified : 11 Jun 2019 13:11

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