Reduction of the Spin-Orbit Splittings at the N=28 Shell Closure

Journal Article · Fri Sep 01 00:00:00 EDT 2006 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.97.092501· OSTI ID:20860742

Gaudefroy, L ^[1]; Sorlin, O ^[2]; Beaumel, D; Blumenfeld, Y; Fortier, S; Franchoo, S; Gibelin, J; Hammache, F; Ibrahim, F; Monrozeau, C; Rich, E; Scarpaci, J A; Tryggestad, E; Verney, D ^[1]; Dombradi, Z ^[3]; Gelin, M; Grevy, S; Roussel-Chomaz, P; St Laurent, M G ^[2]; Kemper, K W ^[4]

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1. IPN, IN2P3-CNRS, F- 91406 Orsay Cedex (France)
2. GANIL, BP 55027, F-14076 Caen Cedex 5 (France)
3. Institute of Nuclear Research, H-4001 Debrecen, Pf. 51 (Hungary)
4. Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)

The N=28 shell closure has been investigated via the {sup 46}Ar(d,p){sup 47}Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p{sub 3/2}, p{sub 1/2}, and f{sub 5/2} states in {sup 47}Ar were determined and compared to those of the {sup 49}Ca isotone. We deduced a reduction of the N=28 gap by 330(90) keV and spin-orbit weakenings of {approx_equal}10(2) and 45(10)% for the f and p states, respectively. Such large variations for the f and p spin-orbit splittings could be accounted for by the proton-neutron tensor force and by the density dependence of the spin-orbit interaction, respectively. This contrasts with the picture of the spin-orbit interaction as a surface term only.

• OSTI ID: 20860742
• Journal Information: Physical Review Letters, Vol. 97, Issue 9; Other Information: DOI: 10.1103/PhysRevLett.97.092501; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ARGON 46
ARGON 47
CALCIUM 49
DEUTERON REACTIONS
KEV RANGE 100-1000
L-S COUPLING
NEUTRONS
P STATES
PROTON-NEUTRON INTERACTIONS
PROTONS
SPECTROSCOPIC FACTORS
SPIN
TENSOR FORCES
TRANSFER REACTIONS