title: Reduction of the spin-orbit splittings at the n = 28 shell closure.
abstract: The N = 28 shell closure has been investigated via the 46Ar(d,p)47Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p(3/2), p(1/2), and f(5/2) states in 47Ar were determined and compared to those of the 49Ca isotone. We deduced a reduction of the N = 28 gap by 330(90) keV and spin-orbit weakenings of approximately 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.
authors.affiliation: IPN, IN2P3-CNRS,F- 91406 Orsay Cedex, France.
authors.forename: L
authors.initials: L
authors.lastname: Gaudefroy
authors.forename: O
authors.initials: O
authors.lastname: Sorlin
authors.forename: D
authors.initials: D
authors.lastname: Beaumel
authors.forename: Y
authors.initials: Y
authors.lastname: Blumenfeld
authors.forename: Z
authors.initials: Z
authors.lastname: Dombrádi
authors.forename: S
authors.initials: S
authors.lastname: Fortier
authors.forename: S
authors.initials: S
authors.lastname: Franchoo
authors.forename: M
authors.initials: M
authors.lastname: Gélin
authors.forename: J
authors.initials: J
authors.lastname: Gibelin
authors.forename: S
authors.initials: S
authors.lastname: Grévy
authors.forename: F
authors.initials: F
authors.lastname: Hammache
authors.forename: F
authors.initials: F
authors.lastname: Ibrahim
authors.forename: K W
authors.initials: KW
authors.lastname: Kemper
authors.forename: K-L
authors.initials: KL
authors.lastname: Kratz
authors.forename: S M
authors.initials: SM
authors.lastname: Lukyanov
authors.forename: C
authors.initials: C
authors.lastname: Monrozeau
authors.forename: L
authors.initials: L
authors.lastname: Nalpas
authors.forename: F
authors.initials: F
authors.lastname: Nowacki
authors.forename: A N
authors.initials: AN
authors.lastname: Ostrowski
authors.forename: T
authors.initials: T
authors.lastname: Otsuka
authors.forename: Yu-E
authors.initials: YE
authors.lastname: Penionzhkevich
authors.forename: J
authors.initials: J
authors.lastname: Piekarewicz
authors.forename: E C
authors.initials: EC
authors.lastname: Pollacco
authors.forename: P
authors.initials: P
authors.lastname: Roussel-Chomaz
authors.forename: E
authors.initials: E
authors.lastname: Rich
authors.forename: J A
authors.initials: JA
authors.lastname: Scarpaci
authors.forename: M G
authors.initials: MG
authors.lastname: St Laurent
authors.forename: D
authors.initials: D
authors.lastname: Sohler
authors.forename: M
authors.initials: M
authors.lastname: Stanoiu
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: E
authors.initials: E
authors.lastname: Tryggestad
authors.forename: D
authors.initials: D
authors.lastname: Verney