title: Enhanced core polarization in (70)Ni and (74)Zn.
abstract: The reduced transition probabilities B(E2;0(+) --> 2(+)(1)) of the neutron-rich (74)Zn and (70)Ni nuclei have been measured by Coulomb excitation in a (208)Pb target at intermediate energy. These nuclei have been produced at Grand Accélérateur National d'Ions Lourds via interactions of a 60A MeV (76)Ge beam with a Be target. The B(E2) value for (70)Ni(42) is unexpectedly large, which indicates that neutrons added above N=40 strongly polarize the Z=28 proton core. In the Zn isotopic chain, the steep rise of B(E2) values beyond N=40 continues up to (74)Zn(44). The enhanced proton core polarization in (70)Ni is attributed to the monopole interaction between the neutron in the g(9/2) and protons in the f(7/2) and f(5/2) spin-orbit partner orbitals. This interaction could result in a weakening of magicity in (78)Ni(50).
authors.affiliation: Institut de Physique Nucléaire, IN2P3-CNRS, F-91406 Orsay Cedex, France.
authors.forename: O
authors.initials: O
authors.lastname: Perru
authors.forename: O
authors.initials: O
authors.lastname: Sorlin
authors.forename: S
authors.initials: S
authors.lastname: Franchoo
authors.forename: F
authors.initials: F
authors.lastname: Azaiez
authors.forename: E
authors.initials: E
authors.lastname: Bouchez
authors.forename: C
authors.initials: C
authors.lastname: Bourgeois
authors.forename: A
authors.initials: A
authors.lastname: Chatillon
authors.forename: J M
authors.initials: JM
authors.lastname: Daugas
authors.forename: Z
authors.initials: Z
authors.lastname: Dlouhy
authors.forename: Zs
authors.initials: Z
authors.lastname: Dombrádi
authors.forename: C
authors.initials: C
authors.lastname: Donzaud
authors.forename: L
authors.initials: L
authors.lastname: Gaudefroy
authors.forename: H
authors.initials: H
authors.lastname: Grawe
authors.forename: S
authors.initials: S
authors.lastname: Grévy
authors.forename: D
authors.initials: D
authors.lastname: Guillemaud-Mueller
authors.forename: F
authors.initials: F
authors.lastname: Hammache
authors.forename: F
authors.initials: F
authors.lastname: Ibrahim
authors.forename: Y
authors.initials: Y
authors.lastname: Le Coz
authors.forename: S M
authors.initials: SM
authors.lastname: Lukyanov
authors.forename: I
authors.initials: I
authors.lastname: Matea
authors.forename: J
authors.initials: J
authors.lastname: Mrazek
authors.forename: F
authors.initials: F
authors.lastname: Nowacki
authors.forename: Yu-E
authors.initials: YE
authors.lastname: Penionzhkevich
authors.forename: F
authors.initials: F
authors.lastname: de Oliveira Santos
authors.forename: F
authors.initials: F
authors.lastname: Pougheon
authors.forename: M G
authors.initials: MG
authors.lastname: Saint-Laurent
authors.forename: G
authors.initials: G
authors.lastname: Sletten
authors.forename: M
authors.initials: M
authors.lastname: Stanoiu
authors.forename: C
authors.initials: C
authors.lastname: Stodel
authors.forename: Ch
authors.initials: Ch
authors.lastname: Theisen
authors.forename: D
authors.initials: D
authors.lastname: Verney