title: Vanishing N = 20 shell gap: study of excited states in (27,28)Ne.
abstract: This Letter reports on the (1)H((28)Ne, (28)Ne) and (1)H((28)Ne, (27)Ne) reactions studied at intermediate energy using a liquid hydrogen target. From the cross section populating the first 2(+) excited state of (28)Ne, and using the previously determined BE(2) value, the neutron quadrupole transition matrix element has been calculated to be M(n)=13.8 +/- 3.7 fm(2). In the neutron knockout reaction, two low-lying excited states were populated in (27)Ne. Only one of them can be interpreted by the sd shell model while the additional state may intrude from the fp shell. These experimental observations are consistent with the presence of fp shell configurations at low excitation energy in (27,28)Ne nuclei caused by a vanishing N=20 shell gap at Z=10.
authors.affiliation: Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, Debrecen, H-4001, Hungary.
authors.forename: Zs
authors.initials: Z
authors.lastname: Dombrádi
authors.forename: Z
authors.initials: Z
authors.lastname: Elekes
authors.forename: A
authors.initials: A
authors.lastname: Saito
authors.forename: N
authors.initials: N
authors.lastname: Aoi
authors.forename: H
authors.initials: H
authors.lastname: Baba
authors.forename: K
authors.initials: K
authors.lastname: Demichi
authors.forename: Zs
authors.initials: Z
authors.lastname: Fülöp
authors.forename: J
authors.initials: J
authors.lastname: Gibelin
authors.forename: T
authors.initials: T
authors.lastname: Gomi
authors.forename: H
authors.initials: H
authors.lastname: Hasegawa
authors.forename: N
authors.initials: N
authors.lastname: Imai
authors.forename: M
authors.initials: M
authors.lastname: Ishihara
authors.forename: H
authors.initials: H
authors.lastname: Iwasaki
authors.forename: S
authors.initials: S
authors.lastname: Kanno
authors.forename: S
authors.initials: S
authors.lastname: Kawai
authors.forename: T
authors.initials: T
authors.lastname: Kishida
authors.forename: T
authors.initials: T
authors.lastname: Kubo
authors.forename: K
authors.initials: K
authors.lastname: Kurita
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuyama
authors.forename: S
authors.initials: S
authors.lastname: Michimasa
authors.forename: T
authors.initials: T
authors.lastname: Minemura
authors.forename: T
authors.initials: T
authors.lastname: Motobayashi
authors.forename: M
authors.initials: M
authors.lastname: Notani
authors.forename: T
authors.initials: T
authors.lastname: Ohnishi
authors.forename: H J
authors.initials: HJ
authors.lastname: Ong
authors.forename: S
authors.initials: S
authors.lastname: Ota
authors.forename: A
authors.initials: A
authors.lastname: Ozawa
authors.forename: H K
authors.initials: HK
authors.lastname: Sakai
authors.forename: H
authors.initials: H
authors.lastname: Sakurai
authors.forename: S
authors.initials: S
authors.lastname: Shimoura
authors.forename: E
authors.initials: E
authors.lastname: Takeshita
authors.forename: S
authors.initials: S
authors.lastname: Takeuchi
authors.forename: M
authors.initials: M
authors.lastname: Tamaki
authors.forename: Y
authors.initials: Y
authors.lastname: Togano
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: Y
authors.initials: Y
authors.lastname: Yanagisawa
authors.forename: K
authors.initials: K
authors.lastname: Yoneda