title: Direct evidence for the breakdown of the N = 8 shell closure in 12Be
abstract: Partial cross sections and corresponding momentum distributions have been studied in the one-neutron knockout reaction ( 12Be,11Be+gamma) on a 9Be target at 78 MeV/nucleon. The resulting spectroscopic factors for the only two bound states of 11Be are 0.42+/-0.06 ( 1/2(+)) and 0.37+/-0.06 ( 1/2(-)), where the errors are experimental only. This result shows that N = 8 is not a good closed shell in the neutron-rich 12Be and that the last neutron pair is two-thirds in the ( 1s(2)+0d(2)) intruder configuration.
authors.affiliation: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 and Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.initials: A
authors.lastname: Navin
authors.initials: DW
authors.lastname: Anthony
authors.initials: T
authors.lastname: Aumann
authors.initials: T
authors.lastname: Baumann
authors.initials: D
authors.lastname: Bazin
authors.initials: Y
authors.lastname: Blumenfeld
authors.initials: BA
authors.lastname: Brown
authors.initials: T
authors.lastname: Glasmacher
authors.initials: PG
authors.lastname: Hansen
authors.initials: RW
authors.lastname: Ibbotson
authors.initials: PA
authors.lastname: Lofy
authors.initials: V
authors.lastname: Maddalena
authors.initials: K
authors.lastname: Miller
authors.initials: T
authors.lastname: Nakamura
authors.initials: BV
authors.lastname: Pritychenko
authors.initials: BM
authors.lastname: Sherrill
authors.initials: E
authors.lastname: Spears
authors.initials: M
authors.lastname: Steiner
authors.initials: JA
authors.lastname: Tostevin
authors.initials: J
authors.lastname: Yurkon
authors.initials: A
authors.lastname: Wagner