Direct evidence for the breakdown of the N=8 shell closure in $^{12}$Be

Partial cross sections and corresponding momentum distributions have been studied in the: one-neutron knockout reaction (Be-12. Be-11 + gamma) on a Be-9 target at 78 MeV/nucleon. The resulting spectroscopic factors for the only two bound starts of Be-11 an 0.42 +/- 0.06 (1/2(+)) and 0.37 +/- 0.06 (1/2(-)), where the errors an experimental only. This result shows that N = 8 is not a good closed shell in the neutron-rich Be-12 and that the last neutron pair is two-thirds in the (1s(2) + 0d(2)) intruder configuration.