Direct experimental evidence for strong admixture of different parity states in 11Li

Peripheral fragmentation of a 287 MeV/u beam of the halo nucleus 11Li incident on a carbon target has been studied in a fragment-neutron coincidence experiment. The momentum distribution of the 10Li fragments gives access to the momentum distribution of the removed neutron in 11Li. From the shape of the distribution, the (1s1/2)2 contribution to the mixture of (1s1/2)2 and (0p1/2)2 components in the ground-state wave function was determined to be 45±10%. The angular correlation between the knocked out neutron and the one from the decay of 10Li shows a skew distribution signalling interference of these two different parity states. (orig.)