Excitation halo states of B-12

Angular distributions for the B-11(d,p)B-12 transfer reactions have been me asured at E-lab = 11.8 MeV. The asymptotic normalization coefficients (ANC) of the ground state, the second and third excitation states for B-12 (B-11 +n) are extracted from the differential cross sections at three forward ang les. With these ANCs, the root-mean-square radii are calculated for these t hree states. The results show that the second and third excitation states o f B-12 are neutron halo states.