Triplet 12B-12C-12N : Search for States with Halo

Abstract

Previously in [1] neutron halo was confirmed for the 2¯, 1.67 MeV and 1¯, 2.62 MeV states in 12B on base of Asymptotic Normalization Coefficients (ANC) method analysis of the obtained experimental data. An unexpected result was received for the unbound 3¯, 3.39 MeV state. Its halo radius was found to be increased and equal to ~5.9 fm. This result can be considered as an evidence of the halo-like structure in this 12B state. It should be noted that last neutron in this state has a non-zero orbital momentum (l = 2). So question arises about possible existence of states with halo in other members of the isobaric triplet 12B–12C–12N. We can expect the formation of a proton halo in the 2¯, 1.19 MeV and 1¯, 1.80 MeV states of 12N and 2¯, 16.62 MeV and 1¯, 17.23 MeV states of 12C. To check this prediction preliminary Modified Diffraction Model (MDM) analysis of existing (3He, t) and (3He, 3He′) experimental data was done.