States of the 12N Nucleus with Increased Radii

The differential cross sections for the ¹²C(³He, t)¹²N reaction leading to formation of the 1⁺ (ground state), 2⁺ (0.96 MeV), 2⁻ (1.19 MeV), and 1⁻ (1.80 MeV) states of ¹²N are measured at E(³He) = 40 MeV. The analysis of the data is carried out within the modified diffraction model and distorted wave Born approximation. Increased rms radii have been obtained for the ground, 2⁻ (1.19 MeV), and 1⁻ (1.80 MeV) states. We revealed that ¹²B, ¹²N, and ¹²C in the isobaric analogue states with T = 1, and spin-parities 2⁻ and 1⁻ have increased radii and exhibit properties of neutron and proton halo states.