States of $^{12}$N with enhanced radii

nucl-ex

/ Authors

A. S. Demyanova, A. N. Danilov, A. A. Ogloblin, V. I. Starastsin, S. V. Dmitriev, W. H. Trzaska, S. A. Goncharov, T. L. Belyaeva, V. A. Maslov, Yu. G. Sobolev

and 8 more authors

Yu. E. Penionzhkevich, S. V. Khlebnikov, G. P. Tyurin, N. Burtebaev, D. Janseitov, Yu. B. Gurov, J. Louko, V. M. Sergeev

/ Abstract

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