Halo Structure of Isobaric Analogue States in A = 21 and 17 Mirror Nuclei

Abstract

The root-mean-square (rms) radii of the last nucleons in the2s1/2 states of 21Ne, 21Na, 17O and 17F arefound to be 4.4±0.5, 5.2±0.6, 4.3±0.5 and5.0±0.6 fm, respectively, from transfer reaction data. Theresults show that the 2s1/2 states of 21Na and 17F areproton halo states, while the analogous states in their mirror nuclei21Ne and 17O can be considered as neutron skin states.Comparisons among the rms radii of these states lead us to expectthat a neutron halo nucleus has a proton halo mirror partner, and theCoulomb barrier is a determinant factor limiting the extension of therms radius of the loosely bound proton.