Evidence for a pairing anti-halo effect in the odd-even staggering in reaction cross sections of weakly bound nuclei

We investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a three-body model, respectively. We show that the odd-even staggering in the reaction cross sections of Ne-30,Ne-31,Ne-32 and C-14,C-15,C-16 are successfully reproduced, and thus the staggering can be attributed to the pairing anti-halo effect. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for s and p waves using the HFB wave functions.