  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 3-body model, respectively. We show that the odd-even
staggering in the reaction cross sections of $^{30,31,32}$Ne and $^{14,15,16}$C
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.
