Structure of N22 and the N=14 subshell

Abstract

One-neutron knockout data for N18-22 are analyzed in the eikonal approximation of the Glauber model. The role of the s-d shell and the crossing of the N=14 neutron subshell are discussed. Of particular interest is the nucleus N22, where the knockout data provide a sensitive experimental test for a possible halo structure of its ground state. The observation of a narrow momentum distribution of the N21 fragments, together with an essential 1s 1/2 contribution needed to describe the observed longitudinal- momentum distribution, allow the firm conclusion that the ground state of N22 is a well-developed nuclear halo. The results also show that the N=14 subshell in N22 is somewhat reduced as compared to that of O23. © 2011 American Physical Society.