Structure of $^{22}$N and the N=14 subshell

One-neutron knockout data for (18-22)N 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 (22)N, 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 (21)N 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 (22)N is a well-developed nuclear halo. The results also show that the N = 14 subshell in (22)N is somewhat reduced as compared to that of (23)O.