β -delayed neutron decay of drip line nuclei 11 Li and 14 Be

Experimental studies of β -decay measurements of the neutron drip line nuclei 11 Li and 14 Be are presented. β - decay schemes of these nuclei are determined by measuring β -rays, delayed neutrons and γ -rays in triple coincidence. The decay schemes of both 11 Li and 14 Be associated with single neutron emission are unambiguously determined. New levels in their daughter nuclei, 11 Be and 14 B, are found. In addition, the deduced level scheme of 14B indicates the lowering of 2 s 1/2 single neutron orbital with respect to 1 p 1/2 orbital in the N =9 isotones. Such behavior is known to exist in N =7.