Generalized seniority scheme in light Sn isotopes

The yrast generalized seniority states are compared with the corresponding shell model states for the case of the Sn isotopes 104−112Sn. For most of the cases the energies agree within 100 keV and the overlaps of the wave functions are greater than 0.7 In the last years the region of light Sn isotopes has been intensively investigated both from experimental and theoretical perspectives. The main goal has been to study the excitation mechanisms around the exotic isotope Sn, the heaviest symmetric double magic nucleus recently produced in nuclear fragmentation reactions [1,2]. The simplest approach in analysing the spectra of light Sn isotopes is to consider Sn as an inert core and to treat only neutron degrees of freedom, using the single-particle orbits of the N = 50− 82 shell as model space, i.e. the orbits 0g7/2, 1d5/2, 1d3/2, 2s1/2 and 0h11/2. Extensive shell model calculations have been performed along this line [3]. Using a Lanczos iteration method states for as many as 12 extra-core neutrons have been calculated. Similar studies have also been done in heavy Sn isotopes [4] and in the N = 82 isotones [5], where systems with up to 14 valence particles have been studied. On the other hand, a large part of the spectra of light Sn isotopes can be rather well described in terms of selected configurations such as those represented by simple quasiparticle excitations [6]. Therefore,