In-beam investigation and the structure of states in "1"1"3Sn

Abstract

The results of in-beam investigations of "1"1"3Sn using the (p,n), (p,3n), (#alpha#,n) and (#alpha#,2n) reactions are summarized. Excited states have been identified until E_x=4715 MeV and J"#pi#=(27/2"-). For a large number of levels mean lifetimes #tau# have been determined with the DSA method. For the J"#pi#=25/2"+ state at E_x=4059 MeV, #tau#=1.0(4) ns has been measured with the #gamma#-RF method. The experimental results are compared with the predictions of shell-model calculations. Most of the positive-parity states may be considered as one- or three-quasiparticle neutron excitations of the 2d_5_/_2, 1g_7_/_2, 3s_1_/_2 and 2d_3_/_2 shells, the negative-parity states as the coupling of one 1h_1_1_/_2 neutron to the two- or four-quasiparticle neutron excitations in the even-mass "1"1"2Sn core. For the 25/2"+ isomer the three-quasiparticle neutron configuration #nu#(h"2_1_1_/_2g"-"1_7_/_2) has been proposed on the basis of a shell-model analysis using the mass formula formalism. The experimentally observed yrast states in _5_0"1"1"3Sn_6_3 are compared with the corresponding states in the valence-mirror nucleus _6_3"1"4"5Eu_8_2 giving remarkable similarities although the parameters for the shell-model calculations differ considerably. The analysis of nearest-neighbour spacing distributions of 5/2"+ states in "1"1"3Sn does not allow definite conclusions about regularity or chaos. (orig.)59 refs.Available from TIB Hannover: RR 1847(95) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman