Superdeformation around 144Gd

Abstract

The study of superdeformation in nuclei around the nucleus 144Gd, which can be considered as doubly-closed at superdeformed shape, provided detailed knowledge about the structure of superdeformed bands in this region. The chain of Gd isotopes showing superdeformation could be extended to 143Gd. Since highly-deformed bands are known in 139,141Gd, it appears that the transition between the regions of superdeformed nuclei with A ≈ 150 and of highly-deformed nuclei with A ≈ 130 is rather sharp and takes place around N = 78 as theoretically predicted. In 144Gd four excited superdeformed bands have been found in addition to the yrast superdeformed band. They form two pairs of signature partner bands of π6 1 π[404]9 2ν7 0 and π6 1 π[411]3 2ν7 0 configurations. In 145Gd for the first time two crossings have been observed in a superdeformed band, which are assigned to the alignment of an i 13 2 proton pair and a subsequent crossing of the i 13 2 [642]5 2 and i 11 2 [651]1 2 neutron orbitals, respectively.