Search For Hyperdeformation In Xe Nuclei

Two experiments to identify hyperdeformation in Xe-nuclei have been made using the reaction 82Se(48Ca,xn)130-xXe, the first one with the EUROBALL-IV array equipped with a BGO calorimeter and the second one with the Gammasphere array. A bombarding energy of 195 MeV was used with the VIVITRON and 206 MeV with the ATLAS accelerator. No discrete hyperdeformed bands have been identified, but a ridge structure with 4 (ℎ/2π)2/J ∼ 0.048 MeV corresponding to a very large deformation was observed. A fluctuation analysis revealed that these ridges are composed of more than 10 rotational bands with ≥ 5 transitions each. Seven and four discrete bands extending from I ∼ 20 to I ∼ 60 have been identified in 125Xe and in 126Xe respectively, with a ΔEγ of 100 - 120 keV. These bands are most probably related to a potential energy minimum at ε ∼ 0.35 and a small γ-deformation predicted by Ultimate Crancker calculations. The transition quadrupole moments, crossing frequencies and alignments observed in the bands compare very well with those expected for this minimum