Study of the Order-to-Chaos transition in W-174 with the AGATA-Demonstrator

Abstract

The transition between order and chaos is studied in the warm rotating nucleus W-174 by gamma-spectroscopy, focusing on the conservation of selection rules of the K quantum number with the excitation energy, where K is the projection of the total angular momentum on the symmetry axis. The W-174 nucleus was populated by the fusion-evaporation reaction of Ti-50 (at 217 MeV) on a Te-128 backed target. The measurement was performed in July 2010 at Legnaro National Laboratories of INFN using the AGATA Demonstrator HPGe-array coupled to an array of 27 BaF2 scintillators, named Helena.

The data analysis concentrates on gamma-gamma coincidence matrices selecting the gamma-decay flow populating low-K and high-K structures. By a statistical fluctuation analysis the total number of low-K and high-K band scan be evaluated as a function of excitation energy. Comparisons with cranked shell model calculations at finite temperature are used to extract in formation on the on set of the chaotic regime as a function of excitation energy.