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

The transition between order and chaos is studied in the warm rotating nucleus 174W by γ-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 174W nucleus was populated by the fusion-evaporation reaction of 80Ti (at 217 MeV) on a 128Te 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 γ-γ coincidence matrices selecting the γ-decay flow populating low-K and high-K structures. By a statistical fluctuation analysis the total number of low-K and high-K bands can be evaluated as a function of excitation energy. Comparisons with cranked shell model calculations at finite temperature are used to extract information on the onset of the chaotic regime as a function of excitation energy.