Coincidence Doppler shift lifetime measurements in 73,74Se and 74Br using the EUROBALL cluster cube array

Subpicosecond lifetimes of high spin states in the rotational nuclei (73)Se, (74)Se and (74)Br have been measured using the (58)Ni + (19)F compound reaction and the Doppler Shift Attenuation method. Six EUROBALL Cluster detectors arranged in cube geometry allowed us to select the relevant transitions in gamma gamma coincidence mode. The high counting statistics achieved in this setup also facilitated the determination of average sidefeeding times, which were found to agree rather well with the results of Monte-Carlo calculations of the particle and gamma-ray evaporation process. The deduced quadrupole strengths and deformations are compared with the results of previous measurements and the predictions of Cranked Shell Model calculations. In (74)Br, a large and constant prolate deformation of beta(2)=0.37(1) was found for the presumed 4(+) and 3(-) two-quasiparticle bands.