HALIMA: A Hybrid Array for LIfetime MeAsurement of neutron-rich nuclei at IMP

A new multi-detector array named HALIMA (Hybrid Array for LIfetime MeAsurement) has been developed at Lanzhou for nuclear structure studies in fission. The array comprises eight BGO-shielded High-Purity Germanium (HPGe) detectors and twenty fast Ce-doped Lanthanum Bromide [LaBr3(Ce)] detectors shielded with CsI(Tl). HALIMA is further complemented by two ancillary detector systems: fission fragment (FF) detectors and β detectors. This configuration enables precise sub-nanosecond lifetime measurements using the four-fold FF/β-Ge-LaBr3(Ce)-LaBr3(Ce) coincidence technique. The performance and specifications of the detectors, associated electronics, and the data acquisition system are presented in detail. The advantage of FF selectivity is emphasized, which signiffcantly enhances sensitivity to specific fission channels. Using this approach, the lifetimes of the nuclear excited states populated in the spontaneous fission of 252Cf were measured, showing good agreement with the established literature values.