In this work, a compact phoswich detector consisting of a cylindrical LaBr₃(Ce) principal crystal and a well-shaped CsI(Tl) sub-crystal was designed and assembled to identify and reject Compton scattering in the LaBr₃(Ce). Two different crystals coupled to the same photomultiplier tube (PMT). The energy deposition in each layer from incident radiation is then determined via digital pulse shape analysis of the PMT’s pulses. The results of Geant4 simulations were used to verify the performance of the pulse shape identification and the effect of Compton background suppression. Experimental tests were conducted on the detector prototype using a ⁶⁰Co gamma source, and the result shown that the detector background suppression coefficient was 2.33(1) which achieved the expected purpose of twice as much as the Compton background was suppressed.

The nucleus ²⁸S (isospin projection $ T_{Z}=-2 $) near the proton drip-line was produced, separated and purified by HIRFL-RIBLL1 facility and the measurement of $\beta$-delayed $\gamma$ decay of ²⁸S was performed using a detector array consisted of double-sided silicon detectors and Clover-type high purity germanium detectors. Five $\gamma$ transitions from $\beta$ decay of ²⁸S were precisely measured and the corresponding energies of the states of daughter ²⁸P were obtained. The branch ratios of low-lying states of ²⁸P populated by $\beta$ decay were extracted for the first time and the new partial ²⁸S $\beta$-decay scheme was deduced. This work provides accurate data for the further study of mirror asymmetry in ²⁸S/²⁸Mg.