Characterization of CLLBC Coupled to Silicon Photomultipliers

Cs ₂ LiLaBr _6-x Cl _x :Ce (CLLBC) has high energy resolution for gamma detection and high sensitivity for neutron detection. It is one of the neutron-gamma dual-mode scintillators developed in recent years. This work studies the performance of an 18-mm CLLBC cube for gamma and neutron detection for temperatures between -20 °C and 50 °C. In addition, the scintillator was coupled to the SensL J- and C-series silicon photomultipliers (SiPMs) for comparison. Throughout the temperature range, better energy resolution is observed for the scintillator coupled to the J-series SiPMs which can be attributed to the higher photon detection efficiency. For thermal neutron detection, the output of the detector was recorded by a waveform digitizer and analyzed offline on a computer. To distinguish neutrons from gammas, a pulse shape discrimination technique was utilized. A good separation between neutrons and gammas is observed for all the temperatures. However, separating neutrons from the intrinsic alphas is somewhat difficult at low temperatures. In spite of this, this 18-mm CLLBC cube is a high-performance scintillator and is suitable for deployment in radiation detectors for nuclear security and safeguards applications.