Characterisation of a LaBr3:LaCl3 Phoswich Array Using 70-230 MeV Protons

Abstract

The study of nuclei far from stability plays an important role in our understanding of matter and the processes involved in nuclear many-body systems, nucleosynthesis, and astrophysical processes. Studying these systems demands the use of radioactive beams, often in reactions done in inverse kinematics. The Reactions with Relativistic Radioactive Beams (R3B) experiment at the future FAIR accelerator facility will fulfill these needs. R3B is in need of a calorimeter for detection of in-flight emitted gamma-rays and high energy light charged particles, abbreviated CALIFA, situated around the target chamber. This thesis reports on a test experiment with a possible prototype for the forward end-cap of CALIFA. The prototype consists of four LaBr3(Ce):LaCl3(Ce) phoswich crystals, arranged in a 2x2 array, consisting of 4 cm LaBr3(Ce) and 6 cm LaCl3(Ce). This phoswich array is characterised by using 70-230 MeV protons of well-defined energy, cosmic muons, and simulations. Integral and correlation based on-line pulse-shape analysis tools are evaluated, optimised, and used to interpret the data. In particular, the energy deposited in the LaBr3(Ce) and the energy deposited in the LaCl3(Ce) are separated from each other, and it is demonstrated that the crystals can be used as a dE-E detector. In addition, the event multiplicity, crystal coincidence distribution, and the energy resolution is determined for protons. Finally, it is shown that the light output of the crystals is linear with respect to energy, and that its time characteristics differs for protons and muons.