Using the LaBr3Ce scintillation detector for mobile gamma-spectrometry

Abstract: When doing mobile gamma-spectrometry the equipment has for severaldecades been limited to NaI(Tl) and Ge-based detectors. Recent developements has led to a possible replacement of NaI(Tl)-based systems in the form of a new scintillation material: LaBr3:Ce (cerium doped lanthanum bromide). LaBr3:Ce-detectors successfully compete with NaI(Tl)-based detectors when considering resolution, efficiency, and decay time of the scintillation light. Its only main drawback is the fact that it is internally contaminated. The detector crystal contains a small percentage of the radioactive isotope 138-La as well as 227-Ac, which places the LaBr3:Ce detectorat a disadvantage in comparison to NaI(Tl)-detectors, when measuring low photon fluences.Several methods for compensating for the internal contamination areexplored in this thesis. Two of those methods were found to work well for usage in a static measurement setup and a mobile setup respectively. The problem of energy calibration drift, caused by temperature change and other causes, is also explored as this is a cause for concern when doing background compensation. Furthermore, a test to study if it is possible to use the LaBr3:Ce-detector in a multi-detector system has been done with positive results