Scintillators on Interplanetary Space Missions

Lanthanum halide scintillators are currently being assessed by ESA for use as remote sensing gamma-ray spectrometers on future planetary missions. Such missions place a raft of constraints and requirements on sensor technology, which invariably stem from environmental and resource issues. In the past, NaI(Tl) and CsI(Tl) based spectrometers offered great advantages in term of device simplicity, reliability and detection efficiency but with poor energy resolution. Lanthanum halides combine these attributes with much higher energy resolution and their extensive deployment in future missions seems assured. In fact, LaBr spectrometers are currently baselined for most missions in planning. In this paper, we describe the needs of remote gamma-ray sensing and efforts by the European Space Agency to develop and qualify the next generation of spectrometers based on LaBr for interplanetary space missions. We contrast their performance to large volume Ge detectors and show that in the context of minimally resourced spacecraft, they represent a more attractive solution.