Hybrid X-ray and γ-ray spectrometer for in-situ planetary science missions

γ-Ray spectroscopy, X-ray spectroscopy and γ-ray backscatter densitometry for planetary science applications are three complementary analytical techniques that can be used to determine surface and sub-surface composition, constrain heat flow through a planetary regolith and hence understand more about the processes that formed planetary bodies. Evaluating different detector types and configurations in order to achieve these scientific objectives is a key enabling step for a successful flight instrument development programme. In this study, we evaluate and compare different detector solutions and configurations including: planar and hemispherical CdTe, a CsI(Tl) scintillator, a LaBr3(Ce) scintillator and a HPGe detector. The LaBr3(Ce) detector was chosen as the most suitable detector for an in-situ planetary science mission due to its high-radiation tolerance, low mass compared with HPGe detector systems, its comparable resolution (∼3.4% at 662 keV) to compound semiconductors (planar CdTe ∼2.4% at 662 keV) and high efficiency.