Next Generation Gamma/Neutron Detectors for Planetary Science

Gamma-ray and neutron spectroscopy are well established techniques for determining the chemical composition of planetary surfaces, and small cosmic bodies such as asteroids and comets; however, new technologies with the potential to significantly improve the performance of planetary nuclear spectroscopy are emerging. We propose to develop new gamma-ray and neutron detectors based on wide-band-gap (WBG) solid-state photomultiplier (SSPM) photodetectors coupled to emerging scintillation materials such as Cs2YLiCl6:Ce (CLYC), and CeBr3 for gamma and neutron spectroscopic studies of planet surfaces and small cosmic bodies. The proposed SSPM photodetector for scintillation readout is based on AlGaAs, a WBG compound semiconductor with aluminum concentration of 60% to 90%. The ~2-eV band-gap energy of this material is engineered to match the emission spectrum of both CLYC and CeBr3. The high band-gap of AlGaAs also provides much lower dark noise and better radiation tolerance than Si-based detectors. Compared to conventional PMTs, the compact size, low voltage operation, and lighter weight of AlGaAs SSPM is ideal for spaced-based instruments. The advantages of AlGaAs SSPMs and the excellent detection properties of CLYC and CeBr3 scintillation materials make them a perfect match in the development of new gamma and neutron spectrometers for planetary science.