Results from a Si(Li) gamma ray detector stack for future Mars missions

The authors present Monte Carlo analysis and experimental data from a novel lithium-drifted silicon detector stack for gamma ray spectroscopy instrumentation in future Mars surface landers and other planetary missions. The Monte Carlo analysis shows full energy photopeaks even in the range of ~100 keV to 2 MeV where. in Si, Compton scattering, dominates the absorption processes. Laboratory data are shown for an experimental detector stack of four planar Si(Li) devices, each 5 mm thick with an active area 2 cm in diameter. All the experimental data were collected with maximum temperature of the stack at 175 K. Background reduction was achieved by using the detector of the stack closest to the source in anticoincidence. Experimental data from the stack are compared with the Monte Carlo model for ¹³⁷Cs (662 keV)