Balloon-flight test of a lanthanum bromide gamma-ray detector with silicon photomultiplier readout

New scintillator materials have been shown to hold great potential for low-cost, reliable gamma-ray detectors in high-energy astronomy and solar physics. New devices for the detection of scintillation light promise to make scintillator-based instruments even more attractive by reducing mass and power requirements. In particular, silicon photomultipliers (SiPMs) are commercially available that offer gains and quantum efficiencies similar to those of photomultiplier tubes (PMTs), but with greatly reduced mass, high ruggedness, low voltage requirements, and no sensitivity to magnetic fields. SiPMs have by now been shown to perform well as readouts for scintillator gamma-ray detectors in the laboratory. Before they may used in space-based instruments, however, it must be shown that 1) sufficiently large light collecting areas may be fabricated without loss of performance; 2) the variability of the gain with temperature can be compensated for; and 3) that SiPMs are sufficiently robust and radiation hard. We present results from ongoing work to investigate whether SiPMs are appropriate for use in space, including data from the successful flight of a combined LaBr₃/SiPM detector on a high-altitude scientific balloon, and the performance of larger gamma-ray spectrometers with improved light collection.