Microphonics in scintillation gamma-spectrometer in vibration environment onboard spacecraft

Scintillation detectors based on photomutiplier tubes (PMT) are widely used for the purposes of space nuclear planetology that studies elemental composition of planets and their moons, as well as cosmic ray fluxes, including secondary radiation. When ionization radiation is absorbed throughout a scintillator, photons are emitted, that is detected by PMT. Measurements with PMT are known for their susceptibility to external vibration that results in electrical noise, known as microphonics. Spacecraft design assumes a number of different vibration sources, like gyros, pumps, rotating devices, etc., that can provide significant effect on measurements. This article describes a study of microvibration effect on performance of the photomutiplier tube, that results in noise generation when neutron and gamma ray fluxes are measured by detectors onboard the spacecraft. Vibration susceptibility test results for Hamamatsu R1840 PMT are provided, and levels of noise generation are determined.