Microchannel plate detector gain decrease through storage under environmental conditions

Open microchannel plate (MCP) detectors are widely used for detection of particles and photons with diverse instruments, including the space flight ones. Space missions preparation and flight instruments construction commonly takes long time during which it is difficult or impossible to ensure the recommended storage conditions (inert gas atmosphere or vacuum) for MCP detectors. We have estimated the gain decrease of a flight laser ionization time-of-flight mass spectrometer LASMA utilizing an MCP detector during its storage under normal conditions (1 atm. pressure, air atmosphere, room temperature, air humidity 40-60%) for almost 10 years. It was found that the detector sensitivity (i.e. gain) over observations period decreased by 2.4-2.8 times. Such decrease can be considered not critical for some instruments using non-position-sensitive MCP-based detectors. The data obtained can be applied to develop requirements for flight instruments constructions, storage, and service, which could simplify some space missions preparation.