Abstract
It is widely recognized that the gain of the microchannel plate (MCP) drops temporally when a particle initiates an electron avalanche, and a large amount of charge is extracted from the channel. Electron multiplication was expected to deplete the charge from the microchannel wall, and this gain-drop phenomenon has been considered to last until the charges were replenished. The gain-recovery time has been measured and compared to the RC constant (i.e., a product of plate electrical resistance and capacitance) in several studies. In this research, the gain-recovery time constant of the same chevron MCP detector was evaluated using two methods (continuous irradiation method and double-pulse method). In the continuous irradiation method, the gain-recovery time constant is determined from a ratio of the MCP output current to the conduction current for continuous irradiation by using an analytical model. In the double-pulse method, the first pulse irradiates the MCP detector to cause the gain-drop, and the second pulse irradiates to monitor the gain. The gain-recovery time constant is determined by changing a time interval between the two pulses. The gain-recovery time constant obtained by the continuous irradiation method was over one order magnitude larger than the RC constant and those by the double-pulse method. This overestimation was attributed to the fact that the model formula used in the continuous irradiation method does not consider the spatial extension of the gain-drop. The gain-recovery time constant obtained by the continuous irradiation method was consistent with that obtained by the double-pulse method, modifying the model formula and assuming the electron multiplications for one photoelectron decrease the gains of the surrounding 20 channels to zero.
Published Version
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