Absolute detection efficiency of a tapered microchannel plate

Matoba, Shiro

A micro channel plate (MCP) consists of a large number of micro channels which are formed by etching a lead glass matrix. Particles are detected if those are injected into the channel of an MCP. Therefore, the detection efficiency of an MCP is limited by the open-area-ratio (OAR) which is defined as the ratio of the total area of the channel entrances(open-area) to the area of the MCP surface. We developed the MCP with tapered micro-pores having a large open-area. The absolute detection efficiencies of conventional (C-) and tapered (T-) MCPs were measured for Xe ions at incident energies between 0.5 and 13.5 keV. The absolute detection efficiencies increase with the incident energy and reach a plateau. Maximum values of the absolute detection efficiencies for the C- and T-MCPs were 65% and 88%, respectively. These values are nearly equal to the OARs which are 62% and 90% for C- and T-MCP, respectively. It is validated that tapered pores are effective to increase OAR.