Performance test of TOP counter prototype

We develop the new PTD device named `TOP counter', which is a kind of RICH detectors and detects the ring image converted to the position and the propagation time. For the timing measurement, about 40 [ps] TTS is required for the photo-detector. Though the square-shaped MCP-PMT which we developed is the best candidate for the TOP counter, we have had a problem on its lifetime span. In this presentation, it is reported that the achievement about the performance test of the TOP counter prototype and the extension of the lifetime of the MCP-PMT.