Speaker
Description
A micro-channel-plate photomultiplier tube (MCP-PMT) has the best timing resolution
for single photon detection, which enabled us to realize the novel RICH detector,
the TOP counter, for particle identification in Belle II. A major concern about using MCP-PMTs under a high background environment like Belle II is a short lifetime of the photocathode because the quantum efficiency drops as a function of the integrated output charge of the MCP-PMT due to outgassing from the MCP.
We succeeded in extending the lifetime of the square-shaped MCP-PMT for the TOP counter step-by-step: from less than 0.1 C/cm$^2$ of the lifetime to about 1 C/cm$^2$ with a conventional MCP, about 9 C/cm$^2$ by applying atomic layer deposition (ALD) to the MCP, and more than 15 C/cm$^2$ by further improvement, while the estimated integrated
output charge in Belle II is about 3 C/cm$^2$. Especially more than 15 C/cm$^2$ was measured for all 10 samples.
This talk will also cover a difference of the performance between the conventional and
ALD-MCP-PMTs as well as a degradation of the performance under a high background.
| Registered | Yes |
|---|
Author
Co-authors
External references
- 064
