Investigating the large signal phenomenon in single photo-electron measurements of the 20-inch MCP-PMT

Abstract

In this paper, we investigated a large signal phenomenon (LSP) in single photo- electron (SPE) measurement of the 20-inch MCP-PMT. The LSP will cause a long tail of the PMT output charge spectrum, and it will affect the calculation of the number of photoelectrons (PEs) collected and the gain of the PMT. To evaluate the LSP of the 20-inch MCP-PMT, a parameterization method is developed, by measurement of the LSP distribution in the full photocathode of the PMT and study of LSP variation with different voltage ratios applied for the PMT.