Study on Relative Collection Efficiency of PMTs with Point Light

Photon detection efficiency is a key parameter of PMTs in high-precision neutrino and dark matter experiments, while most of these experiments are focus on quantum efficiency. More and more experiments are trying to know the detection efficiency for the simulation of the detector such as JUNO. In order to have a good understanding on photon detection efficiency of the large-area PMT , we conducted a detailed comparison of the relative collection efficiencies of a series of dynode PMT with different sizes and collector structures. This study is based on the tests of relative quantum efficiency and relative detection efficiency with cross check by several light intensities. The testing and results will be discussed.