  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.
