Precision measurements of timing characteristics of the 8" ETL9351 series photomultiplier

During the test measurements of the PMTs to be used in the future Borexino experiment, the data from 2200 PMT were accumulated. The unique timing characteristics of the apparatus used and the large statistics acquired, permit resololution of the fine structure of the ETL9351 PMT time response. A method to obtain the probability density function of the single photoelectron counting from the experimental data is proposed and applied to derive the PMT average characteristics. For the first time, an analytical model of the single photoelectron PMT time response is proposed, describing all the features of the single photoelectron time arrival. The origin of the small amplitude pulses is explained.