A laser-based system for a fast and accurate measurement of gain and linearity of photomultipliers

This paper describes a method for the measurement of gain and linearity of photomulti- pliers (PMTs). Gain and linearity are two fundamental parameters to use properly a PMT in several physics experiments. In the developed system light is laser generated and adressed to the PMT through a set of optical fibers. The data acquisition system consists in a commercial 16 channel digitizer coupled to a custom front-end board. With the chosen digitizer the system is scalable to test up to 16 PMTs, with the aid of a light distribution system and a multi-channel version of the front-end board. Data analysis is performed by a custom acquisition software. A 1.5" Hamamatsu PMT is used to validate the system.