Multichannel pulsed light source with LED for photomultiplier testing

Abstract

Photomultipliers are generally used for the measurement of faint light signals produced in detection systems. They are commonly used for the detection of particles, which produce light through interactions with the detection medium. To test photomultipliers in the laboratory, an artificial light source is used to emulate incident light from natural sources. Analysis of the resulting data is used to inform the design and engineering of the detector readout system and as a factor to estimate the detection efficiency of the particle detector. The main parameters of multi-pixel PMTs (Photomultiplier Tubes) and SiPMs (Silicon Photomultipliers) coupled to optical fibers are better measured with a multichannel light source. In this document we describe the electronic design, LED (Light Emitting Diode) selection, and operation of the light source. The flasher design presented here provides light-signals capable of testing the full dynamic range of different photosensitive devices, from the level of single photoelectrons to device and electronics saturation. The optical coupling and the electrical scheme of the source allows for the flashers to be stacked, i.e. from 1 to 64 channels or more. As a result, each channel of a 64-anode PMT can be individually tested. Note that the scalability of the system is neither limited to 64 nor this type of device.