Diagnostic Device for Photomultiplier Tubes at ARP ToF Detector

Long-term usage of photomultiplier tubes (PMTs) led to the discovery of aging effects especially in harsh environment as a radiation is. Aging decreases the efficiency of the PMTs. This means PMTs need to the recalibration after some time. Because CERN's Large Hadron Collider (LHC) runs for few years, the diagnostics of the PMTs is necessary. Eventual recalibration without removing the PMT is possible to accomplish by integrating the light source nearby PMT's chassis. The light source should by as precise as possible. The used LED source needs a driver. The driver consists of controllable power source and timing controller. The perfect timing of the pulses is controlled by FPGA. An attention to the radiation hardened parts was needed because of the device proximity to the radiation source. The development and testing of the PMT diagnostic device (PDD) are described in this paper.