Undergraduate Research at Jefferson Lab

Cherenkov Counter Photomultiplier Studies

Student: Ian Conner

School: Christopher Newport University

Mentored By: William Phelps and Youri Sharabian

Photomultiplier Tubes (PMTs) amplify low light levels by converting photons to electrons and then amplifying them through a series of dynodes. In Hall B at Jefferson Lab, PMTs are used in the High Threshold Cherenkov Counter (HTCC) to detect light from Cherenkov Radiation, mainly generated by electrons due to their low threshold momentum. PMTs are also used to measure the light from scintillators in calorimeters. The PMTs are characterized using a dark box equipped with an adjustable LED pulser and High Voltage (HV) power supply. LED Sweeps assess gain stability and HV Sweeps are performed to determine the relationship between HV and gain. The Bellamy Fit is then applied to analyze this data. Results indicate stability for the R1250 and R7899 PMTs, suitable for the HTCC and Tungsten Powder Calorimeter, respectively. Furthermore, the generated quadratic relationship between gain and HV allows for easy calibration in experiments.