Undergraduate Research at Jefferson Lab

Assessing the Efficiency of Multi-Anode Photomultiplier Tubes for a Ring Imaging Cherenkov Detector

Student: Charles McIntyre

School: Reed College

Mentored By: Valery Kubarovsky

Jefferson Lab's CLAS12 detector in Hall B is currently undergoing an upgrade. This will include the construction of a ring imaging Cherenkov (RICH) detector to measure particle speeds. The RICH detector will make use of a large number of multi-anode photomultiplier tubes (MAPMTs) for photon detection. This project sought to characterize the relative efficiency of two competing models of MAPMT supplied by Hamamatsu Photonics. Efficiency was computed for 80 H12700 series PMTs and 56 H8500 series PMTs. The H12700 was found to perform favorably to the H8500, with 7-8% greater mean relative efficiency; this will provide increased photon detection in the RICH detector, allowing for improved Cherenkov ring re- construction. Analysis of efficiency vs. several electronic parameters suggests that this performance is due to superior photocathode luminous sensitivity and blue light sensitivity. The H12700 was also found to have relatively constant efficiency over a range of angles of incident photons.