Automated System for Assessing PMT Photocathode Non-Uniformity
Résumé
The spatial non-uniformity of the photocathode response in PMTs has long been recognized as a significant factor contributing to the deterioration of energy resolution in scintillation spectrometry. More recently, our research has demonstrated that it can also impact absolute activity measurement techniques such as TDCR counting, introducing additional uncertainty in detection efficiency and counting rates. Therefore, it is advisable to measure and evaluate the spatial non-uniformity of the photocathode response in practical applications. Previous system that we developed for this purpose was manually controlled, limiting the spatial resolution of the tests.
In this study, we have developed an automated system for scanning the uniformity of PMT responses. The low-cost automated system is based on CD drives mechanics controlled by a cheap microcontroller board. This system allows for scanning the photocathode sensitivity with a linear spatial resolution of 0.2 mm. An example of a scan conducted on a Hamamatsu R7600U-200 PMT is shown in Fig. 1. Further details about the system and the results obtained for popular PMTs such as Hamamatsu H11934-203 and R331-05 will be presented and discussed.
Mots clés
photocathode
energy resolution
scintillation
spectrometry
absolute activity measurement
primary activity measurement
triple-to-double-coindence ratio
TDCR
counting rate
detector
instrumentation
nuclear instrumentation
detection efficiency
scintillation counting
spatial resolution
automation
electronic architecture
photocathode sensitivity
metrology
ionizing radiation
Liquid Scintillation
Liquid Scintillation counting