Software Tools for the Analysis of the Photocathode Response of Photomultiplier Vacuum Tubes

TL;DR

This paper describes the development of a comprehensive software system for scanning and analyzing the photocathode response of photomultiplier tubes, integrating hardware control and data analysis tools.

Contribution

It introduces a new cross-platform software based on CERN ROOT and Qt libraries for detailed analysis of PMT photocathode response data.

Findings

Effective scanning of photocathode response achieved

Software enables detailed data analysis and visualization

System improves measurement accuracy and efficiency

Abstract

The central institute of electronics (ZEA-2) in the Forschungszentrum Juelich (FZJ) has developed a system to scan the response of the photocathode of photomultiplier tubes (PMT). The PMT sits tight on a supporting structure, while a blue light emitting diode is moved along its surface by two stepper motors, spanning both the x and y coordinates. All the system is located in a light-tight box made by wood. A graphical software was developed in-situ to perform the scan operations under different configurations (e.g., the step size of the scan and the number of measurements per point). During each point measurement the current output generated in the vacuum photomultiplier is processed in sequence by a pre-amplifier (mainly to convert the current signal into a voltage signal), an amplifier, and by an ADC module (typically a CAEN N957). The information of the measurement is saved in files at the end of the scan. Recently, software based on the CERN ROOT and on the Qt libraries was developed to help the user analyzing deeper the data obtained by the scan. The new software, cross-platform due to its build performed inside the Qt-IDE, is described in this note.