Common Iron Passive Magnetic Shielding for Scintillator Array Photomultiplier Tubes

TL;DR

This paper introduces a combined iron and mu-metal shielding method for photomultiplier tubes in scintillator arrays, effectively reducing magnetic interference in accelerator experiments.

Contribution

It presents a novel common iron passive shielding design for multiple PMTs, simplifying installation and maintaining performance in magnetic fields.

Findings

Shielding preserves PMT gain and timing resolution.

The combined shielding is effective in fringe magnetic fields.

Deployment during a 2022 experiment validated the approach.

Abstract

In accelerator-based experiments, detector arrays constructed from organic plastic scintillators are widely used for measurements of particle timing, hit position, and energy loss. These detectors are often operated in proximity to magnetic spectrometers, where the associated photomultiplier tubes (PMTs) are exposed to fringe magnetic fields. The standard approach to mitigate magnetic interference involves individually shielding each PMT. In this work, we present a combined passive shielding solution consisting of a common iron enclosure for a row of PMTs, supplemented with individual mu-metal cylinders. This configuration was deployed during a 2022 experiment at JINR. Performance evaluations show that the proposed shielding effectively preserves PMT gain and timing resolution, demonstrating its viability for future applications in similar experimental environments.