Characterization and Performance Evaluation of New PMTs for ATLAS and CMS HL-ZDC Using a Table-top Test Setup*

The High Luminosity Upgrade of the ATLAS and CMS Zero Degree Calorimeters (HL-ZDC) necessitates the characterization of new photomultiplier tubes (PMTs), which are present in the design of the detector's Electromagnetic (EM), Reaction Plane Detector (RPD), and Hadronic (HAD) sections. This study aims to characterize the performance and reliability of these new PMTs using a custom designed table-top setup. Building on previous advancements in radiation-hardened PMT technologies, we have developed a reproducible experimental framework to test the PMT signals under controlled conditions.

Our experimental setup includes a waveform generator to send driver pulses to an LED, which illuminates the PMT in a dark box. The resulting signals are captured by a DRS4 evaluation board, converting them from analog to digital for subsequent analysis using a custom program built with CERN ROOT. This setup allows precise measurements of the uniformity of different PMTs across their window.

In this contribution, I will discuss our methodology for PMT evaluation and draw the timeline for future developments in the framework of the HL-ZDC upgrade.