Köln 2025 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 11: Instrumentation IV

HK 11.1: Talk

Monday, March 10, 2025, 16:45–17:00, SR Exp1B Chemie

Detailed Study of Afterpulses in MCP-PMTs — •Gabriele Costi, K. Gumbert, S. Krauss, A. Lehmann, and D. Miehling — ECAP, Universität Erlangen-Nürnberg

The PANDA experiment at FAIR uses two DIRC detectors for pion/kaon separation by Cherenkov light detection. Central to their performance are Microchannel-Plate Photomultipliers (MCP-PMTs), which were chosen for their excellent time performance and suitability in high magnetic fields (1  T). Recent quality control tests of PHOTONIS XP85112-S-BA tubes has provided new insights into performance parameters such as lifetime, quantum efficiency, gain stability, dark count rates, and afterpulses (APs).

APs triggered by feedback ions are suspected to be the main cause of photocathode aging; therefore, it is crucial to understand how, where and how many APs are created in the MCP-PMT. To study this effect in more detail, various measurements and analyses of time-of-flight (TOF) spectra were performed with a TRB/DiRICH DAQ system and compared to simulations. By analyzing the TOF the origin in the PMT and the type of the feedback ions were investigated. In this contribution, we present the results obtained on APs in MCP-PMTs, including comparative data from prototype and series production models.

- Funded by BMBF and GSI -