Aachen 2019 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 56: Neutrino-Detektoren II
T 56.1: Vortrag
Mittwoch, 27. März 2019, 16:00–16:15, S07
Improved approach of monitoring the effective quantum efficiency of Borexino photomultipliers — •Mariia Redchuk1,2, Zara Bagdasarian1, Sale-Iti Kroon1,2, Sindhujha Kumaran1,2, Livia Ludhova1,2, and Ömer Penek1,2 for the Borexino collaboration — 1IKP-2, Forschungszentrum Jülich — 2III B Physikalisches Institut, RWTH Aachen University
Borexino is a liquid scintillator detector located in Laboratori Nazionali del Gran Sasso in the mountains of central Italy. It is equipped with nominally 2212 inward-facing photomultipliers (PMTs) that are used to detect events producing scintillation light.
The effective quantum efficiency (EQE) represents the amount of incident light detected by the PMT. It may vary in time due to various factors like light yield change or the PMT aging. Therefore, in order to accurately represent the detector in terms of light collection, we need to account for these changes.
We calculate the EQE of each PMT and monitor its changes using the low-energy 14C (Q = 156 keV) events, for which the single-photoelectron mode on each PMT dominates. However, this calculation is sensitive to the position and energy of the selected events as well as to the set of PMTs active in the detector in a given time period. We developed a new more stable method of selecting 14C events and improved the accuracy of the EQE calculation. The highlights of the new approach will be summarized in this talk.