Scintillation of XP2020 PMT glass window

The primary objective of the JUNO experiment is to determine the ordering of neutrino masses using a 20-kton liquid-scintillator detector. The 20-inch photomultiplier tube (PMT) plays a crucial role in achieving excellent energy resolution of at least 3 % at 1 MeV. Understanding the characteristics and features of the PMT is vital for comprehending the detector's performance, particularly regarding the occurrence of large pulses in PMT dark counts. This research paper aims to further investigate the origin of these large pulses in the 20-inch PMT dark count through measurements and simulations. Our results confirm that natural radioactivity and muons striking the PMT glass are the main sources of the large pulses. We evaluate their contribution quantitatively by performing spectrum fitting. By analyzing the PMT dark count spectrum, it becomes possible to roughly estimate the radioactivity levels in the surrounding environment.

Section: Cosmic Muonmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Dark count of 20-inch PMTs generated by natural radioactivity

Zhang,

Wang,

et al. 2024

“…These are used in quantum information-related experiments, dark matter detection, flow cytometry, bio-and chemi-luminescence, astronomical photometry, time-of-flight LiDAR and flash LiDAR [2][3][4][5]. In [6] input window scintillation by X-rays and radioactive sources have been addressed using PMT but not SiPM detector systems. The height of output pulses can be used for removing noise from signals [5] collected using PMTs.…”

Section: Jinst 18 T11003mentioning

confidence: 99%

Cosmic muons as PMT and SiPM detector background signals

Fardipour Raki,

Khakzad,

AbdusSalam

2023

Photomultiplier tube (PMT) and Silicon Photo Multiplier (SiPM) are often used for detecting small number of photons or very weak radiations. A light guide usually connects these photodetectors to the test space. In this article, we investigate the effect of background signals caused by cosmic muons scintillation or interactions with PMT and SiPM, their light guide or input window materials. We study such interactions by making simulations using GATE software package and undertaking experiments using detector circuits developed as in [1]. The background cosmic muons can generate photons which will lead to errors in low radiation and single photon detection experiments especially if standard scintillators are not used. For such experiments, we conclude that the most useful method for cutting down the cosmic muons background should be by conducting the experiments deep underground or inside tunnels with several tens of meters of materials above it.

“…It is also valuable to mention that the flashers from PMT HV divider of JUNO is studied in [25]. As known, it will generate a large pulse by Cerenkov radiation when a muon is crossing through the PMT glass (Hamamatsu PMT R5912) as studied in [36,37]. PMT large pulse still needs further study to identify either flasher or others to have a better rejection to noise, in particular for the 20-inch PMTs and the coming rare event detection projects, such as JUNO [1,2], HyperK [38,39].…”

Section: Jinst 17 P10048mentioning

confidence: 99%

Study of 20-inch PMTs dark count generated large pulses

Wang¹,

Li²,

Zhang³

et al. 2022

The main goal of the JUNO experiment is to determine the neutrino mass ordering with a 20 kt liquid-scintillator detector. The 20-inch PMT is crucial as one of JUNO key instruments to realize an excellent energy resolution of at least 3% at 1 MeV. The knowledge on PMT's characterisation and feature is critical for detector performance understanding. Large pulses from PMT dark count such as from the flasher or others are one of the serious concerns for detector noise control. Focusing on the large pulses from 20-inch PMT dark count, this paper is trying to investigate the causes by measurements with a muon tagging system. It is found that the large pules of 20-inch PMT dark count is contributed mainly from muons hitting the PMT glass, and we have a preliminary understanding of the results with a simulation based on Geant4.