Friday 28 March 2025
Scientists at the Institute of High Energy Physics have made significant progress in developing a test system for photomultiplier tubes (PMTs) used in the Jiangmen Underground Neutrino Observatory (JUNO). The JUNO experiment aims to determine the neutrino mass ordering, precisely measure oscillation parameters, and study atmospheric, solar, geoneutrinos, and supernova neutrinos.
The PMTs play a crucial role in detecting these particles by converting them into visible light. To ensure the PMTs function correctly, a test system was established at the JUNO site to evaluate their performance before installation. The system consists of a dark room with geomagnetic field shielding, readout electronics, data acquisition and control systems, and test programs.
The dark room is designed to minimize external light interference and prevent electromagnetic noise from affecting the PMTs. The geomagnetic field shielding ensures that the tests are conducted in a controlled environment, unaffected by the Earth’s magnetic field. This is particularly important for PMTs used in underground experiments like JUNO, where magnetic fields can significantly impact their performance.
The readout electronics and data acquisition systems were developed specifically for the JUNO experiment. They allow scientists to collect and analyze data from each PMT, providing valuable insights into its behavior. The test programs are designed to simulate real-world conditions, enabling researchers to evaluate the PMTs’ response to various stimuli.
In the first phase of testing, over 2000 PMTs were evaluated using a container-based facility at Pan-Asia. The results showed that the majority of PMTs met the required specifications, with only a few exhibiting abnormal behavior. This initial testing helped identify potential issues and ensured that any faulty PMTs were removed from the batch.
The latest phase of testing focuses on evaluating the performance of 20-inch PMTs used in JUNO. These PMTs are deployed in two types: multi-channel plate (MCP) PMTs and dynode PMTs. The MCP PMTs have a higher collection efficiency, while the dynode PMTs offer better energy resolution.
The test system has been successfully used to evaluate the DCR cooling down and threshold scanning curves for both types of PMTs. The results show that the PMTs exhibit consistent behavior, with no significant differences between the two types. This consistency is crucial for ensuring accurate data collection in JUNO.
Cite this article: “Testing and Evaluation of Photomultiplier Tubes for Jiangmen Underground Neutrino Observatory”, The Science Archive, 2025.
Photomultiplier Tubes, Pmts, Neutrino Observatory, Jiangmen Underground Neutrino Observatory, Juno, Dark Room, Geomagnetic Field Shielding, Readout Electronics, Data Acquisition System, Test Programs
