Speaker
Description
The JUNO experiment will install 25k 3-inch PMTs (SPMTs) in the gaps between 18k closely packed 20-inch PMTs (LPMTs). Both systems will detect the same IBD signals, but the SPMTs will almost always work in single photoelectron mode. As a result, they will help constrain some of the systematics in the LPMT energy reconstruction, improving the energy resolution and the sensitivity of neutrino mass hierarchy measurement. They will also improve the muon reconstruction resolution, help reduce muon-related isotope backgrounds, provide an independent measurement of the θ12 and Delta_m^{2}_{21} solar parameters with unprecedented precision, and improve the measurement of supernova neutrinos.
SPMT production started in 2018 at a rate of 1000/month by the HZC Company. Performance test data so far indicate that the SPMTs perform as expected. A first version of the electronics has been done and is working well.Testing of the integration will be done at the end of this year. Other areas like the high voltage divider, SPMT potting, cabling, connector and underwater box are all making good progress.
