JUNO physics and detector
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Abstract
The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton LS detector\nat 700-m underground. An excellent energy resolution and a large fiducial\nvolume offer exciting opportunities for addressing many important topics in\nneutrino and astro-particle physics. With 6 years of data, the neutrino mass\nordering can be determined at 3-4 sigma and three oscillation parameters can be\nmeasured to a precision of 0.6% or better by detecting reactor antineutrinos.\nWith 10 years of data, DSNB could be observed at 3-sigma; a lower limit of the\nproton lifetime of 8.34e33 years (90% C.L.) can be set by searching for\np->nu_bar K^+; detection of solar neutrinos would shed new light on the solar\nmetallicity problem and examine the vacuum-matter transition region. A\ncore-collapse supernova at 10 kpc would lead to ~5000 IBD and ~2000 (300)\nall-flavor neutrino-proton (electron) scattering events. Geo-neutrinos can be\ndetected with a rate of ~400 events/year. We also summarize the final design of\nthe JUNO detector and the key R&D achievements. All 20-inch PMTs have been\ntested. The average photon detection efficiency is 28.9% for the 15,000 MCP\nPMTs and 28.1% for the 5,000 dynode PMTs, higher than the JUNO requirement of\n27%. Together with the >20 m attenuation length of LS, we expect a yield of\n1345 p.e. per MeV and an effective energy resolution of 3.02%/\\sqrt{E (MeV)}$\nin simulations. The underwater electronics is designed to have a loss rate\n<0.5% in 6 years. With degassing membranes and a micro-bubble system, the radon\nconcentration in the 35-kton water pool could be lowered to <10 mBq/m^3.\nAcrylic panels of radiopurity <0.5 ppt U/Th are produced. The 20-kton LS will\nbe purified onsite. Singles in the fiducial volume can be controlled to ~10 Hz.\nThe JUNO experiment also features a double calorimeter system with 25,600\n3-inch PMTs, a LS testing facility OSIRIS, and a near detector TAO.\n