JUNO

JUNO is a multipurpose neutrino experiment designed to determine the neutrino mass ordering and precisely measure the neutrino oscillation parameters with reactor neutrinos, observe supernova neutrinos, study the atmospheric, solar, and geo-neutrinos, and perform exotic searches. 

JUNO is an international collaboration consisting of about 675 researchers from more than 65 institutions. The experiment is located in Kaiping, Jiangmen, China. It is situated 700 m underground and about 53 km from the Yangjiang and the Taishan nuclear power plants. The central detector is filled with 20 kton linear alkyl benzene (LAB)-based liquid scintillator and instrumented with 15,000 20'' and 25,600 3'' photo multiplier tubes (PMTs). The energy of incident neutrinos and the interaction vertex can be reconstructed based on the charge and time information of PMTs. 

The main experimental signature of the reactor neutrinos is the coincident event of the products from the inverse beta decay (IBD) reaction. The reactor electron antineutrino interacts with proton via the IBD reaction in the liquid scintillator and releases a positron and a neutron. One the one hand, the positron deposits energy quickly, providing a prompt signal. On the other hand, the neutron is captured by proton after an average time of 200 μs, releasing a 2.2 MeV gamma, providing a delayed signal. The coincidence of prompt-delayed signals provides a distinctive antineutrino signature. 

Experimental efforts worldwide are continuously improving the precision of the measured oscillation parameters. The current precision of Δm221, Δm232, and sin2θ12 is about 3%, 5%, and 6%, respectively. In six years, JUNO will ultimately reach a precision of below 1% for all the three oscillation parameters.