Status and Prospects of the JUNO Experiment
The aim of the experiment is to determine neutrino mass hierarchy and precision measurement of neutrino oscillation parameters. In autumn 2024, the assembly of the central detector was completed and commissioning will begin in December: filling of the detector and step-by-step switching-on of light-sensitive detecting elements (photomultiplier tubes, PMTs), about 18000 of which are used in the central detector alone.
It is a very important period in the preparation of the experiment, when the first data will be received and a lot of work will have to be done to test the reconstruction and selection algorithms, to measure the radioactivity of the working substance and the noise of the electronics, to measure the contribution of background events, and calibrate the detector response. The physical data acquisition is planned to start in autumn 2025.
News from our colleagues from the spot of the event
The shifts of the JUNO collaboration members have started at the subsystems of the facility. The main detector has not been launched yet, but the water purification and circulation system for the OSIRIS auxiliary detector (it is already collecting data) and the liquid scintillator purification system are in operation. Work is being completed on the “pool” at the bottom of the detector: the bottom is being covered with a reflective coating. The last photomultiplier tubes are being installed at the top of the detector. The planned date for completion of the work and the start of the pool filling is 18 December 2024. As the filling of the pool and detector proceeds, the photomultiplier tubes that will be underwater will be switched on, high voltage will be applied to them, and data will be taken. Accordingly, data acquisition and shifts on the data acquisition system will begin. The filling of the detector with water will continue for two months, followed by ‘water-mode’ data acquisition for a week, and subsequent displacement of water with liquid scintillator that will last for six months. At the same time, data acquisition will take place. As a result, water will be in the pool outside, while the scintillator will be only inside the central detector.
Preparations for the assembly of the Top Tracker muon detector have also started. Assembly of the TAO near detector at the Taishan NPP continues.
The staff members of the DLNP Department of Particle Physics together with Chinese and European colleagues are actively participating in the JUNO detector assembly.