JUNO

Welcome to the JUNO Warwick Group page, where we delve into the fascinating world of neutrino physics and the groundbreaking experiments conducted at the Jiangmen Underground Neutrino Observatory (JUNO). The JUNO group in the UK was first established in Warwick in 2021. We are a founding member of the GANYMEDE Physics Working Group.

Academics: Dr Xianguo Lu

Students: Yaoqi Cao, Ziou He, Mariam Rifai, Qiyu Yan

Completion of the construction of Stainless-Steel Tank, or SST, June 2022

About JUNO

JUNO received approval in 2013 and began construction in 2015 in Jiangmen City, Guangdong Province, China. Situated at coordinates 112.518056 E, 22.118056 NLink opens in a new window, JUNO is strategically located within 200 km of Guangzhou, Shenzhen, and Hong Kong. The experimental site is equidistant, 53 km, from the Yangjiang Nuclear Power Plant (NPP) and the Taishan NPP, with a combined thermal power of 26.6 GW.

In 2018, the Taishan Antineutrino Observatory (TAO) emerged as a satellite experiment affiliated with JUNO, aiming to establish a reference spectrum at 30 m from the reactor core of the Taishan NPP.

The JUNO Detector

Location and Construction

The JUNO detector is housed in an underground laboratory beneath Dashi Hill, providing an overburden of about 1800 meter water equivalent. The detector comprises three main components:

Central Detector (CD): A liquid scintillator (LS) detector with an effective energy resolution of σ_E/E = 3%/√E(MeV). The CD, containing 20 kilotons of LS, is enclosed in a spherical acrylic vessel submerged in a water pool.
Water Cherenkov Detector (WCD): Optically separated from the CD, the WCD serves to detect Cherenkov light from cosmic muons, acting as a veto detector.
Top Tracker (TT): Atop the water pool, a plastic scintillator array is designed for muon track measurements.

Optical Setup

The CD utilises a combination of 17,612 PMTs with a 20-inch size and 25,600 PMTs with a 3-inch size, achieving a photocathode coverage of 77.9%. Scintillation light is observed, and the water pool aids in detecting Cherenkov light.

Research Focus

Reactor antineutrinos are the primary signal in the JUNO detector, crucial for determining the Normal Mass Ordering (NMO) and enabling precision measurements of neutrino oscillation parameters. JUNO is projected to observe 60 Inverse Beta Decay (IBD) events per day, with a 6% background contamination. Over six years, NMO can be determined with a significance of 3–4σ.

Reactor electron antineutrinos oscillate into muon and tau antineutrinos as they travel. Illustration: VISOS

Beyond Neutrino Oscillations

JUNO's diverse physics programme extends beyond neutrino oscillation studies:

Supernova Detection: With ten years of data, JUNO can detect neutrinos from all past core-collapse supernovae at a 3σ significance.
Proton Decay: JUNO aims to set a lower limit on the proton lifetime through the search for proton decay.
Solar Neutrinos: JUNO contributes to understanding the solar metallicity problem and exploring the vacuum-matter transition region.
Geo-neutrinos: JUNO is poised to detect geo-neutrinos at a rate of approximately 400 events per year.

Recent Developments

JUNO has made strides in atmospheric neutrino sensitivity, offering a complementary perspective to reactor neutrinos. Recent advancements in reconstruction and analysis techniques enhance the sensitivity to atmospheric neutrinos, playing a crucial role in the early discovery of NMO.

GeV Neutrino Interaction in JUNO

Interactions involving atmospheric neutrinos produce a range of final-state particles, introducing challenges in estimating both incoming neutrino energy and event rates. The establishment of the GeV v-A high-eNergY MEDium Effect (GANYMEDE) Physics Working Group in 2022 addresses these challenges, ensuring high-quality atmospheric neutrino interaction models within the JUNO framework.

Thank you for joining us on this scientific journey at JUNO! For inquiries or collaboration opportunities, please feel free to contact Dr Xianguo Lu at xianguo dot lu at warwick dot ac dot uk.

Physics Elementary Particle Physics Group