Thermal reliability analysis of the central detector of JUNO

Introduction The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose neutrino experiment designed to determine neutrino mass hierarchy, precisely measure oscillation parameters and study solar neutrinos, supernova neutrinos and geo-neutrinos, etc. The central detector (CD) of JUNO has 20,000 tons liquid scintillator as target mass, which contains inside a huge acrylic sphere with inner diameter of 35.4 m, supported by a stainless steel structure. The whole structure of CD will be installed inside a cylindrical water pool, and the acrylic sphere will be submerged in the center of water pool. The operating temperature of CD is designed to be 21 °C as long as over 20 years, which is determined by the mechanical requirement of the structure and physics consideration.