Mass production and performance study on the 20-inch PMT acrylic protection covers in JUNO

The Jiangmen Underground Neutrino Observatory is a neutrino experiment that incorporates 20,012 20-inch photomultiplier tubes (PMTs) and 25,600 3-inch PMTs. A dedicated system was designed to protect the PMTs from an implosion chain reaction underwater. As a crucial element of the protection system, over 20,000 acrylic covers were manufactured through injection molding, ensuring high dimensional precision, mechanical strength, and transparency. This paper presents the manufacturing technology, mass production process, and performance characteristics of the acrylic covers.