Production, waterproof potting and testing of the 20-inch microchannel plate photomultiplier tubes (MCP-PMT) for the water Cherenkov detector array (WCDA) of the Large High Altitude Air Shower Observatory (LHAASO) have now been completed. The last set of 150 PMTs passed inspection in Nanjingand were sent to LHAASO on March 24, ending a 13-month manufacturing and testing process. 

According to the latest developments in the international frontier, the design of WCDA was optimized during the construction process. The critical component of the detector unit used a new type of 20-inch photomultiplier with the independent intellectual property rights in China and the largest sensitive area in the world. The implementation of 20-inch photomultiplier tubes has further improved the localization of scientific facilities, enhanced the detection capability of LHAASO detectors for gamma rays in the 50-300GeV energy range, and greatly improved transient phenomena such as gamma-ray burst detection sensitivity. 

Northern Night Vision Technology Co., Ltd. (NNVT) designed and optimized the 20-inch MCP-PMT achieving excellent performance, including small transit time spread, good time consistency, and low after-pulse ratio. In addition, NNVT also helped IHEP complete the waterproof potting of the PMTs.

PMT waterproof potting workshop site (Image by IHEP)

Engineers perform test work at Daocheng laboratory. (Image by IHEP)