Summary of the R&D of 20-inch MCP-PMTs for neutrino detection

Abstract

The Jiangmen Underground Neutrino Observatory (JUNO) in China aiming to determine the neutrino mass hierarchy is under construction. A new kind of large area microchannel-plate photomultiplier tube (MCP-PMT) was put forward for the JUNO by the researchers in Institute of High Energy Physics (IHEP) in China. After breaking through several core technotical barriers, the 20-inch MCP-PMT prototype with great performance was successfully produced by the MCP-PMT group in China and got 75% PMT orders (15,000 pics) from JUNO. The mass production line and batch test system was completed in North Night Vision Technology Co., Ltd. (NNVT). The performance of the MCP-PMT including the gain, the quantum efficiency, the P/V ratio, the dark count rate and the transit time spread can be batch tested. During the mass production process, the technical progress in the cathode deposition method improved the quantum efficiency of the photocathode from 30% to 35%. The aging behaviour, temperature effect, the after-pulse distribution and the flash signal of the 20-inch MCP-PMT are all detailly studied. By August of 2020, the 15,000 MCP-PMTs, which will be installed as the central liquid scintillator detector of JUNO, have been completed and delivered to Jiangmen. The average QE at 400 nm for the 15,000 pieces of MCP-PMTs is 32%.

A Co3O4 Nanoparticle-Modified Screen-Printed Electrode Sensor for the Detection of Nitrate Ions in Aquaponic Systems

“…Figure 3 shows that the XRD pattern showed peaks at 2θ = 18.72 • , 30.98 • , 36.73 • , 44.41 • , 58.96 • , and 64.96 • , which can be assigned to the (111), ( 220), (311), (400), (511), and (440) crystal planes of Co 3 O 4 (JCPDS card No. 42-1467) [24]. There were no peaks visible for additional impurity phases, demonstrating that the product was extremely pure.…”

“…Among them, cobalt oxide (Co 3 O 4 ) has a high specific capacitance (3560 Fg −1 ), and its electrochemical performance is primarily determined by the structural morphology and electronic state (Co 3+ or Co 2+ ) of the material. Furthermore, Co 3 O 4 is easy to synthesize, and various synthetic methods, including hydrothermal [24], coprecipitation [25], and sol-gel reactions [26], have been employed to develop various forms of Co 3 O 4 nanocomposites used to improve sensor performance, lithium-ion batteries, catalytic materials, and supercapacitors [27].…”

Investigating the large signal phenomenon in single photo-electron measurements of the 20-inch MCP-PMT

“…For PANDA experiment and Belle II TOP counter, small sized MCP-PMTs also adopted [10,11]. For the 20-inch MCP-PMTs, many studies have been performed [12][13][14][15][16][17][18], but many are still ongoing [19,20]. One issue with further study needed is the large signal phenomenon (LSP), especially in single photoelectron (SPE) measurement with a few photons.…”

The time resolution improvement of Cherenkov-Radiator-Window Photomultiplier tube

“…Since 2009, our team has been conducting research on large-area 20-inch microchannel plate based photomultiplier tubes (MCP-PMTs) and successfully applied them in the Jiangmen Underground Neutrino Observatory (JUNO) [1][2][3][4].…”