An electrostatic focusing microchannel plate photomultiplier tube

Abstract

Disclosed is a photomultiplier of electrostatic focusing micro-channel plates. The photomultiplier comprises a photocathode, an electron multiplier, an anode, a focusing electrode, a power supply electrode and a support post supporting the focusing electrode, the electron multiplier and the anode; the focusing electrode, the electron multiplier and the anode are arranged in a glass vacuum container, and a signal lead of the anode and the power supply electrode penetrate through the glass vacuum container to be connected with an external circuit. The photomultiplier is characterized in that the focusing electrode, the electron multiplier and the anode are centrally coaxial; the electron multiplier consists of two pairs of micro-channel plates arranged in parallel and having a certain gap therebetween. Compared with the prior art, high gains and good single photoelectron spectra are realized by independently regulating the voltages of micro-channel plate assemblies at all levels.

Description

technical field [0001] The invention relates to a vacuum photodetection device, specifically a photomultiplier tube, especially a photomultiplier that focuses photoelectrons generated by a large-size photocathode on an electron multiplier composed of a microchannel plate assembly through an electrostatic focusing electrode Tube. [0002] technical background [0003] As a photomultiplier tube (PMT) that converts weak optical signals into electrical signals, it is widely used in various fields of the national economy because of its high sensitivity and fast time response. Judging from the development direction of current applications, one is miniaturization, and the other is giantization. The latter will play an irreplaceable role in the detection of neutrinos in high-energy physics. Hamamatsu Photonics Co., Ltd. of Japan and Photonis Company of France have successively developed 8-inch, 10-inch, 12-inch, 13-inch and 20-inch ellipsoidal or near-spherical photomultiplier tubes...

AI Technical Summary

Problems solved by technology

With the development of high-energy physics, its requirements for photodetectors are constantly increasing. First, because the coverage of the photocathode of the above-mentioned large-scale photomultiplier tube is not high, it is difficult to reach 80% if it is formed into an array. The design of the focusing electrode and the dynode, the photoelectrons coming from different directions, after passing through the focusing electrode and the dynode, the transit time distribution of the electrons becomes wider, which is not conducive to the accurate measurement of neutrinos

In recent years, the Argonne National Laboratory of the United States has jointly formed a cooperation group with relevant units of microchannel plate (MCP) and photocathode in the United States to develop a 200×200mm close-fit focusing microchannel plate photomultiplier tube (MCP-PMT). Cathode technology and ALD technology try to solve the above-mentioned difficulties faced by large-size photomultiplier tubes, but the technology is difficult and progress is slow

Scientists from the Institute of High Energy Physics of the Chinese Academy of Sciences proposed to make a photocathode that completely covers the inner surface of a spherical transparent vacuum container, place an MCP or similar electron multiplier in the center of the sphere, and use electron optics design to make photoelectrons from everywhere It can effectively hit the electron multiplier, and filed a patent application with the State Intellectual Property Office on June 10, 2009, and obtained the patent right on June 27, 2012 (name of invention: a photomultiplier tube, application number: 200910147915.4, authorized announcement number: CN101924007B), this patent proposes to make full use of the characteristics of the transmissive cathode and the reflective cathode for the first time, thereby improving the quantum efficiency of the photocathode, and adopting a reasonable electron optical design to ensure that the electron multiplier can collect nearly 4π Optoelectronics within a solid angle, but as far as it uses MCP as an electron multiplier, especially 2 to 3 blocks are directly connected in series as an electron multiplier. In actual production, it is difficult to clean and degas the electrons. After degassing, each MCP The resistance is unpredictable, and it is difficult to realize that each MCP is in the best working state. The direct series connection of two MCPs generally has a gain of ~10 5 magnitude, even with an amplifier, sometimes it is difficult to detect a single photoelectron

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