High-sensitivity K-Na-Cs-Sb reflective multi-alkali photocathode and preparation method and system thereof

Abstract

The invention belongs to the technical field of photomultipliers, particularly relates to a photocathode, and discloses a high-sensitivity K-Na-Cs-Sb reflective multi-alkali photocathode and a preparation method and system thereof. The alkali source assembly comprises three alkali sources, namely a K source, a Na source and a Cs source. The alkali source assembly is connected with the exhaust table through a tail pipe to obtain an ultrahigh vacuum degree. The side window type photomultiplier comprises a glass shell, a cathode and a plurality of multipliers. The cathode and the multipliers areconfigured to be metal sheets with certain radians, and the inner surfaces of the cathode and the multipliers are plated with metal antimony layers. The side window type photomultiplier is connected to the alkali source assembly through an exhaust tail pipe. The corresponding alkali source applies current to realize self-heating, and releases alkali metal vapor to react with the antimony layer toform a multi-alkali cathode structure. The introduction process of K, Na and Cs is monitored by monitoring changes of leakage current and photocurrent, the introduction amount of K, Na and Cs is accurately controlled, and the problem that the cathode sensitivity is low due to the fact that too much or too little K, Na and Cs are introduced is solved.

Description

Technical field [0001] The invention belongs to the technical field of photocathodes, and specifically relates to a high-sensitivity K-Na-Cs-Sb reflective multi-alkali photocathode for side-window photomultiplier tubes and a preparation method thereof. Background technique [0002] The photocathode, especially the photocathode used in vacuum optoelectronic devices such as photomultiplier tubes, is a device used to capture photons incident from the outside and excite photoelectrons based on the external photoelectric effect. In vacuum optoelectronic devices such as photomultiplier tubes, the conversion of radiation signals of different wavelengths into electrical signals is achieved by the photocathode. Commonly used photocathodes mainly include double-alkali cathodes and multi-alkali cathodes, which are used to complement the same type of entire tube. [0003] Reflective multi-alkali photocathode is a kind of photoemission material commonly used in side-window photomultiplier tube...

AI Technical Summary

Problems solved by technology

Therefore, in the experimental stage, we realized the control of the three stages of K, Na, and Cs by monitoring the photocurrent and reflectivity to control the evaporation of the film layer, but in the mass production process, we found that due to the above photocurrent Extremely small and inconspicuous changes, especially in the process of introducing Cs and K, the photocurrent is extremely small, and the process of introducing Na is due to the slow reaction, which makes it difficult to pass the photocurrent to reflective multi-alkali cathode K in the mass production process. , Na, Cs activation process is accurately monitored, and even in some stages of activation, the photocurrent monitoring will be completely ineffective, and the monitoring effect cannot be achieved

This leads to the use of photoelectric monitoring cathodes with low sensitivity or even no sensitivity

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