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arXiv · 0904.4881

Ion-induced secondary electron emission from K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes and its relevance to the operation of gaseous avalanche photomultipliers

A. Lyashenko·A. Breskin·R. Chechik·T. H. V. T. Dias
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Abstract

The operation of visible-sensitive gaseous- and, to some extent, vacuum-photomultipliers is critically affected by secondary electrons originating from ion impact on the photocathode. A simple method for indirect measurement of the effective ion-induced secondary-electron emission (IISEE) coefficient from the photocathode into a gas medium, $γ_+^{eff}$ was developed. The experimental results with visible-sensitive K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes, yielded $γ_+^{eff}$ - values between 0.02 and 0.03 in Ar/CH$_{4}$ (95/5) at 700 mbar; these are in good agreement with theoretical calculations. The corresponding vacuum IISEE coefficients, $γ_+$, were estimated, based on a theoretical model, to be 0.47, 0.49 and 0.47 for K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes, respectively. The ratio of gas $γ_+^{eff}$ and vacuum $γ_+$ IISEE coefficients, calculated to be $\sim$0.06, is the fraction of secondary electrons surmounted the backscattering in the gas media.

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A. Lyashenko, A. Breskin, R. Chechik, T. H. V. T. Dias. 2009-04-30. Ion-induced secondary electron emission from K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes and its relevance to the operation of gaseous avalanche photomultipliers. https://doi.org/10.1063/1.3197063

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