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Optical properties of bialkali photocathodes

Dario Motta·Stefan Schoenert
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Abstract

The optical properties of the `bialkali' KCsSb and RbCsSb photomultiplier cathodes have been experimentally investigated in the visible range. The measurements carried out include the absolute reflectance at near-normal incidence, the polarization-dependent relative reflectance at various angles and the change in polarization upon reflection from the photocathode. These experimental inputs have been combined with a theoretical model to determine the complex refractive index of the photocathodes in the wavelength range 380 to 680 nm and their thickness. As a result of this work, we derive a model which predicts the fraction of light impinging on a photomultiplier tube that is reflected, absorbed or transmitted, as a function of wavelength and angle, and dependent on the medium to which the photomultiplier is coupled.

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Dario Motta, Stefan Schoenert. 2004-08-17. Optical properties of bialkali photocathodes. https://doi.org/10.1016/j.nima.2004.10.009

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