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

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, ${\gamma }_{+}^{eff}$ was developed. The experimental results with visible-sensitive K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes, yielded ${\gamma }_{+}^{eff}$ - 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, ${\gamma }_{+}$, 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 ${\gamma }_{+}^{eff}$ and vacuum ${\gamma }_{+}$ IISEE coefficients, calculated to be $\sim$0.06, is the fraction of secondary electrons surmounted the backscattering in the gas media.

10 pages, 10 figures, for submission to J. Appl. Phys; (2009) accepted

References in corpus (3)

• Advances in Gaseous Photomultipliers
• Further progress in ion back-flow reduction with patterned gaseous hole-multipliers
• Advances in ion back-flow reduction in cascaded gaseous electron multipliers incorporating R-MHSP elements

Cited by in corpus (3)

• THGEM operation in Ne and Ne/CH4
• Further evaluation of a THGEM UV-photon detector for RICH - comparison with MWPC
• Measurement of the absolute Quantum Efficiency of Hamamatsu model R11410-10 photomultiplier tubes at low temperatures down to liquid xenon boiling point