Further study of electron multiplication in conventional continuous dynode electron multiplier

Abstract

Due to its configurability the continuous dynode is a promising candidate for an electron multiplier of a miniature photomultiplier tube. In order to further understand the repetitive multiplication process in a conventional continuous dynode structure and the dependence of multiplication performance on the secondary electron emission material property, we preformed a comparative study of electron multiplications in a micro-gap electron multiplier operated in linear mode for two different secondary electron emission materials, SiO/sub 2/ and Al/sub 2/O/sub 3/. All output pulse height distributions (PHD) measured under UV light excitation exhibit distinctive peaks and long negative-exponential tails as previously observed in a microchannel plate under similar experimental condition. An analysis of the PHD measured with SiO/sub 2/ films confirms a strong correlation between the PHD shape and the initial energy of secondary electrons generated in the first collision by an input particle with the secondary electron emission surface. Direct comparison of the PHDs measured with SiO/sub 2/ and Al/sub 2/O/sub 3/ films, respectively, reveals that higher secondary electron yield of Al/sub 2/O/sub 3/ material influences mainly the peak region of the PHD leaving the average pulse height mostly unchanged. We concluded that it is necessary to modify the geometry of a conventional continuous dynode electron multiplier to fully reap the benefit of a new material with enhanced secondary electron emission characteristic.