Author/Authors :
Lees، نويسنده , , J.E and Fraser، نويسنده , , G.W. and Pearce، نويسنده , , S.E. and Pearson، نويسنده , , J.F. and Shchemelev، نويسنده , , V.N. and Pavlov، نويسنده , , A.P. and Shulakov، نويسنده , , A.S.، نويسنده ,
Abstract :
We describe the X-ray properties of alkali halide photocathodes subjected to post-evaporation thermal treatments. Measurements made in St. Petersburg on planar CsI photocathodes, over an X-ray energy range 5–10 keV, show up to a five-fold increase in current quantum yield χc (electrons/photon) after thermal annealing. Measurements were also made at Leicester on a microchannel plate (MCP) detector bearing thermally annealed CsI and KBr photocathodes. The MCP quantum efficiency Q (counts/photon) was measured, before and after annealing, at X-ray energies of 0.28, 1.74 and 2.56 keV. A small increase in quantum efficiency was observed at large angles of incidence for the annealed photocathodes. The heat-treated CsI coated MCP half also exhibited a much enhanced mean gain. Both planar photocathode and coated MCP measurements are interpreted with the aid of a semi-empirical photocathode model and scanning electron microscope (SEM) imagery.
