Use of optical filters to improve lead glass shower counter resolution

Abstract

At high energies an important contribution to the resolution of lead glass shower counters, viewed head-on by the phototube, involves the coupling between light attenuation by the glass and longitudinal shower fluctuations. This effect is dominated by the short wavelength end of the spectrum so that the appropriate use of optical filters in front of the photocathode can significantly reduce the effect with only a small loss of light. Results of tests performed with SF2 counters at the Fermilab are discussed. For our counters the resolution is reduced by typically a factor of 0.75.