Studies of optical mixers for use with silicon photomultipliers to ameliorate signal saturation

We have been studying ways in which the light from several optical fibers that transmit light from scintillating tiles can be mixed and combined a single Silicon Photo Multiplier (SiPM). The purpose for mixing is to prevent a single high intensity fiber from saturating an area of the SiPM and thus causing an inaccurate reading of the overall light collected. In particular this is for use in detectors such as CMS HCAL 1, 2 where light is transmitted from scintillating tiles in 940,.m fibers to a single photo-detector. If one tile has a large optical signal it can saturate an area of the SiPM and produce a signal lower than would be expected, resulting in an in-accurate energy measurement. The results of the test and the test setup will be described.