Light mixers

The role of the light mixer is to mix the light coming from the fibres so that there is no correlation between the position of a fibre and the area of the photocathode which receives its light. A look at a drawing of a light mixer?

Below is the response of a R5900 PMT without and with a light mixer as a function of the fibre position:

PMT response without a light mixer

PMT response with a light mixer

These plots under ps files: without and with a light mixer