A general scheme for optimization of trigger rates in an experiment with limited bandwidth

Modern, general purpose high energy physics experiments are designed to record the events of physics processes which greatly differ in rate. Both rare signatures with trigger rates of order 1 Hz and minimum bias interactions with rates sometimes approaching 1 MHz have to be triggered at the same time. The typical means of accommodating these requirements within a limited bandwidth is to downscale individual trigger channels appropriately. This paper describes a novel procedure for finding an optimized set of downscale factors that automatically adapts to the beam conditions. A first application at the H1 experiment at HERA showed that the number of events recorded for specific channels could be significantly increased.