Using Feedback to Control Deadtime in the CDF Trigger System

The CDF experiment uses a three-level trigger system to select events produced during pp macr collisions. As the luminosity of the Tevatron accelerator falls by a factor of four over a 24 hour period, trigger selections are adjusted automatically in order to make full use of the data processing bandwidth. The selections are made to maximize high purity triggers and keep the deadtime as low as possible at any given luminosity thoughout the entire course of a run. We describe the algorithms used to obtain these goals and how the changing conditions are accounted for in the analysis of the data.