Proposal for Level-2 Calorimeter Trigger Upgrade

The current CDF Run II Level-2 calorimeter trigger is implemented in hardware and is based on a simple clustering algorithm that was used in Run I. The global transverse energy information is directly passed from Level 1, a strategy that was chosen 25 years ago for a much lower luminosity. This system has worked well for Run II at low luminosity. However, as the Tevatron instantaneous luminosity increases, the limitations due to the simple algorithm have started to become clear. As a result, some of the most important jet and MET related triggers have large growth terms in cross section and already dominate the L2 accept bandwidth at the highest luminosity seen so far ( 180◊1030 cm 2s 1). If not taken care of, they will cause large DAQ deadtime at higher luminosity, and will jeopardize the CDF Run IIb physics program. In this proposal, we will present an upgrade to the L2CAL system which makes the full calorimeter trigger tower information directly available to the L2 decision CPU using Pulsar boards. The upgraded system allows more sophisticated algorithms to be implemented in software; both L2 jets and MET can be made nearly equivalent to oine quality, thus significantly improving the purity as well as the eciency of the jet and MET related triggers. This is a natural expansion of the already-upgraded L2 trigger system, and is a big step forward to improve the CDF triggering capability at Level 2. We foresee many opportunities for additional improvements in trigger purity and eciency, most notably for Higgs and exotics triggers, with such information available at Level 2 as dijet mass, between jets or between a jet and 6 ET, sum ET of the clusters (HT), and the possibility of better jet-SVT matching for b-jets.