CMS Calorimeter Level 1 Regional Trigger Conceptual Design

The CMS level-1 calorimeter trigger electronics is designed to identify signatures for high-energy electrons, photons, neutrinos and jets. The calorimeter regional trigger system receives and processes digital serial data transmitted from the nearby calorimeter readout electronics on copper cables. This system consists of 19 calorimeter processor crates covering the full calorimeter. Eighteen crates are dedicated to the barrel and two endcaps. The remaining crate covers both forward calorimeters. Each calorimeter regional crate transmits to the calorimeter global trigger processor its sum Et, Ex and Ey. It also sends its 4 highest-ranked isolated and non-isolated electrons and 4 highest energy jets along with information about their location. The global calorimeter trigger then sums the energies and sorts the electrons and jets and forwards the top four calorimeter-wide isolated and non-isolated electrons and jets, as well as the total calorimeter missing and sum Et to the CMS global trigger.