Abstract
In Run 3, the ATLAS Level-1 Calorimeter Trigger will be augmented by an Electron Feature Extractor (eFEX), to identify isolated e/γ and τ particles, and a Jet Feature Extractor (jFEX), to identify energetic jets and calculate various local energy sums. Each module accommodates more than 450 differential signals that can operate at up to 12.8 Gb/s, some of which are routed over 30 cm between FPGAs. Here we present the module designs, the processes that have been adopted to meet the challenges associated with multi-Gb/s PCB design, and the results of tests that characterize the performance of these modules.
Highlights
Extractor, to identify energetic jets and calculate various local energy sums
The Phase-I upgrade of L1Calo includes the Tile Rear Extension (TREX) to the Pre-Processor (PPr) subsystem, which digitizes Tile data and transmits them to the FEXs optically, the Fibre Optical Exchange (FOX), and the FEX Test Module (FTM), which facilitates the testing of FEX modules before system-level commissioning
The Jet Feature Extractor (jFEX) improves on the performance of the Jet Energy Processor (JEP) by a number of means
Summary
In the current L1Calo system, the CP processes data from the calorimeters and identifies energy deposits characteristic of isolated e/γ and particles, using Trigger Towers of typical granularity of 0.1 × 0.1 (η × φ). The jFEX improves on the performance of the JEP by a number of means It receives higher-granularity calorimeter data (0.1×0.1 (η×φ) rather than. It shows how the turnon curves of the jFEX are sharper – a fact that can be used to raise the trigger thresholds without losing efficiency, leading to rate reductions similar to the eFEX
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