Speaker
Description
Future High Luminosity LHC runs introduce more simultaneous proton-proton collisions for the LHC experiments. The ATLAS Tile Calorimeter (TileCal) plans a replacement of the on- and off-detector electronics to meet the requirements for faster data processing. New off-detector electronics provide high-bandwidth data to the upgraded Trigger and Data Acquisition (TDAQ) system. The Tile Calorimeter Trigger and Data Acquisition Interface (TDAQi) as part of the TileCal PreProcessor serves as the connection between the calorimeter electronics and various subsystems of the trigger and read-out system. The TDAQi processes individual cell information into multiple trigger primitives of different granularity under strict latency requirements.
Summary (500 words)
The Phase-II Upgrade of ATLAS prepares the experiment to handle more simultaneous particle collisions delivered by the High Luminosity-Large Hadron Collider, a new phase of the LHC starting in 2030 delivering more than 5 times the instantaneous luminosity to its experiments compared to the LHC original design value. To utilize the higher amount of collisions for physics data while still keeping efficient triggers, ATLAS re-designs the complete trigger and readout architecture of its subsystems.
The ATLAS Tile Calorimeter is upgrading its entire on- and off-detector electronics by replacing them with modern components. Calorimeter cell information will be digitized at 40 MHz in the detector to utilize high-speed optical links to send the data to the off-detector TileCal PreProcessor for further data processing in a radiation free environment. The PreProcessor reconstructs the individual cell energies based on the digitized samples and calibrates their energy before further processing by the Tile Trigger and Data Acquisition interface (TDAQi).
The TDAQi is an ATCA rear transition module, connecting directly to the ATCA Carrierboard to receive the tile calorimeter cell energies at 9.6 Gbps through high-speed electrical links. The TDAQi as part of the TileCal PreProcessor builds trigger primitives which the ATLAS Trigger uses to identify candidates of physical objects. Depending on the individual object of interest the TDAQi builds different inputs to the first trigger level.
For calorimeter trigger objects like electrons and jets, multiple cells are summed by the TDAQi to large trigger objects of lower granularity to meet L0Calo input requirements. The highest energetic cells need to be identified, sorted by energy and a limited selection of them send to the Global Trigger Processor. Muon hits, as grouped cells of high granularity, are identified for L0Muon.
The high-connectivity of the TDAQi at different transmission speeds of 9.6 Gbps (to L0Muon and the read-out system) and 11.2 Gbps (to L0Calo and the Global Trigger Processor) necessitates careful design of the processing with maintaining information of the same event synchronous.
The calculation of the various trigger inputs at 40 MHz underlie strict timing constraints as the TDAQi is part of the real-time chain in ATLAS and has to fulfill low latency requirements. For processing and high transmission speeds up to 11.2 Gbps an AMD Kintex UltraScale+ FPGA hosting over 70 high-speed gigabit transceivers was chosen. Optimized information processing is critical as the latency required is 250ns including deserialization and serialization.
Parallel to the real-time chain, the TDAQi sends the calculated trigger inputs of accepted events to the read-out system of ATLAS upon a positive trigger decisions for individual events.
The TDAQi as part of the ATLAS Phase-II upgrade will be presented. Together with latest
hardware validation and integration tests, results with a custom hardware-based data generator supplying the TileCal PreProcessor with variable inputs will be shown. The latest pre-production version of the TDAQi assembled in-house will be discussed.