Software-based data acquisition system for Level-1 end-cap muon trigger in ATLAS Run-3

In 2019, the ATLAS experiment at CERN is planning an upgrade in order to cope with the higher luminosity requirements. In this upgrade, the installation of the new muon chambers for the end-cap muon system will be carriedout. Muon track reconstruction performance can be improved, and fake triggers can be reduced. It is also necessary to develop readout system of trigger data for the Level-1 end-cap muon trigger.
We have decided to develop software-based data acquisition system. There-fore, we have implemented SiTCP technology, which connects a FPGA with the network, on the FPGA of new trigger processor boards.
Due to this implementation, the new DAQ system can take advantage of the latest developments in computing industry. This new readout system architec-ture is based on multi-process software, and can assemble events at a rate of 100 kHz. For data collection, the 10 Gbit Ethernet network switch is used. Moreover, we have optimized these processes to send data to the following sys-tem without any error. Therefore, the built events can be sent with an average throughput of approximately 211 Mbps.
Our newly developed readout system is very generic and it is flexible for modi-fications, extensions and easyto debug. This paper will present the details of the new software-based DAQ system and report the development status for ATLAS Run-3.


Region Of Interest
The ATLAS detector is nominally forward-backward symmetric with respect to the interaction point.The magnet configuration comprises a thin superconducting solenoid surrounding the inner-detector cavity, and three large superconducting toroids (one barrel and two end-caps) arranged with an eight-fold azimuthal symmetry around the calorimeters.This fundamental choice has driven the design of the rest of the detector.
The inner detector is immersed in a 2 T solenoidal field.Pattern recognition, momentum and vertex measurements, and electron identification are achieved with a combination of discrete, high-resolution semiconductor pixel and strip detectors in the inner part of the tracking volume, and straw-tube tracking detectors with the capability to generate and detect transition radiation in its outer part.
High granularity liquid-argon (LAr) electromagnetic sampling calorimeters, with excellent performance in terms of energy and position resolution, cover the pseudorapidity range |h| < 3.2.The hadronic calorimetry in the range |h| < 1.7 is provided by a scintillator-tile calorimeter, which is separated into a large barrel and two smaller extended barrel cylinders, one on either side of the central barrel.In the end-caps (|h| > 1.5), LAr technology is also used for the hadronic calorimeters, matching the outer |h| limits of end-cap electromagnetic calorimeters.The LAr forward calorimeters provide both electromagnetic and hadronic energy measurements, and extend the pseudorapidity coverage to |h| = 4.9.
The calorimeter is surrounded by the muon spectrometer.The air-core toroid system, with a long barrel and two inserted end-cap magnets, generates strong bending power in a large volume within a light and open structure.Multiple-scattering effects are thereby minimised, and excellent muon momentum resolution is achieved with three layers of high precision tracking chambers.The ATLAS detector is nominally forward-backward symmetric with respect to the interaction point.The magnet configuration comprises a thin superconducting solenoid surrounding the inner-detector cavity, and three large superconducting toroids (one barrel and two end-caps) arranged with an eight-fold azimuthal symmetry around the calorimeters.This fundamental choice has driven the design of the rest of the detector.
The inner detector is immersed in a 2 T solenoidal field.Pattern recognition, momentum and vertex measurements, and electron identification are achieved with a combination of discrete, high-resolution semiconductor pixel and strip detectors in the inner part of the tracking volume, and straw-tube tracking detectors with the capability to generate and detect transition radiation in its outer part.
High granularity liquid-argon (LAr) electromagnetic sampling calorimeters, with excellent performance in terms of energy and position resolution, cover the pseudorapidity range |h| < 3.2.The hadronic calorimetry in the range |h| < 1.7 is provided by a scintillator-tile calorimeter, which is separated into a large barrel and two smaller extended barrel cylinders, one on either side of the central barrel.In the end-caps (|h| > 1.5), LAr technology is also used for the hadronic calorimeters, matching the outer |h| limits of end-cap electromagnetic calorimeters.The LAr forward calorimeters provide both electromagnetic and hadronic energy measurements, and extend the pseudorapidity coverage to |h| = 4.9.
The calorimeter is surrounded by the muon spectrometer.The air-core toroid system, with a long barrel and two inserted end-cap magnets, generates strong bending power in a large volume within a light and open structure.Multiple-scattering effects are thereby minimised, and excellent muon momentum resolution is achieved with three layers of high precision tracking chambers.☞ it is flexible for modifications.☞ it is easy to debug.
❖ SROD can take advantage of the latest developments in computing industry.❖ Collector processes: ■ The total number of processes is 13.■ collect data from each electronics.
• The number of these processes equal to the number of boards.
■ write it to the subsequent shared memory.❖ Ring buffer: ■ The total number of memories is 13.■ is the shared memory to absorb arrival delays.
• The number of the share memory equal to the number of the collector processes.
■ has control parameters.
• The collector processes check this parameter when they write data to this buffer.❖ Event builder process: ■ builds an event.
• Read data from the ring buffers • Check the IDs ■ sends it to ROS.
• By using the special PCIe card.❖ MsgReporter process: ■ collects messages from each process and post it to the ATLAS message reporting system.
❖ RunControlDriver process: ■ to synchronize the process sequence with the central system SROD: Multi-process architecture

Figure 1 . 1 :
Figure 1.1: Cut-away view of the ATLAS detector.The dimensions of the detector are 25 m in height and 44 m in length.The overall weight of the detector is approximately 7000 tonnes.

Figure 1 . 1 :
Figure 1.1: Cut-away view of the ATLAS detector.The dimensions of the detector are 25 m in height and 44 m in length.The overall weight of the detector is approximately 7000 tonnes.

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Thanks to the software-based system:

❖μ❖μ❖
Endcap muon trigger logic boards calculate muon p T. ■ Send the results to Central Trigger Processor.❖ Endcap Level-1 Muon Trigger and Readout System 5 ATLAS Muon Desk Shifter Training -General Introduction 2 L A S Mu o n S p e c t r o me t e r Sub-systems: CSC -Cathode Strip Chambers MDT -Monitored Drift Tubes RPC -Resistive Plate Chambers TGC -Magnetic fields bends the track (For example, 1.03 < |η| < 1.9) CHEP2018 Kosuke Takeda (Kobe University) ❖ Level-1 trigger decision is done by CTP.To record raw data related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.Data size ~ 2000 bit/event/board (For example, 1.03 < |η| < 1.9) Central trigger processor ❖ To record raw data related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.× 12 Sync-signal distributor × 1 SROD × 1 is for 1/6 endcap muon system.(For example, 1.03 < |η| < 1.9) CHEP2018 Kosuke Takeda (Kobe University) ❖ To record the hit information related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.To record the hit information related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.

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To record the hit information related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.

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To record the hit information related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.

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To record the hit information related to the Level-1 trigger ■ Each board sends the hit information to SROD via Ethernet.