RCU2 — The ALICE TPC readout electronics consolidation for Run2

Alme, J.; Alt, T.; Bratrud, L.; Christiansen, P.; Costa, F.; David, E.; Gunji, T.; Kiss, T.; Langoy, R.; Lien, J.; Lippmann, C.; Öskarsson, A.; Rehman, A.; Røed, K.; Röhrich, D.; Tarantola, A.; Torgersen, C.; Torsvik, I Nikolai; Ullaland, K.; Velure, A.; Zhao, C.; Appelshäuser, H.; Österman, L.

doi:10.1088/1748-0221/8/12/c12032

Cited by 13 publications

(16 citation statements)

References 16 publications

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“…After the LHC Run 1, that lasted to the beginning of 2013, parts of the ALICE detector were upgraded for LHC Run 2, which started in 2015. The most important change was the upgrade of the TPC readout electronics, employing a new version of the Readout Control Unit (RCU2) [16] which uses the updated optical link speed of 3.125 Gbps instead of the previous readout rate of 2.125 Gbps. The upgrades, along with an improved TPC readout scheme, doubled the theoretical maximum TPC readout data rate to 48 GB/s, thus allowing ALICE to record twice as many events.…”

Section: From Lhc Run 1 Commissioning To Lhc Run 2 Upgradesmentioning

confidence: 99%

Real-time data processing in the ALICE High Level Trigger at the LHC

2019

Computer Physics Communications

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At the Large Hadron Collider at CERN in Geneva, Switzerland, atomic nuclei are collided at ultrarelativistic energies. Many final-state particles are produced in each collision and their properties are measured by the ALICE detector. The detector signals induced by the produced particles are digitized leading to data rates that are in excess of 48 GB/s. The ALICE High Level Trigger (HLT) system pioneered the use of FPGA-and GPU-based algorithms to reconstruct charged-particle trajectories and reduce the data size in real time. The results of the reconstruction of the collision events, available online, are used for high level data quality and detector-performance monitoring and real-time time-dependent detector calibration. The online data compression techniques developed and used in the ALICE HLT have more than quadrupled the amount of data that can be stored for offline event processing.

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Section: From Lhc Run 1 Commissioning To Lhc Run 2 Upgradesmentioning

confidence: 99%

Real-time data processing in the ALICE High Level Trigger at the LHC

2019

Computer Physics Communications

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“…The ALICE time projection chamber (TPC) readout was upgraded from the readout controlu unit 1 (RCU1) to RCU2 technology [1] using detector data links version 2 (DDL2) links [2] approximately doubling the maximum data throughput compared to Run 1. The data input and output in the HLT is handled by the readout receiver card (C-RORC) [3], see figure 1.…”

Section: Consolidation In the New Readout Systemmentioning

confidence: 99%

ALICE HLT Run 2 performance overview.

Krzewicki¹,

Lindenstruth²

2017

J. Phys.: Conf. Ser.

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Abstract. For the LHC Run 2 the ALICE HLT architecture was consolidated to comply with the upgraded ALICE detector readout technology. The software framework was optimized and extended to cope with the increased data load. Online calibration of the TPC using online tracking capabilities of the ALICE HLT was deployed. Offline calibration code was adapted to run both online and offline and the HLT framework was extended to support that. The performance of this schema is important for Run 3 related developments. An additional data transport approach was developed using the ZeroMQ library, forming at the same time a test bed for the new data flow model of the O 2 system, where further development of this concept is ongoing. This messaging technology was used to implement the calibration feedback loop augmenting the existing, graph oriented HLT transport framework. Utilising the online reconstruction of many detectors, a new asynchronous monitoring scheme was developed to allow real-time monitoring of the physics performance of the ALICE detector, on top of the new messaging scheme for both internal and external communication. Spare computing resources comprising the production and development clusters are run as a tier-2 GRID site using an OpenStack-based setup. The development cluster is running continuously, the production cluster contributes resources opportunistically during periods of LHC inactivity.

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“…With 68 pads in the innermost row of partition 0, pads 0 to 33 belong to branch A while pads 34 to 67 belong to branch B. Interleaved readout means that samples first come from pad 0, then pad 34, followed by pad 1, then pad 35 and so on. The second generation of RCU boards installed early 2016 provide sufficient buffering capabilities to provide the data from all pads in numerical order and with a bandwidth of up to around 310 MB/s [13].…”

Section: Tpc Hardware Cluster Findingmentioning

confidence: 99%

FPGA based data processing in the ALICE High Level Trigger in LHC Run 2

Engel

Kebschull

Alt

2017

J. Phys.: Conf. Ser.

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Abstract. The ALICE High Level Trigger (HLT) is a computing cluster dedicated to the online compression, reconstruction and calibration of experimental data. The HLT receives detector data via serial optical links into FPGA based readout boards that process the data on a per-link level already inside the FPGA and provide it to the host machines connected with a data transport framework. FPGA based data pre-processing is enabled for the biggest detector of ALICE, the Time Projection Chamber (TPC), with a hardware cluster finding algorithm. This algorithm was ported to the Common Read-Out Receiver Card (C-RORC) as used in the HLT for Run 2. It was improved to handle double the input bandwidth and adjusted to the upgraded TPC Readout Control Unit (RCU2). A flexible firmware implementation in the HLT handles both the old and the new TPC data format and link rates transparently. Extended protocol and data error detection, error handling and the enhanced RCU2 data ordering scheme provide an improved physics performance of the cluster finder. The performance of the cluster finder was verified against large sets of reference data both in terms of throughput and algorithmic correctness. Comparisons with a software reference implementation confirm significant savings on CPU processing power using the hardware implementation. The C-RORC hardware with the cluster finder for RCU1 data is in use in the HLT since the start of Run 2. The extended hardware cluster finder implementation for the RCU2 with doubled throughput is active since the upgrade of the TPC readout electronics in early 2016.

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RCU2 — The ALICE TPC readout electronics consolidation for Run2

Cited by 13 publications

References 16 publications

Real-time data processing in the ALICE High Level Trigger at the LHC

Real-time data processing in the ALICE High Level Trigger at the LHC

ALICE HLT Run 2 performance overview.

FPGA based data processing in the ALICE High Level Trigger in LHC Run 2

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