Large-scale real-time signal processing in physics experiments: the ALICE TPC FPGA pipeline

The ALICE TPC collaboration

doi:10.1088/1748-0221/21/04/P04013

Large-scale real-time signal processing in physics experiments: the ALICE TPC FPGA pipeline

The ALICE TPC collaboration

Research output: Contribution to journal › Article › peer-review

Abstract

For LHC Run 3, the ALICE Time Projection Chamber was upgraded to operate in continuous readout mode. Interaction rates of up to 50 kHz in Pb-Pb collisions require real-time processing of more than 3 TB s^-1 of raw detector data. This requirement is met by a custom FPGA-based processing pipeline that performs the complete front-end data treatment fully in-stream, including common-mode correction, pedestal subtraction, ion-tail filtering, zero suppression, and dense data packing. A central element of the design is a highly parallel common-mode correction algorithm operating directly on the streaming data. It robustly identifies signal-free readout channels on a time-bin basis and applies pad-dependent scaling to compensate for local variations in capacitive coupling in the GEM readout. In combination with pedestal subtraction and ion-tail filtering, this enables accurate baseline restoration under extreme high-occupancy conditions, preventing signal loss while efficiently suppressing noise prior to zero suppression. The pipeline operates continuously at the full detector bandwidth and reduces the raw input rate of approximately 3 TB s^-1 to about 900 GBps for Pb-Pb collisions at the target interaction rate. Overall, it represents a large-scale FPGA-based real-time signal-processing implementation for high-energy physics detector readout.

Original language	English
Article number	P04013
Journal	Journal of Instrumentation
Volume	21
Issue number	4
DOIs	https://doi.org/10.1088/1748-0221/21/04/P04013
State	Published - Apr 1 2026

Funding

We gratefully acknowledge the central CRU team for their support, expertise, and valuable discussions. We extend special thanks to Filippo Costa for his dedicated assistance, commitment, and prompt responses to all our questions and requests. His contributions have been invaluable to this work. Furthermore, we acknowledges the following funding agencies for their support in the TPC Upgrade: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Brasil; Ministry of Science and Education, Croatia; The Danish Council for Independent Research | Natural Sciences, the Carlsberg Foundation and Danish National Research Foundation (DNRF), Denmark; Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF), GSI Helmholtzzentrum für Schwerionenforschung GmbH, DFG Cluster of Excellence “Origin and Structure of the Universe”, The Helmholtz International Center for FAIR (HIC for FAIR) and the ExtreMe Matter Institute EMMI at the GSI Helmholtzzentrum für Schwerionenforschung, Germany; National Research, Development and Innovation Office, Hungary; Nagasaki Institute of Applied Science (IIST) and the University of Tokyo, Japan; Fondo de Cooperación Internacional en Ciencia y Technología (FONCICYT), Mexico; The Research Council of Norway, Norway; Ministry of Science and Higher Education and National Science Centre, Poland; Ministry of Education and Scientific Research, Institute of Atomic Physics and Ministry of Research and Innovation, and Institute of Atomic Physics, Romania; Ministry of Education, Science, Research and Sport of the Slovak Republic, Slovakia; Swedish Research Council (VR), Sweden; United States Department of Energy, Office of Nuclear Physics (DOE NP), United States of America.

Keywords

Digital signal processing (DSP)
Electronic detector readout concepts (gas, liquid)
Time projection chambers
VLSI circuits

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10.1088/1748-0221/21/04/P04013

Cite this

@article{6cfebbaf468b42388cd82854e2cbc78d,

title = "Large-scale real-time signal processing in physics experiments: the ALICE TPC FPGA pipeline",

abstract = "For LHC Run 3, the ALICE Time Projection Chamber was upgraded to operate in continuous readout mode. Interaction rates of up to 50 kHz in Pb-Pb collisions require real-time processing of more than 3 TB s-1 of raw detector data. This requirement is met by a custom FPGA-based processing pipeline that performs the complete front-end data treatment fully in-stream, including common-mode correction, pedestal subtraction, ion-tail filtering, zero suppression, and dense data packing. A central element of the design is a highly parallel common-mode correction algorithm operating directly on the streaming data. It robustly identifies signal-free readout channels on a time-bin basis and applies pad-dependent scaling to compensate for local variations in capacitive coupling in the GEM readout. In combination with pedestal subtraction and ion-tail filtering, this enables accurate baseline restoration under extreme high-occupancy conditions, preventing signal loss while efficiently suppressing noise prior to zero suppression. The pipeline operates continuously at the full detector bandwidth and reduces the raw input rate of approximately 3 TB s-1 to about 900 GBps for Pb-Pb collisions at the target interaction rate. Overall, it represents a large-scale FPGA-based real-time signal-processing implementation for high-energy physics detector readout.",

keywords = "Digital signal processing (DSP), Electronic detector readout concepts (gas, liquid), Time projection chambers, VLSI circuits",

author = "\{The ALICE TPC collaboration\} and J. Alme and T. Alt and C. Andrei and V. Anguelov and H. Appelsh{\"a}user and M. Arslandok and R. Averbeck and M. Ball and Barnaf{\"o}ldi, \{G. G.\} and P. Becht and R. Bellwied and A. Berdnikova and B. Blidaru and L. Boldizs{\'a}r and L. Bratrud and P. Braun-Munzinger and M. Bregant and Britton, \{C. L.\} and H. B{\"u}sching and H. Caines and P. Chatzidaki and P. Christiansen and Cormier, \{T. M.\} and L. D{\"o}pper and R. Ehlers and L. Fabbietti and F. Flor and Gaardh{\o}je, \{J. J.\} and Munhoz, \{M. G.\} and C. Garabatos and P. Gasik and Gera and P. Gl{\"a}ssel and N. Gr{\"u}nwald and T. G{\"u}ndem and T. Gunji and H. Hamagaki and Harris, \{J. W.\} and P. Hauer and E. Hellb{\"a}r and H. Helstrup and A. Herghelegiu and \{Hernandez Herrera\}, \{H. D.\} and Y. Hou and C. Hughes and M. Ivanov and J. J{\"a}ger and Y. Ji and Read, \{K. F.\} and J. Schambach",

note = "Publisher Copyright: {\textcopyright} 2026 The Author(s)",

year = "2026",

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doi = "10.1088/1748-0221/21/04/P04013",

language = "English",

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T1 - Large-scale real-time signal processing in physics experiments

T2 - the ALICE TPC FPGA pipeline

AU - The ALICE TPC collaboration

AU - Alme, J.

AU - Alt, T.

AU - Andrei, C.

AU - Anguelov, V.

AU - Appelshäuser, H.

AU - Arslandok, M.

AU - Averbeck, R.

AU - Ball, M.

AU - Barnaföldi, G. G.

AU - Becht, P.

AU - Bellwied, R.

AU - Berdnikova, A.

AU - Blidaru, B.

AU - Boldizsár, L.

AU - Bratrud, L.

AU - Braun-Munzinger, P.

AU - Bregant, M.

AU - Britton, C. L.

AU - Büsching, H.

AU - Caines, H.

AU - Chatzidaki, P.

AU - Christiansen, P.

AU - Cormier, T. M.

AU - Döpper, L.

AU - Ehlers, R.

AU - Fabbietti, L.

AU - Flor, F.

AU - Gaardhøje, J. J.

AU - Munhoz, M. G.

AU - Garabatos, C.

AU - Gasik, P.

AU - Gera,

AU - Glässel, P.

AU - Grünwald, N.

AU - Gündem, T.

AU - Gunji, T.

AU - Hamagaki, H.

AU - Harris, J. W.

AU - Hauer, P.

AU - Hellbär, E.

AU - Helstrup, H.

AU - Herghelegiu, A.

AU - Hernandez Herrera, H. D.

AU - Hou, Y.

AU - Hughes, C.

AU - Ivanov, M.

AU - Jäger, J.

AU - Ji, Y.

AU - Read, K. F.

AU - Schambach, J.

PY - 2026/4/1

Y1 - 2026/4/1

N2 - For LHC Run 3, the ALICE Time Projection Chamber was upgraded to operate in continuous readout mode. Interaction rates of up to 50 kHz in Pb-Pb collisions require real-time processing of more than 3 TB s-1 of raw detector data. This requirement is met by a custom FPGA-based processing pipeline that performs the complete front-end data treatment fully in-stream, including common-mode correction, pedestal subtraction, ion-tail filtering, zero suppression, and dense data packing. A central element of the design is a highly parallel common-mode correction algorithm operating directly on the streaming data. It robustly identifies signal-free readout channels on a time-bin basis and applies pad-dependent scaling to compensate for local variations in capacitive coupling in the GEM readout. In combination with pedestal subtraction and ion-tail filtering, this enables accurate baseline restoration under extreme high-occupancy conditions, preventing signal loss while efficiently suppressing noise prior to zero suppression. The pipeline operates continuously at the full detector bandwidth and reduces the raw input rate of approximately 3 TB s-1 to about 900 GBps for Pb-Pb collisions at the target interaction rate. Overall, it represents a large-scale FPGA-based real-time signal-processing implementation for high-energy physics detector readout.

AB - For LHC Run 3, the ALICE Time Projection Chamber was upgraded to operate in continuous readout mode. Interaction rates of up to 50 kHz in Pb-Pb collisions require real-time processing of more than 3 TB s-1 of raw detector data. This requirement is met by a custom FPGA-based processing pipeline that performs the complete front-end data treatment fully in-stream, including common-mode correction, pedestal subtraction, ion-tail filtering, zero suppression, and dense data packing. A central element of the design is a highly parallel common-mode correction algorithm operating directly on the streaming data. It robustly identifies signal-free readout channels on a time-bin basis and applies pad-dependent scaling to compensate for local variations in capacitive coupling in the GEM readout. In combination with pedestal subtraction and ion-tail filtering, this enables accurate baseline restoration under extreme high-occupancy conditions, preventing signal loss while efficiently suppressing noise prior to zero suppression. The pipeline operates continuously at the full detector bandwidth and reduces the raw input rate of approximately 3 TB s-1 to about 900 GBps for Pb-Pb collisions at the target interaction rate. Overall, it represents a large-scale FPGA-based real-time signal-processing implementation for high-energy physics detector readout.

KW - Digital signal processing (DSP)

KW - Electronic detector readout concepts (gas, liquid)

KW - Time projection chambers

KW - VLSI circuits

UR - https://www.scopus.com/pages/publications/105036008938

U2 - 10.1088/1748-0221/21/04/P04013

DO - 10.1088/1748-0221/21/04/P04013

M3 - Article

AN - SCOPUS:105036008938

SN - 1748-0221

VL - 21

JO - Journal of Instrumentation

JF - Journal of Instrumentation

IS - 4

M1 - P04013

ER -

Large-scale real-time signal processing in physics experiments: the ALICE TPC FPGA pipeline

Abstract

Funding

Keywords

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