Allen: A high level trigger on GPUs for LHCb

R. Aaij; J. Albrecht; M. Belous; P. Billoir; T. Boettcher; A. Brea Rodríguez; D. vom Bruch; D. H. Cámpora Pérez; A. Casais Vidal; D. C. Craik; P. Fernandez Declara; L. Funke; V. V. Gligorov; B. Jashal; N. Kazeev; D. Martínez Santos; F. Pisani; D. Pliushchenko; S. Popov; R. Quagliani; M. Rangel; F. Reiss; C. Sánchez Mayordomo; R. Schwemmer; M. Sokoloff; H. Stevens; A. Ustyuzhanin; X. Vilasís Cardona; M. Williams

doi:10.1007/s41781-020-00039-7

Home/Archive/arXiv

arXiv · 1912.09161

Allen: A high level trigger on GPUs for LHCb

View original source ↗Read source document ↗Export metadata ↓

Abstract

We describe a fully GPU-based implementation of the first level trigger for the upgrade of the LHCb detector, due to start data taking in 2021. We demonstrate that our implementation, named Allen, can process the 40 Tbit/s data rate of the upgraded LHCb detector and perform a wide variety of pattern recognition tasks. These include finding the trajectories of charged particles, finding proton-proton collision points, identifying particles as hadrons or muons, and finding the displaced decay vertices of long-lived particles. We further demonstrate that Allen can be implemented in around 500 scientific or consumer GPU cards, that it is not I/O bound, and can be operated at the full LHC collision rate of 30 MHz. Allen is the first complete high-throughput GPU trigger proposed for a HEP experiment.

Explore related subjects

physics.ins-det hep-ex

Keep this discovery

BibTeX RIS

R. Aaij, J. Albrecht, M. Belous, P. Billoir, T. Boettcher, A. Brea Rodríguez, D. vom Bruch, D. H. Cámpora Pérez, A. Casais Vidal, D. C. Craik, P. Fernandez Declara, L. Funke, V. V. Gligorov, B. Jashal, N. Kazeev, D. Martínez Santos, F. Pisani, D. Pliushchenko, S. Popov, R. Quagliani, M. Rangel, F. Reiss, C. Sánchez Mayordomo, R. Schwemmer, M. Sokoloff, H. Stevens, A. Ustyuzhanin, X. Vilasís Cardona, M. Williams. 2019-12-19. Allen: A high level trigger on GPUs for LHCb. https://doi.org/10.1007/s41781-020-00039-7

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

High-Speed Semi-FE Readout Module for ATLAS MDT at HL-LHC: Design and Production-Level Characterization

The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) introduces increased demands on the ATLAS Muon Spectrometer, particularly in terms of data throughput, timing distribution and system reliability. The Phase-II Chamber Service Module (CSM) is a key component of the upgraded Monitored Drift Tube (MDT) trigger and readout system, providing a high-speed interface between the front-end electronics and the backend systems. This paper describes the design and implementation of the Phase-II CSM, together with its validation. The results show that the CSM supports two independent optical uplinks, each operating at a line rate of 10.24 Gbps, together with clock distribution and slow control in the expected operating environment. Integration with small-diameter MDT (sMDT) chambers and tests with the prototype L0MDT trigger system are also presented. The CSM boards are now in production and will be used for installation and integration during the upcoming LHC Long Shutdown.

physics.ins-det↗

arXiv2026

Spectral Discrimination of Deposited Gamma-Ray Energies in a Simulated CeBr$_3$ Scintillator

We show that wavelength measurements of individual detected optical photons may provide additional information about gamma-ray energy deposited in a CeBr$_3$ crystal when the detected-photon-count distributions overlap for nearby gamma-ray energies. Monoenergetic 662 and 629 keV gammas are used in a Geant4 simulation of a $25\times25\times20~\mathrm{mm^3}$ CeBr$_3$ crystal. Assuming a light yield of $6.0\times10^4$ photons/MeV, a wavelength-independent photon-detection efficiency of 30%, and a wavelength resolution of $\sigma_{\lambda}=40$ nm, we find that the fraction of photons reconstructed above 385 nm gives an event-level separation of $\sim$ 2 standard deviations between the 662 and 629 keV event populations selected within the same $\sim$ 1%-wide detected-photon-count interval. No timing or reconstructed interaction-position information is used. The result demonstrates, within the present simulation model, that event-dependent optical spectra can retain energy information beyond an undifferentiated photon count.

physics.ins-det↗

arXiv2026

Operation of a negative ion gas time projection chamber without electronegative fill gases

The high fidelity reconstruction of particle tracks in micropatterned gaseous time projection chambers renders this technology ideal for future rare-event searches, including direction-sensitive dark matter experiments. Large drift distances are typically required for such experiments, so that the overall spatial resolution is limited by diffusion. Negative ion drift exhibits lower diffusion than electron drift and is thus an attractive option for realising a large-scale detector. The use of electronegative gases to create negative ions introduces technical challenges, most notably a reduction in gain when compared to conventional gas mixtures. In this study, we demonstrate a new method for negative ion generation via dissociative electron attachment using the conventional molecular fill gas CF$_4$. Our optical measurements of negative ion drift indicate electron attachment lengths of $<$1 mm and comparable gain to electron avalanches. The individual negative ion avalanches were also time-resolved, allowing the number of ions reaching the readout to be counted. We measure an improved energy resolution by single ion counting, relative to an integrated electron avalanche signal measured under identical gain conditions.

physics.ins-det↗