Clusters of topologically connected calorimeter cells around cells with large absolute signal-to-noise ratio (topo-clusters) are the basis for calorimeter signal reconstruction in the ATLAS experiment. Topological cell clustering has proven performant in LHC Runs 1 and 2. It is, however, susceptible to out-of-time pile-up of signals from soft collisions outside the 25 ns proton-bunch-crossing window associated with the event’s hard collision. To reduce this effect, a calorimeter-cell timing criterion was added to the signal-to-noise ratio requirement in the clustering algorithm. Multiple versions of this criterion were tested by reconstructing hadronic signals in simulated events and Run 2 ATLAS data. The preferred version is found to reduce the out-of-time pile-up jet multiplicity by ∼50% for jet pT∼20 GeV and by ∼80% for jet pT≳50 GeV, while not disrupting the reconstruction of hadronic signals of interest, and improving the jet energy resolution by up to 5% for 20<30 GeV. Pile-up is also suppressed for other physics objects based on topo-clusters (electrons, photons, τ-leptons), reducing the overall event size on disk by about 6% in early Run 3 pile-up conditions. Offline reconstruction for Run 3 includes the timing requirement.

Improving topological cluster reconstruction using calorimeter cell timing in ATLAS / Zwalinski, L., Zou, W., Zormpa, O., Zorbas, T.G., Zoch, K., Zoccoli, A., Zivkovic, L., Ziolkowski, M., Zinsser, J., Zimine, N.I., Zhulanov, V., Zhukov, K., Zhuang, X., Zhu, Y., Zhu, Y., Zhu, J., Zhu, C.G., Zhou, Y., Zhou, N., Zhou, H., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 84:5(2024). [10.1140/epjc/s10052-024-12657-1]

Improving topological cluster reconstruction using calorimeter cell timing in ATLAS

Ricci E.;Mascione D.;Iuppa R.;Follega F. M.;Di Luca A.;Cristoforetti M.;
2024-01-01

Abstract

Clusters of topologically connected calorimeter cells around cells with large absolute signal-to-noise ratio (topo-clusters) are the basis for calorimeter signal reconstruction in the ATLAS experiment. Topological cell clustering has proven performant in LHC Runs 1 and 2. It is, however, susceptible to out-of-time pile-up of signals from soft collisions outside the 25 ns proton-bunch-crossing window associated with the event’s hard collision. To reduce this effect, a calorimeter-cell timing criterion was added to the signal-to-noise ratio requirement in the clustering algorithm. Multiple versions of this criterion were tested by reconstructing hadronic signals in simulated events and Run 2 ATLAS data. The preferred version is found to reduce the out-of-time pile-up jet multiplicity by ∼50% for jet pT∼20 GeV and by ∼80% for jet pT≳50 GeV, while not disrupting the reconstruction of hadronic signals of interest, and improving the jet energy resolution by up to 5% for 20<30 GeV. Pile-up is also suppressed for other physics objects based on topo-clusters (electrons, photons, τ-leptons), reducing the overall event size on disk by about 6% in early Run 3 pile-up conditions. Offline reconstruction for Run 3 includes the timing requirement.
2024
5
Zwalinski, L.; Zou, W.; Zormpa, O.; Zorbas, T. G.; Zoch, K.; Zoccoli, A.; Zivkovic, L.; Ziolkowski, M.; Zinsser, J.; Zimine, N. I.; Zhulanov, V.; Zhuk...espandi
Improving topological cluster reconstruction using calorimeter cell timing in ATLAS / Zwalinski, L., Zou, W., Zormpa, O., Zorbas, T.G., Zoch, K., Zoccoli, A., Zivkovic, L., Ziolkowski, M., Zinsser, J., Zimine, N.I., Zhulanov, V., Zhukov, K., Zhuang, X., Zhu, Y., Zhu, Y., Zhu, J., Zhu, C.G., Zhou, Y., Zhou, N., Zhou, H., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 84:5(2024). [10.1140/epjc/s10052-024-12657-1]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/428870
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