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arXiv · 2504.13008

Reconstruction and Performance Evaluation of FASER's Emulsion Detector at the LHC

FASER Collaboration·Roshan Mammen Abraham·Xiaocong Ai·Saul Alonso Monsalve·John Anders·Claire Antel·Akitaka Ariga·Tomoko Ariga·Jeremy Atkinson·Florian U. Bernlochner·Tobias Boeckh·Jamie Boyd·Lydia Brenner·Angela Burger·Franck Cadou·Roberto Cardella·David W. Casper·Charlotte Cavanagh·Xin Chen·Kohei Chinone·Dhruv Chouhan·Andrea Coccaro·Stephane Débieu·Ansh Desai·Sergey Dmitrievsky·Radu Dobre·Monica D'Onofrio·Sinead Eley·Yannick Favre·Deion Fellers·Jonathan L. Feng·Carlo Alberto Fenoglio·Didier Ferrere·Max Fieg·Wissal Filali·Elena Firu·Haruhi Fujimori·Edward Galantay·Ali Garabaglu·Stephen Gibson·Sergio Gonzalez-Sevilla·Yuri Gornushkin·Carl Gwilliam·Daiki Hayakawa·Michael Holzbock·Shih-Chieh Hsu·Zhen Hu·Giuseppe Iacobucci·Tomohiro Inada·Luca Iodice·Sune Jakobsen·Hans Joos·Enrique Kajomovitz·Takumi Kanai·Hiroaki Kawahara·Alex Keyken·Felix Kling·Daniela Köck·Pantelis Kontaxakis·Umut Kose·Rafaella Kotitsa·Peter Krack·Susanne Kuehn·Thanushan Kugathasan·Lorne Levinson·Botao Li·Jinfeng Liu·Yi Liu·Margaret S. Lutz·Jack MacDonald·Chiara Magliocca·Toni Mäkelä·Lawson McCoy·Josh McFayden·Andrea Pizarro Medina·Matteo Milanesio·Théo Moretti·Keiko Moriyama·Mitsuhiro Nakamura·Toshiyuki Nakano·Laurie Nevay·Motoya Nonaka·Yuma Ohara·Ken Ohashi·Kazuaki Okui·Hidetoshi Otono·Hao Pang·Lorenzo Paolozzi·Pawan Pawan·Brian Petersen·Titi Preda·Markus Prim·Michaela Queitsch-Maitland·Juan Rojo·Hiroki Rokujo·André Rubbia·Jorge Sabater-Iglesias·Osamu Sato·Paola Scampoli·Kristof Schmieden
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Abstract

This paper presents the reconstruction and performance evaluation of the FASER$ν$ emulsion detector, which aims to measure interactions from neutrinos produced in the forward direction of proton-proton collisions at the CERN Large Hadron Collider. The detector, composed of tungsten plates interleaved with emulsion films, records charged particles with sub-micron precision. A key challenge arises from the extremely high track density environment, reaching $\mathcal{O}(10^5)$ tracks per cm$^2$. To address this, dedicated alignment techniques and track reconstruction algorithms have been developed, building on techniques from previous experiments and introducing further optimizations. The performance of the detector is studied by evaluating the single-film efficiency, position and angular resolution, and the impact parameter distribution of reconstructed vertices. The results demonstrate that an alignment precision of 0.3 micrometers and robust track and vertex reconstruction are achieved, enabling accurate neutrino measurements in the TeV energy range.

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FASER Collaboration, Roshan Mammen Abraham, Xiaocong Ai, Saul Alonso Monsalve, John Anders, Claire Antel, Akitaka Ariga, Tomoko Ariga, Jeremy Atkinson, Florian U. Bernlochner, Tobias Boeckh, Jamie Boyd, Lydia Brenner, Angela Burger, Franck Cadou, Roberto Cardella, David W. Casper, Charlotte Cavanagh, Xin Chen, Kohei Chinone, Dhruv Chouhan, Andrea Coccaro, Stephane Débieu, Ansh Desai, Sergey Dmitrievsky, Radu Dobre, Monica D'Onofrio, Sinead Eley, Yannick Favre, Deion Fellers, Jonathan L. Feng, Carlo Alberto Fenoglio, Didier Ferrere, Max Fieg, Wissal Filali, Elena Firu, Haruhi Fujimori, Edward Galantay, Ali Garabaglu, Stephen Gibson, Sergio Gonzalez-Sevilla, Yuri Gornushkin, Carl Gwilliam, Daiki Hayakawa, Michael Holzbock, Shih-Chieh Hsu, Zhen Hu, Giuseppe Iacobucci, Tomohiro Inada, Luca Iodice, Sune Jakobsen, Hans Joos, Enrique Kajomovitz, Takumi Kanai, Hiroaki Kawahara, Alex Keyken, Felix Kling, Daniela Köck, Pantelis Kontaxakis, Umut Kose, Rafaella Kotitsa, Peter Krack, Susanne Kuehn, Thanushan Kugathasan, Lorne Levinson, Botao Li, Jinfeng Liu, Yi Liu, Margaret S. Lutz, Jack MacDonald, Chiara Magliocca, Toni Mäkelä, Lawson McCoy, Josh McFayden, Andrea Pizarro Medina, Matteo Milanesio, Théo Moretti, Keiko Moriyama, Mitsuhiro Nakamura, Toshiyuki Nakano, Laurie Nevay, Motoya Nonaka, Yuma Ohara, Ken Ohashi, Kazuaki Okui, Hidetoshi Otono, Hao Pang, Lorenzo Paolozzi, Pawan Pawan, Brian Petersen, Titi Preda, Markus Prim, Michaela Queitsch-Maitland, Juan Rojo, Hiroki Rokujo, André Rubbia, Jorge Sabater-Iglesias, Osamu Sato, Paola Scampoli, Kristof Schmieden. 2025-05-02. Reconstruction and Performance Evaluation of FASER's Emulsion Detector at the LHC. https://arxiv.org/abs/2504.13008

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