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

TL;DR

This paper details the reconstruction methods and performance assessment of the FASERν emulsion detector at the LHC, demonstrating high precision in tracking and vertex reconstruction in a high-density environment for neutrino detection.

Contribution

It introduces optimized alignment and track reconstruction techniques for emulsion detectors operating in extremely dense particle environments at the LHC.

Findings

Alignment precision of 0.3 micrometers achieved

High-efficiency track and vertex reconstruction demonstrated

Detector capable of accurate neutrino measurements in TeV range

Abstract

This paper presents the reconstruction and performance evaluation of the FASER$\nu$ 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.