Determination of muon momentum in the MicroBooNE LArTPC using an improved model of multiple Coulomb scattering

Abstract

A: We discuss a technique for measuring a charged particle's momentum by means of multiple Coulomb scattering (MCS) in the MicroBooNE liquid argon time projection chamber (LArTPC). This method does not require the full particle ionization track to be contained inside of the detector volume as other track momentum reconstruction methods do (range-based momentum reconstruction and calorimetric momentum reconstruction). We motivate use of this technique, describe a tuning of the underlying phenomenological formula, quantify its performance on fully contained beam-neutrino-induced muon tracks both in simulation and in data, and quantify its performance on exiting muon tracks in simulation. Using simulation, we have shown that the standard Highland formula should be re-tuned specifically for scattering in liquid argon, which significantly improves the bias and resolution of the momentum measurement. With the tuned formula, we find agreement between data and simulation for contained tracks, with a small bias in the momentum reconstruction and with resolutions that vary as a function of track length, improving from about 10% for the shortest (one meter long) tracks to 5% for longer (several meter) tracks. For simulated exiting muons with at least one meter of track contained, we find a similarly small bias, and a resolution which is less than 15% for muons with momentum below 2 GeV/c. Above 2 GeV/c, results are given as a first estimate of the MCS momentum measurement capabilities of MicroBooNE for high momentum exiting tracks.

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“…With the fully active and high-resolution MicroBooNE LArTPC detector, the outgoing muon phase space can be probed with full acceptance in both angle and momentum for the first time. The momentum of the outgoing muon is measured by using multiple Coulomb scattering (MCS) [8], thus allowing the analysis sample to include both exiting and contained muons.…”

“…The momentum of the muon is measured using multiple Coulomb scattering. Here, the magnitude of the momentum is a fit parameter that describes the scattering pattern of the track [8]. The strength of this algorithm is that it can estimate the muon momentum for muon tracks spatially contained in the detector as well as exiting tracks, which is important given that only 30% of neutrino-induced muons are spatially contained.…”

Neutrino topology reconstruction at DUNE and applications to searches for dark matter annihilation in the Sun

“…If the track is contained within the detector, then the muon energy can be determined precisely ( ∼ 0.05) from the length of the track. If the track is only partially contained, however, then the energy can still be estimated, albeit with less precision, from the deflection of the track due to small angle scattering of the muon as it passes through the detector [26,27] ( ∼ 0.23). But these estimates were obtained for charged leptons with E ≤ 3 GeV.…”