Multiple Coulomb Scattering In the LArIAT Detector
Abstract
LArIAT is a liquid argon time projection chamber (LArTPC) deployed in a
dedicated charged particle test beam line at the Fermilab Test Beam Facility.
LArIAT aims to measure an interaction process known as multiple coulomb
scattering, which describes the process of a charged particle passing through a slab of material. As it passes, it will experience millions of scatters due to the Coulombic interactions with the nuclei of the material. This work presents a characterization of charged particle multiple coulomb scattering as a function of incoming momentum and particle type as it passes through the LArIAT detector. Employing data collected by the LArIAT experiment as well as single particle Monte Carlo reconstruction to match experimental momentum profiles, we measure the scattering angles of single particle tracks at specified momentum ranges. The scattering angles are modeled as an exponential distribution with a slope parameter that is used to calculate sigma, a value that is characterized by the Highland Formula. The Highland formula ultimately relates a charged particle’s multiple scattering angle to the particle’s momentum. The results of the data and simulation measurement are compared against the Highland Formula and fit to a tuned variation of the Highland formula to extract a new particle-dependent, data-driven parameter for various particles in liquid argon. This method and its results are compared to the standard Highland formula and previous measurements on argon nuclei performed by the MicroBooNE experiment. This cross-check provides a more accurate understanding of k+, pi+, mu+, and p scattering behavior in LArTPC detectors and highlights a discrepancy between Monte Carlo reconstruction and data.