Michel electron reconstruction using cosmic-ray data from the MicroBooNE LArTPC

Abstract

The MicroBooNE liquid argon time projection chamber (LArTPC) has been taking\ndata at Fermilab since 2015 collecting, in addition to neutrino beam,\ncosmic-ray muons. Results are presented on the reconstruction of Michel\nelectrons produced by the decay at rest of cosmic-ray muons. Michel electrons\nare abundantly produced in the TPC, and given their well known energy spectrum\ncan be used to study MicroBooNE's detector response to low-energy electrons\n(electrons with energies up to ~50 MeV). We describe the fully-automated\nalgorithm developed to reconstruct Michel electrons, with which a sample of\n~14,000 Michel electron candidates is obtained. Most of this article is\ndedicated to studying the impact of radiative photons produced by Michel\nelectrons on the accuracy and resolution of their energy measurement. In this\nenergy range, ionization and bremsstrahlung photon production contribute\nsimilarly to electron energy loss in argon, leading to a complex electron\ntopology in the TPC. By profiling the performance of the reconstruction\nalgorithm on simulation we show that the ability to identify and include energy\ndeposited by radiative photons leads to a significant improvement in the energy\nmeasurement of low-energy electrons. The fractional energy resolution we\nmeasure improves from over 30% to ~20% when we attempt to include radiative\nphotons in the reconstruction. These studies are relevant to a large number of\nanalyses which aim to study neutrinos by measuring electrons produced by\n$\\nu_e$ interactions over a broad energy range.\n