UNSPECIFIED (2016) Study of Space Charge Effects in MicroBooNE. Other. UNSPECIFIED.
Full text not available from this repository.Abstract
We present a study of the impact of space charge effects within the MicroBooNE liquid argon time projection chamber (LArTPC). The space charge effect is the build-up of slow-moving positive ions in a detector due to, for instance, ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacement in the reconstructed position of signal ionization electrons in LArTPC detectors, as well as variations in the amount of charge quenching experienced by ionization throughout the volume of the TPC. The LArTPC utilized in MicroBooNE is expected to be modestly impacted from the space charge effect, with the electric field magnitude changing by up to 15% (at a drift field of 273 V/cm) in some locations within the TPC. Studying tracks in the TPC matched to an external small cosmic ray counter system, we observe offsets in the reconstructed track ends from their expected positions at the TPC edges, consistent with the presence of space charge effects in the detector. Data is compared to a simulation including space charge effects, which reproduces the observed track distortions. Finally, the derivation of a correction for the reconstruction of track direction is described, illustrating how one might remove the impact of these effects within the MicroBooNE LArTPC.