Quantitative Impurity Distribution Model and Field Response Calibration for LArTPC

by Dr Yichen Li (BNL)

Wednesday 9 Nov 2016, 10:00 → 12:00 Asia/Shanghai

A419

ABSTRACT: As the chosen technology of the short-baseline neutrino (SBN) program at Fermi National Accelerator Laboratory (FNAL) and the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF), LArTPCs (Liquid Argon Time Projection Chamber) provide a key technology to address many important physics topics including search for light sterile neutrino(s), to search for CP violation in the neutrino sector, and to determine the neutrino mass hierarchy etc. Therefore, the fundamental properties of LAr are of particular interest for experimentalists. Achieving long electron lifetime is crucial to reach the high performance of large LArTPC envisioned for next-generation neutrino experiments. We have built up a quantitative model to describe the distribution and transport of impurities in a cryostat. Henry’s constants of oxygen and water, which describe the partition of impurities between gas and liquid argon, have been deduced through this model from measurements made in the BNL 20-L LAr test stand. The model accurately reproduces the distribution and evolution of impurity concentrations, and quantifies the importance of gas purification systems. Consequences for large LArTPC detectors will be discussed. Furthermore, we will describe the ongoing work to construct the Liquid Argon Field Calibration System (LArFCS) aiming for a direct calibration of the induction response impulse function. The results obtained with this new system are expected to significantly improve the processing of the induction signals of single-phase LArTPCs and build a solid foundation for high quality, automated event reconstruction.