No Arabic abstract
Liquid Argon Time Projection Chambers (LArTPCs) are ideal detectors for precision neutrino physics. These detectors, when located deep underground, can also be used for measurements of proton decay, and astrophysical neutrinos. The technology must be completely developed, up to very large mass scales, and fully mastered to construct and operate these detectors for this physics program. As part of an integrated plan of developing these detectors, accurate measurements in LArTPC of known particle species in the relevant energy ranges are now deemed as necessary. The LArIAT program aims to directly achieve these goals by deploying LArTPC detectors in a dedicated calibration test beam line at Fermilab. The set of measurements envisaged here are significant for both the short-baseline (SBN) and long-baseline (LBN) neutrino oscillation programs in the US, starting with MicroBooNE in the near term and with the adjoint near and far liquid argon detectors in the Booster beam line at Fermilab envisioned in the mid-term, and moving towards deep underground physics such as with the long-baseline neutrino facility (LBNF) in the longer term.
The LArIAT liquid argon time projection chamber, placed in a tertiary beam of charged particles at the Fermilab Test Beam Facility, has collected large samples of pions, muons, electrons, protons, and kaons in the momentum range 300-1400 MeV/c. This paper describes the main aspects of the detector and beamline, and also reports on calibrations performed for the detector and beamline components.
A filter system for removing electronegative impurities from liquid argon is described. The active components of the filter are adsorbing molecular sieve and activated-copper-coated alumina granules. The system is capable of purifying liquid argon to an oxygen-equivalent impurity concentration of better than 30 parts per trillion, corresponding to an electron drift lifetime of at least 10 ms. Reduction reactions that occur at about 250 degrees Celsius allow the filter material to be regenerated in-situ through a simple procedure. In the following work we describe the filter design, performance, and regeneration process.
Particle detectors based on liquid argon (LAr) have recently become recognized as an extremely attractive technology for the direct detection of dark matter as well as the measurement of coherent elastic neutrino-nucleus scattering (CE$ u$NS). The Chinese argon group at Institute of High Energy Physics has been studying the LAr detector technology and a LAr detector has been operating steadily. A program of using a dual phase LAr detector to measure the CE$ u$NS at Taishang Nuclear Power Plant has been proposed and the R&D work is ongoing. Considering the requirements of ultra-low radio-purity and high photon collection efficiency, SiPMs will be a good choice and will be used in the detector. In this proceeding, an introduction of the LAr detector and the measurement results of SiPM array at LAr temperature will be presented.
Impurities in noble liquid detectors used for neutrino and dark matter experiments can significantly impact the quality of data. We present an experimentally verified model for describing the dynamics of impurity distributions in liquid argon (LAr) detectors. The model considers sources, sinks, and transport of impurities within and between the gas and liquid argon phases. Measurements of oxygen concentrations in a 20-L LAr multi-purpose test stand are compared to calculations made with this model to show that an accurate description of the concentrations under various operational conditions can be obtained. A result of this analysis is a determination of Henrys coefficient for oxygen in LAr. These calculations also show that some processes have small effects on the impurity dynamics and excluding them yields a solution as a sum of two exponential terms. This solution provides a simple way to extract Henrys coefficient with negligible approximation error. It is applied to the data and the Henrys coefficient for oxygen in LAr is obtained as 0.84$^{+0.09}_{-0.05}$, consistent with literature results. Based on the analysis of the data with the model, we further suggest that, for a large liquid argon detector, barriers to flow (baffles) installed in the gas phase to restrict flow can help reduce the ultimate impurity concentration in the LAr.
We report the measurement of longitudinal electron diffusion coefficients in liquid argon for electric fields between 100 and 2000 V/cm with a gold photocathode as a bright electron source. The measurement principle, apparatus, and data analysis are described. Our results, which are consistent with previous measurements in the region between 100 to 350 V/cm [1] , are systematically higher than the prediction of Atrazhev-Timoshkin[2], and represent the worlds best measurement in the region between 350 to 2000 V/cm. The quantum efficiency of the gold photocathode, the drift velocity and longitudinal diffusion coefficients in gas argon are also presented.