16 research outputs found
Argon Purification Studies and a Novel Liquid Argon Re-circulation System
Future giant liquid argon (LAr) time projection chambers (TPCs) require a
purity of better than 0.1 parts per billion (ppb) to allow the ionised
electrons to drift without significant capture by any electronegative
impurities. We present a comprehensive study of the effects of electronegative
impurity on gaseous and liquid argon scintillation light, an analysis of the
efficacy of various purification chemicals, as well as the Liverpool LAr setup,
which utilises a novel re-circulation purification system. Of the impurities
tested - Air, O_2, H_2O, N_2 and CO_2 in the range of between 0.01 ppm to 1000
ppm - H_2O was found to have the most profound effect on gaseous argon
scintillation light, and N_2 was found to have the least. Additionally, a
correlation between the slow component decay time and the total energy
deposited with 0.01 ppm - 100 ppm O_2 contamination levels in liquid argon has
been established. The superiority of molecular sieves over anhydrous complexes
at absorbing Ar gas, N_2 gas and H_2O vapour has been quantified using BET
isotherm analysis. The efficiency of Cu and P_2O5 at removing O_2 and H_2O
impurities from 1 bar N6 argon gas at both room temperature and -130 ^oC was
investigated and found to be high. A novel, highly scalable LAr re-circulation
system has been developed. The complete system, consisting of a motorised
bellows pump operating in liquid and a purification cartridge, were designed
and built in-house. The system was operated successfully over many days and
achieved a re-circulation rate of 27 litres/hour and high purity
Neutrino Interactions In Oscillation Experiments
We calculate neutrino induced cross-sections relevant for oscillation
experiments, including the -lepton threshold for quasi-elastic, resonance
and deep inelastic scattering. In addition to threshold effects, we include
nuclear corrections for heavy targets which are moderate for quasi-elastic and
large for single pion production. Nuclear effects for deep inelastic reactions
are small. We present cross sections together with their nuclear corrections
for various channels which are useful for interpreting the experimental results
and for determining parameters of the neutrino sector..Comment: 24 pages, 18 figure
Reconstruction of interactions in the ProtoDUNE-SP detector with Pandora
The Pandora Software Development Kit and algorithm libraries provide pattern-recognition logic essential to the reconstruction of particle interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at ProtoDUNE-SP, a prototype for the Deep Underground Neutrino Experiment far detector. ProtoDUNE-SP, located at CERN, is exposed to a charged-particle test beam. This paper gives an overview of the Pandora reconstruction algorithms and how they have been tailored for use at ProtoDUNE-SP. In complex events with numerous cosmic-ray and beam background particles, the simulated reconstruction and identification efficiency for triggered test-beam particles is above 80% for the majority of particle type and beam momentum combinations. Specifically, simulated 1 GeV/c charged pions and protons are correctly reconstructed and identified with efficiencies of 86.1Âą0.6% and 84.1Âą0.6%, respectively. The efficiencies measured for test-beam data are shown to be within 5% of those predicted by the simulation.ISSN:1434-6044ISSN:1434-605
Discovery of underground argon with low level of radioactive 39Ar and possible applications to WIMP dark matter detectors.
Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 à 10²š protons on target
The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3)Ă10²Ⱐprotons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7Ă10²ⰠPOT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin² θââ and the impact of priors on the δ_CP measurement. Both analyses prefer the normal mass ordering and upper octant of sin² θââ with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin² θââ from reactors, sin² θââ = 0.561âşâ°.â°Â˛Âšââ.âââ using FeldmanâCousins corrected intervals, and Îm²ââ = 2.494âşâ°.â°â´Âšââ.ââ
âĂ10â3 eV² using constant ÎĎ² intervals. The CP-violating phase is constrained to δCP=â1.97âşâ°.âšâˇââ.ââ using FeldmanâCousins corrected intervals, and δ_CP = 0,Ď is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2Ď credible level using a flat prior in δCP, and just below 2Ď using a flat prior in sin δ_CP. When the external constraint on sin² θââ is removed, sin² θââ = 28.0+2.8â6.5Ă10â3, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.ISSN:1434-6044ISSN:1434-605
First measurement of muon neutrino charged-current interactions on hydrocarbon without pions in the final state using multiple detectors with correlated energy spectra at T2K
This paper reports the first measurement of muon neutrino charged-current interactions without pions in the final state using multiple detectors with correlated energy spectra at T2K. The data was collected on hydrocarbon targets using the off-axis T2K near detector (ND280) and the on-axis T2K near detector (INGRID) with neutrino energy spectra peaked at 0.6 GeV and 1.1 GeV, respectively. The correlated neutrino flux presents an opportunity to reduce the impact of the flux uncertainty and to study the energy dependence of neutrino interactions. The extracted double-differential cross sections are compared to several Monte Carlo neutrino-nucleus interaction event generators showing the agreement between both detectors individually and with the correlated result.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236
Updated T2K measurements of muon neutrino and antineutrino disappearance using 3.6Ă10²š protons on target
Muon neutrino and antineutrino disappearance probabilities are identical in the standard three-flavor neutrino oscillation framework, but CPT violation and nonstandard interactions can violate this symmetry. In this work we report the measurements of sin²θââ and Îm²ââ independently for neutrinos and antineutrinos. The aforementioned symmetry violation would manifest as an inconsistency in the neutrino and antineutrino oscillation parameters. The analysis discussed here uses a total of 1.97 Ă 10²š and 1.63 Ă 10²š protons on target taken with a neutrino and antineutrino beam respectively, and benefits from improved flux and cross section models, new near-detector samples and more than double the data reducing the overall uncertainty of the result. No significant deviation is observed, consistent with the standard neutrino oscillation picture.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236