The effects of dissolved methane upon liquid argon scintillation light

Jones, B. J. P.; Alexander, T.; Back, H. O.; Collin, Gabriel; Conrad, J. M.; Greene, Austen T.; Katori, T.; Pordes, S.; Toups, M.

doi:10.1088/1748-0221/8/12/p12015

Cited by 20 publications

(36 citation statements)

References 39 publications

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“…Absorption cross sections of different molecules in gaseous phase as a function of the incident wavelength. The grey circles a and b represent the estimated cross sections of CH 4 [10] and N 2 [12] diluted in LAr. The LAr emission spectrum is taken from [14] and plotted in grey (arb.…”

Section: Vuv [M]mentioning

confidence: 99%

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Measurement of the attenuation length of argon scintillation light in the ArDM LAr TPC

Calvo

Cantini

Daniel

et al. 2018

Astroparticle Physics

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Abstract. We report on a measurement of the attenuation length for the scintillation light in the tonne size liquid argon target of the ArDM dark matter experiment. The data was recorded in the first underground operation of the experiment in single-phase operational mode. The results were achieved by comparing the light yield spectra from 39 Ar and 83m Kr to a description of the ArDM setup with a model of full light ray tracing. A relatively low value close to 0.5 m was found for the attenuation length of the liquid argon bulk to its own scintillation light. We interpret this result as a presence of optically active impurities in the liquid argon which are not filtered by the installed purification systems. We also present analyses of the argon gas employed for the filling and discuss cross sections in the vacuum ultraviolet of various molecules in respect to purity requirements in the context of large liquid argon installations.

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Section: Vuv [M]mentioning

confidence: 99%

“…Its exact quantitative estimation often lacks the knowledge of the collisional cross section. The effect of impurity quenching in LAr due to the varying concentrations of O 2 , N 2 and CH 4 can be found in literature [6,[8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Measurement of the attenuation length of argon scintillation light in the ArDM LAr TPC

Calvo

Cantini

Daniel

et al. 2018

Astroparticle Physics

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“…Unlike the SPE parameter of Ref. [9], therefore, it should not be interpreted as a proxy for the PMT gain, Data Sample N PE SPE Scale Shift Far-measurement 1 37.5 ± 0.5…”

Section: Description Of Apparatus and Measurement Of N Pementioning

confidence: 97%

“…In this analysis, we make a small departure from the approach of Ref. [9]. In that paper, a modified Poisson function was used, corrected for source occlusion and normalized to an independently measured SPE scale.…”

Section: Description Of Apparatus and Measurement Of N Pementioning

confidence: 99%

A model for the Global Quantum Efficiency for a TPB-based wavelength-shifting system used with photomultiplier tubes in liquid argon in MicroBooNE

et al. 2018

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A: We present a model for the Global Quantum Efficiency (GQE) of the MicroBooNE optical units. An optical unit consists of a flat, circular acrylic plate, coated with tetraphenyl butadiene (TPB), positioned near the photocathode of a 20.2-cm diameter photomultiplier tube. The plate converts the ultra-violet scintillation photons from liquid argon into visible-spectrum photons to which the cryogenic phototubes are sensitive. The GQE is the convolution of the efficiency of the plates that convert the 128 nm scintillation light from liquid argon to visible light, the efficiency of the shifted light to reach the photocathode, and the efficiency of the cryogenic photomultiplier tube. We develop a GEANT4-based model of the optical unit, based on first principles, and obtain the range of probable values for the expected number of detected photoelectrons (N PE ) given the known systematic errors on the simulation parameters. We compare results from four measurements of the N PE determined using alpha-particle sources placed at two distances from a TPB-coated plate in a liquid argon cryostat test stand. We also directly measured the radial dependence of the quantum efficiency, and find that this has the same shape as predicted by our model. Our model results in a GQE of 0.0055 ± 0.0009 for the MicroBooNE optical units. While the information shown here is MicroBooNE specific, the approach to the model and the collection of simulation parameters will be widely applicable to many liquid-argon-based light collection systems.

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“…Consequently the scintillation light cannot travel infinite inside the LAr but is attenuated during its propagation due to impurities in the LAr [3][4][5], providing a limit on the effective active volume of the LAr veto. In order to estimate the efficiency of the LAr veto the attenuation length of the scintillation light was measured inside the Gerda cryostat.…”

Section: Introductionmentioning

confidence: 99%

In-situ measurement of the scintillation light attenuation in liquid argon in the Gerda experiment

Barros

Domula

Lehnert

et al. 2020

Nuclear Instruments and Methods in Physics Research Section A:

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The Gerda experiment searches for the neutrinoless double beta (0νββ) decay in 76 Ge in order to probe whether the neutrino is a Majorana particle and to shed light on the neutrino mass ordering. For investigating such a rare decay it is necessary to minimize the background of the experiment. In Phase II of the Gerda experiment the scintillation light of liquid argon (LAr) is used as an additional background veto. In order to estimate the efficiency of such a LAr veto it has to be known how far the scintillation light can travel within the LAr. A dedicated setup was built to measure the attenuation length of the scintillation light in the LAr in-situ within the cryostat of Gerda. The setup is composed of a steel tube with a photomultiplier tube (PMT) at one side and a moveable 90 Sr source at the other side to measure the light intensity at different distances between source and PMT.Furthermore, a sophisticated simulation was developed in order to determine the solid angle correction as well as the background for this measurement, both are needed for the analysis. Additionally, a set of simulation data was generated to confirm the analysis which is performed for the measured data afterwards and to find a combination of simulation parameters that matches the measured data. The analysis results in an absorption length of 15.79±0.70(stat) +1.42 −3.14 (syst) cm under the assumption of a scattering length of 70 cm at 128 nm. The simulation matching best was produced with an absorption length of 18 cm and a light yield of 2500 γ/MeV.

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The effects of dissolved methane upon liquid argon scintillation light

Cited by 20 publications

References 39 publications

Measurement of the attenuation length of argon scintillation light in the ArDM LAr TPC

Measurement of the attenuation length of argon scintillation light in the ArDM LAr TPC

A model for the Global Quantum Efficiency for a TPB-based wavelength-shifting system used with photomultiplier tubes in liquid argon in MicroBooNE

In-situ measurement of the scintillation light attenuation in liquid argon in the Gerda experiment

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