Emanation and bulk fluorescence in liquid argon from tetraphenyl butadiene wavelength shifting coatings

Asaadi, J.; Jones, B. J. P.; Tripathi, A.; Parmaksiz, I.; Sullivan, H.; Williams, Z.

doi:10.1088/1748-0221/14/02/p02021

Cited by 20 publications

(27 citation statements)

References 31 publications

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“…It is used for coating PMTs, detector walls and other elements of optical systems [10,11]. The main disadvantage of any WLS film is low geometrical efficiency, since the light is re-emitted in 4π solid angle, sensitivity to mechanical stress, long term stability [12], scattering and re-absorption of the re-emitted light inside the WLS layer [11,13] and also dependence of the WLS efficiency on the coating method.An elegant idea is to use volume-distributed WLS, which can provide a higher efficiency of re-emission and better collection of the scintillation light. This improves position reconstruction since the re-emission occurs in the point of interaction.It was shown that gaseous xenon doped in LAr works as a volume-distributed WLS shifting the wave length from 128 nm to around 175 nm [14][15][16].…”

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confidence: 99%

Fast component re-emission in Xe-doped liquid argon

Akimov¹,

Belov²,

Konovalov³

et al. 2019

J. Inst.

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A: We present the first direct experimental confirmation of the fast component re-emission in liquid argon (LAr) doped with xenon (Xe). This effect was studied at various Xe concentrations up to ∼3000 ppm. The rate constant of energy transfer for the fast component was quantified. It was shown that LAr doped with a high concentration of Xe without TPB has a better PSD efficiency than pure LAr or Xe-doped LAr with TPB. The stability of LAr+Xe mixture was tested for the first time at high Xe concentration for long continuous runtimes. K: Ionization and excitation processes; Noble liquid detectors (scintillation, ionization, double-phase); Particle identification methods; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators) 1Corresponding author.The most commonly used WLS for LAr is tetraphenyl butadiene (TPB). It is used for coating PMTs, detector walls and other elements of optical systems [10,11]. The main disadvantage of any WLS film is low geometrical efficiency, since the light is re-emitted in 4π solid angle, sensitivity to mechanical stress, long term stability [12], scattering and re-absorption of the re-emitted light inside the WLS layer [11,13] and also dependence of the WLS efficiency on the coating method.An elegant idea is to use volume-distributed WLS, which can provide a higher efficiency of re-emission and better collection of the scintillation light. This improves position reconstruction since the re-emission occurs in the point of interaction.It was shown that gaseous xenon doped in LAr works as a volume-distributed WLS shifting the wave length from 128 nm to around 175 nm [14][15][16]. Currently several groups are studying its wavelength shifting parameters and the properties of the LAr+Xe mixture [17][18][19][20]. As shown previously [21], Xe doped in small concentrations (up to 260 ppm by mass) re-emits only the slow component of LAr scintillation. Thus, at small concentrations it is impossible to use Xe as a single stage WLS and to keep PSD capability of the LAr+Xe mixture at the same time.In previous studies with a broad concentration range (up to 1000 ppm by mass) [19,20], it was shown that Xe-doping slightly improves the light yield and the energy resolution. Also they demonstrated that the PSD capability degrades with decreasing of Xe concentration in LAr. Both experiments [19,20] have shown that at the concentrations of Xe > 300 ppm the PSD capability of the LAr+Xe mixture is higher than that of pure LAr.One experimental study [20] indicated evidence of fast component re-emission at high Xe concentrations. However, the measurement scheme was very complicated, statistics were quite low, and the effect of the re-emission by Xe was obscured by the use of TPB. In our study, we confirm the clear observation of the fast component re-emission in LAr doped at high Xe concentration (∼1100 ppm by mass). We show the dependence of this effect on the increase of Xe concentration and its relation to PSD efficiency. We also present the first experimental measur...

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Fast component re-emission in Xe-doped liquid argon

Akimov¹,

Belov²,

Konovalov³

et al. 2019

J. Inst.

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“…It is thus necessary to convert the VUV into visible light using a wavelenght shifter (WLS), namely tetraphenyl-butadiene (TPB). An issue with TPB is that it may not be stable over long time scales, in particular due to its dissolving in liquid Ar [12] and peeling off from the substrate under cryogenic conditions [13]. Another known issue is related to difficulties in achieving uniform levels of WLS deposits over large detector areas.…”

Section: Introductionmentioning

confidence: 99%

“…As noted above, this may lead to more stable operation of two-phase argon detectors, avoiding the problems of Fig. 3 "Standard" concept of SiPM-matrix readout of two-phase argon detectors with an EL gap WLS degradation and its dissolving in liquid Ar [12], as well as that of WLS peeling off from the substrate.…”

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confidence: 99%

SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

Aalseth¹,

Abdelhakim²,

Agnes³

et al. 2021

Eur. Phys. J. C

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Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the visible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neutral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields, is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a silicon photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The amplitude yield and position resolution were measured for these readout techniques, which allowed to assess the detection threshold for electron and nuclear recoils in two-phase argon detectors for dark matter searches. To the best of our knowledge, this is the first practical application of the NBrS effect in detection science.

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“…Figure26. Left: proportional EL gain expressed in photoelectrons (PE) recorded by PMT as a function of applied voltage for 10 μm anode wire in liquid Xe[30].…”

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Electroluminescence and Electron Avalanching in Two-Phase Detectors

Buzulutskov

2020

Instruments

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Electroluminescence and electron avalanching are the physical effects used in two-phase argon and xenon detectors for dark matter searches and neutrino detection, to amplify the primary ionization signal directly in cryogenic noble-gas media. We review the concepts of such light and charge signal amplification, including a combination thereof, both in the gas and in the liquid phase. Puzzling aspects of the physics of electroluminescence and electron avalanching in two-phase detectors are explained, and detection techniques based on these effects are described.

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Emanation and bulk fluorescence in liquid argon from tetraphenyl butadiene wavelength shifting coatings

Cited by 20 publications

References 31 publications

Fast component re-emission in Xe-doped liquid argon

Fast component re-emission in Xe-doped liquid argon

SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

Electroluminescence and Electron Avalanching in Two-Phase Detectors

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