Notizen: Energy of the Quasi-free Electron State in Liquid Argon, Krypton, and Xenon

Tauchert, Wolfgang; Schmidt, Werner F.

doi:10.1515/zna-1975-0827

Cited by 25 publications

(5 citation statements)

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“…This obtained quantum efficiency value is higher than that reported for stainless steel (unspecified grade) by a factor of 2 [48]. This increase is mostly explained by the reduction of the effective work function of the metal by the electron affinity of liquid xenon [49,50]; the contribution from the Schottky effect in reducing the steel work function is subdominant (10 times smaller than the liquid xenon affinity effect) for the electric fields on the grid surfaces in LUX. Other possibilities include differences in the stainless steel grades, the accumulation of positive ions on the grid surfaces [51], and changes to the electrode surface composition due to collection of positively charged impurities from the liquid.…”

Section: A Photoionization Yieldcontrasting

confidence: 51%

“…On the other hand, their strong and robust correlation with electronegative impurities makes photoionization electrons a possible xenon purity monitor. We also evaluated the photoelectric efficiency of the LUX stainless steel grids at the xenon light wavelength, and obtained a result that is significantly higher than that measured for stainless steel in vacuum [48], consistent with a reduction of its work function in liquid xenon [49,50].…”

Section: Discussionmentioning

confidence: 58%

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Investigation of background electron emission in the LUX detector

Akerib¹,

Alsum²,

Araújo³

et al. 2020

Phys. Rev. D

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Dual-phase xenon detectors, as currently used in direct detection dark matter experiments, have observed elevated rates of background electron events in the low energy region. While this background negatively impacts detector performance in various ways, its origins have only been partially studied. In this paper we report a systematic investigation of the electron pathologies observed in the LUX dark matter experiment. We characterize different electron populations based on their emission intensities and their correlations with preceding energy depositions in the detector. By studying the background under different experimental conditions, we identified the leading emission mechanisms, including photoionization and the photoelectric effect induced by the xenon luminescence, delayed emission of electrons trapped under the liquid surface, capture and release of drifting electrons by impurities, and grid electron emission. We discuss how these backgrounds can be mitigated in LUX and future xenon-based dark matter experiments.

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Section: A Photoionization Yieldcontrasting

confidence: 51%

Section: Discussionmentioning

confidence: 58%

Investigation of background electron emission in the LUX detector

Akerib¹,

Alsum²,

Araújo³

et al. 2020

Phys. Rev. D

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“…We were not able to derive accurate I-V curves from our measurements and our results cannot be directly compared with the classical studies on field emission at much higher currents. While our fields are not sufficient for a measurable field emission from a perfect surface with work function as high as that of stainless steel (4.3 eV)even considering a 0.61 eV reduction due to the electron affinity of LXe [45]-the introduction of protrusions, each characterised by a 'field enhancement factor' β (the ratio of the locally enhanced field to the average field for the perfect geometry), is an attractive explanation that could conceivably lead to the minute currents we observe (∼10 −16 A). Enhancement factors β ∼100-1000 can be estimated for extremely long and sharp (nanometre-sized) filaments [46,47], and such large factors would be required to explain macroscopic emission currents from stainless steel wires in LXe.…”

Section: Discussionmentioning

confidence: 80%

Study and mitigation of spurious electron emission from cathodic wires in noble liquid time projection chambers

Tomás

Araújo

Bailey

et al. 2018

Astroparticle Physics

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Noble liquid radiation detectors have long been afflicted by spurious electron emission from their cathodic electrodes. This phenomenon must be understood and mitigated in the next generation of liquid xenon (LXe) experiments searching for WIMP dark matter or neutrinoless double beta decay, and in the large liquid argon (LAr) detectors for the longbaseline neutrino programmes. We present a systematic study of this spurious emission involving a series of slow voltage-ramping tests on fine metal wires immersed in a two-phase xenon time projection chamber with single electron sensitivity. Emission currents as low as 10 −18 A can thus be detected by electron counting, a vast improvement over previous dedicated measurements. Emission episodes were recorded at surface fields as low as ∼10 kV/cm in some wires and observed to have complex emission patterns, with average rates of 10-200 counts per second (c/s) and outbreaks as high as ∼10 6 c/s. A fainter, less variable type of emission was also present in all untreated samples. There is evidence of a partial conditioning effect, with subsequent tests yielding on average fewer emitters occurring at different fields for the same wire. We find no evidence for an intrinsic threshold particular to the metal-LXe interface which might have limited previous experiments up to fields of at least 160 kV/cm. The general phenomenology is not consistent with enhanced field emission from microscopic filaments, but it appears instead to be related to the quality of the wire surface in terms of corrosion and the nature of its oxide layer. This study concludes that some surface treatments, in particular nitric acid cleaning applied to stainless steel wires, can bring about at least order-of-magnitude improvements in overall electron emission rates, and this should help the next generation of detectors achieve the required electrostatic performance.

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“…The potential energy of a free electron in the liquid xenon is lower than in the gaseous phase by 0.67 eV [16]. This creates a potential barrier that electrons must cross if they are to be extracted from the liquid into the gas.…”

Section: Introductionmentioning

confidence: 99%

Extraction efficiency of drifting electrons in a two-phase xenon time projection chamber

et al. 2018

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A: We present a measurement of the extraction efficiency of quasi-free electrons from the liquid into the gas phase in a two-phase xenon time-projection chamber. The measurements span a range of electric fields from 2.4 to 7.1 kV/cm in the liquid xenon, corresponding to 4.5 to 13.1 kV/cm in the gaseous xenon. Extraction efficiency continues to increase at the highest extraction fields, implying that additional charge signal may be attained in two-phase xenon detectors through careful high-voltage engineering of the gate-anode region.

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Notizen: Energy of the Quasi-free Electron State in Liquid Argon, Krypton, and Xenon

Abstract: The energy of the conduction state in liquid argon, krypton, and xenon was measured by means of the photo-effect. The data are used to calculate the scattering lengths. The relation between scattering length and electron mobility is discussed.

Cited by 25 publications

References 0 publications

Investigation of background electron emission in the LUX detector

Investigation of background electron emission in the LUX detector

Study and mitigation of spurious electron emission from cathodic wires in noble liquid time projection chambers

Extraction efficiency of drifting electrons in a two-phase xenon time projection chamber

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