LBECA: A Low Background Electron Counting Apparatus for Sub-GeV Dark Matter Detection

Bernstein, Adam; Clark, Michael; Essig, Rouven; Fernández-Serra, Mariví; Kopec, A.; Lang, R. F.; Long, Jianyu; Ni, Kan; Pereverzev, Sergey; Qi, J.; Sørensen, P.; Xu, J.; Ye, J.; Zhen, C.

doi:10.1088/1742-6596/1468/1/012035

Cited by 28 publications

(20 citation statements)

References 35 publications

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“…All of these experiments do still observe unexplained excesses at low energy, as shown in Table I. 2 A significant amount of work has been put into better understanding the source of these excess event rates in xenon TPCs [27][28][29][30]; however, we note that at very least some event rate appears to scale with detector mass [31], as would be expected from a dark matter signal.…”

Section: B Electron Recoil Searchesmentioning

confidence: 77%

Dark matter interpretation of excesses in multiple direct detection experiments

et al. 2020

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We present a novel unifying interpretation of excess event rates observed in several dark matter directdetection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of ∼10 Hz=kg. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.

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Section: B Electron Recoil Searchesmentioning

confidence: 77%

Dark matter interpretation of excesses in multiple direct detection experiments

et al. 2020

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“…This may be achieved with a good liquid xenon purity, a short drift length and a low ionization rate in the active region especially where the anticipated electron drifts are long. Possible experimental methods to improve the liquid xenon purity include eliminating high-outgassing materials from the TPC volume, isolating the clean active xenon from TPC components that may outgas significantly [66,67], and investigating novel purification techniques. It is worth noting that, as the liquid xenon purity increases, delayed emission of surface-trapped electrons lasts longer, and a veto method as discussed in this analysis will become less efficient.…”

Section: Discussionmentioning

confidence: 99%

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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“…The TPC concept demonstrated here serves as a basis for further development of the sealed TPC technique aiming to significantly improve the purification efficiency of LXe in the target, and to reduce the single/few electrons background for future experiments to search for sub-GeV dark matter via electron scattering [25], reactor neutrino detection via the CEνNS process [26], and the next generation multi-purpose liquid xenon experiment, e.g. DARWIN [27], for dark matter and neutrino physics.…”

Section: Discussionmentioning

confidence: 99%

Development and Performance of a Sealed Liquid Xenon Time Projection Chamber

Wei,

Long,

Lombardi

et al. 2020

Preprint

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The liquid xenon (LXe) time projection chamber (TPC) technology is leading the dark matter direct detection in a wide range of dark matter masses from sub-GeV to a few TeV. To further improve its sensitivity to sub-GeV dark matter and its application in reactor neutrino monitoring via coherent elastic neutrino-nucleus scattering (CEνNS), more understanding and suppression of single/few electrons background rate are needed. Here we report on the design and performance of a sealed LXeTPC with a graphene-coated fused silica window as the cathode. The purpose of the sealed TPC is for isolating the liquid xenon target volume from the majority of outgassing materials in the detector vessel, thus improving the liquid xenon purification efficiency and reducing the impurity-induced single/few electrons background. We investigated the out-gassing rate and purification efficiency using the data from the sealed TPC with a simple purification model. The single electron signals from the photoionization of impurities in LXe are obtained and their correlation with the LXe purity is investigated. The photo-electron emission rate on the graphenecoated electrode is compared to that from stainless steel, the electrode material typically used in LXe detectors. We discuss the possible further improvement and potential applications of the sealed TPC for the next generation liquid xenon experiments for dark matter and neutrino physics.

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LBECA: A Low Background Electron Counting Apparatus for Sub-GeV Dark Matter Detection

Cited by 28 publications

References 35 publications

Dark matter interpretation of excesses in multiple direct detection experiments

Dark matter interpretation of excesses in multiple direct detection experiments

Investigation of background electron emission in the LUX detector

Development and Performance of a Sealed Liquid Xenon Time Projection Chamber

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