FPGA-based trigger system for the LUX dark matter experiment

et al. 2018

Phys. Rev. D

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The LUX experiment has performed searches for dark-matter particles scattering elastically on xenon nuclei, leading to stringent upper limits on the nuclear scattering cross sections for dark matter. Here, for results derived from 1.4 × 10 4 kg days of target exposure in 2013, details of the calibration, event-reconstruction, modeling, and statistical tests that underlie the results are presented. Detector performance is characterized, including measured efficiencies, stability of response, position resolution, and discrimination between electron-and nuclear-recoil populations. Models are developed for the drift field, optical properties, background populations, the electron-and nuclear-recoil responses, and the absolute rate of low-energy background events. Innovations in the analysis include in situ measurement of the photomultipliers' response to xenon scintillation photons, verification of fiducial mass with a low-energy internal calibration source, and new empirical models for low-energy signal yield based on large-sample, in situ calibrations.

“…[31]. It is a digital field-programmable gate array (FPGA)-based system that flags events in the DAQ data stream for further analysis.…”

Section: B Triggermentioning

confidence: 99%

Calibration, event reconstruction, data analysis, and limit calculation for the LUX dark matter experiment

Akerib¹,

Alsum²,

et al. 2018

Phys. Rev. D

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“…In addition to the large scale live-time exclusions, the LUX experiment also excluded live-time segments at much smaller time scales. The LUX trigger system implemented a hold off after each acknowledged trigger, and the value was set to be 4 ms in early WS2013 and was reduced to 1 ms later [40]. In addition, if a trigger occurred within 500 µs before the data acquisition is deactivated, the recorded waveform may be incomplete; these triggers were therefore excluded from the analysis.…”

Section: Live-time Exclusionsmentioning

confidence: 99%

Search for annual and diurnal rate modulations in the LUX experiment

Akerib¹,

Alsum²,

et al. 2018

Phys. Rev. D

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Various dark matter models predict annual and diurnal modulations of dark matter interaction rates in Earth-based experiments as a result of the Earth's motion in the halo. Observation of such features can provide generic evidence for detection of dark matter interactions. This paper reports a search for both annual and diurnal rate modulations in the LUX dark matter experiment using over 20 calendar months of data acquired between 2013 and 2016. This search focuses on electron recoil events at low energies, where leptophilic dark matter interactions are expected to occur and where the DAMA experiment has observed a strong rate modulation for over two decades. By using the innermost volume of the LUX detector and developing robust cuts and corrections, we obtained a stable event rate of 2.3±0.2 cpd/keVee/tonne, which is among the lowest in all dark matter 2 experiments. No statistically significant annual modulation was observed in energy windows up to 26 keVee. Between 2 and 6 keVee, this analysis demonstrates the most sensitive annual modulation search up to date, with 9.2σ tension with the DAMA/LIBRA result. We also report no observation of diurnal modulations above 0.2 cpd/keVee/tonne amplitude between 2 and 6 keVee.

“…The 85 Kr is largely removed from the xenon prior to filling by chromatographic separation in activated charcoal [3]. Additional information on the experimental setup [4][5][6] and backgrounds [7] has been previously published.…”

mentioning

confidence: 99%

Results from a Search for Dark Matter in the Complete LUX Exposure

Akerib¹,

Alsum²,

et al. 2017

Phys. Rev. Lett.

Self Cite

1,656

1,919

We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35 × 10 4 kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50 GeV c −2 , WIMP-nucleon spin-independent cross sections above 2.2 × 10 −46 cm 2 are excluded at the 90% confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1 × 10 −46 cm 2 at 50 GeV c −2 .