The Large Underground Xenon (LUX) experiment operates at the Sanford Underground Research Facility to detect nuclear recoils from the hypothetical Weakly Interacting Massive Particles (WIMPs) on a ...liquid xenon target. Liquid xenon typically contains trace amounts of the noble radioactive isotopes 85Kr and 39Ar that are not removed by the in situ gas purification system. The decays of these isotopes at concentrations typical of research-grade xenon would be a dominant background for a WIMP search experiment. To remove these impurities from the liquid xenon, a chromatographic separation system based on adsorption on activated charcoal was built. 400 kg of xenon was processed, reducing the average concentration of krypton from 130 ppb to 3.5 ppt as measured by a cold-trap assisted mass spectroscopy system. A 50 kg batch spiked to 0.001 g/g of krypton was processed twice and reduced to an upper limit of 0.2 ppt.
The Large Underground Xenon (LUX) experiment operates at the Sanford Underground Research Facility to detect nuclear recoils from the hypothetical Weakly Interacting Massive Particles (WIMPs) on a ...liquid xenon target. Liquid xenon typically contains trace amounts of the noble radioactive isotopes $^{85}$Kr and $^{39}$Ar that are not removed by the in situ gas purification system. The decays of these isotopes at concentrations typical of research-grade xenon would be a dominant background for a WIMP search exmperiment. To remove these impurities from the liquid xenon, a chromatographic separation system based on adsorption on activated charcoal was built. 400 kg of xenon was processed, reducing the average concentration of krypton from 130 ppb to 3.5 ppt as measured by a cold-trap assisted mass spectroscopy system. A 50 kg batch spiked to 0.001 g/g of krypton was processed twice and reduced to an upper limit of 0.2 ppt.
FPGA-based trigger system for the LUX dark matter experiment Akerib, D. S.; Araújo, H. M.; Bai, X. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2016, Volume:
818, Issue:
C
Journal Article
First Results of the LUX Dark Matter Experiment Carmona-Benitez, M.C.; Akerib, D.S.; Araújo, H.M. ...
Nuclear and particle physics proceedings,
04/2016, Volume:
273-275, Issue:
C
Journal Article
Peer reviewed
Open access
LUX (Large Underground Xenon) is a dark matter direct detection experiment deployed at the 4850' level of the Sanford Underground Research Facility (SURF) in Lead, SD, operating a 370 kg dual-phase ...xenon TPC. Results of the first WIMP search run were presented in late 2013, for the analysis of 85.3 live-days with a fiducial volume of 118 kg, taken during the period of April to August 2013. The experiment exhibited a sensitivity to spin-independent WIMP-nucleon elastic scattering with a minimum upper limit on the cross section of 7.6×10−46cm2 at a WIMP mass of 33 GeV/c2, becoming the world's leading WIMP search result, in conflict with several previous claimed hints of discovery.
Results from the LUX dark matter experiment Horn, Markus; Akerib, D. S.; Araújo, H. M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2014, Volume:
784
Journal Article
Peer reviewed
Open access
The LUX (Large Underground Xenon) experiment aims at the direct detection of dark matter particles via their collisions with xenon nuclei. The 370 kg two-phase liquid xenon time projection chamber ...measures simultaneously the scintillation and ionization from interactions in the target. The ratio of these two signals provides very good discrimination between potential nuclear recoil and electronic recoil signals to search for WIMP-nucleon scattering. The LUX detector operates at the Sanford Underground Research Facility (Lead, South Dakota, USA) since February 2013. Of note, first results were presented in late 2013 setting the world's most stringent limits on WIMP-nucleon scattering cross-sections over a wide range of WIMP masses. A 300 day run beginning in 2014 will further improve the sensitivity and new calibration techniques will reduce systematics for the WIMP signal search.
The Large Underground Xenon (LUX) dark matter experiment aims to detect rare low-energy interactions from Weakly Interacting Massive Particles (WIMPs). The radiogenic backgrounds in the LUX detector ...have been measured and compared with Monte Carlo simulation. Measurements of LUX high-energy data have provided direct constraints on all background sources contributing to the background model. The expected background rate from the background model for the 85.3 day WIMP search run is (2.6±0.2stat±0.4sys) ×10-3 events keV$ ee\atop{-1}$ kg-1 day-1 in a 118 kg fiducial volume. The observed background rate is (3.6±0.4stat)×10-3 events keV$ ee\atop{-1}$ kg-1 day-1, consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.
The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. One tonne of plastic scintillator is ...arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. Particular attention has been paid to radiological content. The overall aim has been to achieve a veto detector of low threshold and high efficiency without the creation of additional background in ZEPLIN-III, all at a reasonable cost. Extensive experimental measurements of the components have been made, including radioactivity levels and performance characteristics. These have been used to inform a complete end-to-end Monte Carlo simulation that has then been used to calculate the expected performance of the new instrument, both operating alone and as an anti-coincidence detector for ZEPLIN-III. The veto device will be capable of rejecting over 65% of coincident nuclear recoil events from neutron background in the energy range of interest in ZEPLIN-III. This will reduce the background in ZEPLIN-III from ≃0.4 to ≃0.14
events per year in the WIMP acceptance region, a significant factor in the event of a non-zero observation. Furthermore, in addition to providing valuable diagnostic capabilities, the veto is capable of tagging over 15% for
γ-ray rejection, all whilst contributing no significant additional background. In conjunction with the replacement of the internal ZEPLIN-III photomultiplier array, the new veto is expected to improve significantly the sensitivity of the ZEPLIN-III instrument to dark matter, allowing spin-independent WIMP-nucleon cross sections below 10
−8
pb to be probed.
The Large Underground Xenon (LUX) dark matter experiment aims to detect rare low-energy interactions from Weakly Interacting Massive Particles (WIMPs). The radiogenic backgrounds in the LUX detector ...have been measured and compared with Monte Carlo simulation. Measurements of LUX high-energy data have provided direct constraints on all background sources contributing to the background model. The expected background rate from the background model for the 85.3 day WIMP search run is (2.6±0.2stat±0.4sys) ×10-3 events keV$ ee\atop{-1}$ kg-1 day-1 in a 118 kg fiducial volume. The observed background rate is (3.6±0.4stat)×10-3 events keV$ ee\atop{-1}$ kg-1 day-1, consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.
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