Large Underground Xenon Research Articles

China carves out larger role in underground science

As it is doing in so many areas of science, China is racing onto the world stage of underground astroparticle physics.

No Dark Matter? Prediction from Dynamic Universe Model Came True!

This paper discusses about the theoretical “non-requirement” of dark matter, or in other words, there is no missing mass in galaxies. A singularity free and collision free n-body problem solution called dynamic universe model was used to find out the theoretical star circular velocity curves in a galaxy. Here five cases are presented. In the first case a HUGE mass at the center of galaxy, sun like stars and external galaxies are assumed, when plotted, the graph of last iteration shows disk formation and velocities achieved. This circular velocities verses radius graph looks exactly similar to observations by astronomers. In all the other cases, either the central mass is missing or external galaxies are missing or both are missing where resulting graphs look different. It can be inferred that the theoretical requirement of dark matter is calculation error, that no dark matter (missing mass) is required according to dynamic universe model. This prediction was first presented in Tokyo University in 2005. Later the findings from LUX in 2013 the (Large Underground Xenon) experiment confirmed this prediction. This new Tensor math in dynamic universe model was used for solving a large variety of physical problems which are otherwise not possible with present day physics. This method solved many unsolved problems earlier like existence of blue shifted galaxies galaxy disk formations, missing mass in galaxies, pioneer anomaly, non-collapsing large scale mass structures and new horizons trajectory predictions etc. AMS subject classifications: 70F10 (n-body problems), 70F15 (celestial mechanics), 70E55 (dynamics of multi body systems) 70-05 (experimental work) 70-08 (computational methods).

Results from the LUX dark matter experiment

The LUX (Large Underground Xenon) experiment aims at the direct detection of dark matter particles via their collisions with xenon nuclei. The 370kg 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. 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.

Radiogenic and muon-induced backgrounds in the LUX dark matter detector

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 85.3day WIMP search run is (2.6±0.2stat±0.4sys)×10-3 events keVee-1kg-1day-1 in a 118kg fiducial volume. The observed background rate is (3.6±0.4stat)×10-3 events keVee-1kg-1day-1, consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.

First Results from the LUX Dark Matter Experiment at the Sanford Underground Research Facility

The Large Underground Xenon (LUX) experiment is a dual-phase xenon time-projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota). The LUX cryostat was filled for the first time in the underground laboratory in February 2013. We report results of the first WIMP search data set, taken during the period from April to August 2013, presenting the analysis of 85.3 live days of data with a fiducial volume of 118 kg. A profile-likelihood analysis technique shows our data to be consistent with the background-only hypothesis, allowing 90% confidence limits to be set on spin-independent WIMP-nucleon elastic scattering with a minimum upper limit on the cross section of 7.6 × 10(-46) cm(2) at a WIMP mass of 33 GeV/c(2). We find that the LUX data are in disagreement with low-mass WIMP signal interpretations of the results from several recent direct detection experiments.

Dynamic Universe Model’s Prediction “No Dark Matter” in the Universe Came True!

This paper discusses about Dark matter or Missing mass in Galaxies. In this work the tensor mathematics called Dynamic Universe Model was used to find out theoretical star circular velocity curves in a Galaxy. Here we are presenting four main cases. In the first case, there is a Galaxy with huge central mass at the center, sun like stars and external galaxies are present in the calculations; only in this case the theoretical predictions of circular velocity curves (star circular velocity verses star distance from the center of galaxy) were matching with the observed velocities. In the later three cases either the huge central mass was absent or external galaxies were absent or both were absent, the theoretical circular velocities did not match the observations. Hence the question of missing mass / dark matter does not arise as it is only a calculations error. This prediction was first presented in Tokyo University in 2005, that No dark matter (Missing mass) is required according to Dynamic Universe Model. Later the findings from LUX in 2013 the (Large Underground Xenon) experiment confirmed this prediction.

Measuring double-electron capture with liquid xenon experiments

We investigate the possibilities of observing the decay mode for $^{124}$Xe in which two electrons are captured, two neutrinos are emitted, and the final daughter nucleus is in its ground state, using dark matter experiments with liquid xenon. The first upper limit of the decay half-life is calculated to be 1.66$\times10^{21}$ years at a 90% confidence level (C.L.) obtained with the published background data from the XENON100 experiment. Employing a known background model from the Large Underground Xenon (LUX) experiment, we predict that the detection of double-electron capture of $^{124}$Xe to the ground state of $^{124}$Te with LUX will have approximately 115 events, assuming a half-life of 2.9 $\times$ 10$^{21}$ years. We conclude that measuring $^{124}$Xe 2$\nu$ double-electron capture to the ground state of $^{124}$Te can be performed more precisely with the proposed LUX-Zeplin (LZ) experiment.

New Experiment Torpedoes Lightweight Dark Matter

This week, researchers working with the Large Underground Xenon (LUX) detector at the Sanford Underground Research Facility in Lead, South Dakota, announced that they see no signs of the lightweight dark matter particles hinted at by other experiments.

The LUX Dark Matter Search – Status Update

We report on the design, construction and commissioning of the Large Underground Xenon (LUX) dark matter detector at the Sanford Laboratory in Lead, SD, USA. From its inception in 2007, to its construction at a surface laboratory in lead in 2009–2010, its operation in 2011, and its re-installation 1 mile underground in 2012, we review the relevant achievements already obtained and give an outlook on how LUX will become the most sensitive detector in the field in 2013.

Technical results from the surface run of the LUX dark matter experiment

We present the results of the three-month above-ground commissioning run of the Large Underground Xenon (LUX) experiment at the Sanford Underground Research Facility located in Lead, South Dakota, USA. LUX is a 370kg liquid xenon detector that will search for cold dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The commissioning run, conducted with the detector immersed in a water tank, validated the integration of the various sub-systems in preparation for the underground deployment. Using the data collected, we report excellent light collection properties, achieving 8.4 photoelectrons per keV for 662keV electron recoils without an applied electric field, measured in the center of the WIMP target. We also find good energy and position resolution in relatively high-energy interactions from a variety of internal and external sources. Finally, we have used the commissioning data to tune the optical properties of our simulation and report updated sensitivity projections for spin-independent WIMP-nucleon scattering.

The LUX prototype detector: Heat exchanger development

The LUX (large underground xenon) detector is a two-phase xenon time projection chamber (TPC) designed to search for WIMP–nucleon dark matter interactions. As with all noble element detectors, continuous purification of the detector medium is essential to produce a large (>1ms) electron lifetime; this is necessary for efficient measurement of the electron signal which in turn is essential for achieving robust discrimination of signal from background events. In this paper, we describe the development of a novel purification system deployed in a prototype detector. The results from the operation of this prototype indicated heat exchange with an efficiency above 94% up to a flow rate of 42 slpm, allowing for an electron drift length greater than 1m to be achieved in approximately 2 days and sustained for the duration of the testing period.

Cryogenic Large Liquid Xenon Detector for Dark Matter Searches

Observation of rotational curve of spiral galaxies shows that a large fraction (∼23%) of the mass density of the universe is unaccounted for. Such a significant percentage of missing dark matter suggests that the universe may consist of new types of elementary particles. A compelling explanation for the new particles is the existence of Weakly Interacting Massive Particles (WIMPs), which are non-baryonic particles characterized by particle physics theories beyond the Standard Model. WIMPs are believed to only interact through the weak force and gravity; hence the interaction cross section with ordinary matter is extremely small. Therefore, experimental techniques that combine low radioactivity, low energy thresholds, efficient discrimination against electronic recoil backgrounds, and scalability to large detector masses can only be performed at a deep underground environment where the interference of cosmic rays is obviated. In this paper, we report a cryogenic large liquid xenon detector for dark matter searches at Sanford Lab (Davis Cavern) in the Homestake Mine, USA. The goal of the large underground xenon (LUX) dual-phase detector is to clearly detect (or exclude) WIMPs with a spin independent cross-section per nucleon of 7 × 10−46 cm2, equivalent to ∼0.5 events/100 kg/month in an inner 100 kg fiducial volume (FV) of a 300 kg LXe detector.

The Large Underground Xenon (LUX) experiment

The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles (WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross-section per nucleon of 2×10−46cm2, equivalent to ∼1event/100kg/month in the inner 100-kg fiducial volume (FV) of the 370-kg detector. The overall background goals are set to have <1 background events characterized as possible WIMPs in the FV in 300 days of running.This paper describes the design and construction of the LUX detector.

The LUX dark matter search

The Large Underground Xenon (LUX) experiment is a liquid xenon time projection chamber designed for extremely low levels of radioactive background in its fiducial volume. The overall liquid xenon mass is 300 kg, with a 100 kg fiducial mass. LUX is currently under construction, and integration of the full detector will begin in Fall 2009 at the Sanford Underground Science and Engineering Laboratory in South Dakota. The LUX sensitivity to the WIMP-nucleon spin-independent scattering cross-section will be 7 × 10-46 cm2 at 100 GeV after 300 days of low-background operation.