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

Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Bernard, E.; Bernstein, A.; Bradley, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J. J.; Chiller, A. A.; Chiller, C.; Coffey, T.; Currie, A.; Viveiros, L. de; D
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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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 View the MathML source in a 118 kg fiducial volume. The observed background rate is (3.6±0.4stat)×10-3 events View the MathML source, consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.

Do nobre ao soviete: "Antologia do conto russo", Editôra Lux Ltda.; From noble to soviet: "Anthology of russian short stories", Editôra Lux Ltda.

Pelissaro, Bárbara Rosa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/08/2013 PT
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A Antologia do conto russo, publicada pela Editôra Lux Ltda. no início dos anos 1960 e organizada por Otto Maria Carpeaux, é a primeira tradução de contos russos realizada diretamente da língua de origem. Este estudo resgata as informações e a situação em que essa coletânea de textos foi criada, numa tentativa de remontar seu contexto histórico, momento literário e mercado editorial, buscando hipóteses que auxiliem no entendimento dos aparatos que a constituem, num esforço de aproximação do escasso material de divulgação localizado sobre obra, editora e organizador pesquisado nos periódicos da época e constante dos anexos , numa reflexão sobre os laços de interesse existentes entre o Brasil e a União Soviética.; The Anthology of Russian Short Stories, edited by Otto Maria Carpeaux and published in the early 1960s by Editôra Lux Ltda, marks the first time Russian short stories were published from direct translation of the original language to Portuguese. This study retrieved information about the Brazilian historical and literary context as well as its publishing market during the time the work was created in an effort to promote a better understanding of how it was influenced by them. The presented information about the work...

Efeito da dimensão do site-A na sequência de fases do sistema Eu1-x Lux MnO3

Oliveira, Juliana Alice Ferreira
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em //2010 POR
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Dissertação de mestrado em Física dos Materiais Avançados (área de especialização em Materiais Funcionais para a Nano e Microtecnologia); Nesta dissertação apresentamos um estudo experimental do efeito do tamanho do ião do site-A na sequência de fases da manganita EuMnO3 dopada com Lu3+, focando principalmente a estrutura e as propriedades físicas do sistema Eu1-x Lux MnO3, com x= 0, 0.1, 0.2, e 0.3.Para tal, foram utilizadas a técnica de difracção de raios-X em pós, e técnicas de caracterização das propriedades magnéticas, dieléctricas, do calor específico e das propriedades polares. Uma vez que o sistema em tudo é semelhante ao sistema EuMnO3 dopado com Y 3+, cujo raio iónico para a coordenação 12 é superior ao do Lu3+, a comparação dos resultados obtidos neste trabalho com os publicados para o sistema Eu1-x Yx MnO3, constitui um dos elementos fundamentais utilizado para a caracterização estrutural e polar das fases magnéticas e o desenho do diagrama de fases do sistema Eu1-x Lux MnO3 , com os valores de x no intervalo 0 ≤ x ≤ 0:3. A estrutura cristalográfica das amostras à temperatura ambiente foi determinada a partir da análise dos espectros de difracção de raios-X em pós, e estudada a dependência dos parâmetros cristalográficos em função da concentração x de Lu3+. Os comprimentos de ligação Mn-O e R-O...

Synergistic binding of the Vibrio fischeri LuxR transcriptional activator domain and RNA polymerase to the lux promoter region.

Stevens, A M; Dolan, K M; Greenberg, E P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 20/12/1994 EN
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LuxR, the Vibrio fischeri luminescence gene (lux) activator, is the best-studied member of a family of bacterial transcription factors required for cell density-dependent expression of specific genes involved in associations with eukaryotic hosts. Neither LuxR nor any other LuxR homolog has been shown to bind DNA directly. We have purified the LuxR C-terminal transcriptional activator domain from extracts of recombinant Escherichia coli in which this polypeptide was expressed. The purified polypeptide by itself binds to lux regulatory DNA upstream of the lux box, a 20-bp palindrome that is required for LuxR activity in vivo, but it does not bind to the lux box. However, the LuxR C-terminal domain together with RNA polymerase protects a region including the lux box and the lux operon promoter from DNase I cleavage. There is very little protection of the lux operon promoter region from DNase I digestion in the presence of RNA polymerase alone. Apparently, there is a synergistic binding of the LuxR C-terminal domain and RNA polymerase to the promoter region. The upstream binding region for the purified polypeptide encompasses a binding site for cAMP receptor protein (CRP). Under some conditions, CRP binding can block the binding of the LuxR C-terminal domain to the upstream binding region...

LuxR- and Acyl-Homoserine-Lactone-Controlled Non-lux Genes Define a Quorum-Sensing Regulon in Vibrio fischeri

Callahan, Sean M.; Dunlap, Paul V.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2000 EN
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The luminescence (lux) operon (luxICDABEG) of the symbiotic bacterium Vibrio fischeri is regulated by the transcriptional activator LuxR and two acyl-homoserine lactone (acyl-HSL) autoinducers (the luxI-dependent 3-oxo-hexanoyl-HSL [3-oxo-C6-HSL] and the ainS-dependent octanoyl-HSL [C8-HSL]) in a population density-responsive manner called quorum sensing. To identify quorum-sensing-regulated (QSR) proteins different from those encoded by lux genes, we examined the protein patterns of V. fischeri quorum-sensing mutants defective in luxI, ainS, and luxR by two-dimensional polyacrylamide gel electrophoresis. Five non-Lux QSR proteins, QsrP, RibB, AcfA, QsrV, and QSR 7, were identified; their production occurred preferentially at high population density, required both LuxR and 3-oxo-C6-HSL, and was inhibited by C8-HSL at low population density. The genes encoding two of the QSR proteins were characterized: qsrP directs cells to synthesize an apparently novel periplasmic protein, and ribB is a homolog of the Escherichia coli gene for 3,4-dihydroxy-2-butanone 4-phosphate synthase, a key enzyme for riboflavin synthesis. The qsrP and ribB promoter regions each contained a sequence similar to the lux operon lux box, a 20-bp region of dyad symmetry necessary for LuxR/3-oxo-C6-HSL-dependent activation of lux operon transcription. V. fischeri qsrP and ribB mutants exhibited no distinct phenotype in culture. However...

Role of the C-Terminal Domain of the Alpha Subunit of RNA Polymerase in LuxR-Dependent Transcriptional Activation of the lux Operon during Quorum Sensing

Finney, Angela H.; Blick, Robert J.; Murakami, Katsuhiko; Ishihama, Akira; Stevens, Ann M.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2002 EN
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27.31%
During quorum sensing in Vibrio fischeri, the luminescence, or lux, operon is regulated in a cell density-dependent manner by the activator LuxR in the presence of an acylated homoserine lactone autoinducer molecule [N-(3-oxohexanoyl) homoserine lactone]. LuxR, which binds to the lux operon promoter at a position centered at −42.5 relative to the transcription initiation site, is thought to function as an ambidextrous activator making multiple contacts with RNA polymerase (RNAP). The specific role of the α-subunit C-terminal domain (αCTD) of RNAP in LuxR-dependent transcriptional activation of the lux operon promoter has been investigated. The effects of 70 alanine substitution variants of the α subunit were determined in vivo by measuring the rate of transcription of the lux operon via luciferase assays in recombinant Escherichia coli. The mutant RNAPs from strains exhibiting at least twofold-increased or -decreased activity in comparison to the wild type were further examined by in vitro assays. Since full-length LuxR has not been purified, an autoinducer-independent N-terminally truncated form of LuxR, LuxRΔN, was used for in vitro studies. Single-round transcription assays were performed using reconstituted mutant RNAPs in the presence of LuxRΔN...

Multiple repetitive elements and organization of the lux operons of luminescent terrestrial bacteria.

Meighen, E A; Szittner, R B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1992 EN
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The complete nucleotide sequences of the luxA to luxE genes, as well as the flanking regions, were determined for the lux operons of two Xenorhabdus luminescens strains isolated from insects and humans. The nucleotide sequences of the corresponding lux genes (luxCDABE) were 85 to 90% identical but completely diverged 350 bp upstream of the first lux gene (luxC) and immediately downstream of the last lux gene (luxE). These results show that the luxG gene found immediately downstream of luxE in luminescent marine bacteria is missing at this location in terrestrial bacteria and raise the possibility that the lux operons are at different positions in the genomes of the X. luminescens strains. Four enteric repetitive intergenic consensus (ERIC) or intergenic repetitive unit (IRU) sequences of 126 bp were identified in the 7.7-kbp DNA fragment from the X.luminescens strain isolated from humans, providing the first example of multiple ERIC structures in the same operon including two ERIC structures at the same site. Only a single ERIC structure between luxB and luxE is present in the 7-kbp lux DNA from insects. Analysis of the genomic DNAs from five X. luminescens strains or isolates by polymerase chain reaction has demonstrated that an ERIC structure is between luxB and luxE in all of the strains...

The luxR gene product of Vibrio harveyi is a transcriptional activator of the lux promoter.

Swartzman, E; Silverman, M; Meighen, E A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1992 EN
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27.41%
Expression of the lux operon from the marine bacterium Vibrio harveyi is dependent on cell density and requires an unlinked regulatory gene, luxR, and other cofactors for autoregulation. Escherichia coli transformed with the lux operon emits very low levels of light, and this deficiency can be partially alleviated by coexpression of luxR in trans. The V. harveyi lux promoter was analyzed in vivo by primer extension mapping to examine the function of luxR. RNA isolated from E. coli transformed with the Vibrio harveyi lux operon was shown to have a start site at 123 bp upstream of the first ATG codon of luxC. This is in sharp contrast to the start site found for lux RNA isolated from V. harveyi, at 26 bp upstream of the luxC initiation codon. However, when E. coli was cotransformed with both the lux operon and luxR, the start site of the lux mRNA shifted from -123 to -26. Furthermore, expression of the luxR gene caused a 350-fold increase in lux mRNA levels. The results suggest that LuxR of V. harveyi is a transcriptional activator stimulating initiation at the -26 lux promoter.

Transcriptional regulation of lux genes transferred into Vibrio harveyi.

Miyamoto, C M; Meighen, E A; Graham, A F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1990 EN
Relevância na Pesquisa
27.31%
Past work has shown that transformed Escherichia coli is not a suitable vehicle for studying the expression and regulation of the cloned luminescence (lux) genes of Vibrio harveyi. Therefore, we have used a conjugative system to transfer lux genes cloned into E. coli back into V. harveyi, where they can be studied in the parental organism. To do this, lux DNA was inserted into a broad-spectrum vector, pKT230, cloned in E. coli, and then mobilized into V. harveyi by mating aided by the conjugative plasmid pRK2013, also contained in E. coli. Transfer of the wild-type luxD gene into the V. harveyi M17 mutant by this means resulted in complementation of the luxD mutation and full restoration of luminescence in the mutant; expression of transferase activity was induced if DNA upstream of luxC preceded the luxD gene on the plasmid, indicating the presence of a strong inducible promoter. To extend the usefulness of the transfer system, the gene for chloramphenicol acetyltransferase was inserted into the pKT230 vector as a reporter. The promoter upstream of luxC was verified to be cell density regulated and, in addition, glucose repressible. It is suggested that this promoter may be the primary autoregulated promoter of the V. harveyi luminescence system. Strong termination signals on both DNA strands were recognized and are located downstream from luxE at a point complementary to the longest mRNA from the lux operon. Structural lux genes transferred back into V. harveyi under control of the luxC promoter are expressed at very high levels in V. harveyi as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis: the gene transfer system is thus useful for expression of proteins as well as for studying the regulation of lux genes in their native environment.

Natural Merodiploidy of the lux-rib Operon of Photobacterium leiognathi from Coastal Waters of Honshu, Japan▿ †

Ast, Jennifer C.; Urbanczyk, Henryk; Dunlap, Paul V.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
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Sequence analysis of the bacterial luminescence (lux) genes has proven effective in helping resolve evolutionary relationships among luminous bacteria. Phylogenetic analysis using lux genes, however, is based on the assumptions that the lux genes are present as single copies on the bacterial chromosome and are vertically inherited. We report here that certain strains of Photobacterium leiognathi carry multiple phylogenetically distinct copies of the entire operon that codes for luminescence and riboflavin synthesis genes, luxCDABEG-ribEBHA. Merodiploid lux-rib strains of P. leiognathi were detected during sequence analysis of luxA. To define the gene content, organization, and sequence of each lux-rib operon, we constructed a fosmid library of genomic DNA from a representative merodiploid strain, lnuch.13.1. Sequence analysis of fosmid clones and genomic analysis of lnuch.13.1 defined two complete, physically separate, and apparently functional operons, designated lux-rib1 and lux-rib2. P. leiognathi strains lelon.2.1 and lnuch.21.1 were also found to carry lux-rib1 and lux-rib2, whereas ATCC 25521T apparently carries only lux-rib1. In lnuch.13.1, lelon.2.1, lnuch.21.1, and ATCC 25521T, lux-rib1 is flanked upstream by lumQ and putA and downstream by a gene for a hypothetical multidrug efflux pump. In contrast...

Phylogenetic Analysis of the Incidence of lux Gene Horizontal Transfer in Vibrionaceae▿ †

Urbanczyk, Henryk; Ast, Jennifer C.; Kaeding, Allison J.; Oliver, James D.; Dunlap, Paul V.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.56%
Horizontal gene transfer (HGT) is thought to occur frequently in bacteria in nature and to play an important role in bacterial evolution, contributing to the formation of new species. To gain insight into the frequency of HGT in Vibrionaceae and its possible impact on speciation, we assessed the incidence of interspecies transfer of the lux genes (luxCDABEG), which encode proteins involved in luminescence, a distinctive phenotype. Three hundred three luminous strains, most of which were recently isolated from nature and which represent 11 Aliivibrio, Photobacterium, and Vibrio species, were screened for incongruence of phylogenies based on a representative housekeeping gene (gyrB or pyrH) and a representative lux gene (luxA). Strains exhibiting incongruence were then subjected to detailed phylogenetic analysis of horizontal transfer by using multiple housekeeping genes (gyrB, recA, and pyrH) and multiple lux genes (luxCDABEG). In nearly all cases, housekeeping gene and lux gene phylogenies were congruent, and there was no instance in which the lux genes of one luminous species had replaced the lux genes of another luminous species. Therefore, the lux genes are predominantly vertically inherited in Vibrionaceae. The few exceptions to this pattern of congruence were as follows: (i) the lux genes of the only known luminous strain of Vibrio vulnificus...

The Evolution of the Bacterial Luciferase Gene Cassette (lux) as a Real-Time Bioreporter

Close, Dan; Xu, Tingting; Smartt, Abby; Rogers, Alexandra; Crossley, Robert; Price, Sarah; Ripp, Steven; Sayler, Gary
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 11/01/2012 EN
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27.38%
The bacterial luciferase gene cassette (lux) is unique among bioluminescent bioreporter systems due to its ability to synthesize and/or scavenge all of the substrate compounds required for its production of light. As a result, the lux system has the unique ability to autonomously produce a luminescent signal, either continuously or in response to the presence of a specific trigger, across a wide array of organismal hosts. While originally employed extensively as a bacterial bioreporter system for the detection of specific chemical signals in environmental samples, the use of lux as a bioreporter technology has continuously expanded over the last 30 years to include expression in eukaryotic cells such as Saccharomyces cerevisiae and even human cell lines as well. Under these conditions, the lux system has been developed for use as a biomedical detection tool for toxicity screening and visualization of tumors in small animal models. As the technologies for lux signal detection continue to improve, it is poised to become one of the first fully implantable detection systems for intra-organismal optical detection through direct marriage to an implantable photon-detecting digital chip. This review presents the basic biochemical background that allows the lux system to continuously autobioluminesce and highlights the important milestones in the use of lux-based bioreporters as they have evolved from chemical detection platforms in prokaryotic bacteria to rodent-based tumorigenesis study targets. In addition...

A new Vibrio fischeri lux gene precedes a bidirectional termination site for the lux operon.

Swartzman, A; Kapoor, S; Graham, A F; Meighen, E A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1990 EN
Relevância na Pesquisa
27.38%
The DNA downstream of the lux structural genes in the Vibrio fischeri lux operon has been sequenced and a new lux gene (luxG) has been identified. A hairpin loop that begins with a poly(A) region and ends with a poly(T) region and thus can function as a bidirectional termination site for luxG and a convergent gene is located immediately downstream of luxG. 3' S1 nuclease mapping has demonstrated that the luxG mRNA was induced in a cell-density-dependent fashion consistent with it being part of the lux system and that the lux mRNA terminated immediately after the hairpin loop. The mRNA coded by an open reading frame convergent to luxG on the complementary strand was also shown by S1 nuclease mapping to overlap the lux mRNA for at least 20 nucleotides before termination. Expression of DNA containing the hairpin loop, placed between a strong promoter and a reporter gene and transferred by conjugation into luminescent bacteria, demonstrated the very high efficiency of termination by this hairpin loop oriented in either direction. These results also demonstrate that the organization of the genes at the 3' ends of the lux operons of V. fischeri and V. harveyi has clearly diverged.

First Dark Matter Search Results from the Large Underground Xenon (LUX) Experiment

Faham, Carlos; Collaboration, for the LUX
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/05/2014
Relevância na Pesquisa
37.08%
The Large Underground Xenon (LUX) dark matter experiment is operating 1.5 km underground at the Sanford Underground Research Facility in Lead, South Dakota, USA. In 2013, the experiment had a WIMP search exposure of 10,091 kg-days over a period of 85.3 live-days. This first dark matter search placed the world's most stringent limits on WIMP-nucleon interaction cross-sections over a wide range of WIMP masses, and is in tension with signal hints of low-mass WIMPs from DAMA, CoGeNT and CDMS-II Si. LUX will commence a 300 day run in 2014 that will improve the sensitivity by a factor of 5. Low-energy calibrations obtained from a neutron double-scattering technique will further constrain and reduce systematics, particularly for low WIMP masses.; Comment: Proceedings for the 2014 Rencontres de Moriond (Cosmology Session), La Thuile, Italy

The LUX Dark Matter Search -- Status Update

Fiorucci, S.; Collaboration, for the LUX
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/01/2013
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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.; Comment: 3 pages, no figures. To appear in the proceedings of the Sixth symposium of large TPCs for low energy rare events detection, Paris, December 2012

Underground Commissioning of LUX

Woods, Michael; Collaboration, for the LUX
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/05/2013
Relevância na Pesquisa
37.18%
LUX is a dual-phase xenon TPC designed for the direct detection of dark matter. Using 370 kg of xenon, LUX is capable of setting a WIMP-nucleon cross section limit at 2 x 10^-46 cm^2 after 300 days of running. LUX will surpass all existing dark matter limits for WIMP masses above 10 GeV within weeks of beginning its science run. Following a successful six month surface run, the detector has recently been deployed underground, and we expect completed commission in the near future. Updates on status and results are provided.; Comment: 4 pages, 4 figures, Moriond 2013

Technical Results from the Surface Run of the LUX Dark Matter Experiment

LUX Collaboration; Akerib, D. S.; Bai, X.; Bernard, E.; Bernstein, A.; Bradley, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chapman, J. J.; Coffey, T.; Dobi, A.; Dragowsky, E.; Druszkiewicz, E.; Edwards, B.; Faham, C. H.; Fiorucci, S.; Gaitskell,
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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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 370 kg 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 of the underground deployment. Using the data collected, we report excellent light collection properties, achieving 8.4 photoelectrons per keV for 662 keV 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.

First results from the LUX dark matter experiment at the Sanford Underground Research Facility

LUX Collaboration; Akerib, D. S.; Araujo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Bedikian, S.; Bernard, E.; Bernstein, A.; Bolozdynya, A.; Bradley, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J. J.; Chiller, A. A.; Chiller
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.08%
The Large Underground Xenon (LUX) experiment, a dual-phase xenon time-projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), was cooled and filled in February 2013. We report results of the first WIMP search dataset, taken during the period 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 $7.6 \times 10^{-46}$ cm$^{2}$ at a WIMP mass of 33 GeV/c$^2$. We find that the LUX data are in strong disagreement with low-mass WIMP signal interpretations of the results from several recent direct detection experiments.; Comment: Accepted by Phys. Rev. Lett. Appendix A included as supplementary material with PRL article

Improved WIMP scattering limits from the LUX experiment

LUX Collaboration; Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bradley, A.; Bramante, R.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/12/2015
Relevância na Pesquisa
36.93%
We present constraints on WIMP-nucleus scattering from the 2013 data of the Large Underground Xenon (LUX) dark matter experiment, including $1.4\times10^{4}\,\mathrm{kg\cdot days}$ of search exposure. This new analysis incorporates several advances: single-photon calibration at the scintillation wavelength; improved event-reconstruction algorithms; a revised background model including events originating on the detector walls in an enlarged fiducial volume; and new calibrations from decays of an injected tritium $\beta$ source and from kinematically constrained nuclear recoils down to 1.1 keV. Sensitivity, especially to low-mass WIMPs, is enhanced compared to our previous results which modeled the signal only above a 3 keV minimum energy. Under standard dark matter halo assumptions and in the mass range above 4 $\mathrm{GeV}\,c^{-2}$, these new results give the most stringent direct limits on the spin-independent WIMP-nucleon cross section. The 90% CL upper limit has a minimum of 0.4 zb at 33 $\mathrm{GeV}\,c^{-2}$ WIMP mass.; Comment: 6 pages, 3 figures

Tritium calibration of the LUX dark matter experiment

LUX Collaboration; Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bradley, A.; Bramante, R.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/12/2015
Relevância na Pesquisa
37.18%
We present measurements of the electron-recoil (ER) response of the LUX dark matter detector based upon 170,000 highly pure and spatially-uniform tritium decays. We reconstruct the tritium energy spectrum using the combined energy model and find good agreement with expectations. We report the average charge and light yields of ER events in liquid xenon at 180 V/cm and 105 V/cm and compare the results to the NEST model. We also measure the mean charge recombination fraction and its fluctuations, and we investigate the location and width of the LUX ER band. These results provide input to a re-analysis of the LUX Run3 WIMP search.; Comment: Submitted to Phys. Rev. D