يعرض 1 - 10 نتائج من 65 نتيجة بحث عن '"Fearon, Nm"', وقت الاستعلام: 1.15s تنقيح النتائج
  1. 1
    دورية أكاديمية

    المصدر: Physical Review D. 109(9)

    الوصف: Following the first science results of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time projection chamber operating from the Sanford Underground Research Facility in Lead, South Dakota, USA, we report the initial limits on a model-independent nonrelativistic effective field theory describing the complete set of possible interactions of a weakly interacting massive particle (WIMP) with a nucleon. These results utilize the same 5.5 t fiducial mass and 60 live days of exposure collected for the LZ spin-independent and spin-dependent analyses while extending the upper limit of the energy region of interest by a factor of 7.5 to 270 keV. No significant excess in this high energy region is observed. Using a profile-likelihood ratio analysis, we report 90% confidence level exclusion limits on the coupling of each individual nonrelativistic WIMP-nucleon operator for both elastic and inelastic interactions in the isoscalar and isovector bases.

  2. 2
    دورية أكاديمية

    المصدر: Physical Review D. 108(7)

    الوصف: The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5 t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axionlike particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.

  3. 3
    دورية أكاديمية

    المصدر: Physical Review Letters. 131(4)

    الوصف: The LUX-ZEPLIN experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This Letter reports results from LUX-ZEPLIN's first search for weakly interacting massive particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross sections for WIMP masses above 9  GeV/c^{2}. The most stringent limit is set for spin-independent scattering at 36  GeV/c^{2}, rejecting cross sections above 9.2×10^{-48}  cm at the 90% confidence level.

  4. 4
    دورية أكاديمية

    المصدر: Physical Review D. 108(1)

    الوصف: The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to 9.2×10-48 cm2 for the spin-independent interaction of a 36 GeV/c2 WIMP at 90% confidence level. In this paper, we present a comprehensive analysis of the backgrounds important for this result and for other upcoming physics analyses, including neutrinoless double-beta decay searches and effective field theory interpretations of LUX-ZEPLIN data. We confirm that the in-situ determinations of bulk and fixed radioactive backgrounds are consistent with expectations from the ex-situ assays. The observed background rate after WIMP search criteria were applied was (6.3±0.5)×10-5 events/keVee/kg/day in the low-energy region, approximately 60 times lower than the equivalent rate reported by the LUX experiment.

  5. 5
    دورية أكاديمية

    المصدر: Physical Review D. 105(8)

    مصطلحات موضوعية: Nuclear and Plasma Physics, Physical Sciences

    الوصف: We estimate the amount of Ar37 produced in natural xenon via cosmic-ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth's surface. We then calculate the resulting Ar37 concentration in a 10-tonne payload (similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage, and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea-level production rate of Ar37 in natural xenon is estimated to be 0.024 atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1 tonne/month, the average Ar37 activity after 10 tons are purified and transported underground is 0.058-0.090 μBq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic Ar37 will appear as a noticeable background in the early science data, while decaying with a 35-day half-life. This newly noticed production mechanism of Ar37 should be considered when planning for future liquid-xenon-based experiments.

    وصف الملف: application/pdf

  6. 6
    دورية أكاديمية

    المصدر: Physical Review C. 104(6)

    الوصف: The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double β decay of Xe134 is presented. LZ is a 10-tonne xenon time-projection chamber optimized for the detection of dark matter particles and is expected to start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass of natural xenon provides an exceptional opportunity to search for the double β decay of Xe134, for which xenon detectors enriched in Xe136 are less effective. For the two-neutrino decay mode, LZ is predicted to exclude values of the half-life up to 1.7×1024 years at 90% confidence level (CL) and has a three-sigma observation potential of 8.7×1023 years, approaching the predictions of nuclear models. For the neutrinoless decay mode LZ, is projected to exclude values of the half-life up to 7.3×1024 years at 90% CL.

  7. 7
    دورية أكاديمية

    المصدر: Physical Review D. 104(9)

    الوصف: LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a ∼7-tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for pp-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the

    وصف الملف: application/pdf

  8. 8
    دورية أكاديمية

    مصطلحات موضوعية: physics.ins-det, nucl-ex

    الوصف: The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrinoand neutrinoless double beta decay of $^{134}$Xe is presented. LZ is a 10-tonnexenon time projection chamber optimized for the detection of dark matterparticles, that is expected to start operating in 2021 at Sanford UndergroundResearch Facility, USA. Its large mass of natural xenon provides an exceptionalopportunity to search for the double beta decay of $^{134}$Xe, for which xenondetectors enriched in $^{136}$Xe are less effective. For the two-neutrino decaymode, LZ is predicted to exclude values of the half-life up to1.7$\times$10$^{24}$ years at 90% confidence level (CL), and has a three-sigmaobservation potential of 8.7$\times$10$^{23}$ years, approaching thepredictions of nuclear models. For the neutrinoless decay mode LZ, is projectedto exclude values of the half-life up to 7.3$\times$10$^{24}$ years at 90% CL.

    وصف الملف: application/pdf

  9. 9
    دورية أكاديمية

    مصطلحات موضوعية: hep-ex, astro-ph.CO, hep-ph

    الوصف: LUX-ZEPLIN (LZ) is a dark matter detector expected to obtain world-leadingsensitivity to weakly interacting massive particles (WIMPs) interacting vianuclear recoils with a ~7-tonne xenon target mass. This manuscript presentssensitivity projections to several low-energy signals of the complementaryelectron recoil signal type: 1) an effective neutrino magnetic moment and 2) aneffective neutrino millicharge, both for pp-chain solar neutrinos, 3) an axionflux generated by the Sun, 4) axion-like particles forming the galactic darkmatter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic darkmatter. World-leading sensitivities are expected in each case, a result of thelarge 5.6t 1000d exposure and low expected rate of electron recoil backgroundsin the $

    وصف الملف: application/pdf

  10. 10
    دورية أكاديمية

    مصطلحات موضوعية: astro-ph.IM, physics.ins-det

    الوصف: Two-phase xenon detectors, such as that at the core of the forthcoming LZdark matter experiment, use photomultiplier tubes to sense the primary (S1) andsecondary (S2) scintillation signals resulting from particle interactions intheir liquid xenon target. This paper describes a simulation study exploringtwo techniques to lower the energy threshold of LZ to gain sensitivity tolow-mass dark matter and astrophysical neutrinos, which will be applicable toother liquid xenon detectors. The energy threshold is determined by the numberof detected S1 photons; typically, these must be recorded in three or morephotomultiplier channels to avoid dark count coincidences that mimic realsignals. To lower this threshold: a) we take advantage of the doublephotoelectron emission effect, whereby a single vacuum ultraviolet photon has a$\sim20\%$ probability of ejecting two photoelectrons from a photomultipliertube photocathode; and b) we drop the requirement of an S1 signal altogether,and use only the ionization signal, which can be detected more efficiently. Forboth techniques we develop signal and background models for the nominalexposure, and explore accompanying systematic effects, including the dependenceon the free electron lifetime in the liquid xenon. When incorporating doublephotoelectron signals, we predict a factor of $\sim 4$ sensitivity improvementto the dark matter-nucleon scattering cross-section at $2.5$ GeV/c$^2$, and afactor of $\sim1.6$ increase in the solar $^8$B neutrino detection rate.Dropping the S1 requirement may allow sensitivity gains of two orders ofmagnitude in both cases. Finally, we apply these techniques to even lowermasses by taking into account the atomic Migdal effect; this could lower thedark matter particle mass threshold to $80$ MeV/c$^2$.

    وصف الملف: application/pdf