67 research outputs found
Design and characterization of AmLi neutron sources for the LZ experiment
In this paper we describe the development, testing, and characterization of
three low-emission rate AmLi neutron sources. The sources are used to calibrate
the nuclear recoil response of the LUX-ZEPLIN (LZ) dark matter experiment. The
sources' neutron emission rate was measured using He proportional tubes.
The sources' gamma emissions were characterized using a high-purity germanium
(HPGe) detector. Source-validated GEANT4 Monte Carlo simulations allowed to
calibrate the Ge and neutron detector responses.Comment: 20 pages, 13 figures, 4 tables, revised manuscripts after
accommodating the reviewer's comment
Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment
The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus
interactions from its initial science run, down to cm
for the spin-independent interaction of a 36 GeV/c 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 events/keV/kg/day in the
low-energy region, approximately 60 times lower than the equivalent rate
reported by the LUX experiment.Comment: 25 pages, 15 figure
First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment
The LUX-ZEPLIN (LZ) 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
LZ'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. The most stringent limit is set at 30 GeV/c, excluding
cross sections above 5.9 cm at the 90\% confidence level.Comment: 9 pages, 6 figures. See https://tinyurl.com/LZDataReleaseRun1 for a
data release related to this pape
A search for new physics in low-energy electron recoils from the first LZ exposure
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 5.5t. 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 axion-like 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.Comment: 13 pages, 10 figures. See https://tinyurl.com/LZDataReleaseRun1ER for
a data release related to this pape
A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics
The nature of dark matter and properties of neutrinos are among the mostpressing issues in contemporary particle physics. The dual-phase xenontime-projection chamber is the leading technology to cover the availableparameter space for Weakly Interacting Massive Particles (WIMPs), whilefeaturing extensive sensitivity to many alternative dark matter candidates.These detectors can also study neutrinos through neutrinoless double-beta decayand through a variety of astrophysical sources. A next-generation xenon-baseddetector will therefore be a true multi-purpose observatory to significantlyadvance particle physics, nuclear physics, astrophysics, solar physics, andcosmology. This review article presents the science cases for such a detector.<br
Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils
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
p
p
-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
<
100
keV
energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout
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