27 research outputs found
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
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 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
Accelerated surgery versus standard care in hip fracture (HIP ATTACK): an international, randomised, controlled trial
A next-generation liquid xenon observatory for dark matter and neutrino physics
The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector
Cosmogenic production of 37Ar in the context of the LUX-ZEPLIN experiment
We estimate the amount of 37Ar 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 37Ar 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 37Ar 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 37Ar activity after 10~tonnes 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 37Ar 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 37Ar should be considered when planning for future liquid xenon-based experiments