3,371 research outputs found
Field dependence of electronic recoil signals in a dual-phase liquid xenon time projection chamber
We present measurements of light and charge signals in a dual-phase time
projection chamber at electric fields varying from 10 V/cm up to 500 V/cm and
at zero field using 511 keV gamma rays from a Na source. We determine
the drift velocity, electron lifetime, diffusion constant, and light and charge
yields at 511 keV as a function of the electric field. In addition, we fit the
scintillation pulse shape to an effective exponential model, showing a decay
time of 43.5 ns at low field that decreases to 25 ns at high fields.Comment: 14 pages, 8 figure
On positive solutions and the Omega limit set for a class of delay differential equations
This paper studies the positive solutions of a class of delay differential
equations with two delays. These equations originate from the modeling of
hematopoietic cell populations. We give a sufficient condition on the initial
function for such that the solution is positive for all time .
The condition is "optimal". We also discuss the long time behavior of these
positive solutions through a dynamical system on the space of continuous
functions. We give a characteristic description of the limit set of
this dynamical system, which can provide informations about the long time
behavior of positive solutions of the delay differential equation.Comment: 15 pages, 2 figure
Monte Carlo Simulation Variance Reduction Techniques for Photon Transport in Liquid Xenon Detectors
Monte Carlo simulations are a crucial tool for the analysis and prediction of
various background components in liquid xenon (LXe) detectors. With improving
shielding in new experiments, the simulation of external backgrounds, such as
induced by gamma rays from detector materials, gets more computationally
expensive. We introduce and validate an accelerated Monte Carlo simulation
technique for photon transport in liquid xenon detectors. The method simulates
photon-induced interactions within a defined geometry and energy range with
high statistics while interactions outside of the region of interest are not
simulated directly but are taken into account by means of probability weights.
For a simulation of gamma induced backgrounds in an exemplary detector geometry
we achieve a three orders of magnitude acceleration compared to a standard
simulation of a current ton-scale LXe dark matter experiment
Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of <sup>136</sup> Xe
Effective field theory search for high-energy nuclear recoils using the XENON100 dark matter detector
Material radioassay and selection for the XENON1T dark matter experiment
The XENON1T dark matter experiment aims to detect weakly interacting massive particles (WIMPs) through low-energy interactions with xenon atoms. To detect such a rare event necessitates the use of radiopure materials to minimize the number of background events within the expected WIMP signal region. In this paper we report the results of an extensive material radioassay campaign for the XENON1T experiment. Using gamma-ray spectroscopy and mass spectrometry techniques, systematic measurements of trace radioactive impurities in over one hundred samples within a wide range of materials were performed. The measured activities allowed for stringent selection and placement of materials during the detector construction phase and provided the input for XENON1T detection sensitivity estimates through Monte Carlo simulations
The XENON1T Dark Matter Experiment
The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2 t liquid xenon inventory, 2.0 t constitute the active target of the dual-phase time projection chamber. The scintillation and ionization signals from particle interactions are detected with low-background photomultipliers. This article describes the XENON1T instrument and its subsystems as well as strategies to achieve an unprecedented low background level. First results on the detector response and the performance of the subsystems are also presented
First Dark Matter Search Results from the XENON1T Experiment
We report the first dark matter search results from XENON1T, a ∼2000−kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042±12)−kg fiducial mass and in the [5,40]  keVnr energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93±0.25)×10−4  events/(kg×day×keVee), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10  GeV/c2, with a minimum of 7.7×10−47  cm2 for 35−GeV/c2 WIMPs at 90% C.L
Search for two-neutrino double electron capture of <sup>124</sup>Xe<sup>Â </sup>with XENON100
Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For 124Xe this process has not yet been observed and its detection would provide a new reference for nuclear matrix element calculations. We have conducted a search for two-neutrino double electron capture from the K shell of 124Xe using 7636 kgd of data from the XENON100 dark matter detector. Using a Bayesian analysis we observed no significant excess above background, leading to a lower 90% credibility limit on the half-life T1/2>6.5×1020 yr. We have also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and found a sensitivity of T1/2> 6.1 × 1022 yr after an exposure of 2 t yr
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