Showing papers by "F. Gao published in 2017"
Columbia University1, University of Amsterdam2, University of Mainz3, University of Coimbra4, New York University Abu Dhabi5, University of Zurich6, Stockholm University7, Rensselaer Polytechnic Institute8, Max Planck Society9, Weizmann Institute of Science10, University of Freiburg11, Purdue University12, University of Nantes13, University of Bologna14, University of California, San Diego15, University of Münster16, University of Chicago17, Rice University18, Pierre-and-Marie-Curie University19, University of California, Los Angeles20
TL;DR: 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, are reported and a profile likelihood analysis shows that the data are consistent with the background-only hypothesis.
Abstract: 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 342 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 (193±025)×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 77×10-47 cm2 for 35-GeV/c2 WIMPs at 90% CL
1,061 citations
TL;DR: 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.
Abstract: 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.
238 citations
TL;DR: 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 as discussed by the authors.
Abstract: 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 3.2t liquid xenon inventory, 2.0t 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.
117 citations
Columbia University1, University of Amsterdam2, University of Mainz3, University of Coimbra4, New York University Abu Dhabi5, University of Zurich6, Stockholm University7, Rensselaer Polytechnic Institute8, Max Planck Society9, Weizmann Institute of Science10, University of Freiburg11, Purdue University12, École des mines de Nantes13, University of Bologna14, University of California, San Diego15, University of Münster16, Rice University17, University of Paris18, University of California, Los Angeles19
TL;DR: A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events.
Abstract: We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 years, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of $431^{+16}_{-14}$ days in the low energy region of $(2.0-5.8)$ keV in the single scatter event sample, with a global significance of $1.9\,\sigma$, however no other more significant modulation is observed. The expected annual modulation of a dark matter signal is not compatible with this result. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at $5.7\,\sigma$.
61 citations
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, New York University Abu Dhabi6, University of Zurich7, Stockholm University8, Rensselaer Polytechnic Institute9, Max Planck Society10, Weizmann Institute of Science11, University of Freiburg12, Purdue University13, École des mines de Nantes14, University of California, San Diego15, University of Münster16, University of Chicago17, University of California, Los Angeles18, Rice University19, Pierre-and-Marie-Curie University20, Karlsruhe Institute of Technology21
TL;DR: In this article, the design, construction and test of a novel cryogenic distillation column using the common McCabe-Thiele approach is described, which demonstrated a krypton reduction factor of 6.4\cdot 10^5.
Abstract: The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the $$\beta $$
-emitter $$^{85}$$
Kr which is present in the xenon. For XENON1T a concentration of natural krypton in xenon $$\mathrm {^{nat}\mathrm{Kr/Xe}\,<\,200\,ppq}$$
(parts per quadrillion,
$$1~\mathrm{ppq}~=10^{-15} \mathrm{mol/mol}$$
) is required. In this work, the design, construction and test of a novel cryogenic distillation column using the common McCabe–Thiele approach is described. The system demonstrated a krypton reduction factor of $$6.4\cdot 10^5$$
with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of $$\mathrm {^{nat}\mathrm{Kr/Xe}<26\,ppq}$$
is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN.
57 citations
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, New York University Abu Dhabi6, University of Zurich7, Stockholm University8, Rensselaer Polytechnic Institute9, Max Planck Society10, Weizmann Institute of Science11, University of Freiburg12, Purdue University13, École des mines de Nantes14, University of California, San Diego15, University of Münster16, University of Chicago17, Rice University18, Pierre-and-Marie-Curie University19, University of California, Los Angeles20
TL;DR: In this article, the authors 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.
Abstract: 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.
55 citations
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, University of Zurich6, Stockholm University7, Rensselaer Polytechnic Institute8, Max Planck Society9, Weizmann Institute of Science10, University of Bern11, University of Freiburg12, Purdue University13, New York University Abu Dhabi14, University of California, San Diego15, University of Münster16, Rice University17, University of California, Los Angeles18, University of Chicago19
TL;DR: In this article, weakly interacting massive particles (WIMPs) search results in the XENON100 detector using a non-relativistic effective field theory approach were reported.
Abstract: We report on weakly interacting massive particles (WIMPs) search results in the XENON100 detector using a nonrelativistic effective field theory approach. The data from science run II (34 kg×224.6 live days) were reanalyzed, with an increased recoil energy interval compared to previous analyses, ranging from (6.6–240) keVnr. The data are found to be compatible with the background-only hypothesis. We present 90% confidence level exclusion limits on the coupling constants of WIMP-nucleon effective operators using a binned profile likelihood method. We also consider the case of inelastic WIMP scattering, where incident WIMPs may up-scatter to a higher mass state, and set exclusion limits on this model as well.
54 citations
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, New York University Abu Dhabi6, University of Zurich7, Stockholm University8, Rensselaer Polytechnic Institute9, Max Planck Society10, Weizmann Institute of Science11, University of Freiburg12, Purdue University13, École des mines de Nantes14, University of California, San Diego15, University of Münster16, University of Chicago17, University of California, Los Angeles18, Rice University19, Pierre-and-Marie-Curie University20, Karlsruhe Institute of Technology21
TL;DR: In this article, a cryogenic distillation column was integrated into the gas purification loop of the XENON100 detector for online radon removal, which enabled the authors to significantly reduce the constant radon background originating from radon emanation.
Abstract: We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column was integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant $$^{222}$$
Rn background originating from radon emanation. After inserting an auxiliary $$^{222}$$
Rn emanation source in the gas loop, we determined a radon reduction factor of $$R\,>\,27$$
(95% C.L.) for the distillation column by monitoring the $$^{222}$$
Rn activity concentration inside the XENON100 detector.
43 citations
TL;DR: In this article, the spin-dependent, inelastic scattering cross section of weakly interacting massive particles (WIMPs) on nucleons from XENON100 data with an exposure of $7.64 \times 10^3 kg \cdot$ days is presented.
Abstract: We present the first constraints on the spin-dependent, inelastic scattering cross section of weakly interacting massive particles (WIMPs) on nucleons from XENON100 data with an exposure of $7.64 \times 10^3 kg \cdot$ days. XENON100 is a dual-phase xenon time projection chamber with 62 kg of active mass, operated at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy and designed to search for nuclear recoils from WIMP-nucleus interactions. Here we explore inelastic scattering, where a transition to a low-lying excited nuclear state of $^{129}Xe$ is induced. The experimental signature is a nuclear recoil observed together with the prompt deexcitation photon. We see no evidence for such inelastic WIMP-$^{129}Xe$ interactions. A profile likelihood analysis allows us to set a 90% C.L. upper limit on the inelastic, spin-dependent WIMP-nucleon cross section of $3.3 \times 10^{−38} cm^2$ at 100 $GeV/c^2$. This is the most constraining result to date, and sets the pathway for an analysis of this interaction channel in upcoming, larger dual-phase xenon detectors.
37 citations
TL;DR: In this article, the authors presented searches for solar axions and galactic axion-like particles (ALPs) in the data collected by the XENON100 experiment (with an exposure of 224.6 days).
Abstract: n our paper, we presented searches for solar axions and galactic axionlike particles (ALPs) in the data collected by the XENON100 experiment (with an exposure of 224.6 days). We recently found a bug in the code to calculate the exclusion limit for galactic ALPs. This resulted in an underestimation of the ALP expected rate, which in turn led to an overly conservative limit, compared to what it should really be.
We corrected the code, and the result of the XENON100 90% C.L. exclusion limit on galactic ALPs (shown in Fig. 1) was reevaluated. The corrected limit is stronger than the one previously published by approximately a factor of 5 across all masses and sets the best published limit on the axion-electron coupling, $g_{Ae}$, in the (1–40) keV/$c^2$ mass range.
35 citations
TL;DR: In this article, the authors present results of searches for vector and pseudoscalar bosonic super-weakly interacting massive particles (WIMPs) with the XENON100 experiment.
Abstract: We present results of searches for vector and pseudoscalar bosonic super-weakly interacting massive particles (WIMPs), which are dark matter candidates with masses at the keV-scale, with the XENON100 experiment. XENON100 is a dual-phase xenon time projection chamber operated at the Laboratori Nazionali del Gran Sasso. A profile likelihood analysis of data with an exposure of 224.6 live days $\ifmmode\times\else\texttimes\fi{}34\text{ }\text{ }\mathrm{kg}$ showed no evidence for a signal above the expected background. We thus obtain new and stringent upper limits in the $(8--125)\text{ }\text{ }\mathrm{keV}/{\mathrm{c}}^{2}$ mass range, excluding couplings to electrons with coupling constants of ${g}_{ae}g3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ for pseudo-scalar and ${\ensuremath{\alpha}}^{\ensuremath{'}}/\ensuremath{\alpha}g2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}$ for vector super-WIMPs, respectively. These limits are derived under the assumption that super-WIMPs constitute all of the dark matter in our galaxy.
TL;DR: In this paper, the authors show that the $212Pb$ beta emission can be used for low-energy electronic recoil calibration in searches for dark matter in the XENON100 detector.
Abstract: A $^{220}Rn$ source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. We show that the $^{212}Pb$ beta emission can be used for low-energy electronic recoil calibration in searches for dark matter. The isotope spreads throughout the entire active region of the detector, and its activity naturally decays below background level within a week after the source is closed. We find no increase in the activity of the troublesome $^{222}Rn$ background after calibration. Alpha emitters are also distributed throughout the detector and facilitate calibration of its response to $^{222}Rn$. Using the delayed coincidence of $^{220}Rn−^{216}Po$, we map for the first time the convective motion of particles in the XENON100 detector. Additionally, we make a competitive measurement of the half-life of $^{212}Po$, $t_{1/2}=(293.9 \pm(1.0)stat \pm(0.6)sys$) ns.
TL;DR: In this paper, a cryogenic distillation column is integrated into the gas purification loop of the XENON100 detector for online radon removal, which enabled the authors to significantly reduce the constant background originating from radon emanation.
Abstract: We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column is integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant $^{222}$Rn background originating from radon emanation. After inserting an auxiliary $^{222}$Rn emanation source in the gas loop, we determined a radon reduction factor of R > 27 (95% C.L.) for the distillation column by monitoring the $^{222}$Rn activity concentration inside the XENON100 detector.
TL;DR: In this article, the authors 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.
Abstract: 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.
TL;DR: In this paper, the authors conducted a search for two-neutrino double electron capture from the $K$ shell of the XENON100 dark matter detector, and found no significant excess above background, leading to a lower 90% credibility limit on the half-life.
Abstract: Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For $^{124}\mathrm{Xe}$ 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 $^{124}\mathrm{Xe}$ using 7636 $\mathrm{kg}\phantom{\rule{0.16em}{0ex}}\mathrm{d}$ 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 ${T}_{1/2}g6.5\ifmmode\times\else\texttimes\fi{}{10}^{20}$ yr. We have also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and found a sensitivity of ${T}_{1/2}g6.1\ifmmode\times\else\texttimes\fi{}{10}^{22}$ yr after an exposure of 2 $\mathrm{t}\phantom{\rule{0.16em}{0ex}}\mathrm{yr}$.
TL;DR: In this article, the authors describe the XENON100 data analyses used to assess the target-intrinsic background sources radon, thoron and krypton, and report an observed reduction in concentrations of radon daughters that they attribute to the plating-out of charged ions on the negatively biased cathode.
Abstract: In this paper, we describe the XENON100 data analyses used to assess the target-intrinsic background sources radon ($^{222}$Rn), thoron ($^{220}$Rn) and krypton ($^{85}$Kr). We detail the event selections of high-energy alpha particles and decay-specific delayed coincidences. We derive distributions of the individual radionuclides inside the detector and quantify their abundances during the main three science runs of the experiment over a period of $\sim$ 4 years, from January 2010 to January 2014. We compare our results to external measurements of radon emanation and krypton concentrations where we find good agreement. We report an observed reduction in concentrations of radon daughters that we attribute to the plating-out of charged ions on the negatively biased cathode.
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, New York University Abu Dhabi6, University of Zurich7, Stockholm University8, Rensselaer Polytechnic Institute9, Max Planck Society10, Weizmann Institute of Science11, University of Freiburg12, Purdue University13, University of Nantes14, University of California, San Diego15, University of Münster16, Rice University17, University of California, Los Angeles18, University of Chicago19
TL;DR: In this article, the authors presented the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II.
Abstract: We present the first search for dark matter-induced delayed coincidence
signals in a dual-phase xenon time projection chamber, using the 224.6 live
days of the XENON100 science run II. This very distinct signature is predicted
in the framework of magnetic inelastic dark matter which has been proposed to
reconcile the modulation signal reported by the DAMA/LIBRA collaboration with
the null results from other direct detection experiments. No candidate event
has been found in the region of interest and upper limits on the WIMP's
magnetic dipole moment are derived. The scenarios proposed to explain the
DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of
WIMPs with masses of 58.0 GeV/c$^2$ and 122.7 GeV/c$^2$ are excluded at 3.3
$\sigma$ and 9.3 $\sigma$, respectively.
TL;DR: In this article, the authors presented the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II.
Abstract: We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the DAMA/LIBRA collaboration with the null results from other direct detection experiments. No candidate event has been found in the region of interest and upper limits on the WIMP's magnetic dipole moment are derived. The scenarios proposed to explain the DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of WIMPs with masses of 58.0 GeV/c$^2$ and 122.7 GeV/c$^2$ are excluded at 3.3 $\sigma$ and 9.3 $\sigma$, respectively.