Author
D. Ramírez García
Other affiliations: University of Mainz
Bio: D. Ramírez García is an academic researcher from University of Freiburg. The author has contributed to research in topics: Dark matter & Weakly interacting massive particles. The author has an hindex of 19, co-authored 30 publications receiving 2908 citations. Previous affiliations of D. Ramírez García include University of Mainz.
Papers
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Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, New York University Abu Dhabi7, University of Zurich8, Stockholm University9, Rensselaer Polytechnic Institute10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of Nantes14, University of California, San Diego15, University of Chicago16, Purdue University17, Rice University18, Pierre-and-Marie-Curie University19, University of California, Los Angeles20
TL;DR: In this article, a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS is reported.
Abstract: We report on a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass of (1.30±0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of interest, [1.4,10.6] keVee ([4.9,40.9] keVnr), exhibits an ultralow electron recoil background rate of [82-3+5(syst)±3(stat)] events/(ton yr keVee). No significant excess over background is found, and a profile likelihood analysis parametrized in spatial and energy dimensions excludes new parameter space for the WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c2, with a minimum of 4.1×10-47 cm2 at 30 GeV/c2 and a 90% confidence level.
1,808 citations
Columbia University1, University of Bologna2, Istituto Nazionale di Fisica Nucleare3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, University of Amsterdam8, New York University Abu Dhabi9, University of Zurich10, Rensselaer Polytechnic Institute11, Weizmann Institute of Science12, Max Planck Society13, Purdue University14, University of Freiburg15, University of L'Aquila16, University of Tokyo17, Nagoya University18, Konan University19, University of California, San Diego20, University of Chicago21, Rice University22, University of California, Los Angeles23
TL;DR: In this article, the XENON1T data was used for searches for new physics with low-energy electronic recoil data recorded with the Xenon1T detector, which enabled one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter.
Abstract: We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background rate of 76±2stat events/(tonne×year×keV) between 1 and 30 keV, the data enable one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV.
The solar axion model has a 3.4σ significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by gae<3.8×10-12, gaeganeff<4.8×10-18, and gaegaγ<7.7×10-22 GeV-1, and excludes either gae=0 or gaegaγ=gaeganeff=0. The neutrino magnetic moment signal is similarly favored over background at 3.2σ, and a confidence interval of μν∈(1.4,2.9)×10-11 μB (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by β decays of tritium at 3.2σ significance with a corresponding tritium concentration in xenon of (6.2±2.0)×10-25 mol/mol. Such a trace amount can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are decreased to 2.0σ and 0.9σ, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at (2.3±0.2) keV (68% C.L.) with a 3.0σ global (4.0σ local) significance over background.
This analysis sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210 keV/c2. We also consider the possibility that Ar37 may be present in the detector, yielding a 2.82 keV peak from electron capture. Contrary to tritium, the Ar37 concentration can be tightly constrained and is found to be negligible.
452 citations
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, University of Amsterdam11, Max Planck Society12, Weizmann Institute of Science13, University of Freiburg14, University of Nantes15, Purdue University16, University of California, San Diego17, University of Chicago18, Nagoya University19, Pierre-and-Marie-Curie University20, Université Paris-Saclay21, Rice University22, University of California, Los Angeles23
TL;DR: Constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment are reported, and no DM or CEvNS detection may be claimed because the authors cannot model all of their backgrounds.
Abstract: We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe 30 MeV/c2, and absorption of dark photons and axionlike particles for mχ within 0.186–1 keV/c2.
412 citations
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, New York University Abu Dhabi7, University of Zurich8, Rensselaer Polytechnic Institute9, University of Amsterdam10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of Nantes14, University of California, San Diego15, University of Chicago16, Nagoya University17, Purdue University18, Pierre-and-Marie-Curie University19, Université Paris-Saclay20, Rice University21, University of California, Los Angeles22
TL;DR: The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases and sets exclusion limits on the WIMP-nucleon interactions.
Abstract: We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10-42 cm2 at 30 GeV/c2 and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.
241 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
Cited by
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Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, New York University Abu Dhabi7, University of Zurich8, Stockholm University9, Rensselaer Polytechnic Institute10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of Nantes14, University of California, San Diego15, University of Chicago16, Purdue University17, Rice University18, Pierre-and-Marie-Curie University19, University of California, Los Angeles20
TL;DR: In this article, a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS is reported.
Abstract: We report on a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass of (1.30±0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of interest, [1.4,10.6] keVee ([4.9,40.9] keVnr), exhibits an ultralow electron recoil background rate of [82-3+5(syst)±3(stat)] events/(ton yr keVee). No significant excess over background is found, and a profile likelihood analysis parametrized in spatial and energy dimensions excludes new parameter space for the WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c2, with a minimum of 4.1×10-47 cm2 at 30 GeV/c2 and a 90% confidence level.
1,808 citations
Columbia University1, University of Amsterdam2, University of Bologna3, University of Mainz4, University of Coimbra5, Weizmann Institute of Science6, New York University Abu Dhabi7, University of Zurich8, Stockholm University9, Rensselaer Polytechnic Institute10, Max Planck Society11, University of Münster12, University of Bern13, Purdue University14, École des mines de Nantes15, University of California, Los Angeles16, Rice University17
TL;DR: In this article, the expected sensitivity of the Xenon1T experiment to the spin-independent WIMP-nucleon interaction cross section was investigated based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds.
Abstract: The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in 1 tonne fiducial volume and (1, 12) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80 ± 0.15) · 10(−)(4) (kg·day·keV)(−)(1), mainly due to the decay of (222)Rn daughters inside the xenon target. The nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) keV, is composed of (0.6 ± 0.1) (t·y)(−)(1) from radiogenic neutrons, (1.8 ± 0.3) · 10(−)(2) (t·y)(−)(1) from coherent scattering of neutrinos, and less than 0.01 (t·y)(−)(1) from muon-induced neutrons. The sensitivity of XENON1T is calculated with the Profile Likelihood Ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. We take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. The main contribution comes from the relative scintillation efficiency Script L(eff), which affects both the signal from WIMPs and the nuclear recoil backgrounds. After a 2 y measurement in 1 t fiducial volume, the sensitivity reaches a minimum cross section of 1.6 · 10(−)(47) cm(2) at m(χ) = 50 GeV/c(2).
580 citations
Columbia University1, Istituto Nazionale di Fisica Nucleare2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, University of Amsterdam8, New York University Abu Dhabi9, University of Zurich10, Rensselaer Polytechnic Institute11, Weizmann Institute of Science12, Max Planck Society13, Purdue University14, University of Freiburg15, University of L'Aquila16, University of Tokyo17, Nagoya University18, Konan University19, University of California, San Diego20, University of Chicago21, Rice University22, University of California, Los Angeles23
TL;DR: In this article, the XENON1T data was used for searches for new physics with low-energy electronic recoil data recorded with the Xenon1T detector, which enabled one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter.
Abstract: We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background rate of 76±2stat events/(tonne×year×keV) between 1 and 30 keV, the data enable one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV.
The solar axion model has a 3.4σ significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by gae<3.8×10-12, gaeganeff<4.8×10-18, and gaegaγ<7.7×10-22 GeV-1, and excludes either gae=0 or gaegaγ=gaeganeff=0. The neutrino magnetic moment signal is similarly favored over background at 3.2σ, and a confidence interval of μν∈(1.4,2.9)×10-11 μB (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by β decays of tritium at 3.2σ significance with a corresponding tritium concentration in xenon of (6.2±2.0)×10-25 mol/mol. Such a trace amount can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are decreased to 2.0σ and 0.9σ, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at (2.3±0.2) keV (68% C.L.) with a 3.0σ global (4.0σ local) significance over background.
This analysis sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210 keV/c2. We also consider the possibility that Ar37 may be present in the detector, yielding a 2.82 keV peak from electron capture. Contrary to tritium, the Ar37 concentration can be tightly constrained and is found to be negligible.
452 citations
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, University of Amsterdam11, Max Planck Society12, Weizmann Institute of Science13, University of Freiburg14, University of Nantes15, Purdue University16, University of California, San Diego17, University of Chicago18, Nagoya University19, Pierre-and-Marie-Curie University20, Université Paris-Saclay21, Rice University22, University of California, Los Angeles23
TL;DR: Constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment are reported, and no DM or CEvNS detection may be claimed because the authors cannot model all of their backgrounds.
Abstract: We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe 30 MeV/c2, and absorption of dark photons and axionlike particles for mχ within 0.186–1 keV/c2.
412 citations