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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Dark matter detection, Standard Model parameters and Intermediate Scale Supersymmetry

The vanishing of the Higgs quartic coupling at a high energy scale may be explained by Intermediate Scale Supersymmetry, where supersymmetry breaks at (10 9 -10 12 ) GeV. The possible range of supersymmetry breaking scales can be narrowed down by precise measurements of the top quark mass and the strong coupling constant. On the other hand, nuclear recoil experiments can probe Higgsino or sneutrino dark matter up to a mass of 1012 GeV. We derive the correlation between the dark matter mass and precision measurements of standard model parameters, including supersymmetric threshold corrections. The dark matter mass is bounded from above as a function of the top quark mass and the strong coupling constant. The top quark mass and the strong coupling constant are bounded from above and below respectively for a given dark matter mass. We also discuss how the observed dark matter abundance can be explained by freeze-out or freeze-in during a matter-dominated era after inflation, with the inflaton condensate being dissipated by thermal effects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Neutrino constraints on inelastic dark matter captured in the Sun

Abstract The flux of neutrinos from annihilation of gravitationally captured dark matter in the Sun has significant constraints from direct-detection experiments. However, these constraints are relaxed for inelastic dark matter as inelastic dark matter interactions generate less energetic nuclear recoils compared to elastic dark matter interactions. In this paper, we explore the possibility for large volume underground neutrino experiments to detect the neutrino flux from captured inelastic dark matter in the Sun. The neutrino spectrum has two components: a mono-energetic “spike” from pion and kaon decays at rest and a broad-spectrum “shoulder” from prompt primary meson decays. We focus on detecting the shoulder neutrinos from annihilation of hadrophilic inelastic dark matter with masses in the range 4–100 GeV and the mass splittings in up to 300 keV. We determine the event selection criterion for DUNE to identify GeV-scale muon neutrinos and anti-neutrinos originating from hadrophilic dark matter annihilation in the Sun, and forecast the sensitivity from contained events. We also map the current bounds from Super-Kamiokande and IceCube on elastic dark matter, as well as the projected limits from Hyper-Kamiokande, to the parameter space of inelastic dark matter. We find that there is a region of parameter space that these neutrino experiments are more sensitive to than the direct-detection experiments. For dark matter annihilation to heavy-quarks, the projected sensitivity of DUNE is weaker than current (future) Super (Hyper) Kamiokande experiments. However, for the light-quark channel, only the spike is observable and DUNE will be the most sensitive experiment.

Astronomy & Astrophysics↗
DOE OSTI2020

DIREXENO—an apparatus for measuring correlated scintillation signatures in liquid xenon

We present a detector apparatus, DIREXENO (DIREctional XENOn), designed to measure the spatial and temporal properties of scintillation in liquid xenon to very high accuracy. The properties of scintillation are of primary importance for dark matter and neutrinoless double beta decay experiments; however the complicated microphysics involved limits theoretical predictions. We will explore the possibility that scintillation emission exhibits spatial correlations such as super-radiance which manifests in temporal and spatial structure, depending on the interaction type. Such properties of scintillation light may open a new window for background rejection as well as directionality measurements. We present the apparatus' technical design and the concepts driving it. We demonstrate that for an energy deposition of ~2.5 keV (~7.5 keV) electron (nuclear) recoil the detector is sensitive to an anisotropy fraction of as little as ~ 20% of the total photons emitted over a solid angle of ~0.85 steradian or less. We show results from commissioning runs in which the detector operated with 17 PMTs for over 44 days in stable conditions. The time resolution for individual photons in different PMTs was measured to be ≲1.4 ns full-width at half-maximum

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

A direct test of Auger cascade induced nucleation from heavy element contamination in C 3 F 8 bubble chambers

Understanding and quantifying the gamma-induced bubble nucleation background in clean nuclear recoil detection bubble chambers is of utmost importance to bubble chamber based dark matter searches. Here, we present data confirming the hypothesis that large Auger cascades from high-Z elements such as iodine and xenon dramatically increase the response of C 3 F 8 bubble chambers to gamma rays. These tests, performed with a small calibration bubble chamber filled with C 3 F 8 +$\mathcal{O}$ (10) ppm xenon, show that the probability of bubble nucleation scales with the rate of xenon inner-shell vacancies, reaching values >10% per K-Shell vacancy for Seitz thresholds of interest to future dark matter searches in bubble chambers. We also place an upper limit on bubble nucleation probability for argon Auger events, relevant to large future bubble chambers which may contain some residual atmospheric argon after the active fluid fill.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

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. Furthermore, the sources' neutron emission rate was measured using 3He proportional tubes. The sources' gamma emissions were characterized using a high-purity germanium (HPGe) detector. Source-validated Geant4Monte Carlo simulations allowed to calibrate the Ge and neutron detectors' responses.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Spin-dependent scattering of sub-GeV dark matter: Models and constraints

We calculate the scattering rate of sub-GeV dark matter in solid-state targets for spin-dependent dark matter–nucleon interactions. For dark matter particles with mass below 100 MeV, the scattering occurs predominantly through incoherent phonon production. For dark matter heavier than 100 MeV, we match onto the nuclear recoil calculation. To compare the sensitivity of future direct detection experiments with existing constraints, we consider three models with interactions that are mediated by spin-0 or spin-1 particles. This allows us to derive bounds on the cross section from searches for the mediating particle, including bounds from stellar cooling, beam dump experiments, meson factories, and dark matter self-interactions. The existing bounds are very stringent, though for 𝑚 𝜒 ≳100 MeV there is parameter space, which may be accessible with direct detection, depending on the exposure and background rates.

Gori, Stefania [University of California, Santa Cr↗
DOE OSTI2025

Dark Matter Search Results from 4.2 Tonne−Years of Exposure of the LUX-ZEPLIN (LZ) Experiment

We report results of a search for nuclear recoils induced by weakly interacting massive particle (WIMP) dark matter using the LUX-ZEPLIN (LZ) two-phase xenon time projection chamber. This analysis uses a total exposure of 4.2 ±0.1 tonne-years from 280 live days of LZ operation, of which 3.3 ± 0.1 tonne-years and 220 live days are new. A technique to actively tag background electronic recoils from 214 Pb 𝛽 decays is featured for the first time. Enhanced electron-ion recombination is observed in two-neutrino double electron capture decays of 124 Xe, representing a noteworthy new background. After removal of artificial signal-like events injected into the dataset to mitigate analyzer bias, we find no evidence for an excess over expected backgrounds. World-leading constraints are placed on spin-independent (SI) and spin-dependent WIMP-nucleon cross sections for masses ≥9 GeV/𝑐 2 . The strongest SI exclusion set is 2.2×10 −48 cm 2 at the 90% confidence level and the best SI median sensitivity achieved is 5.1 ×10 −48 cm 2 , both for a mass of 40 GeV/𝑐 2 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment

We present searches for light dark matter (DM) with masses 3–9 GeV/𝑐 2 in the presence of coherent elastic neutrino-nucleus scattering (CE⁢𝜈⁢NS) from 8 B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-yr exposure with data collected between March 2023 and April 2025. In an energy range spanning 1–6 keV, we report no significant excess of events attributable to dark matter nuclear recoils, but we observe a significant signal from 8 B CE ⁢𝜈 ⁢NS interactions that is consistent with expectation. We set world-leading limits on spin-independent and spin-dependent-neutron DM-nucleon interactions for masses down to 5 GeV/𝑐 2 . In the no-dark-matter scenario, we observe a signal consistent with 8 B CE⁢ 𝜈 ⁢NS events, corresponding to a 4.5⁢𝜎 statistical significance. This is the most significant evidence of 8 B CE 𝜈 ⁢NS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ’s ability to detect rare signals at keV-scale energies.

Dark matter detectors↗
DOE OSTI2025

New Constraints on Cosmic Ray-Boosted Dark Matter from the LUX-ZEPLIN Experiment

While dual-phase xenon time projection chambers have driven the sensitivity toward weakly interacting massive particles at the GeV/c 2 to TeV/c 2 mass scale, the scope for sub-GeV/c 2 dark matter particles is hindered by a limited nuclear recoil energy detection threshold. One approach to probe for lighter candidates is to consider cases where they have been boosted by collisions with cosmic rays in the Milky Way, such that the additional kinetic energy lifts their induced signatures above the nominal threshold. In this Letter, we report first results of a search for cosmic ray-boosted dark matter (CRDM) with a combined 4.2 metric ton/yr exposure from the LUX-ZEPLIN experiment. We observe no excess above the expected backgrounds and establish world-leading constraints on the spin-independent CRDM-nucleon cross section as small as 3.9×10 −33 cm 2 at 90% confidence level for sub-GeV/c 2 masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

High-Precision Mapping of Diamond Crystal Strain Using Quantum Interferometry

Crystal-strain variation imposes significant limitations on many quantum sensing and information applications for solid-state defect qubits in diamond. Thus, the precision measurement and control of diamond crystal strain is a key challenge. Here, we report diamond strain measurements with a unique set of capabilities, including micron-scale spatial resolution, a millimeter-scale field of view, and a 2-order-of-magnitude improvement in volume-normalized sensitivity over previous work, reaching 5(2)×10 -8 /√Hzμm -3 (with spin-strain coupling coefficients representing the dominant systematic uncertainty). We use strain-sensitive spin-state interferometry on ensembles of nitrogen-vacancy (N-V) color centers in single-crystal bulk diamond with low strain gradients. This quantum interferometry technique provides insensitivity to magnetic-field inhomogeneity from the electronic and nuclear spin bath, thereby enabling long N-V–ensemble electronic spin dephasing times and enhanced strain sensitivity, as well as broadening the potential applications of the technique beyond isotopically enriched or high-purity diamond. We demonstrate the strain-sensitive measurement protocol first on a confocal scanning laser microscope, providing quantitative measurement of sensitivity as well as three-dimensional strain mapping; and second on a wide-field-imaging quantum diamond microscope. Our strain-microscopy technique enables fast, sensitive characterization for diamond material engineering and nanofabrication; as well as diamond-based sensing of strains applied externally, as in diamond anvil cells or embedded diamond stress sensors, or internally, as by crystal damage due to particle-induced nuclear recoils.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Constraints on effective field theory couplings using 311.2 days of LUX data

We report here the results of an Effective Field Theory (EFT) WIMP search analysis using LUX data. We build upon previous LUX analyses by extending the search window to include nuclear recoil energies up to $\sim$180 keV$_{nr}$, requiring a reassessment of data quality cuts and background models. In order to use a binned Profile Likelihood statistical framework, the development of new analysis techniques to account for higher-energy backgrounds was required. With a 3.14$\times10^4$ kg$\cdot$day exposure using data collected between 2014 and 2016, we set 90\% C.L. exclusion limits on non-relativistic EFT WIMP couplings to neutrons and protons, providing the most stringent constraints on a significant fraction of the possible EFT WIMP interactions. Additionally, we report world-leading exclusion limits on inelastic EFT WIMP-nucleon recoils.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Atmospheric neutrinos in next-generation xenon and argon dark matter experiments

In this work, we study the sensitivity of future xenon- and argon-based dark matter and neutrino detection experiments to low-energy atmospheric neutrinos. Not accounting for experimental backgrounds, the primary obstacle for identifying nuclear recoils induced by atmospheric neutrinos in xenon is the tail of the electron recoil distribution due to pp solar neutrinos. We use the NEST code to model the solar and atmospheric neutrino signals in a xenon detector and find that an exposure of 700 tonne-years will produce a 5σ detection of atmospheric neutrinos. We explore the effect of different detector properties and find that a sufficiently long electron lifetime is essential to the success of such a measurement.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Detection of astrophysical neutrinos at prospective locations of dark matter detectors

We study the prospects for detection of solar, atmospheric neutrino, and diffuse supernova neutrino background (DSNB) fluxes at future large-scale dark matter detectors through both electron and nuclear recoils. We specifically examine how the detection prospects change for several prospective detector locations [Sanford Underground Research Facility (SURF), SNOlab, Gran Sasso, China Jinping Underground Laboratory (CJPL), and Kamioka] and improve upon the statistical methodologies used in previous studies. Because of its ability to measure lower neutrino energies than other locations, we find that the best prospects for the atmospheric neutrino flux are at the SURF location, while the prospects are weakest at CJPL because it is restricted to higher neutrino energies. On the contrary, the prospects for the DSNB are best at CJPL, due largely to the reduced atmospheric neutrino background at this location. Including full detector resolution and efficiency models, the CNO component of the solar flux is detectable via the electron recoil channel with exposures of ∼ 10 3 ton-yr for all locations. These results highlight the benefits for employing two detector locations, one at high and one at low latitude. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2025

Athermal phonon collection efficiency in diamond crystals for low mass dark matter detection

Here, we explored the efficacy of lab-grown diamonds as potential target materials for the direct detection of sub-GeV dark matter (DM) using metallic magnetic calorimeters (MMCs). Diamond, with its excellent phononic properties and the low atomic mass of the constituent carbon, can play a crucial role in detecting low mass dark matter particles. The relatively long electron-hole pair lifetime inside the crystal may provide discrimination power between the DM-induced nuclear recoil events and the background-induced electron recoil events. Utilizing the fast response times of the MMCs and their unique geometric versatility, we deployed a novel methodology for quantifying phonon dynamics inside diamond crystals. We demonstrated that lab-grown diamond crystals fabricated via the chemical vapor deposition (CVD) technique can satisfy the stringent quality requirements for sub-GeV dark matter searches. The high-quality polycrystalline CVD diamond showed a superior athermal phonon collection efficiency compared to that of the reference sapphire crystal, and achieved energy resolution 62.7 eV at the 8.05 keV copper fluorescence line. With this energy resolution, we explored the low-energy range below 100 eV and confirmed the existence of so-called low-energy excess (LEE) reported by multiple cryogenic experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Results on low-mass weakly interacting massive particles from an 11 kg d target exposure of DAMIC at SNOLAB

We present constraints on the existence of weakly interacting massive particles (WIMPs) from a 11 kg-day target exposure of the DAMIC experiment at the SNOLAB underground laboratory. The observed energy spectrum and spatial distribution of ionization events with electron-equivalent energies $>$200 eV$_{\rm ee}$ in the DAMIC CCDs are consistent with backgrounds from natural radioactivity. An excess of ionization events is observed above the analysis threshold of 50 eV$_{\rm ee}$. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections $\sigma_{\chi-n}$ as low as $3\times 10^{-41}$ cm$^2$ for WIMPs with masses $m_{\chi}$ from 7 to 10 GeV$c^{-2}$ . These results are the strongest constraints from a silicon target on the existence of WIMPs with $m_{\chi}$$<$9 GeV$c^{-2}$ and are directly relevant to any dark matter interpretation of the excess of nuclear-recoil events observed by the CDMS silicon experiment in 2013.

WIMP search, Dark Matter, DAMIC, SNOLAB↗
DOE OSTI2026

Testing thermal-relic dark matter with a dark-photon mediator

In light of recent DAMIC-M results, we present the status of thermal-relic dark matter χ coupled to a kinetically mixed dark photon A ′ . In the predictive “direct annihilation” regime, m A ′ > m χ , the relic abundance depends on the kinetic mixing parameter, and there is a minimum value compatible with thermal freeze-out. Using only electron- and nuclear-recoil direct-detection results, we find that, for complex scalar dark matter, the direct annihilation regime is now excluded for nearly all values of m χ ; the only exception is the resonant annihilation regime where m A ′ ≈ 2 m χ . Direct annihilation relic targets for other representative models, including Majorana and pseudo-Dirac candidates, remain viable across a wide range of model parameters but will be tested with a combination of dedicated accelerator searches in the near future. In the opposite “secluded annihilation” regime, where m χ > m A ′ , this scenario is excluded by cosmic microwave background measurements for all m χ ≲ 30 GeV . Similar conclusions in both the direct and secluded regimes hold for all anomaly-free vector mediators that couple to the first generation of electrically charged Standard Model particles.

Krnjaic, Gordan [Fermilab; Chicago U., KICP] (ORCI↗
DOE OSTI2020

Velocity Independent Constraints on Spin-Dependent DM-Nucleon Interactions from IceCube and PICO

Adopting the Standard Halo Model (SHM) of an isotropic Maxwellian velocity distribution for dark matter (DM) particles in the Galaxy, the most stringent current constraints on their spin-dependent scattering cross-section with nucleons come from the IceCube neutrino observatory and the PICO-60 $\hbox {C}_3\hbox {F}_8$ superheated bubble chamber experiments. The former is sensitive to high energy neutrinos from the self-annihilation of DM particles captured in the Sun, while the latter looks for nuclear recoil events from DM scattering off nucleons. Although slower DM particles are more likely to be captured by the Sun, the faster ones are more likely to be detected by PICO. Recent N-body simulations suggest significant deviations from the SHM for the smooth halo component of the DM, while observations hint at a dominant fraction of the local DM being in substructures. We use the method of Ferrer et al. (JCAP 1509: 052, 2015) to exploit the complementarity between the two approaches and derive conservative constraints on DM-nucleon scattering. Our results constrain $\sigma _{\mathrm{SD}} \lesssim 3 \times 10^{-39} \mathrm {cm}^2$ ($6 \times 10^{-38} \mathrm {cm}^2$) at $\gtrsim 90\%$ C.L. for a DM particle of mass 1 TeV annihilating into $\tau ^+ \tau ^-$ ($b\bar{b}$) with a local density of $\rho _{\mathrm{DM}} = 0.3~\mathrm {GeV/cm}^3$. The constraints scale inversely with $\rho _{\mathrm{DM}}$ and are independent of the DM velocity distribution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Primary track recovery in high-definition gas time projection chambers

Abstract We develop and validate a new algorithm called primary track recovery () that effectively deconvolves known physics and detector effects from nuclear recoil tracks in gas time projection chambers (TPCs) with high-resolution readout. This gives access to the primary track charge, length, and vector direction (helping to resolve the “head-tail” ambiguity). Additionally, provides a measurement of the transverse and longitudinal diffusion widths, which can be used to determine the absolute position of tracks in the drift direction for detector fiducialization. Using simulated helium recoils in an atmospheric pressure TPC with a 70:30 mixture of $$\hbox {He:CO}_2$$ He:CO 2 we compare the performance of to traditional methods for all key track variables. We find that the algorithm reduces reconstruction errors, including those caused by charge integration, for tracks with mean length-to-width ratios 1.4 and above, corresponding to recoil energies of 20 keV and above in the studied TPCs. We show that improves on existing methods for head-tail disambiguation, particularly for highly inclined tracks, and improves the determination of the absolute position of recoils on the drift axis via transverse diffusion. We find that can partially recover charge structure integrated out by the detector in the z direction, but that its determination of energy and length have worse resolution compared to existing methods. We use experimental data to qualitatively verify these findings and discuss implications for future directional detectors at the low-energy frontier.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗