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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Searching for dark matter annihilation to monoenergetic neutrinos with liquid scintillation detectors

We consider searches for dark matter annihilation to monoenergetic neutrinos in the core of the Sun. We find that liquid scintillation neutrino detectors have enhanced sensitivity to this class of dark matter models, due to the energy and angular resolution possible for electron neutrinos and antineutrinos that scatter via charged-current interactions. In particular we find that KamLAND, utilizing existing data, could provide better sensitivity to such models than any current direct detection experiment for m{sub X}≲15 Gev. KamLAND’s sensitivity is signal-limited, and future liquid scintillation or liquid argon detectors with similar energy and angular resolution, but with larger exposure, will provide significantly better sensitivity. These detectors may be particularly powerful probes of dark matter with mass O(10) GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

First Sterile Neutrino Search at NOvA Experiment Using both Neutrino and Anti-Neutrino Data

NOvA is a long-baseline experiment with two functionally identical detectors with a Near Detector placed 1 km from the neutrino source at Fermilab and a Far Detector 810 km away at Ash River, Minnesota. NOvA uses a very high-intensity ($\sim$900 kW) beam of neutrinos and antineutrinos from Fermilab's NuMI beamline, together with two functionally identical detectors placed 14 mrad off the beam axis. NOvA is built to investigate the complex properties of neutrinos with an emphasis on neutrino oscillations. NOvA not only probes active neutrino mixing but also explores exotic oscillations, including sterile neutrino searches. This analysis uses the joint $\nu_{\mu}$ and neutral current (NC) disappearance channels to probe active-sterile mixing in the 3+1 model. Furthermore, this analysis leverages our statistics of 27$\times$10$^{20}$ protons on target (POT) in neutrino mode and 12.5$\times$10$^{20}$ protons on target (POT) in antineutrino mode. In this poster, we will present the first dual-baseline search for sterile neutrinos using both the neutrino and antineutrino datasets.

Chaudhary, S. [Indian Inst. Tech., Guwahati]↗
DOE OSTI2014

DESI and other Dark Energy experiments in the era of neutrino mass measurements

Here we present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant $-$ DESI and other experiments can measure the sum of neutrino masses to ~ 0.02 eV or better, while the minimum possible sum is 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. Finally, we do not try to be especially innovative, e.g., with complex treatments of potential systematic errors $-$ these projections are intended as a straightforward baseline for comparison to more detailed analyses.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Active to Sterile Neutrino Mixing Limits from Neutral-Current Interactions in MINOS

Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07x10{sup 20} protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754{+-}28(stat){+-}37(syst) for oscillations among three active flavors. The fraction f{sub s} of disappearing {nu}{sub {mu}} that may transition to {nu}{sub s} is found to be less than 22% at the 90% C.L.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Probing a New Regime of Neutrino Self-Interactions with Astrophysical Neutrinos and the Relativistic Cosmic Neutrino Background

Neutrino self-interactions beyond the standard model have profound implications in astrophysics and cosmology. In this Letter, we study an uncharted scenario in which one of the three neutrino species has a mass smaller than the temperature of the cosmic neutrino background. This results in a relativistic component that significantly broadens the absorption feature on the astrophysical neutrino spectra, in contrast to the sharply peaked absorption expected in the extensively studied scenarios assuming a fully nonrelativistic cosmic neutrino background. By solving the Boltzmann equations for neutrino absorption and regeneration, we demonstrate that this mechanism provides novel sensitivity to sub-keV mediator masses, well below the traditional ∼1–100 MeV range. Future observations of the diffuse supernova neutrino background with Hyper-Kamiokande could probe coupling strengths down to 𝑔 ∼10 −8 , surpassing existing constraints by orders of magnitude. These findings open new directions for discoveries and offer crucial insights into the interplay between neutrinos and the dark sector.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

BEAMING NEUTRINOS AND ANTI-NEUTRINOS ACROSS THE EARTH TO DISENTANGLE NEUTRINO MIXING PARAMETERS

A result from MINOS seemed to indicate that the mass splitting and mixing angle of anti-neutrinos is different from that of neutrinos, suggesting a charge-parity-time (CPT) violation in the lepton sector. However, more recent MINOS data reduced the {nu}{sub {mu}}-{nu}-bar{sub {mu}} differences leading to a narrow discrepancy nearly compatible with no CPT violation. However, the last few years of OPERA activity on the appearance of a tau lepton (one unique event) still has not been probed and more tools may be required to disentangle a list of parameters ({mu}-{tau} flavor mixing, tau appearance, any eventual CPT violation, {theta}{sub 13} angle value, and any hierarchy neutrino mass). Atmospheric anisotropy in muon neutrino spectra in the DeepCore, at ten to tens of GeV (unpublished), can hardly reveal asymmetry in the eventual {nu}{sub {mu}}-{nu}-bar{sub {mu}} oscillation parameters. Here we considered how the longest baseline neutrino oscillation available, crossing most of Earth's diameter, may improve the measurement and at best disentangle any hypothetical CPT violation occurring between the earliest (2010) and the present (2012) MINOS bounds (with 6{sigma} a year), while testing {tau} and even the appearance of {tau}-bar at the highest rate. The {nu}{sub {mu}} and {nu}-bar{sub {mu}} disappearance correlated with the tau appearance is considered for those events at the largest distances. We thus propose a beam of {nu}{sub {mu}} and {nu}-bar{sub {mu}} crossing through the Earth, within an OPERA-like experiment from CERN (or Fermilab), in the direction of the IceCube-DeepCore {nu} detector at the South Pole. The ideal energy lies at 21 GeV to test the disappearance or (for any tiny CPT violation) the partial {nu}-bar{sub {mu}} appearance. Such a tuned detection experiment may lead to a strong signature of {tau} or {tau}-bar generation even within its neutral current noise background events: nearly one {tau}-bar or two {tau} a day. The tau appearance signal is above (or within) 10{sigma} a year, even for a 1% OPERA-like experiment. Peculiar configurations for {theta}{sub 13} and the hierarchy neutrino mass test may also be better addressed by a DeepCore-PINGU array detector beaming {nu}{sub {mu}} and observing {nu}{sub e} at 6 GeV neutrino energy windows.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Pseudo-Dirac neutrinos and relic neutrino matter effect on the high-energy neutrino flavor composition

We show that if neutrinos are pseudo-Dirac, they can potentially affect the flavor ratio predictions for the high-energy astrophysical neutrino flux observed by IceCube. In this context, we point out a novel matter effect induced by the cosmic neutrino background (CνB) on the flavor ratio composition. Specifically, the active-sterile neutrino oscillations over the astrophysical baseline lead to an energy-dependent flavor ratio at Earth due to the CνB matter effect, which is in principle distinguishable from the vacuum oscillation effect, provided there is an asymmetry between the neutrino and antineutrino number densities, as well as a local CνB overdensity. Considering the projected precision of the 3-neutrino oscillation parameter measurements and improved flavor triangle measurements, we show that the next-generation neutrino telescopes, such as KM3NeT and IceCube-Gen2, can in principle probe the pseudo-Dirac neutrino hypothesis and the CνB matter effect.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Directional searches at DUNE for sub-GeV monoenergetic neutrinos arising from dark matter annihilation in the Sun

Here, we consider the use of directionality in the search for monoenergetic sub-GeV neutrinos arising from the decay of stopped kaons, which can be produced by dark matter annihilation in the core of the Sun. When these neutrinos undergo charged-current interactions with a nucleus at a neutrino detector, they often eject a proton which is highly peaked in the forward direction. The direction of this track can be measured at DUNE, allowing one to distinguish signal from background by comparing on-source and off-source event rates. We discover that directional information can enhance the signal to background ratio by up to a factor of 5.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Background study on electron neutrino appearance from a muon neutrino beam in very long baseline neutrino oscillation experiments with a large water Cherenkov detector.

There is a growing interest in very long baseline neutrino oscillation experimentation using an accelerator produced neutrino beam as a machinery to probe the last three unmeasured neutrino oscillation parameters: the mixing angle {theta}{sub 13}, the possible CP violating phase {delta}{sub CP} and the mass hierarchy, namely, the sign of {Delta}m{sub 32}{sup 2}. Water Cherenkov detectors such as IMB, Kamiokande and Super-Kamiokande have shown to be very successful at detecting neutrino interactions. Scaling up this technology may continue to provide the required performance for the next generation of experiments. This report presents the latest effort to demonstrate that a next generation (>100 kton) water Cherenkov detector can be used effectively for the rather difficult task of detecting v{sub e}s from the neutrino oscillation v{sub {mu}} {yields} v{sub e} despite the large expected potential background resulting from {pi}{sup 0}s produced via neutral current interactions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Neutrino Fluxes from NUHM LSP Annihilations in the Sun

We extend our previous studies of the neutrino fluxes expected from neutralino LSP annihilations inside the Sun to include variants of the minimal supersymmetric extension of the Standard Model (MSSM) with squark, slepton and gaugino masses constrained to be universal at the GUT scale, but allowing one or two non-universal supersymmetry-breaking parameters contributing to the Higgs masses (NUHM1,2). As in the constrained MSSM (CMSSM) with universal Higgs masses, there are large regions of the NUHM parameter space where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate, and there are also large regions where the capture rate is not dominated by spin-dependent LSP-proton scattering. The spectra possible in the NUHM are qualitatively similar to those in the CMSSM. We calculate neutrino-induced muon fluxes above a threshold energy of 10 GeV, appropriate for the IceCube/DeepCore detector, for points where the NUHM yields the correct cosmological relic density for representative choices of the NUHM parameters. We find that the IceCube/DeepCore detector can probe regions of the NUHM parameter space in addition to analogues of the focus-point strip and the tip of the coannihilation strip familiar from the CMSSM. These include regions with enhanced Higgsino-gaugino mixing in the LSP composition, that occurs where neutralino mass eigenstates cross over. On the other hand, rapid-annihilation funnel regions in general yield neutrino fluxes that are unobservably small.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

The galactic contribution to IceCube's astrophysical neutrino flux

High energy neutrinos have been detected by IceCube, but their origin remains a mystery. Determining the sources of this flux is a crucial first step towards multi-messenger studies. Here, we systematically compare two classes of sources with the data: Galactic and extragalactic. We assume that the neutrino sources are distributed according to a class of Galactic models. We build a likelihood function on an event by event basis including energy, event topology, absorption, and direction information. We present the probability that each high energy event with deposited energy E dep >60 TeV in the HESE sample is Galactic, extragalactic, or background. Lastly, for Galactic models considered the Galactic fraction of the astrophysical flux has a best fit value of 1.3% and is <9.5% at 90\% CL. A zero Galactic flux is allowed at <1σ.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

The history of neutrinos, 1930-1985. What have we learned about neutrinos? What have we learned using neutrinos?

An attempt to remember some of the main events which highlight the evolution of our knowledge of the neutrinos and their properties, the 'families' of particles, a few of the very interesting persons who contributed to this progress, as well as the contribution of neutrino beam experiments to the validation of the electro-weak and quantum-chromo-dynamic theories, and the structure of the nucleon. - Highlights: Black-Right-Pointing-Pointer Early history: continuity of {beta}-spectrum, Pauli letter, universal Fermi interaction. Black-Right-Pointing-Pointer Neutrino beams and the discovery of the muon neutrino. Black-Right-Pointing-Pointer Gargamelle, the discovery of the neutral current and the verification of the quark-gluon nature of the parton. Black-Right-Pointing-Pointer Deep inelastic scattering at higher energies: scaling, quantitative verification of QCD, structure functions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Neutrino-induced reactions and neutrino scattering with nuclei in low and high neutrino energy

We reviewed present status regarding theoretical approaches for neutrino-induced reactions and neutrino scattering. With a short introduction of relevant data, our recent calculations by distorted-wave Born approximation (DWBA) for quasielastic region are presented for MiniBooNE data. We also discussed that one step-process estimated by the DWBA is comparable to the two-step process, which has been usually used in the neutrino-nucleosynthesis. For much higher energy neutrino data, such as NOMAD data, elementary process approach was shown to be useful instead of using complicated nuclear models. But, in the low energy region, detailed nuclear structure model, such as QRPA and shell model, turn out to be inescapable to explain the reaction data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗