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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Flavor ratios of extragalactic neutrinos and neutrino shortcuts in extra dimensions

The recent measurement of high energy extragalactic neutrinos by the IceCube Collaboration has opened a new window to probe non-standard neutrino properties. Among other effects, sterile neutrino altered dispersion relations (ADRs) due to shortcuts in an extra dimension can significantly affect astrophysical flavor ratios. We discuss two limiting cases of this effect, first active-sterile neutrino oscillations with a constant ADR potential and second an MSW-like resonant conversion arising from geodesics oscillating around the brane in an asymmetrically warped extra dimension. We demonstrate that the second case has the potential to suppress significantly the flux of specific flavors such as ν{sub μ} or ν{sub τ} at high energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Probing nonstandard neutrino cosmology with terrestrial neutrino experiments

Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. Here, we explore the possibility for reconciliation of otherwise discrepant findings in a simple model containing a light scalar field which produces Mass Varying Neutrinos (MaVaNs). We extend prior work on MaVaNs to consider issues of neutrino clumping, the effects of additional contributions to neutrino mass, and reconciliation of eV mass sterile neutrinos with cosmology.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Radiative model of neutrino mass with neutrino interacting MeV dark matter

We consider the radiative generation of neutrino mass through the interactions of neutrinos with MeV dark matter. We construct a realistic renormalizable model with one scalar doublet (in additional to the standard model doublet) and one complex singlet together with three light singlet Majorana fermions, all transforming under a dark U(1){sub D} symmetry which breaks softly to Z{sub 2}. We study in detail the scalar sector which supports this specific scenario and its rich phenomenology.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Neutron star kick velocity induced by neutrino chirality flip and a lower bound for the neutrino magnetic moment

We study the neutrino chirality flip during the birth of a neutron star, produced in a core made of strange quark matter. This mechanism is applied to the neutron star kick velocity problem and we show that it is efficient when the neutrino magnetic moment is not smaller than 4.7 × 10 −15 μ B , where μ B is the Bohr magneton. When this lower bound is combined with the most stringent upper bound, our results set a range for the neutrino magnetic moment given by 4.7 × 10 −15 ≤ μ ν / μ B ≤ (0.1 − 0.4) × 10 −11 . The obtained kick velocities for natal conditions are consistent with the observed ones and span the correct range of radii for typical magnetic field intensities.

Ayala, Alejandro↗
DOE OSTI2021

Electron-beam energy reconstruction for neutrino oscillation measurements

Neutrinos exist in one of three types or ‘flavours’—electron, muon and tau neutrinos—and oscillate from one flavour to another when propagating through space. This phenomena is one of the few that cannot be described using the standard model of particle physics (reviewed in ref. 1), and so its experimental study can provide new insight into the nature of our Universe (reviewed in ref. 2). Neutrinos oscillate as a function of their propagation distance (L) divided by their energy (E). Therefore, experiments extract oscillation parameters by measuring their energy distribution at different locations. As accelerator-based oscillation experiments cannot directly measure E, the interpretation of these experiments relies heavily on phenomenological models of neutrino–nucleus interactions to infer E. Here we exploit the similarity of electron–nucleus and neutrino–nucleus interactions, and use electron scattering data with known beam energies to test energy reconstruction methods and interaction models. We find that even in simple interactions where no pions are detected, only a small fraction of events reconstruct to the correct incident energy. More importantly, widely used interaction models reproduce the reconstructed energy distribution only qualitatively and the quality of the reproduction varies strongly with beam energy. This shows both the need and the pathway to improve current models to meet the requirements of next-generation, high-precision experiments such as Hyper-Kamiokande (Japan) and DUNE (USA).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

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

Neutrinos are among the most abundant fundamental particles in the universe, and yet they are so elusive that they pass through almost everything without leaving a trace. For decades, researchers have measured neutrino oscillations in great detail, refining our understanding of the theories. Yet, once again, neutrino shows their incredibly surprising nature through some recent experimental results, suggesting that our current understanding might be incomplete. Several experiments have observed an unexpected difference in the observed neutrino behaviour from what the Standard Model predicts, showing an excess in some cases (e.g. LSND, MiniBooNE) and a deficit of neutrino events in others (e.g. SAGE, GALLEX). These anomalies challenge our conventional theories of standard three neutrino flavors and phenomenologically motivate the sterile neutrino hypothesis, which does not interact through the usual weak force. While some results appear consistent with this idea, others have found no supporting evidence (e.g. MicroBooNE), leaving the question unanswered. NOvA is one such long-baseline neutrino experiment with its Near Detector (ND) at Fermilab and a Far Detector (FD) at 810 km in Minnesota. It uses the NuMI beam as its primary source of neutrinos for oscillation studies. Its two-detector setup, extended baseline, and ability to conduct combined $\nu$-$\bar\nu$ analyses position it to explore these phenomena in new ways. We use the joint $\nu_{\mu}$ and neutral current (NC) disappearance channels to probe active-sterile mixing in the 3+1 model. This analysis utilizes a data sample 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. We found no evidence of sterile neutrino at 90$\%$ C.L. We present the limits in $\sin^{2}\theta_{24}$ vs $\Delta m^{2}_{41}$, $\sin^{2}\theta_{34}$ vs $\Delta m^{2}_{41}$, and $\sin^{2}2\theta_{\mu\tau}$ vs $\Delta m^{2}_{41}$ parameter spaces. The limits provided by this analysis are world leading in most of the parameter spaces.

Chaudhary, Shivam [Indian Inst. of Info. Tech. Guw↗
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 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 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 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 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↗
DOE OSTI2018

Comparisons and challenges of modern neutrino scattering experiments (TENSIONS2016 report)

Over the last decade, there has been enormous effort to measure neutrino interaction cross sections important to oscillation experiments. However, a number of results from modern experiments appear to be in tension with each other, despite purporting to measure the same processes. The TENSIONS2016 workshop was held at University of Pittsburgh July 24–31, 2016 and was sponsored by the Pittsburgh Particle Physics, Astronomy, and Cosmology Center (PITT PACC). The focus was on bringing experts from three experimental collaborations together to compare results in detail and try to find the source of tension by clarifying and comparing signal definitions and the analysis strategies used for each measurement. A set of comparisons between the measurements using a

Betancourt, M.↗
DOE OSTI2016

Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE): Conceptual Design Report. Volume 3: Long-Baseline Neutrino Facility for DUNE

This volume of the LBNF/DUNE Conceptual Design Report covers the Long-Baseline Neutrino Facility for DUNE and describes the LBNF Project, which includes design and construction of the beamline at Fermilab, the conventional facilities at both Fermilab and SURF, and the cryostat and cryogenics infrastructure required for the DUNE far detector.

43 PARTICLE ACCELERATORS↗