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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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423 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Atmospheric neutrino oscillation analysis with neutron tagging and an expanded fiducial volume in Super-Kamiokande I–V

We present a measurement of neutrino oscillation parameters with the Super-Kamiokande detector using atmospheric neutrinos from the complete pure-water SK I–V (April 1996–July 2020) dataset, including events from an expanded fiducial volume. The dataset corresponds to 6511.3 live days and an exposure of 484.2 kiloton-years. Measurements of the neutrino oscillation parameters Δ⁢𝑚$^2_{3⁢2}$, sin 2 ⁡𝜃 2⁢3 , sin 2⁡ 𝜃 1⁢3 , 𝛿 CP , and the preference for the neutrino mass ordering are presented with atmospheric neutrino data alone, and with constraints on sin 2 ⁡𝜃 1⁢3 from reactor neutrino experiments. Our analysis including constraints on sin 2 ⁡𝜃 1⁢3 favors the normal mass ordering at the 92.3% level.

Cherenkov detectors↗
DOE OSTI2024

Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

We present the results of the charge ratio (𝑅) and polarization (𝑃$^{𝜇}_{0}$) measurements using decay electron events collected between September 2008 and June 2022 with the Super-Kamiokande detector. Because of its underground location and long operation, we are able to perform high-precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be 𝑅 = 1.32 ± 0.02⁢(stat +syst) at 𝐸 𝜇 ⁢cos⁡𝜃 Zenith = 0.7$^{+0.3}_{−0.2}$ TeV, where 𝐸 𝜇 is the muon energy and 𝜃 Zenith is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while indicating a tension with the 𝜋⁢𝐾 model of 1.9⁢𝜎. We also measured the muon polarization at the production location to be 𝑃$^{𝜇}_{0}$ = 0.52 ± 0.02 (stat+syst) at the muon momentum of 0.9$^{+0.6}_{−0.1}$ TeV/𝑐 at the surface of the mountain; this also suggests a tension with the Honda flux model of 1.5⁢𝜎. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near 1 TeV/𝑐. These measurement results are useful to improve atmospheric neutrino simulations.

Atmospheric neutrino oscillations↗
DOE OSTI2021

Overcoming timestep limitations in boosted-frame particle-in-cell simulations of plasma-based acceleration

Explicit electromagnetic Particle-In-Cell (PIC) codes are typically limited by the Courant- Friedrichs-Lewy (CFL) condition, which implies that the timestep multiplied by the speed of light must be smaller than the smallest cell size. In the case of boosted-frame PIC simulations of plasma-based acceleration, this limitation can be a major hinderance as the cells are often very elongated along the longitudinal direction and the timestep is thus limited by the small, transverse cell size. This entails many small-timestep PIC iterations, and can limit the potential speed-up of the boosted-frame technique. Here, by using a CFL-free analytical spectral solver, and by mitigating additional numerical instabilities that arise at large timestep, we show that it is possible to overcome traditional limitations on the timestep and thereby realize the full potential of the boosted-frame technique over a much wider range of parameters.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Unusual Near-Horizon Cosmic-Ray-like Events Observed by ANITA-IV

ANITA’s fourth long-duration balloon flight in 2016 detected 29 cosmic-ray (CR)-like events on a background of 0.37 - 0.17 + 0.27 anthropogenic events. CRs are mainly seen in reflection off the Antarctic ice sheets, creating a phase-inverted waveform polarity. However, four of the below-horizon CR-like events show anomalous noninverted polarity, a p = 5.3 × 10 - 4 chance if due to background. Furthermore, all anomalous events are from locations near the horizon; ANITA-IV observed no steeply upcoming anomalous events similar to the two such events seen in prior flights.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Search for neutron decay into an antineutrino and a neutral kaon in 0.401 megaton-years exposure of Super-Kamiokande

We searched for bound neutron decay via 𝑛 → $\bar{𝜈}$ +𝐾 0 predicted by the grand unified theories in 0.401 Mton·years exposure of all pure water phases in the Super-Kamiokande detector. About 4.4 times more data than in the previous search have been analyzed by a new method including a spectrum fit to kaon invariant mass distributions. No significant data excess has been observed in the signal regions. As a result of this analysis, we set a lower limit of 7.8 × 10 32 years on the neutron lifetime at a 90% confidence level.

Cherenkov detectors↗
DOE OSTI2020

Measurement of beam-correlated background neutrons from the Fermilab Booster Neutrino Beam in ANNIE Phase-I (Final Technical Report)

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) aims to make a unique measurement of neutron yield from neutrino-nucleus interactions and to perform R&D for the next generation of water-based neutrino detectors. In this paper, we characterize beam-induced neutron backgrounds in the experimental hall at Fermi National Accelerator Laboratory. It is shown that the background levels are sufficiently low to allow the next stage of the experiment to proceed. These measurements are relevant to other Booster Neutrino Beam (BNB) experiments located adjacent to ANNIE Hall, where dirt neutrons and sky-shine could present similar backgrounds.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1993

Comparison of GPS and GLONASS common-view time transfers

It was already shown than even with a simple daily averaging of GLONASS data at each site, continental GLONASS time transfer can be achieved at a level of several tens of nanoseconds. A further step is to carry out observations of GLONASS satellites by the common-view method. A comparison of GPS and GLONASS common-view time transfers between Russia and Western Europe are reported. At each site, a GPS receiver and a GLONASS receiver are connected to the same atomic clock. Both GPS receivers are of NBS type and the GLONASS receivers are of type A-724. As GPS common-view time transfer between Sevres and Mendeleevo is accomplished at a level of a few nanoseconds in precision, it gives an excellent reference with which to evaluate the performance of GLONASS common-view time transfer.

Lewandowski, W.↗
NASA NTRS2002

Antarctic Impulsive Transient Antenna (ANITA) instrumentation

We will report on the details of the ANITA instrument. This instrument is fundamentally a broadband antenna, which is arrayed and constructed in such a way as to be optimized for the detection and characterization of high-energy neutrino cascades.

ANITA↗