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Results for “Proton acceleration”

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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Cherenkov and Scintillation Properties of Cubic Zirconium

Cubic zirconium (CZ) is a high index of refraction (n =2.17) material that we have investigated for Cherenkov counter applications. Laboratory and proton accelerator tests of an 18cc sample of CZ show that the expected fast Cherenkov response is accompanied by a longer scintillation component that can be separated by pulse shaping. This presents the possibility of novel particle spectrometers which exploits both properties of CZ. Other high index materials being examined for Cherenkov applications will be discussed. Results from laboratory tests and an accelerator exposure will be presented and a potential application in solar energetic particle instruments will be discussed

Christl, M.J.↗
NASA NTRS2012

Fermi-Lat and WMAP Observations of the Puppis a Supernova Remnant

We report the detection of GeV gamma-ray emission from the supernova remnant Puppis A with the Fermi Gamma-Ray Space Telescope. Puppis A is among the faintest supernova remnants yet detected at GeV energies, with a luminosity of only 2.7×10(exp 34) (D/2.2 kpc)(exp 2) erg s(exp −1) between 1 and 100 GeV. The gamma-ray emission from the remnant is spatially extended, with a morphology matching that of the radio and X-ray emission, and is well described by a simple power law with an index of 2.1. We attempt to model the broadband spectral energy distribution, from radio to gamma-rays, using standard nonthermal emission mechanisms. To constrain the relativistic electron population we use 7 years of WMAP data to extend the radio spectrum up to 93 GHz. Both leptonic and hadronic dominated models can reproduce the nonthermal spectral energy distribution, requiring a total content of cosmic ray (CR) electrons and protons accelerated in Puppis A of at least WCR is approx. (1 - 5)×10 (exp 49) erg.

Observations↗
NASA NTRS2014

Tanami Blazars in the IceCube Pev Neutrino Fields

The IceCube Collaboration has announced the discovery of a neutrino flux in excess of the atmospheric background. Owing to the steeply falling atmospheric background spectrum, events at PeV energies most likely have an extraterrestrial origin. We present the multiwavelength properties of the six radio-brightest blazars that are positionally coincident with these events using contemporaneous data of the TANAMI blazar sample, including high-resolution images and spectral energy distributions. Assuming the X-ray to γ-ray emission originates in the photoproduction of pions by accelerated protons, the integrated predicted neutrino luminosity of these sources is high enough to explain the two detected PeV events.

TANAMI↗
NASA NTRS1972

Integration of a Fire Detector into a Spacecraft

A detector sensitive to only the ultraviolet radiation emitted by flames has been selected as the basic element of the NASA Skylab fire detection system. It is sensitive to approximately 10(exp -12)W of radiation and will detect small flames at distances in excess of 3m. The performance of the detector was verified by experiments in an aircraft flying zero-gravity parabolas to simulate the characteristics of a fire which the detector must sense. Extensive investigation and exacting design was necessary to exclude all possible sources of false alarms. Optical measurements were made on all the spacecraft windows to determine the amount of solar radiation transmitted. The lighting systems and the onboard experiments also were appraised for ultraviolet emissions. Proton-accelerator tests were performed to determine the interaction of the Earth's trapped radiation belts with the detectors and the design of the instrument was modified to negate these effects.

Linford, R. M. F.↗
NASA NTRSDate not supplied

SiPM-based Technologies for Solar and Heliospheric Science

Neutrons and γ-rays are produced throughout the heliosphere and offer a unique window to understanding the fundamental processes of energetic particles. At the Sun, because neutrons and γ rays are produced by the interaction of accelerated ions in solar eruptive events, they can further our understanding of space-weather agents, processes and effects. Neutron measurements from 20-150 MeV complement high- and low-energy solar γ-ray measurements and fill the decade-wide energy gap (30-300 MeV) in the accelerated proton spectrum at the Sun, i.e., a critical missing piece in understanding the production mechanisms of solar energetic particles. For lunar or planetary studies, broadband neutron spectroscopy (covering thermal, epithermal, and fast neutrons) and γ-ray spectroscopy can serve as an effective probe of regolith composition and in situ resource utilization, including the localization of water-ice. Furthermore, fast neutrons are a particularly hazardous form of radiation for astronauts and space assets within orbiting habitats and on lunar/planetary surfaces. We discuss the critical role of SiPM-based technology in enabling the next-generation neutron/γ-ray instruments.

Georgia de Nolfo↗
NASA NTRS2022

Energetic Ions Downtail of the Reconnection Site

Using combined MHD/test particle simulations, we explore characteristics of ion (proton) acceleration tailward of a near-Earth reconnection site. We present spatial distributions and explore acceleration mechanisms and sources of accelerated ions. Acceleration is due primarily due simple crossings of the enhanced electric field near the x-line or in the departing plasmoid. The energetic particle distributions show the expected energy dispersed tailward streaming at the plasma sheet boundary, while equatorial distributions are more complicated, resulting from different acceleration sites within the moving plasmoid. Sources are mostly inside the central plasma sheet dawnward of the plasmoid.

Joachim Birn↗
NASA NTRS2025

Mars Ground Level Enhancements in the Context of the Solar Energetic Particle Clock

In this work we discuss the growing ensemble of solar particle events registered on the Martian surface, including their temporal appearance and solar sources. Solar energetic particle events from the surface of Mars have been observed starting soon after the August 2012 landing of the Radiation Assessment Detector onboard Curiosity. The Martian atmosphere prevents protons and heavy ions of up to 180 MeV/n kinetic energy from directly reaching the Martian surface. This cut-off is high enough to limit the number of solar energetic particle events measured on the surface to only 15 in ~12 ½ years. Yet we find in this analysis that Mars ground level enhancements follow the distinct SEP clock pattern as proton events observed at lower energies as reported in Posner, Richardson and Strauss (2024). Proton acceleration occurs predominantly near the solar surface, while transport to Mars incurs a delay in onset, and, as we show here, peak, that is a function of the longitudinal magnetic connection distance. between the foot point of solar wind magnetic field lines that intersect the Mars environment with the source longitude of the solar magnetic eruption. A distinct clustering of relative solar source locations at or near the Mars foot points at the Sun’s western limb is apparent, indicating lower flux thresholds from such preferred locations. Our findings have implications for astronaut safety at Mars.

Mars Ground Level Enhancements↗
DOE OSTI2023

On the Neutrino and Gamma-Ray Emission from NGC 1068

IceCube has recently reported the detection of $\sim 1-10 \,{\rm TeV}$ neutrinos from the nearby active galaxy, NGC 1068. The lack of TeV-scale emission from this source suggests that these neutrinos are generated in the dense corona that surrounds NGC 1068's supermassive black hole. In this paper, we present a physical model for this source, including the processes of pair production, pion production, synchrotron, and inverse Compton scattering. We have also performed a new analysis of Fermi-LAT data from the direction of NGC 1068, finding that the gamma-ray emission from this source is very soft but bright at energies below $\sim 1 \, {\rm GeV}$. Our model can predict a gamma-ray spectrum that is consistent with Fermi-LAT observations, but only if the magnetic field within the corona of this active galactic nucleus (AGN) is quite high, namely $B\gtrsim 6 \, {\rm kG}$. To explain the observed neutrino emission, this source must accelerate protons with a total power that is comparable to its intrinsic X-ray luminosity. In this context, we consider two additional nearby active galaxies, NGC 4151 and NGC 3079, which have been identified as promising targets for IceCube.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Overview of Shielding Analyses at Oak Ridge National Laboratory’s Spallation Neutron Source Second Target Station

The Neutronics Group of the Second Target Station project at Oak Ridge National Laboratory is responsible for all neutronics analyses related to design and construction. This paper provides an overview of four neutronics analyses performed for the Second Target Station project, which is representative of all the ongoing work but especially tasks related to shielding. These analyses extend from the proton accelerator through the target monolith and bunker to the end of a neutron beamline. Each example highlights the tools and methods the Neutronics Group uses for analysis. The primary tool is the Monte Carlo radiation transport code MCNP 6.2, but this is augmented by other codes that supplement the input of MCNP. The other codes specifically highlighted in this paper include Attila4MC, ADVANTG, and AARE.

Miller, Thomas↗
DOE OSTI2024

Adaptation of the Fermilab proton source to support new muon facilities

The PIP-II proton accelerator will provide the intensity sufficient to power a new generation of high energy facilities at Fermilab. Extension of that linac to higher energy with following acceleration and bunching rings could provide the intensity needed to feed a muon production target for a high-energy $\mu^{+} - \mu^{-}$ collider. Scenarios using a rapid-cycling synchrotron or an $\sim$8 GeV Linac are presented and discussed. Some near-term opportunities at Fermilab for muon collider R\&D are introduced.

43 PARTICLE ACCELERATORS↗
NASA NTRS1983

First-order Fermi acceleration in solar flares as a mechanism for the second-step acceleration of prompt protons and relativistic electrons

Solar flare data from June 27, 1980 balloon-based observations were studied in terms of the hard X ray component. A temporal delay of 3 sec was observed for the X ray emissions above 235 keV. The delay occurred relative to the low-energy electrons and indicated a second acceleration stage. An estimation of the acceleration rate of the first-order Fermi process operating in a closed flare loop was found to be in agreement with the resulting data, including the acceleration of both protons and relativistic electrons. Additional support for the first-order Fermi process is noted in the fact that flares generally occur in magnetic loops, a condition which allows energetic particles to continually interact with the upward moving shock fronts. A correlation has also been observed between the delay times and the H-alpha areas, encouraging the interpretation that the delay times are the shock transit times.

Bai, T.↗
NASA NTRS1988

Particle acceleration in accreting magnetospheres

The possibility that energetic protons are accelerated within the closed magnetosphere of accelerating neutron stars is considered. The accelerating mechanism is suggested to be plasma turbulence excited by the accretion flow. Rough estimates show that this mechanism may be capable of accelerating protons to the energies of about 10 to the 16th eV required to explain observations of about 10 to the 15th eV gamma rays from some thermal X-ray sources. Proton synchrotron radiation may be observable at energies ranging from the infrared to about GeV gamma rays.

Katz, J. I.↗
NASA NTRS1993

Lower hybrid turbulence at cometary bow wave and acceleration of cometary protons

The wave measurements at the spacecraft encounters with Comet Halley have shown intense wave activity at the lower hybrid frequency. The excitation of the lower hybrid instability by the pickup cometary ions (protons and water group) in the bow wave region and the quasi-linear diffusion of the ions in these fluctuations are discussed. The quasi-linear diffusion of the pickup protons takes place over a scale length shorter than that of the heavier water group ions. This enhances damping of the waves by protons, and when the pickup proton density is large enough, it can result in the saturation of the instability as this damping balances the heavy ion driven growth. The observed electric field amplitude and the scale length of proton relaxation are in agreement with the theory. For small pickup proton density the instability can saturate due to the wave energy cascade arising from the modulation instability of the large-amplitude lower hybrid waves. This saturation mechanism leads to electron acceleration and suprathermal tail formation.

Shapiro, V. D.↗
NASA NTRS1985

The starting conditions for an optically small solar gamma ray flare

It is suggested that optically small gamma-ray flares result from gradual pre-flare acceleration of protons over approximately 1,000 s by a series of magnetohydrodynamic shocks in the low corona. A fraction of the accelerated protons are trapped in the corona where they form a seed population for future acceleration. If the shock acceleration is sufficiently rapid proton energies may exceed the gamma-ray production threshold and trigger gamma-ray emission. This occurs without the total flare energy being necessarily large. Magnetic field geometry is an important parameter.

Simnett, G. M.↗
NASA NTRS1992

Shock drift acceleration of energetic protons at a planetary bow shock

Results are presented of numerical orbit integrations of the interaction of suprathermal charged particles (protons) with a planetary bow shock, performed in order to investigate the effect of the changing geometry of the shock, due to its curvature, on the kinematics of the particle/shock interaction. Results obtained for both the 2D and 3D bow-shock geometries show that the introduction of shock curvature to the shock in the simulations leads to an increase of the reflection probability of incident suprathermal protons. It was also found that the curvature of the planetary bow shock allows protons to enter at a given value of theta(Bn) (where theta(Bn) is the angle between the local shock normal and the incident magnetic field) and to exit at a different theta(Bn) value. The result has consequences in the characteristics of the energetic charged particle environment in the planetary foreshock.

Giacalone, Joe↗