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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 91 records · Page 5
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NASA NTRS1984

Results from the Helios galactic and solar cosmic ray experiment (E7)

Energy spectra, charge composition, and flow patterns of solar and galactic cosmic rays were investigated using three nuclear-particle telescopes on Helios to measure electrons (50 keV to 8 MeV) protons (100 eV to 800 MeV) alpha particles (to 600 MeV per nucleon) heavier elements up to neon, (to 200 MeV per nucleon). The experiment includes a proportional counter to monitor solar X-rays in the range 2 to 8 keV. A collection of solar flare associated particle events are observed whereby coronal effects and spatial distribution of flare particles are determined over almost a whole solar cycle; a typical solar particle events are also observed. Earlier explanations concerning corotating energetic particle streams in the inner and outer solar system are confirmed. Solar modulation of galactic cosmic rays is identified. Gamma ray bursts are detected and the sources in the sky are precisely determined, proving the suspected galactic origin.

Trainor, J. H.↗
NASA NTRSDate not supplied

Understanding Solar Energetic Particles With STEREO HET

The project evaluates solar energetic particles (SEPs) in the Heliosphere utilizing in situ data from the STEREO mission. More specifically, raw data from the High Energy Telescope (HET) corresponding to the abundances and energy spectra of electrons, protons, He, and heavier nuclei was extracted. C codes were modified and written to analyze Pulse heights and fluxes in a readable format. Plots of the data were formulated in Python. Low fluxes of heavier elements prompted a revaluation of the onboard binning process. New selection criteria will be generated to orient the particle energy loss in the detectors with the expected locations of the energy tracks corresponding to each element.

Energetic Particles↗
NASA NTRS2014

Inferred Cosmic-Ray Spectrum from Fermi-LAT Gamma-Ray Observations of the Earths Limb

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly-discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the -ray emission from the Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range approx. 90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 +/- 0.04 and 2.61 +/- 0.08 above approx. 200 GeV, respectively.

fermi↗
NASA NTRS1977

On propagation direction of ring current proton ULF waves observed by ATS 6 at 6.6 R sub E

From June 11 to September 16, 1974, the NOAA low-energy proton detector on board the ATS 6 satellite observed 71 cases of ultralow-frequency oscillations of proton flux intensities. The oscillation periods varied from 40 s to 6 min, and the events were observed most frequently during moderate geomagnetic conditions. The flux oscillations occurred at various local times, yet almost two thirds of the events were detected in the near-dusk region of the magnetosphere. For a majority of the events in this set a substantial phase shift in flux oscillation was detected between different energy channels and/or between two oppositely oriented detector telescopes. The phase shift is mainly due to the finite gyroradius effect of the protons gyrating in the geomagnetic field. By examining this finite gyroradius effect on the perturbed particle distribution function associated with the wave in a nonuniform magnetic field, the propagation direction of the wave from particle observations made by a single spacecraft is determined

Su, S.-Y.↗
NASA NTRS1973

Reaction Li-6/p, pt/ at 590 MeV.

A lithium target enriched to 95.6 per cent of Li-6 and 0.685 cm thick was bombarded in the 590-MeV proton beam of a synchrocyclotron. Coincident events were detected in a double telescope arrangement. The characteristics of the unobserved three-nucleon residual system calculated for each event include the missing energy, the longitudinal recoil, and the transverse recoil. The cross-section data obtained indicate that zero recoil momentum for the unobserved three-nucleon recoil system is the most likely situation.

Dollhopf, W.↗
NASA NTRS1991

The estimation of background production by cosmic rays in high-energy gamma ray telescopes

A calculational method of estimating instrumental background in high-energy gamma-ray telescopes, using the hadronic Monte Carlo code FLUKA87, is presented. The method is applied to the SAS-2 and EGRET telescope designs and is also used to explore the level of background to be expected for alternative configurations of the proposed GRITS telescope, which adapts the external fuel tank of a Space Shuttle as a gamma-ray telescope with a very large collecting area. The background produced in proton-beam tests of EGRET is much less than the predicted level. This discrepancy appears to be due to the FLUKA87 inability to transport evaporation nucleons. It is predicted that the background in EGRET will be no more than 4-10 percent of the extragalactic diffuse gamma radiation.

Edwards, H. L.↗
NASA NTRS1981

Observations of interplanetary energetic charged particles from gamma-ray line solar flares

Observations of interplanetary energetic ions from the 7 June, 21 June and 1 July 1980 gamma ray line solar flares are presented. The observations are from the Max-Planck-Institut/University of Maryland Ultra Low Energy Wide Angle Telescope aboard the ISEE-3 spacecraft. Both June flares produced relatively low intensity proton events at earth with peak intensities at 10-20 MeV approximately 5 x .01 protons square cm sec sr MeV)-1. Neither flare showed evidence of being enriched in either 3He or Fe at approximately 1 MeV/nucleon. The 1 July flare produced no observable ion or electron enhancements.

Pesses, M. E.↗
NASA NTRS2001

An Overview of the Performance and Scientific Results From the Chandra X-Ray Observatory (CXO)

The Chandra X-Ray Observatory (CXO), the x-ray component of NASA's Great Observatories, was launched on 1999, July 23 by the Space Shuttle Columbia. After satellite systems activation, the first x-rays focused by the telescope were observed on 1999, August 12. Beginning with the initial observation it was clear that the telescope had survived the launch environment and was operating as expected. Despite an initial surprise due to the discovery that the telescope was far more efficient for concentrating CCD-damaging low-energy protons than had been anticipated, the observatory is performing well and is returning superb scientific data. Together with other space observatories, most notably XMM-Newton, it is clear that we have entered a new era of discovery in high-energy astrophysics.

Weisskopf, M. C.↗
NASA NTRS2003

Proton-Induced Transients and Charge Collection Mechanisms in a LWlR HgCdTe Focal Plane Array

Low noise performance of IR detectors is required, even in the presence of charged particles. Galactic cosmic rays, trapped protons & solar energetic particles. Particle induced transients identified as an important source of noise on ESA's ISO satellite. Also observed on NICMOS Instrument on NASA% Hubble Space Telescope. Tools to analyse particle induced transients have been developed. To date, comparisons of model have been made to flight data for a HgCdTe array exposed to trapped protons, and to a Si array exposed to laboratory protons. We report ground based proton transient measurements in a modem LWlR HgCdTe array operating under cryogenic conditions. Demonstration of charge collection mechanisms. Provide benchmarks for modeling tools.

Marshall, Paul↗
NASA NTRS2015

The JPL Uranian Radiation Model (UMOD)

The objective of this study is the development of a comprehensive radiation model (UMOD) of the Uranian environment for JPL mission planning. The ultimate goal is to provide a description of the high energy electron and proton environments and the magnetic field at Uranus that can be used for engineering design. Currently no model exists at JPL. A preliminary electron radiation model employing Voyager 2 data was developed by Selesnick and Stone in 1991. The JPL Uranian Radiation Model extends that analysis, which modeled electrons between 0.7 MeV and 2.5 MeV based on the Voyager Cosmic Ray Subsystem electron telescope, down to an energy of 0.022 MeV for electrons and from 0.028 MeV to 3.5 MeV for protons. These latter energy ranges are based on measurements by the Applied Physics Laboratory Low Energy Charged Particle Detector on Voyager 2. As in previous JPL radiation models, the form of the Uranian model is based on magnetic field coordinates and requires a conversion from spacecraft coordinates to Uranian-centered magnetic "B-L" coordinates. Two magnetic field models have been developed for Uranus: 1) a simple "offset, tilted dipole" (OTD), and 2) a complex, multi-pole expansion model ("Q3"). A review of the existing data on Uranus and a search of the NASA Planetary Data System (PDS) were completed to obtain the latest, up to date descriptions of the Uranian high energy particle environment. These data were fit in terms of the Q3 B-L coordinates to extend and update the original Selesnick and Stone electron model in energy and to develop the companion proton flux model. The flux predictions of the new model were used to estimate the total ionizing dose for the Voyager 2 flyby, and a movie illustrating the complex radiation belt variations was produced to document the uses of the model for planning purposes.

Garrett, Henry↗
NASA NTRS2019

Fermi, Wind, and SOHO Observations of Sustained Gamma-Ray Emission from the Sun

We report on the linear relationship between the durations of two types of electromagnetic emissions associated with shocks driven by coronal mass ejections: sustained gamma-ray emission (SGRE) and interplanetary type II radio bursts. The relationship implies that shocks accelerate approximately 10 kiloelectronvolts electrons (for type II bursts) and more than 300 megaelectronvolts protons (for SGRE) roughly over the same duration. The SGRE events are from the Large Area Telescope (LAT) on board the Fermi satellite, while the type II bursts are from the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft. Here we consider five SGRE events that were not included in a previous study of events with longer duration (more than 5 hours). The five events are selected by relaxing the minimum duration to 3 hours. We found that some SGRE events had a tail that seems to last until the end of the associated type II burst. We pay special attention to the 2011 June 2 SGRE event that did not have a large solar energetic particle event at Earth or at the STEREO spacecraft that was well connected to the eruption. We suggest that the preceding CME (Coronal Mass Ejection) acted as a magnetic barrier that mirrored protons back to Sun.

Gopalswamy, N.↗
NASA NTRS1983

Energetic solar cosmic rays in the outer heliosphere

Intermediate-energy protons (3.5-56 MeV) in the outer heliosphere are studied using data from the GSFC-UNH cosmic-ray telescopes on Pioneer 10 and 11. Flux and anisotropy information in this energy region is used to investigate the properties of the solar-flare-associated flux increases detected between September 1977 and September 1982 for radial distances between 5.8 and 28.5 AU. A propagation model is discussed, and its predictions for the 3-5 MeV protons are presented in diagrams.

Goeman, R.↗
NASA NTRS1977

Neutral particle background in cosmic ray telescopes composed of silicon solid state detectors

The energy loss-spectrum of secondary charged particles produced by the interaction of gamma-rays and energetic neutrons in silicon solid state detectors has been measured with a satellite-borne cosmic ray telescope. In the satellite measurements presented here two distinct neutral background effects are identified: secondary protons and alpha particles with energies of about 2 to 100 MeV produced by neutron interactions, and secondary electrons with energies of about 0.2 to 10 MeV produced by X-ray interactions. The implications of this neutral background for satellite measurements of low energy cosmic rays are discussed, and suggestions are given for applying these results to other detector systems in order to estimate background contamination and optimize detector system design.

Mewaldt, R. A.↗
NASA NTRS2013

Solar Energetic Particle Anisotropies Observed by STEREO/LET

The Low Energy Telescopes (LETs) onboard the twin STEREO spacecraft can measure the anisotropies of energetic particles for protons through iron at energies of 1.8-12 MeV/nucleon, depending on species. A large variety of anisotropies are observed. Unidirectional beamed distributions often appear at the onset of magnetically well-connected solar energetic particle (SEP) events, while long-lasting bidirectional flows are seen within several interplanetary coronal mass ejections (ICMEs) due to either injection of particles at both footpoints of the CME or mirroring of a unidirectional beam. Several examples of a loss-cone distribution are clearly seen, in which particles with pitch angles far from the field direction are mirrored while those with smaller pitch angles are not, either because the magnetic field strength did not become large enough to turn the smaller pitch angle particles around, or more scattering occurred between the observer and the more distant mirror points of these particles. Distributions with pronounced depletions at 90 deg to the field, as well as those that instead have enhancements at 90 deg (i.e., trapped distributions) are also seen. The magnitude of the anisotropies often depends on particle energy and species, with lower energy particles typically more anisotropic than higher energy particles. We present some of the more interesting LET anisotropy observations throughout the STEREO mission to date and discuss the implications of these observations for SEP transport in the heliosphere.

coronal mass ejections↗
NASA NTRS2005

Overview of Results from the Cassini Magnetospheric Imaging Instrument (MIMI) During the First Year of Operations

The MIMI investigation comprises three sensors covering the indicated energy ranges: the Ion and Neutral Camera (INCA) -- 7 keV/nuc 3 Mev) and protons (1.6 < E < 160 Mev) from the back end of the dual field-of-view telescope. The Saturn observation sequences began in January, 2004 and culminated in Saturn Orbit Insertion on July 1, 2004. The MIMI sensors observed substantial activity in interplanetary space for several months prior to SOI, including several interplanetary shocks associated with corotating interaction regions, numerous increases most likely originating from particle streams in the vicinity of the Saturnian bow shock and energetic neutral atoms (ENA) emanating from Saturn s magnetosphere. Results following SOI revealed: a dynamical magnetosphere with a day-night asymmetry and an 11-hour periodicity; several water-product ions (O+, OH+, H2O+), but little N+; inferred quantities of neutral gas sufficient to cause major losses in the trapped ions and electrons in the middle and inner magnetosphere; a Titan exosphere that is a copious source of ENA; INCA imaging through ENA has also revealed a previously unknown radiation belt residing inward of the D-ring that is most likely the result of double charge-exchange between the main radiation belt and the upper layers of Saturn s exosphere. Finally, there is ample evidence for the presence of substorm-like injections of plasma that subsequently corotates for a number of days before dissipating on the night-side magnetotail. The observations will be presented and discussed in the context of current theoretical models.

Krimigis, S. M.↗
NASA NTRS1988

Observations related to the acceleration, injection, and interplanetary propagation of energetic protons during the solar cosmic ray event on February 16, 1984

This paper presents an analysis of data collected by the worldwide network of neutron monitors and from IMP-8 cosmic-ray telescopes, as well as by particle detectors on the GOES 5 and 6 and ICE satellites, on the solar cosmic ray event that took place on February 16, 1984. Using these data, the intensity-time (IT) profiles, the anisotropy-time profiles, the energy spectra, and the pitch angle distributions of the solar protons near earth were deduced. It was found that the solar protons propagated essentially scatter-free from the sun to the earth. The solar protons had easy access to the IMF lines to earth; the time from the onset to maximum intensity and the shape of the IT profiles at earth as a function of energy could be explained by the diffusion of the flare protons near the acceleration region. The energy spectrum of the solar flare protons injected into the undisturbed IMF at the sun was changing with time in both amplitude and shape. The observations suggest a shock acceleration process.

Debrunner, H.↗
NASA NTRS1982

Association between magnetic field fluctuations and energetic particle bursts in the earth's magnetotail

The association between energetic protons (0.29-0.50 MeV) and simultaneous local fluctuations of magnetic field at 35 to 45 earth radii in the magnetotail is examined statistically with data from APL/JHU particle telescopes aboard IMP 7 and IMP 8. About four satellite years of 5.5 min averaged measurements are used in this study. In addition to confirming that the level of magnetic field fluctuations generally increases with the presence of energetic protons and their streaming anisotropy, it is found that increases in occurrence frequency of streaming of energetic protons are ordered far better by magnetic field fluctuations than by proximity to the neutral sheet. However, the presence of large magnetic field fluctuations (delta B greater than 5 nT or delta B/B greater than 50%) is neither a necessary nor a sufficient condition for the detection of large streaming in energetic protons.

Lui, A. T. Y.↗
NASA NTRS1973

Propagation anisotropies of solar flare protons and electrons at low energies in interplanetary space.

Flux anisotropies in interplanetary space were investigated for protons with E greater than 0.66 MeV and electrons with E greater than 400 keV. Data were taken from the University of Chicago charged-particle telescope aboard the deep-space probe Pioneer 7 and from the Goddard Space Flight Center magnetometer aboard the same spacecraft. Flux anisotropies lying to the east of the average interplanetary magnetic field direction were first reported by McCracken et al. (1971), late in a solar particle event, for proton energies greater than 7.5 MeV. This work extends this investigation to much lower proton energies, studies the proton and electron anisotropies during both early and late phases of a particle event, and makes use of detailed magnetic field data. The investigation consists of two parts, a study of many periods taken at random during solar events, for both protons and electrons, and a detailed analysis of one period, early in an event, during which the magnetic field was near the solar direction.

Pyle, K. R.↗