SEARCH · Search NASA

Results for “Cosmic ray composition & spectra”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

NASA NTRS1974

Mean isotopic composition of cosmic rays with 12 less than Z less than or equal to 26 at 2.7 to 3.0 GV

Results are presented from a high-altitude balloon flight in September 1972 near 3-GV geomagnetic cutoff. The detector is a combination of ionization chambers and a Lucite Cerenkov counter with a charge resolution of 0.34 charge units. Following the technique described by Lund et al. (1971), use is made of the geomagnetic rigidity cutoff and measured momentum-per-nucleon spectra of individual elements to determine values of A/Z for even Z elements of 16 less than or equal to Z less than or equal to 26 relative to A/Z of silicon.

Maehl, R. C.↗

NASA NTRS1975

The isotopic composition of hydrogen and helium in low energy cosmic rays

The Caltech Electron/Isotope Spectrometer on IMP-7 has been used to identify the isotopes H-2 and He-3 in low energy cosmic rays during solar quiet periods from October 1972 to October 1974. These observations cover the energy intervals 5 to 29 MeV/nuc for H-2 and 7 to 50 MeV/nuc for He-3. The energy spectra of H-1, H-2, and He-3 all fall rapidly with decreasing energy, giving H-2/H-1 and He-3/H-1 ratios essentially independent of energy as expected from adiabatic acceleration. The measured He-4 spectrum, however, was essentially flat over this energy interval, and therefore the H-2/He-4 ratio observed at 1 AU is not simply related to the interstellar abundances of these nuclei. However, comparisons of the H-2/H-1 and He-3/H-1 ratios with calculated spectra are possible.

Mewaldt, R. A.↗

NASA NTRS2019

CALET Results After Three Years on Orbit on the International Space Station

The CALorimetric Electron Telescope (CALET) is an astroparticle physics experiment installed on the International Space Station since August 2015. The CALET mission was conceived to address several outstanding questions of high-energy astroparticle physics, like indirect detection of dark matter, the origin of cosmic rays (CRs), their mechanisms of acceleration and galactic propagation, the presence of possible nearby astrophysical CR sources. That can be achieved by precise measurements of the fluxes of CR electrons and gamma-rays up to the unexplored region above 1 TeV, and the energy spectra and composition of CR nuclei from a few tens of GeV to hundreds of TeV. In order to perform these observations, the instrument combines a thick total absorption PWO crystal calorimeter for energy measurement, a scintillator hodoscope for charge identi cation and thin imaging tungsten-scintillating fiber calorimeter providing accurate particle tracking and complementary charge measurement. In this paper, we will present an overview of the main CALET results based on the data collected in the first three years of the mission.

P Maestro↗

NASA NTRS1976

The isotopic composition of hydrogen and helium in low-energy cosmic rays

The isotopes H-2 and He-3 have been identified in low-energy cosmic rays during solar-quiet periods from 1973 January to 1974 October. These observations, made with the electron/isotope spectrometer on IMP-7, cover the energy intervals 5-29 MeV per nucleon for H-2 and 7-50 MeV per nucleon for He-3. The energy spectra of H-1, H-2, and He-3 fall rapidly with decreasing energy, giving H-2/H-1 and He-3/H-1 ratios which are essentially independent of energy as expected from current theories of the solar modulation of galactic cosmic rays. The measured He-4 spectrum, however, is essentially flat below 40 MeV per nucleon, suggesting that there may be contributions from a local, nonsolar source of He-4. Comparisons of the H-1, H-2, and He-3 observations with calculated spectra at 1 AU imply a mean interstellar path length of 7 plus or minus 2 g/sq cm. However, present low-energy measurements of H and He isotopes at 1 AU do not discriminate between possible cosmic-ray source spectra.

Mewaldt, R. A.↗

NASA NTRS1985

On the cosmic ray diffusion in a violent interstellar medium

A variety of the available observational data on the cosmic ray (CR) spectrum, anisotropy and composition are in good agreement with a suggestion on the diffusion propagation of CR with energy below 10(15) eV in the interstellar medium. The magnitude of the CR diffusion coefficient and its energy dependence are determined by interstellar medium (ISM) magnetic field spectra. Direct observational data on magnetic field spectra are still absent. A theoretical model to the turbulence generation in the multiphase ISM is resented. The model is based on the multiple generation of secondary shocks and concomitant large-scale rarefactions due to supernova shock interactions with interstellar clouds. The distribution function for ISM shocks are derived to include supernova statistics, diffuse cloud distribution, and various shock wave propagation regimes. This permits calculation of the ISM magnetic field fluctuation spectrum and CR diffusion coefficient for the hot phase of ISM.

Bykov, A. M.↗

NASA NTRS2001

Mid- and far-infrared spectroscopic studies of the influence of temperature, ultraviolet photolysis and ion irradiation on cosmic-type ices

Infrared (IR) studies of laboratory ices can provide information on the evolution of cosmic-type ices as a function of different simulated space environments involving thermal, ultraviolet (UV), or ion processing. Laboratory radiation experiments can lead to the formation of complex organic molecules. However, because of our lack of knowledge about UV photon and ion fluxes, and exposure lifetimes, it is not certain how well our simulations represent space conditions. Appropriate laboratory experiments are also limited by the absence of knowledge about the composition, density, and temperature of ices in different regions of space. Our current understanding of expected doses due to UV photons and cosmic rays is summarized here, along with an inventory of condensed-phase molecules identified on outer solar system surfaces, comets and interstellar grains. Far-IR spectra of thermally cycled H2O are discussed since these results reflect the dramatic difference between the amorphous and crystalline phases of H2O ice, the most dominant condensed-phase molecule in cosmic ices. A comparison of mid-IR spectra of products in proton-irradiated and UV-photolyzed ices shows that few differences are observed for these two forms of processing for the simple binary mixtures studied to date. IR identification of radiation products and experiments to determine production rates of new molecules in ices during processing are discussed. A new technique for measuring intrinsic IR band strengths of several unstable molecules is presented. An example of our laboratory results applied to Europa observations is included.

Spectrophotometry, Infrared/methods↗

NASA NTRS1975

Low energy particle composition

A review is given of current knowledge of low-energy cosmic ray particles produced in the solar system. It is argued that the notion that the sun alone can accelerate particles in the solar system must be abandoned in light of evidence that Jupiter and earth may be sources of observed low-energy particles. Measurements of the composition and energy spectra of low-energy particles during quiet times are examined, emphasizing the abundance of protons and helium and of anomalous N, O, and Ne. The abundance of heavy particles (B, C, N, O, Ne, Ca and Fe) of unknown origin in the earth magnetosphere is examined. Reported observations of Jovian electrons are discussed and solar particle events with anomalous compositions (He-3 rich events and Fe rich events) are treated in detail. Nuclear abundances of solar particles, emphasizing their temporal and spatial variations are considered together with the nature of nuclear reaction products in solar flares.

Gloeckler, G.↗

NASA NTRS2005

Effects of Cutoffs on Galactic Cosmic-Ray Interactions in Solar-System Matter

The energetic particles in the galactic cosmic rays (GCR) induce many interactions in a variety of solar-system matter. Cosmogenic nuclides are used to study the histories of meteorites and lunar samples. Gamma rays and neutrons are used to map the compositions of planetary surfaces, such as Mars, the Moon, and asteroids. In almost all of these cases, the spectra of incident GCR particles are fairly similar, with only some modulation by the Sun over an 11-year cycle. Strong magnetic fields can seriously affect the energy spectrum of GCR particles hitting the surface of objects inside the magnetic fields. The Earth s geomagnetic field is strong enough that only GCR particles with magnetic rigidities above approx. 17 GV (a proton energy of approx. 17 GeV) reach the atmosphere over certain regions near the equator. This effect of removing lower-energy GCR particles is called a cutoff. The jovian magnetic fields are so strong that the fluxes of GCR particles hitting the 4 large Galilean satellites are similarly affected. The cutoff at Europa is estimated to be similar to or a little higher than at the Earth s equator.

Kim, K. J.↗

NASA NTRS1974

An interpretation of the carbon-oxygen to iron ratio

Data from recent measurements on the composition of primary cosmic rays above 1 GeV/nucleon are critically reviewed for information pertaining to selection of suitable energy-dependent composition models. Areas where crucial experimental information may result in selection of a suitable model are pointed out. In particular, the study of the energy distribution of VVH nuclei, and the derivation of more accurate energy spectra of 10 less than or equal to Z less than or equal to 14, 15 less than or equal to Z less than or equal to 23 and Z greater than 24 would contribute to discriminate between models which rely on interstellar propagation and those that ascribe a different source mechanism for Fe group nuclei.

Balasubrahmanyan, V. K.↗

NASA NTRS1982

Energy dependence in solar cosmic ray composition

An investigation is conducted concerning an occurrence of effects related to energy dependence in studies of solar flare particle composition, taking into account eight large solar-flares associated particle events. The ratios C/O (carbon/oxygen), (MG plus Si)/O, and Fe(group)/O as a function of energy/nucleon are presented in a graph. A wide range of variation in the Fe(group)/O ratios is found from event to event. While the energy dependence is consistent in most events with individual element spectra, several events show unusual behavior in the Fe(group)/O ratio, due to the existence of several distinct spectral components. These multiple spectral components may imply multiple phases of acceleration or substantial interplanetary shock contamination at low energies at times well below the arrival time of these shocks at 1 AU.

Mcguire, R. E.↗

NASA NTRS1973

Results on the energy dependence of cosmic-ray charge composition

Results of measurements by a balloon-borne ionization spectrometer of the energy dependence of high-energy cosmic-ray charge composition. The results presented are greatly improved over those obtained earlier by Ormes et al. (1971) by the use of a multidimensional charge analysis with more efficient background rejection, and a more accurate energy determination. Complex couplings between the charge, energy, and trajectory information were taken into account and are discussed. The spectra of individual elements up to oxygen and of groups of nuclei up through iron were measured up to almost 100 GeV per nucleon. The energy spectrum of the secondary nuclei, B + N, is found to be steeper than that of the primary nuclei, C + O, in agreement with Smith et al. (1973). The most dramatic finding is that the spectrum of the iron nuclei is flatter than that of the carbon and oxygen nuclei by 0.57 plus or minus 0.14 of a power.

Balasubrahmanyan, V. K.↗

NASA NTRS2006

Updated Computational Model of Cosmic Rays Near Earth

An updated computational model of the galactic-cosmic-ray (GCR) environment in the vicinity of the Earth, Earth s Moon, and Mars has been developed, and updated software has been developed to implement the updated model. This model accounts for solar modulation of the cosmic-ray contribution for each element from hydrogen through iron by computationally propagating the local interplanetary spectrum of each element through the heliosphere. The propagation is effected by solving the Fokker-Planck diffusion, convection, energy-loss boundary-value problem. The Advanced Composition Explorer NASA satellite has provided new data on GCR energy spectra. These new data were used to update the original model and greatly improve the accuracy of prediction of interplanetary GCR.

ONeill, Patrick M.↗

NASA NTRS1985

Measurement of low energy cosmic rays aboard Spacelab-1

In December 1983 the first Spacelab mission was launched for a duration of 10 days. Aboard was the Kiel experiment Isotopic Stack designed for measurement of heavy cosmic ray nuclei with nuclear charge equal to or greater than 3 and energies up to some 100MeV/nuc. One part of the stack was rotated in well defined steps registered by an angle encoder to receive information on impact times of the nuclei. Using this time resolving system geomagnetically forbidden particles can be detected. The chemical composition and energy spectra of mainly CNO particles are examined using a rotated 300 microns m thick CR-39 foil beneath a fixed 100 microns m thick Kodak-Cellulose Nitrate foil. About 600 sq cm have been scanned yielding nearly 100 nuclear tracks within an energy range of approximately 8 to 30 MeV/nuc. The calibration is done by means of a postflight irradiation with 410 MeV/nuc Fe-56 at Berkeley Laboratory, California, USA. Relative abundances and energy spectra are presented.

Beaujean, R.↗

NASA NTRSDate not supplied

Electron Bombardment on Dione: Surface Compositional Effects and Temperature Anomalies

Saturn’s icy moons are composed primarily of water ice with minor other “contaminants,” such as CO2 ice, and a dark component thought to be organics, hematite and/or metallic Fe. The space weathering process of electron bombardment is expected to be particularly important on the surfaces of Saturn’s inner moons (Mimas, Tethys, Dione, and Rhea), as they orbit within Saturn’s inner magnetosphere. Terrains exhibiting thermal anomalies (i.e., colder temperatures in the day and warmer temperatures at night than surrounding areas) correspond to regions of high energy electron bombardment. Energetic electrons impact the surfaces, sintering ice grains together, and this process becomes more effective for increasing particle energies. Solar UV radiation, cosmic rays, dust in-fall, and cold plasma particles trapped in Saturn’s magnetic field also play an important role in altering the nature and the structure of the native surface ices by the implantation of contaminants, ionization, sputtering, and dissociation of water ice molecules. Additionally, CO2 could be sourced from irradiation of dark organic material. Many of these surface alterations are observable in Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) spectra. We used similar methodologies as have been employed in previous works to derive surface temperatures from Cassini’s Composite Infrared Spectrometer (CIRS), which helped to isolate areas where space weathering due to electron bombardment is more predominant. The subtle changes in VIMS spectra were investigated using machine learning techniques. We present here our results for Dione.

C L Young↗

NASA NTRSDate not supplied

Electron Bombardment on Dione: Surface Compositional Effects and Temperature Anomalies

Saturn’s icy moons are composed primarily of water ice with minor other “contaminants,” such as CO2 ice, and a dark component thought to be organics, hematite and/or metallic Fe [1]. The space weathering process of electron bombardment is expected to be particularly important on the surfaces of Saturn’s inner moons (Mimas, Tethys, Dione, and Rhea), as they orbit within Saturn’s inner magnetosphere. Terrains exhibiting thermal anomalies (i.e., colder temperatures in the day and warmer temperatures at night than surrounding areas) correspond to regions of high energy electron bombardment [2; 3; 4; 5]. Energetic electrons impact the surfaces, sintering ice grains together, and this process becomes more effective for increasing particle energies [6]. Solar UV radiation, cosmic rays, dust in-fall, and cold plasma particles trapped in Saturn’s magnetic field also play an important role in altering the nature and the structure of the native surface ices by the implantation of contaminants, ionization, sputtering, and dissociation of water ice molecules [7]. Additionally, CO2 could be sourced from irradiation of dark organic material [8]. Many of these surface alterations are observable in Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) spectra [9]. We used similar methodologies as have been employed in previous works [e.g., 10] to derive surface temperatures from Cassini’s Composite Infrared Spectrometer (CIRS), which helped to isolate areas where space weathering due to electron bombardment is more predominant. The subtle changes in VIMS spectra were investigated using machine learning techniques. We present here our results for Dione.

Cindy Lee Young↗

NASA NTRSDate not supplied

Electron Bombardment on Dione: Surface Compositional Effects and Temperature Abnormalities

C L Young↗

NASA NTRS1986

Studies of the composition of solar particles and of energetic oxygen and sulfur nuclei trapped in the Jovian magnetosphere

The Cosmic Ray System (CRS) experiment on board each of the Voyager 1 and 2 spacecraft consists of four Low Energy Telescopes (LETs), two High Energy Telescopes (HETs), the Electron Telescope (TET), and associated electronics. With these instruments it is possible to measure the energy spectrum of electrons over the 3-110MeV energy range and the energy spectra and nuclear charge of atomic nuclei from hydrogen through zinc over the 3-500 MeV/nuc energy range. The exclusive use of solid-state detectors in the CRS telescopes achieves the objectives of reliability over a long mission life, high resolution determinations of energy and charge, and high-count-rate capability during large solar flares and passage through the magnetospheres of the outer planets. Summarized here are some of the many accomplishments that have resulted from the CRS measurements during the period covered by this report, May 15, 1981 to May 15, 1984, including studies of the energetic oxygen and sulfur nuclei trapped in the Jovian magnetosphere.

Stone, E. C.↗

NASA NTRS1974

Lunar surface cosmic ray experiment

The galactic cosmic ray and solar flare experiment on Apollo 16 is reported. The published papers presented describe the experiment, equipment, data processing techniques, and operational history. The principle findings include: (1) The composition of heavy ions in interplanetary space at energies between approximately 30 and 130 MeV/nucleon is the same, within experimental errors. (2) The ability of a Lexan stack to determine simultaneously the energy spectra of major elements from He up to Fe in the energy interval 0.2 to 30 MeV/nucleon revealed systematic changes in the composition of solar flare particles as a function of energy. (3) Heavy ions emitted in a solar flare appear to be completely stripped of electrons, and are not in charge equilibrium at the time of acceleration and releases from the sun.

Price, P. B.↗