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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 271 records · Page 15
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NASA NTRS1975

The interplanetary acceleration of energetic nucleons

Co-rotating proton and electron streams are the dominant type of low-energy (0.1-10 MeV/nucleon) particle event observed at 1 A.U. The radial dependence of these events was studied between 1 and 4.6 A.U. using essentially identical low-energy detector systems on IMP 7, Pioneer 10 and Pioneer 11. It was expected that at a given energy, the intensity of these streams would decrease rapidly with heliocentric distance due to the effects of interplanetary adiabatic deceleration. Instead it was found that from event to event the intensity either remains roughly constant or increases significantly (more than an order of magnitude) between 1 and 3 A.U. It appears that interplanetary acceleration processes are the most plausible explanation. Several possible acceleration models are explored.

Mcdonald, F. B.↗
NASA NTRS1975

The 1964-1972 quiet-time spectra of protons and helium at 2-20 MeV per nucleon

Instruments on the IMP 4 and 5 satellites are used to observe quiet-time proton and helium fluxes in the energy range from 2 to 30 MeV/nucleon and to extend the total observation period through the solar maximum to about the solar minimum (1964-1972). The nature of quiet time at low energies is discussed, selection of quiet-time periods is described, and data are presented on the fluxes during recovery from the solar maximum. The long-term time-dependence of the proton and helium spectra over solar cycle 20 is determined. The fluxes are found to vary by a factor of approximately 7, the variation is shown to be similar to the modulation of medium-energy cosmic rays, and the observed relative abundance of protons and helium is found to be closer to the medium-energy galactic rather than the average solar-flare relative abundance. A galactic origin is suggested for the low-energy quiet-time turnup, although a solar or heliospheric acceleration mechanism is not ruled out.

Zamow, R.↗
NASA NTRS1975

Origin and composition of heavy nuclei between 10 and 60 MeV per nucleon during interplanetary quiet times in 1968-1972

Results are reported for measurements of the relative abundances of nuclei from boron through iron in the energy range between 10 and 60 MeV/nucleon which were made with an instrument on board OGO 5 during the period of changing solar modulation from 1968 to 1971. The investigation was conducted to determine whether the heavy nuclei in this energy range were of solar or galactic origin. It is found that the relative abundances are in good agreement with the nuclear abundances of galactic cosmic rays, that the differential energy spectra of carbon and oxygen at these energies diverged from the characteristic modulated galactic spectrum, that changes in the C + N + O flux during this period underwent a temporal phase lag with respect to high-energy galactic cosmic rays, and that this phase lag was the same as that for helium nuclei of galactic origin with energies of 30 to 100 MeV/nucleon. It is concluded that the experimental evidence favors a galactic origin for the present nuclei. Some implications of the energy-spectrum results for cosmic-ray modulation theory are discussed.

Mogro-Campero, A.↗
NASA NTRS1975

The magnetospheric contribution to the quiet-time low energy nucleon spectrum in the vicinity of earth

Proton intensity observations obtained by Explorer 47 during March 9-12, 1973 are analyzed. Results show that the magnetosphere is the primary contributor to the quiet time interplanetary proton population in the range 0.29 less than or equal to Ep less than or equal to 0.5 MeV, and indicate that it may be an important contributor up to about 1.5 MeV. Maximum intensity is coming from the direction of the bow shock. The H/He ratio at less than 2 MeV/nucleon is about 10, and the He/Z greater than or equal to 3 ratio at about 1 MeV/nucleon is approximately 8. It is suggested that the low energy (less than 20 MeV) upturn observed in the quiet time interplanetary proton spectrum may be related to particle emissions from planetary magnetospheres.

Krimigis, S. M.↗
NASA NTRS1975

A measurement of abundances of VVH nuclei above 0.6 GeV per nucleon

The abundance distribution of very very heavy (VVH) nuclei just beyond the iron group has been measured with a balloon-borne counter telescope flown in 1971 and 1972. While the statistical accuracy of these observations is limited, they are of considerable interest since very little work has so far been done to determine the abundance of nuclei with charge between 27 and 36. It is found that the element distribution in the cosmic rays arriving at the top of the atmosphere is quite similar to the solar-system abundance distribution in this interval.

Juliusson, E.↗
NASA NTRS1979

Improved nucleonic coal-thickness monitor

Design for coal-thickness-sensing instrument features independent hydropneumatic suspension of radiation source and detector. Monitor uses source and detector which are independently mounted, to follow contour of coal surface more closely and to eliminate errors caused by variations in airgap along radiation path. Device may help to bring fully-automated coal mining closer to reality.

Crouch, C. E.↗
NASA NTRS1978

An instrument to measure the spectrum of cosmic ray iron and other nuclei to above 100 GeV-nucleon

A balloon-borne detector system for extending the study of cosmic ray composition to the energy region beyond 100 GeV/nucleon is described. The instrument incorporates an ionization calorimeter and a gas Cherenkov counter filled with freon for the determination of energies, and a charge module, consisting of scintillation and a lucite Cherenkov counter, for determining the charge of the incoming particle. The scintillators were utilized to determine the position of the incoming particle in addition to its charge. The characteristics of these detectors with respect to resolution, and the methods employed in laboratory calibration, cross-checks with flight data and actual performance in the flights are described in detail. Monte Carlo simulation of the ionization calorimeter and comparison of the response of the calorimeter and gas Cherenkov counter for complex nuclei was used to convert the observed calorimeter signal to absolute energy in a consistent manner.

Arens, J. F.↗
NASA NTRS1978

Abundances and spectra for cosmic-ray nuclei from lithium to iron for 2 to 150 GeV per nucleon

Measurements of primary cosmic-ray composition and energy spectra made with a balloon-borne superconducting magnetic spectrometer are described. Results for both 6.7 g/sq cm equivalent vertical atmospheric depth and the top of the atmosphere are presented for the absolute and relative integral abundances, the differential energy spectra, and the spectral indices for cosmic-ray nuclei from Li to Fe and energies of 2 to 50 GeV/n. It is found that propagation effects can explain essentially all the elemental abundances, that the abundances of Li, Be, and B for rigidities below 10 GV/c are consistent with an energy-independent mean interstellar path length of 4.5 + or - 0.5 g/sq cm for the 'leaky box' propagation model, that the abundances of all elements above 10 GV/c are consistent with a path length that decreases as the inverse n-th power of rigidity, and that n equals 0.6 (+0.4, -0.3) for the simplest assumptions made in fitting the source spectra.

Orth, C. D.↗
NASA NTRS1978

The quiet-time low energy nucleon spectrum during 1975

The paper reports measurements during quiet time periods in 1975 over the range of Ep from about 0.3 to 5 MeV for protons and E-alpha from about 0.7 to 11 MeV/nuc for helium nuclei. The data are obtained from the JHU/APL experiments on earth-orbiting IMP-7 and IMP-8 spacecraft. Both spacecraft are spinning, and data from the experiment are acquired in both spin-averaged and sectored form. It is shown that the earth's atmosphere continues to be a most important contributor to the proton population in the Ep range of 0.29-0.5 MeV, and that the 1975 intensities are virtually identical to those measured in 1973, suggesting the absence of solar modulation at these low (no more than about 5 MeV/nuc) energies. Lack of solar modulation argues against a galactic origin.

Krimigis, S. M.↗