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All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Systematics in the Electron Spectrum Measured by ATIC

An analysis of different parameters to separate electrons from protons in the ATIC experiment has been performed. Five separate discriminants were studied by different Monte Carlo programs, leading to a variety of results. Application to the ATIC data indicates the range of variation possible in the interpretation of the data. The results of this analysis, when compared with the published results [5], show good agreement in the most interesting region of energy (from 90 GeV to 600 GeV). The measured electron spectrum is compared with the recent data reported by Fermi/LAT, and there is no major disagreement between ATIC s results and Fermi/LAT. Finally, possible systematics-free, short energy scale features of the ATIC electron spectrum are mentioned. Keywords: ATIC, electron spectrum, fine structure

Panov, A. D.↗
NASA NTRS1985

The Jovian electron spectrum: 1978-1984

Observations of Jovian electrons through six consecutive 13-month Jovian synodic periods from 1978 to 1984 have been made by the University of Chicago electron spectrometer onboard the ISEE-3 (ICE) spacecraft. The Jovian electron spectrum was determined from 5 to 30 Mev and was found to have a shape which is not a power law in kinetic energy, but cuts off at approximately 30 MeV. The average shape of the spectrum over each of the six intervals of best magnetic connection remains the same for all intervals within uncertainties.

Evenson, P. A.↗
NASA NTRS1975

Measurement of the primary cosmic electron spectrum from 10 to about 250-GeV

The intensity and energy spectrum of primary cosmic electrons from 10 to approximately 250 GeV was studied using balloon-borne detectors. Both of the detectors were large area ionization calorimeters with frequent sampling of showering particles and were capable of energy resolution of approximately 7%. A time-of-flight system and detectors to sample the lateral properties of showers were used to examine and improve background rejection. The results of the balloon flights from Alamogordo, N.M. in 1970 and Cape Girardeau, Missouri in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. These results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the Galaxy, although other more complex models cannot be excluded on the basis of these data.

Silverberg, R. F.↗
NASA NTRS1976

Measurement of the primary cosmic electron spectrum from 10 to about 250 GeV

The intensity and energy spectrum of primary cosmic electrons from 10 to about 250 GeV have been studied by using balloon-borne detectors. The detectors were large-area ionization calorimeters which sampled showering particles frequently and demonstrated an energy resolution of about 7% in calibration tests. On one of the flights a time-of-flight system and detectors to sample the lateral properties of showers were used to examine and to test background rejection. The results of the balloon flights from Alamogordo, N. Mex., in 1970 and Cape Girardeau, Mo., in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. The results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the galaxy, although other more complex models cannot be excluded on the basis of these data.

Silverberg, R. F.↗
NASA NTRS1974

The cosmic ray electron spectrum and its modulation from 1968 through 1972

Over the past five years we have measured the energy spectrum of primary cosmic ray electrons with both a balloon-borne and a satellite absorption spectrometer. All of the balloon flights used identical equipment that was launched each summer from Fort Churchill, Manitoba, Canada. The satellite, OGO-5, has been in an eccentric orbit since March 1968. Together these instruments provide the electron spectrum over a range of energy from 20 MeV to 20 GeV. This wide range and the substantial span of time covered by the measurements permit a detailed study of the solar modulation of electrons. These results are compared with the modulation of the nuclear components as observed by a neutron monitor and interpreted using the cosmic ray transport equation.

Fulks, G.↗
NASA NTRS1973

The first integrated interplanetary electron spectrum

Observations of a quiet-time interplanetary electron component in the 20 keV to 2 MeV energy range are reported. The measurements fill in the gap between the highest-energy known solar wind and the lowest-energy previously observed electron populations, and connect for the first time the entire solar-quiet interplanetary electron spectrum over a dynamic range of nearly 10 to the 12th power in energy.

Cline, T. L.↗
NASA NTRS2002

The Non-Thermal Electron Spectrum of the Supernova Remnant SN 1006

We present the results of a spectral analysis of a compilation of X-ray, radio, and gamma-ray data for the supernova remnant SN 1006. The data are used to constrain models of the electron spectrum of the remnant. We present the results for the electron spectrum and review the implications for cosmic-ray acceleration and the strength of the magnetic field in the remnant.

Allen, Glenn E.↗
NASA NTRS1974

Measurements of the primary cosmic ray electron spectrum from 1965 to 1972

Data on the primary electron spectrum from 5 MeV to 30 GeV are presented for a large number of balloon flights in the years 1965-1972. A new much larger area electron telescope was introduced to these studies in 1971 and the results from this new telescope are given and compared with earlier results. Detailed electron spectra are presented and the effects of solar modulation are examined over a wide energy range. The phase lag or hysteresis in the electron intensity observed after 1969 is also examined between 40 MeV and 1 GeV.

Webber, W. R.↗
NASA NTRS1989

The nature of the cosmic-ray electron spectrum, and supernova remnant contributions

The observed cosmic-ray (CR) electron spectrum and position fraction e+/(e- + e+) spectrum above 1 GeV are examined, and it is found that a deconvolution of the total spectrum into three components is necessary because of the increase of e+/(e- + e+) above 5 GeV: (1) secondary electrons e+ or e- from the interaction of the CR protons with the interstellar gas provide the total e+ for energies less than 3 GeV, but for energies above 3 GeV these electrons cannot account for the observed positron flux; (2) Electrons (e-) generally thought to derive from supernova remnants (SNRs), probably via shock acceleration, dominate the total spectrum for E of 10 GeV or less but definitely decline relative to total at higher energies; (3) Another (e- + e+) source dominates the total spectrum at E of 40 GeV or greater. The derived spectrum of (2) is consistent in its energy cutoff (though gradual) with that deduced from the observed synchrotron emission of some old SNRs and follows naturally from shock acceleration with synchrotron and inverse Compton scattering losses taken into account. As for (3), nearby pulsars may be important contributors.

Boulares, Ahmed↗