703 research outputs found
Cosmic ray charge and energy spectra above 10 GeV
The composition and energy spectra of cosmic rays above 1.6 nJ (10 GeV) on balloons and ultimately on the HEAO satellite is discussed. Some results from a balloon flight in November of 1970 are presented. The instrument is shown schematically. It is designed to identify cosmic ray electrons, protons, and nuclei up through iron and to measure their energies
Implications of HEAO-3 data for the acceleration and propagation of galactic cosmic rays
The energy dependence of the mean escape length of cosmic rays from the galaxy in the light of recent measurements of cosmic ray abundances from the Danish-French experiment on HEAO-3 is re-examined. The energy dependence is found to be steeper than previously thought
An upper limit on the quiet time solar neutron flux at energies greater than 60 MeV
Upper limit on quiet time solar neutron flux at energies above 60 MeV determined by using balloon flights with Cerenkov scintillation counter
Origin and propagation of galactic cosmic rays
The study of systematic trends in elemental abundances is important for unfolding the nuclear and/or atomic effects that should govern the shaping of source abundances and in constraining the parameters of cosmic ray acceleration models. In principle, much can be learned about the large-scale distributions of cosmic rays in the galaxy from all-sky gamma ray surveys such as COS-B and SAS-2. Because of the uncertainties in the matter distribution which come from the inability to measure the abundance of molecular hydrogen, the results are somewhat controversial. The leaky-box model accounts for a surprising amount of the data on heavy nuclei. However, a growing body of data indicates that the simple picture may have to be abandoned in favor of more complex models which contain additional parameters. Future experiments on the Spacelab and space station will hopefully be made of the spectra of individual nuclei at high energy. Antiprotons must be studied in the background free environment above the atmosphere with much higher reliability and presion to obtain spectral information
Interpretation of cosmic ray composition: The pathlength distribution
For abstract see A81-43868
Observations of nuclei heavier than iron in the primary cosmic radiation
Charge and energy spectra of primary cosmic rays made with large area Cerenkov scintillation counter on baloon flights - heavier than iron nucle
Cosmic ray nuclei of energy 50 GeV/NUC
Preliminary results from the High Energy Gas Cerenkov Spectrometer indicate that the sub-iron to iron ratio increases beyond 100 GeV/nucleon. This surprising finding is examined in light of various models for the origin and propagation of galactic cosmic rays
Antiprotons in cosmic rays
Recent experimental observations and results are discussed. It was found that the approximately 50 antiprotons collected in balloon experiments to date have generated considerable theoretical interest. Clearly, confirmatory experiments and measurements over an extended energy range are required before definite conclusions are drawn. Antiproton measurements have a bearing on astrophysical problems ranging from cosmic ray propagation to issues of cosmological import. The next generation of balloon experiments and the Particle Astrophysics Magnet Facility being discussed for operation on NASA's space station should provide data and insights of highest interest
Challenging cosmic ray propagation with antiprotons. Evidence for a "fresh" nuclei component?
Recent measurements of the cosmic ray (CR) antiproton flux have been shown to
challenge existing CR propagation models. It was shown that the reacceleration
models designed to match secondary to primary nuclei ratios (e.g.,
boron/carbon) produce too few antiprotons. Matching both the secondary to
primary nuclei ratio and the antiproton flux requires artificial breaks in the
diffusion coefficient and the primary injection spectrum suggesting the need
for other approaches.
In the present paper we discuss one possibility to overcome these
difficulties. Using the measured antiproton flux AND B/C ratio to fix the
diffusion coefficient, we show that the spectra of primary nuclei as measured
in the heliosphere may contain a fresh local "unprocessed" component at low
energies perhaps associated with the Local Bubble, thus decreasing the measured
secondary to primary nuclei ratio. The independent evidence for SN activity in
the solar vicinity in the last few Myr supports this idea. The model reproduces
antiprotons, B/C ratio, and elemental abundances up to Ni (Z<=28). Calculated
isotopic distributions of Be and B are in perfect agreement with CR data. The
abundances of three "radioactive clock" isotopes in CR, 10Be, 26Al, 36Cl, are
all consistent and indicate a halo size z_h~4 kpc based on the most accurate
data taken by the ACE spacecraft.Comment: To be published in The Astrophysical Journal, v.586, 2003 April 1;
final version: 19 pages, 24 ps-figures, emulateapj5.sty (modified),
natbib.sty, aastex.cls. More details can be found at
http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm
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