ISSN:
1572-946X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract During three balloon flights of a 1 m2 sr ionizationchamber Čerenkov counter detector system, we have measured the atmospheric attenuation, flux, and charge composition of cosmic-ray nuclei with 16≤Z≤30 and rigidity greater than 4.5 GV. The attenuation mean-free-path in air of VH (20≤Z≤30) nuclei is found to be 19.7±1.6 g cm−2, a value somewhat greater than the best previous measurement. The attenuation mean-free-path of iron is found to be 15.6±2.2 g cm−2, consistent with predictions of geometric cross-section formulae. We measure an absolute flux of VH nuclei 10 to 20% higher than earlier experiments at similar geomagnetic cutoff and level of solar activity. The relative abundances of evencharged nuclei are found to be in good agreement with results of other recent high-resolution counter experiments. We calculate that our observed cosmic ray chemical composition implies relative abundances at the cosmic-ray source of Ca/Fe=0.12±0.04 and S/Fe=0.14±0.05. The results are consistent with all other elements of charge between 16 and 26 being absent at the source and being produced by cosmic-ray fragmentation in interstellar hydrogen. The results show the ratios A/Fe and S/Fe to be significantly lower in the cosmic-ray source than in the solar system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00642821
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