Charge dependence of the solar modulation of multiply charged cosmic ray nuclei

• Published in: Astrophysics and space science Vol. 44; no. 1; pp. 167 - 175
• Main Authors: Paruthi, S., Bhatia, V. S., Kainth, G. S., Biswas, S., Ramadurai, S.
• Format: Journal Article
• Language: English
• Published: 01.09.1976
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/BF00650481

The intensity and energy spectra of multiply charged cosmic-ray nuclei in the energy interval from 250 to 1500 MeV/n were studied at three different levels of solar activity. Nuclear emulsion stacks flown from Fort Churchill, Canada, were used to determine simultaneously the energy spectra of helium, carbon, nitrogen, oxygen, and heavy (Z = 10-28) nuclei. Analysis of the measured spectra indicates that these can be interpreted in terms of: (1) a Fermi source spectrum with a spectral index of 2.65; (2) interstellar propagation in a Gaussian distribution of path lengths with a mean path length of 4 g/sq cm; and (3) interplanetary propagation as given by the numerical solution to the Fokker-Planck equation incorporating diffusion, convection, and adiabatic deceleration. On comparing the measured ratios of helium to heavy nuclei (mean Z about 14) with the theoretically calculated values for the three levels of solar activity, it is found that within experimental uncertainties, solar modulation is essentially the same for nuclei with the same mass-to-charge ratio and is not dependent on the charge of the nuclei.