Energy Spectrum of Heavy Nuclei of the Primary Cosmic Radiation during Solar Maximum

Abstract

The energy spectrum of nuclei with $Z>~13$ has been determined using the knock-on electron method in a stack of nuclear emulsions flown on 4 February 1959 from Texas, U.S.A. ($\ensuremath{\lambda}=41$\ifmmode^\circ\else\textdegree\fi{}N). In the interval of kinetic energy from 1.5 to 10 GeV/nucleon, the exponents of the integral energy spectra for nuclei with charge $Z>~13$, $13<~Z<~16$ and for those with $Z>~17$ have been determined to be 1.70\ifmmode\pm\else\textpm\fi{}0.30, ${1.85}_{\ensuremath{-}0.20}^{+0.23}$, and ${1.55}_{\ensuremath{-}0.30}^{+0.20}$, respectively. From this and other similar experiments it is surmised that within the experimental uncertainties the observations are consistent with the assumption that the energy spectra of all the components of the primary cosmic radiation have the same exponent; also the exponent seems to be the same during solar minimum and during solar maximum. The flux of nuclei with $Z>~10$ has been obtained as 1.26\ifmmode\pm\else\textpm\fi{}0.09 particles/${\mathrm{m}}^{2}$ sec sr and that of nuclei with $Z>~20$ as 0.39\ifmmode\pm\else\textpm\fi{}0.06 particle/${\mathrm{m}}^{2}$ sec sr. These values are \ensuremath{\sim}50% lower than those determined over Texas during solar minimum.