Differential energy spectra of low energy (less than 8.5 MeV per nucleon) heavy cosmic rays during solar quiet times

Explorer 47 satellite observations of carbon, oxygen, and heavier nuclei differential energy spectra below 8.5 MeV/nucleon are presented for solar quiet time periods. A dE/dx vs E method for particle identification and energy determination was used. The instrumentation telescope included an isobutane proportional counter, a surface barrier Si detector, and a cylindrical plastic scintillator anticoincidence shield. The observations were performed outside the bow-shock and in the ecliptic plane. Results show an anisotropy of about 25% at 22 degrees west of the sun with a C/O ratio of 0.5 supporting a solar origin. The low energy portions of the C and O spectra have steep negative slopes, and the corresponding power law is given. Peculiarities in the O spectrum are discussed