Primary Cosmic Ray and Solar Protons. II

During July and August, 1961, the energy spectrum of primary cosmic-ray protons was investigated in the energy range from 80 to 350 MeV. The observations were made in five high-altitude balloon flights at geomagnetic latitudes $\lambda \ge 73$° N. Solar flare and quiet day spectra were obtained. A comparison of the 1960 and 1961 results leads to the following conclusions: (1) A significant flux of low-energy protons is continually present in the primary radiation in the years of high solar activity. (2) This flux decreases with the declining level of solar activity as the galactic cosmic-ray flux increases. It is, therfeore, suggested that it is of solar origin. (3) The time dependence of the observed proton flux suggests the following alternatives: (a) The particles are produced or released more or less continuously by the sun and do not originate only in the large flare events; or (b) The particles are produced in individual large solar flares and subsequently stored over long periods of time. This second alternative would require a new and as yet unknown storage mechanism with a characteristic time of about 30 or more days.