Spectra of particles in the quiet stage of the sun and solar activity.

Time variations of proton energy spectra at energies up to 1 MeV are investigated on the basis of interplanetary measurements made in quiet periods of solar activity, i.e., in the absence of solar-cosmic-ray flares. It is suggested that background protons with energies of 1-4.5 MeV possibly have a solar origin. It is proposed that the background flux be defined as the particle flux at the minimum of the cycle. SInce in other phases of the solar cycle minimum levels of proton intensity and quiet-time intensity levels correlate with the solar-activity cycle, this additional flux into interplanetary space is lkely to be of solar origin.