Energy spectra of protons, deuterium, and helium nuclei during quiet solar activity periods in 1996-97
Valtonen, E.; Torsti, J.; Kecskemety, Karoly; Kunow, H.; Kiraly, P.; Muller-Mellin, R.; Bothmer, V.
Hungary, Germany, Finland
Abstract
A background reduction method based on pulse-height analysis (see accompanying paper by Valtonen et al.) is applied for the data of the ERNE and EPHIN energetic particle telescopes aboard SOHO. Energy spectra of protons, deuterons, 3He and 4He nuclei have been obtained during very low activity periods in 1996-97 in the energy range of 1.3 to 22 MeV/n. The proton spectra are comparable to the lowest spectra of the Ulysses (COSPIN/LET, 1996) and near-Earth IMP-8 (1985-87) measurements. Deuterons and 3He are only significantly seen above about 10 MeV/n, their spectra are consistent with an increase proportional to kinetic energy, expected for purely galactic origin.