Background reduction for quiet time particle fluxes aboard the Solar and Heliospheric Observatory

Two versions of a method are presented to determine the background of energ etic particle telescopes during low-flux periods at low energies. Tradition al procedures first evaluate pulse heights of particle sensors working in c oincidence then select certain areas of the DeltaE/Deltax versus E plane, w here E is energy, and finally, accept all events falling on those areas as real particles. Such methods, however, often fail during low-flux condition s, as the background may become comparable to the genuine particle flux. Th e alternative methods suggested here analyze the shape of the distribution near the track of genuine particles and provide statistical estimation of i ts parameters to separate the background from the real particle flux. Resul ts are presented for protons and helium during quiet activity periods of th e recent solar minimum using data from energetic particle telescopes Energe tic and Relativistic Nuclei and Electron (ERNE) Low Energy Detector (LED) a nd Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) Elec tron Proton Helium Instrument (EPHIN) aboard the Solar and Heliospheric Obs ervatory (SOHO) spacecraft. SOHO is a project of international collaboratio n between the European Space Agency and NASA.