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

Abstract

Two versions of a method are presented to determine the background of energetic particle telescopes during low‐flux periods at low energies. Traditional procedures first evaluate pulse heights of particle sensors working in coincidence then select certain areas of the ΔE/Δx versus E plane, where E is energy, and finally, accept all events falling on those areas as real particles. Such methods, however, often fail during low‐flux conditions, as the background may become comparable to the genuine particle flux. The alternative methods suggested here analyze the shape of the distribution near the track of genuine particles and provide statistical estimation of its parameters to separate the background from the real particle flux. Results are presented for protons and helium during quiet activity periods of the recent solar minimum using data from energetic particle telescopes Energetic and Relativistic Nuclei and Electron (ERNE) Low Energy Detector (LED) and Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) Electron Proton Helium Instrument (EPHIN) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft. SOHO is a project of international collaboration between the European Space Agency and NASA.