The Solar Electron and Proton Telescope aboard STEREO -- understanding proton spectra

TL;DR

The paper describes the design and simulation of the SEPT instrument aboard STEREO, which measures energetic electrons and protons in space, providing detailed 3D distribution data and improved response functions through GEANT4 simulations.

Contribution

It introduces an extended model of the SEPT instrument and uses GEANT4 simulations to enhance understanding and correction of instrumental effects in space particle measurements.

Findings

Improved response functions for SEPT telescopes were calculated.

Simulation results aid in correcting instrumental effects.

Enhanced understanding of proton and electron spectra in space.

Abstract

The Solar Electron and Proton Telescope (SEPT) aboard the Solar Terrestrial Relations Observatory (STEREO) is designed to provide the three-dimensional distribution of energetic electrons and protons with good energy and time resolution. Each SEPT instrument consists of two double-ended magnet/foil particle telescopes which cleanly separate and measure electrons in the energy range from 30 keV to 400 keV and protons from 60 keV to 7000 keV. Anisotropy information on a non spinning spacecraft is provided by two separate but identical instruments: SEPT-E aligned along the Parker spiral magnetic field in the ecliptic plane along looking both towards and away from the Sun, and SEPT-NS aligned vertical to the ecliptic plane looking towards North and South. The dual set-up refers to two adjacent sensor apertures for each of the four viewing directions SUN, ANTISUN, NORTH, and SOUTH: one for protons, one for electrons. In this contribution a simulation of SEPT utilizing the GEANT4 toolkit has been set up with an extended instrument model in order to calculate improved response functions of the four different telescopes. This will help to understand and correct instrumental effects in the measurements.