Capabilities and Performance of the High-Energy Energetic-Particles Instrument for the Parker Solar Probe Mission

Abstract

with a planned heliocentric orbit that will carry it on a series of close passes by the Sun with perihelion distances that eventually will get below 10 solar radii. Among other in-situ and imaging sensors, the PSP payload includes the two-instrument "Integrated Science Investigation of the Sun" suite, which will make coordinated measurements of energetic ions and electrons. The high-energy instrument (EPI-Hi), operating in the MeV energy range, consists of three detector-telescopes using silicon solid-state sensors for measuring composition, energy spectra, angular distributions, and time structure in solar energetic particle events. The expected performance of this instrument has been studied using accelerator calibrations, radioactive-source tests, and simulations. We present the EPI-Hi measurement capabilities drawing on these calibration data and simulation results for illustrations.

Parker Solar Probe observations of He/H abundance variations in SEP events inside 0.5 au

“…Orbit 5 spanned 2020 April 3 to 2020 August 2, with a perihelion of 29 R S (0.13 au). During this time the Integrated Science Investigation of the Sun (IS IS, McComas et al 2016) made observations of energetic particles via the Energetic Particle Instrument-Low (EPI-Lo, Hill et al 2017) and the Energetic Particle Instrument-High (EPI-Hi, Wiedenbeck et al 2017). EPI-Lo consists of 80 time-of-flight apertures providing observations of particles from 20 keV/nuc to 1.5 MeV/nuc over 2π steradians.…”

“…Figure 1 gives an overview of orbit 5 and the energetic particle measurements. The height and color of the bars on the outside of the orbit correspond to the EPI-Hi LETA rate of protons stopping in the second detector (referred to hereafter as 'range 1' particles, corresponding to ∼1-2 MeV protons; see Wiedenbeck et al 2017), while the height and color of the inside bars indicate the EPI-Lo ∼30-200 keV ion observations (summed over all the apertures and dominated by protons). The period of interest is just before perihelion when PSP was at 0.45-0.3 au and is evident as the larger bars colored orange and red for EPI-Hi.…”

Energetic particle observations close to the Sun by Solar Orbiter and Parker Solar Probe

“…EPI-Lo [24] comprises 80 time-of-flight apertures providing particle observations from 20 keV/nuc to 1.5 MeV/nuc over 2π steradians. EPI-Hi [25] encompasses three telescopes of stacked solid-state detectors, utilizing the standard dE/dx versus residual energy technique to measure ions from ~1 to >100 MeV/nuc and efrom ~0.5 to 6 MeV. Solar Orbiter (SolO) [26], an ESA-led mission with strong NASA participation, was launched on 2020 February 10.…”

Parker Solar Probe’s Measurements of the 29 November 2020 Solar Energetic Particle Event

“…The ISʘIS suite is comprised of two instruments, Energetic Particle Instrument-Low (EPI-Lo, [11]) and Energetic Particle Instrument-High (EPI-Hi, [12]) which together measure energetic ions H-Fe at energies of ~20 keV to >100 MeV/nuc and energetic electrons from ~15 keV to ~6 MeV. EPI-Lo utilizes the time-of-flight versus energy technique in 80 separate apertures to obtain a 2p-sr field of view.…”