The Fly’s Eye Energetic Particle Spectrometer (FEEPS) Sensors for the Magnetospheric Multiscale (MMS) Mission

Abstract

The Energetic Particle Detector (EPD) Investigation is one of five particles and fields investigations on the Magnetospheric Multiscale (MMS) mission. This mission consists of four satellites operating in close proximity in elliptical, low-inclination orbits, and is focused upon the fundamental physics of magnetic reconnection. The Energetic Particle Detector (EPD) investigation aboard the four MMS spacecraft consists of two instrument designs, the EIS (Energetic Ion Spectrometer) and the FEEPS (Fly's Eye Electron Proton Spectrometer). This present paper describes FEEPS from an instrument physics and engineering point of view, and provides some test and calibration data to facilitate effective analysis and use of the flight data for scientific purposes.A FEEPS consists of six Heads, each composed of two Eyes. Each eye is a particle telescope with a single silicon detector; there are nine electron eyes and three ion eyes per FEEPS. The energy coverage is from 25 keV to 650 keV for electrons and 45 keV to 650 keV for ions. Each eye has sixteen energy channels, the spacing of which can be modified by command. The fields of view and pointing of each eye are designed to provide a broad, instantaneous field of view for the twelve eyes per FEEPS.There are two FEEPS per MMS spacecraft mounted such that the pair along with the single EIS provide more than 3π-sr instantaneous solid-angle coverage and complete coverage in the equatorial region. A twenty-second spacecraft rotation period is divided into sixty-four sectors to provide detailed temporal and spatial sampling.

Microinjections observed by MMS FEEPS in the dusk to midnight region

“…Examples from four FEEPS eyes are shown inFigure 4a. The vertical purple lines across the panels show that the different eyes observe the electrons at different spin phase consistent with their field-of-view azimuthal position[Blake et al, 2016, Figure 2]. Eyes ID-3 and ID-11 view north of the spin plane, while eyes ID-4 and ID-12 view south of the spin plane.…”

Magnetospheric Multiscale Overview and Science Objectives

“…Also listed in Table 1 is the SOC (Science Operations Center). Details of these mission elements are provided in other papers in this issue (Torbert et al 2014;Ergun 2014;Russell et al 2014;Lindqvist et al 2014;Pollock 2015;Mauk et al 2014;Blake 2015;Young et al 2014;Torkar et al 2014). The arrangement of the scientific payload of each spacecraft is shown in Fig.…”

Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)

“…Part of the Energetic Particle Detector (EPD) investigation on MMS, EIS measures energetic ion energy, angle, and compositional distributions from ∼20 keV (protons), ∼60 keV (helium), and ∼130 keV (oxygen) up to ∼1 MeV [Mauk et al, 2014]. EIS also measures energetic electrons from 25 to 600 keV in support of the faster and more sensitive electron measurements made by the EPD Fly's Eye Energetic Particle Spectrometer (FEEPS) sensors [Blake et al, 2015]. In the survey mode utilized here, EIS samples at 1/8 the spacecraft spin rate (∼2.5 s).…”