Observations and Analysis of MeV Electrons from REPT PHA Data and REPTile-2 data

The Relativistic Electron-Proton Telescope (REPT) Pulse Height Analysis (PHA) data captures individual particle event for each of REPT’s nine silicon detectors onboard the Van Allen Probes. The PHA data set was taken every 12 milliseconds (ms), including the pulse height that is proportional to the energy deposit of each individual particle from all nine detectors. Geant4 simulations are used to extend and improve the electron detecting capabilities of REPT (beyond its nominal data) using the PHA data. After replicating the nominal characteristics of REPT in the Geant4 toolbox, new channels for REPT, going from 12 nominal electron channels to 47 and lowering the minimum energy to ~1 MeV, have been formulated. By applying these newly simulated electron channels to PHA data and combining with the detector singles rates, an estimated count rate data product for finer-resolution, lower-energy channels is created. This method enables higher resolution observations of electrons of 1.1 – 12 MeV, revealing more detailed characteristics of these high energy electrons in the magnetosphere, especially in the inner edge of the outer belt, slot region, and inner belt. Similarly, Relativistic Electron and Proton Telescope integrated little experiment -2 (REPTile-2) onboard Colorado Inner Radiation Belt Experiment (CIRBE), launched on 15 April 2023 into a low Earth orbit (LEO), has implemented PHA processing onboard, measuring 0.25 – 6 MeV electrons in 60 channels and protons in 60 channels and revealing detailed structures of the energetic electrons and protons, especially in the inner belt.