The 2Layer.csv file contains ionizing dose results of simulating the shielding performance of all 2500 two-layer permutations of the first 50 chemical elements against trapped particles in Geostationary Transfer Orbit (GTO). The material properties are sourced from the Geant4 material database, with materials referenced by their Geant4 material database names. For elements that are gases under normal conditions, the liquified version from the Geant4 database is used if available, denoted by an "l" prefix (e.g., "G4_lH2"). The particle spectra used for this simulation are provided in the files AE9500keV.mac and AP910MeV.mac. The simulated geometry is provided in the file 2Layer.gdml. The particle spectra were generated with the AE9/AP9 models on SPENVIS, with electron energies starting at 500 keV and proton energies starting at 10 MeV. The simulation was performed with GRAS / Geant4 with the FTFP_BERT physics model using 2.1e+11 electrons and 8.4e+09 protons directed against slabs of shielding materials of 1.5 g/cm2 total depth with each of the two layers being 0.75 g/cm2 in depth. The ionizing dose is recorded in 0.5mm thick silicon plates behind the shielding plates. Column A: ID of the material combination Column B: Z-Number of Material 1 Column C: Z-Number of Material 2 Column D: Name of the first layer material. Column E: Name of the second layer material. Column F: Ionizing dose due to electrons in units of kRad per month. Column G: Statistical error in the electron dose in kRad per month. Column H: Ionizing dose due to protons in kRad per month. Column I: Statistical error in the proton dose in kRad per month. Column J: Total ionizing dose from electrons and protons in kRad per month. Column K: Statistical error in the total ionizing dose in kRad per month. Column L: Rank of the material combination sorted from lowest electron dose to highest. Column M: Rank of the material combination sorted from lowest proton dose to highest. Column N: Rank of the material combination sorted from lowest total ionizing dose to highest. All dose values are rounded according to their statistical uncertainty as reported by GRAS/Geant4.