The purpose of this experiment was to extend the first measurements of the trapped radiation belt discovered with Explorer 1 and Explorer 3 and to provide measurements of artificially injected electrons from the three high-altitude Argus nuclear detonations. Four separate radiation detectors were used in the experiment: a shielded directional plastic scintillation counter sensitive to electrons (E>700 keV) and protons (E>10 MeV), a shielded directional caesium iodide scintillation counter sensitive to electrons (E>20 keV) and protons (E>400 keV), an omnidirectional Anton type 302 Geiger–Müller (GM) counter sensitive to electrons (E>3 MeV) and protons (E>30 MeV), and a shielded omnidirectional Anton type 302 Geiger-Müller tube sensitive to electrons (E>5 MeV) and protons (E>40 MeV).
The purpose of this research was to expand upon the initial radiation findings from Explorer 1 and Explorer 3, while also gathering data on artificially injected electrons resulting from the three high-altitude Argus nuclear detonations. Four distinct radiation detection instruments were employed: a directional counter sensitive to heavy particles, a directional counter sensitive to light particles, an all-directional Geiger-Müller counter sensitive to moderate-energy particles, and a shielded all-directional Geiger-Müller tube sensitive to high-energy particles.