Advanced cosmic-ray composition experiment for the space station (ACCESS)

ACCESS is a large electronic cosmic-ray detector, designed for one of the zenith-pointing external attach points on the International Space Station. ACCESS addresses the fundamental astrophysical question: How do cosmic rays gain their enormous energies? It does this by combining two kinds of measurements. By determining the energy spectra of individual elements with atomic number (Z) in the interval 1⩽Z⩽28 up to an energy of 1015 eV, ACCESS will probe a region of the spectra where theories of supernova acceleration predict changes in the cosmic-ray element composition. By measuring individual element abundances at more moderate energies of every element in the entire periodic table, ACCESS will distinguish between competing theories of how the cosmic-ray nuclei are initially injected into the accelerator that gives them their high energies. ACCESS will identify the atomic number of incident cosmic-ray nuclei using silicon solid-state detectors Cherenkov detectors, and scintillators. It will measure the e...