The Imaging Calorimeter for ACCESS (ICA)

A mission concept study to define the “Advanced Cosmic-ray Composition Experiment for Space Station (ACCESS)” is being sponsored by the National Aeronautics and Space Administration (NASA). The ACCESS instrument complement contains an ionization calorimeter to measure the spectrum of protons, helium, and heavier nuclei up to ~10 eV to search for the limit of S/N shock wave acceleration. Several calorimeters are under study, including the “baseline” totally active bismuth germanate instrument and sampling calorimeters utilizing various detectors. The ICA comprises a carbon target and a high atomic number absorber sampled approximately each radiation length (rl) by thin scintillating fiber (SCIFI) detectors. The main features of the ICA instrument concept are described in this paper.