Lawrence Berkeley National Laboratory

Measurements using silicon detectors to characterize the radiation transmitted through the EMU spacesuit and a human phantom have been performed using 155 and 250 MeV proton beams at the Loma Linda University Medical Center (LLUMC). The beams simulate radiation encountered in space, where trapped protons having kinetic energies on the order of 100 MeV are copious. Protons with 100 MeV kinetic energy and above can penetrate many centimeters of water of other light materials, so that astronauts exposed to such energetic particles will receive doses to their internal organs. This dose can be enhanced or reduced by shielding - either from the spacesuit or the self-shielding of the body - but minimization of the risk depends on details of the incident particle flux (in particular the energy spectrum) and on the dose responses of the various critical organs.