Intercomparison of radiation instruments for cosmic-ray with heavy ion beams at NIRS (ICCHIBAN project).

The first InterComparison for Cosmic-ray with Heavy Ion Beams At NIRS (ICCHIBAN) project is an ongoing, international collaboration organized at the National Institute of Radiological Sciences (NIRS), Japan, for the purpose of characterizing and comparing at a controlled, ground-based heavy ion facility the radiation response of instruments used aboard piloted spacecraft for crew and area dosimetry. We present preliminary results from the first set of ICCHIBAN exposures made at HIMAC heavy ion accelerator in February 2002. The initial series of exposures (1st ICCHIBAN run) was designed to establish the response of active detectors to two well-characterized heavy ion beams; 400 MeV/nucleon 12C and 400 MeV/nucleon 56Fe. These beams are representative in charge and energy of two of the most significant heavy ion components present in the galactic cosmic radiation spectrum. The properties of the incident beam, including intensity, profile, charge and total energy, were characterized using several different detector systems, including silicon detectors, CR-39 plastic nuclear track detectors and plastic scintillation counters. Once the response of each detector to heavy ion beams of known composition has been measured, results from on-orbit measurements made by the different instruments can be more meaningfully compared. We conclude by discussing plans for future ICCHIBAN runs, including next 2nd ICCHIBAN run for passive detectors in early summer 2002.