Measured microdosimetric spectra of energetic ion beams of Fe, Ar, Ne, and C: limitations of LET distributions and quality factors in space research and radiation effects

Microdosimetric spectra for energetic beams of Fe, Ar, Ne, N, and C with incident energies between 500 and 600 MeV/amu have been measured as a function of absorber thickness. The experiments were performed at the Bevalac Accelerator of the Lawrence Berkeley Laboratory, CA. Data obtained with two different types of detectors are compared in order to examine the production of delta rays by energetic heavy ions and their effect on distributions of energy deposition. Recent controversies in the literature are examined in terms of the present observations. Consequent limitations of LET distributions and/or single-hit-particle concepts in reference to personnel and equipment in space are discussed.>