Physical aspects on the neutron irradiation. 5. Measurement of neutron LET distributions using LET counters

Biological radiation effect differs from one radiation to another even if the absorbed doses are the same. Evaluation of the biological effect is made based on the LET (linear energy transfer) distribution. In this paper the radiation quality (LET distribution) of the neutron, which is a high LET radiation, is introduced. The LET distribution of the neutron in tissue equivalent materials is measured by Tissue Equivalent Proportional Counter, TEPC), which was developed by Rossi employing the principle of micro-dosimetry. The outline of the TEPC and examples of neutron measurements are presented. (K.Y.)