Measurement of lineal energy distributions for energetic ion beams using a wall-less tissue equivalent proportional counter

Tsuda, Shuichi  ; Sato, Tatsuhiko   ; Ogawa, Tatsuhiko   

Microdosimetric deposit energy spectra have been measured for various energetic heavy ion beams using a wall-less tissue equivalent proportional counter (wall-less TEPC) and used for the verification of the microdosimetric function for calculating y distributions incorporated in the PHITS code. In the previous studies, since uniformly spread beam were used to simulate a uniform irradiation to cells, the measured deposit energy spectra include the contribution of both incident heavy ion beams and secondarily produced electrons (delta rays). In this study, to investigate the radial dependence of y distributions, y distributions are measured in radial direction for energetic ions using the wall-less TEPC.