Dosimetry of 40 and 70 MeV/n 16O beams

Using CR-39 plastic track detectors the range values of O-16 ions at two different energies (initially in the beam line, 39.97 MeV/n and 69.98 MeV/n) were measured after escaping the beam pipe and found to be (3050 +/- 40) mu m and (8210 +/- 90) mu m, respectively. The longitudinal and projected angular spread of oxygen ions of an initial energy of 69.98 MeV/n in the region of the Bragg peak was derived from the measured geometrical parameters of tracks. Based on a calibration curve (etch rate ratio vs total linear energy transfer in CR-39) and the measured track length distribution at the range end of oxygen ions, the complete depth dose profile of a 67.7 MeV/n O-16 beam in CR-39 (plateau, extended Bragg peak and residual ionization caused by projectile like fragments) was obtained.