Induced radioactivity in air and water at medical accelerators

Activation of air and water has been evaluated at the 10 and 15 MeV linear electron accelerator facilities. At 15 MeV irradiation, the activity of 10-min-half-life 13N was observed in the case of the air in the glove box. Air and water samples were also bombarded by 250 MeV protons and 400 MeV/u carbon, and the irradiation dose was 10 Gy at the isocenter. Upon the ion-chamber monitoring of the air sampled from the glove box, 15O, 13N, and 11C activities were mainly observed. At the end of proton and carbon irradiation, the activity of the water was found to be about 10 kBq·cm-3 and several kBq·cm-3, respectively. From the decay analysis of the induced activity in water, 15O, 13N, and 11C were detected. (author)