[New investigations about the activation of air by the 42-Mev continuous radiation of a betatron (author's transl)].

Measurements of the activity of urea are a simple and reproducible method to determine the activation of air produced by the continuous radiation of a medically used accelerator [3,4]. The authors studied the activity produced by photonuclear induction using a 42 MeV betatron under unfavorable irradiation conditions. The activity measured per individual irradiation is 1.56 x 10(5) Bq 13N and 4.93 x 10(5) Bq 15O. The limit values indicated in the Radioprotection Regulation are not reached if an intensive air exchange and a waiting-time between the end of the irradiation and the entering of the irradiation room is guaranteed.