Residual radioactivity and neutron fluence monitoring in the cyclotron using activation detectors

Characterization of residual radioactivity in a cyclotron is an important radiation safety issue, especially during maintenance interventions. Stainless steel and zinc-iron foils were used in this work as neutron activation foils to indicate the accumulation of residual radioactivity in the metallic parts of the cyclotron and to monitor the secondary neutron fluence. The foils were positioned near the 201Tl and 67Ga production target system. The main activation products in the foils were 51Cr, 60Co, 54Mn, and 59Fe. The variation of the generated radionuclides in the foils versus the monitoring time was obtained. Moreover, the fast neutron fluence was monitored by measuring 54Mn radioactivity in the foils. Thus, the stainless steel and zinc-iron foils have been successfully used to indicate the residual radioactivity and the neutron fluence. Highlights Characterization of residual radioactivity in a cyclotron is an important radiation safety issue;Stainless steel and zinc- iron foils were used as neutron activation foils to indicate the residual radioactivity in metallic parts of the cyclotron and to monitor the neutron fluence;The main activation products in the foils were 51Cr, 60Co, 54Mn, and 59Fe;The fast neutron fluence was monitored by 54Mn radioactivity in the foils.