Airborne gaseous N-13 species and noxious gases produced at the 12 GeV proton synchrotron

The irradiation of atmospheric air with high-energy protons has been perfor med at the 12 GeV proton synchrotron. The specific activity of N-13, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6.10(16) eV/g/s, and compared with the calculated values. The predominant chemical species of N-13 produced w ere found to be N-13(2) and (NO2)-N-13. Their proportions were approximatel y 55% for N-13(2), and 45% for (NO2)-N-13, being almost independent of the irradiation time. Smaller quantities of (NO)-N-13 and (HNO2)-N-13 were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO2 predominates among the products of nitrogen compounds, including HNO2 and HNO3. The G-value for ozone formation in air was estima ted from the experimental data as 6.4 molecules/100 eV.