The irradiation of atmospheric air with high-energy protons has been performed at the 12 GeV proton synchrotron. The specific activity of 13N, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6·1016 eV/g/s, and compared with the calculated values. The predominant chemical species of 13N produced were found to be 13N2and 13NO2. Their proportions were approximately 55% for 13N2 and 45% for13NO2, being almost independent of the irradiation time. Smaller quantities of 13NO and H13NO2 were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO2predominates among the products of nitrogen compounds, including HNO2 and HNO3. The G-value for ozone formation in air was estimated from the experimental data as 6.4 molecules/100 eV.
Although the estimation of 14C radioactivity is very important from a radiation safety viewpoint at high-intensity and high-energy accelerator facilities, it is very difficult, since there is little information concerning the production cross sections by high-energy nuclear reactions. In this work, the 14C production cross section was measured for the nuclear spallation reaction of aluminum with 12-GeV protons. The chemical separation method of 14C was also studied.
The polymerization process of bisphenol-A dicyanate (BADCy) has been studied using a positron-annihilation lifetime technique (PAL). The polymerization was conducted at 150°C, and the process was followed by PAL. Seven kinds of samples with different curing times were also formed at 150°C, and the relation between the period of the curing time and the degree of polymerization was studied. It has been shown that theo-Ps lifetime increases in samples with a higher polymerization than 85%, which is consistent with measurements of the specific volume of BADCy.