Abstract
In order to measure the trace amounts electric charge which exists in the atmosphere, we have developed a device of differential type using two magnetically levitated electrode ionization chambers. This device is 100-fold higher sensitivity than the ionization chamber on the market. In the case of ionization volume 1 L and time interval 30 minutes, the detection limit of device is 0.3×10-16C/s, which corresponds to 0.2 ions/cm3·s. Using this device, we have measured space charge around an insulation board made of Bakelite during low level gamma ray irradiation, and the electric charge originating from several kinds of photocatalyst paint lighted up by ultraviolet rays and a visible ray. As a result of measurement, the amount of space charge collected by Bakelite board is about 10-16-10-15C/s, and that of electric charge by photocatalyst paint is about 10-17-10-15C/s.
