Pressurized-gas spherical ionization chamber

A pressurized ionization chamber detector able to measure radioactive sources in internal 2 π or 4 π geometry was built in order to characterize alpha and beta radioactive sources, i.e. to calibrate these sources by a relative method, and to test the behavior of gas mixtures in pressurized-gas radiation detectors. The detector we made is of spherical shape and works by collecting in a uniform electric field the ionization charges resulting from the interaction of ionizing radiation with gas in the sensitive volume of the chamber. An ionizing current proportional to the activity of the radioactive source to be measured is obtained. Pressure inside the detector in standard conditions is upmost 6 x 1.013· 105 Pa and the maximum allowed voltage is 3000 V. (author)