Ionization chamber type detector with dielectric liquid

The ionization chamber with dielectric liquid is especially used for laboratory measurement of very low radiation doses and activities. The detector is of well ionization chamber type with glass walls of cylindrical shape having an external diameter of 60 mm and 200 mm length. Inside, there is a small cylinder (chamber's well) of internal diameter 20 mm and 100 mm length. These two coaxial cylinders form a sealed chamber, the internal surface of which is metal plated, representing the high voltage electrode. The collecting electrode, a metallic grid is placed between the two cylinders. This electrode is PTFE-insulated at the chamber's top and has at its bottom a glass-passing wolfram terminal connected to the electronic measurement system (electrometer). The ionization chamber is filled with a dielectric liquid (isooctane, hexane) of high purity and a resistivity of about 1017 Ohm.cm. The main purpose of this instrument is to measure the radioactivity of 125 I, 131 I and 198 Au for nuclear medicine applications and research. The performance and design features have been chosen to meet nuclear medicine requirements. (author)