Electret dosimeter

The dosimeters for personal radiation exposure, such as film badges, pocket ionization chambers, fluorescence glass dosimeters and thermoluminescence dosimeters (TLD), have some problems, respectively. On the other hand, electret dosimeters, of which the practical use is lately forecast, are described in this report for the operating principle and research, and in addition, the highly sensitive dosimeters utilizing gas multiplication using recent fluorinated polymers and the neutron dosimeters are reported. Electret is a permanently polarized dielectric, and has been named as a material corresponding to a magnet. Electret has been investigated as an application of electrostatic engineering, and has been used for sound equipment such as microphones and headphones. In general, however, it is not known as radiation dosimeters to the specialists of radiation measurement or static electricity. The electret dosimeters utilize the attenuation of surface charge caused by radiation. Its practical use has just become possible thanks to the recent progress of polymer materials. Specifically, the trial production of a dosimeter that can be used in proportional counting region due to the gas multiplying action of ions has improved the detecting sensitivity to allow 0.1 mrad detection. This dosimeter is superior to TLD in a point that it is an integration dosimeter in which the information does not disappear by read out. (Wakatsuki, Y.)