Radiation detectors utilizing extremely low temperature

Generally when radiation detectors are made to low temperature, the good performance is mostly obtained. For example, the semiconductor detectors such as silicon and germanium become good energy resolution at liquid nitrogen temperature. On the other hand, certain kinds of metals and oxides become superconducting state at extremely low temperature. By utilizing these phenomena at extremely low temperature, there is the possibility to obtain characteristic detectors. If the detector which has the energy resolution better by ten times as compared with semiconductor detectors is developed, it will be utilized effectively in many fields through the measurement with high resolution, for example, the identification of atoms and atomic nuclei with X-ray or gamma ray becomes easy. The review regarding the radiation sensors utilizing extremely low temperature has been published, and in this paper, these radiation sensors are described centering around their principles. The transition to normal conduction of superconducting thin films and the fine powder of superconducting materials, the detection of quasiparticles using tunnel joining, the measurement of phonon medium by tunnel joining, the utilization of high temperature superconductors and the calorimeters at extremely low temperature are explained. (K.I.)