Recent improvement in solid state track detector

The report reviews various applications during the last decay in the field of the development of track detecting solid materials, track etching techniques and automatic track counting techniques as well as in atomic power related areas. The discovery of the CR-39 plastics as a track detecting solid triggered a great expansion of applications of solid state track detectors. The CR-39 plastics permits the detection of proton beams, which cannot be detected by polycarbonate or cellulose nitrate. In addition, CR-39 provides a smooth surface after being etched, permitting easy observation of etch pits. An electrochemical etching technique has been developed in addition to the conventional chemical etching technique. The new technique can form etch pits with a diameter of about 100 μm. Two practical automatic track counting techniques are available at present: electrical spark counting and image analysis. In the field of neutron dose measurement, the development of CR-39 and advanced image analysis techniques has recently led to practical recoil solid state track detectors that can serve as individual neutron exposure dosimeters or environmental monitors. (Nogami, K.)