Commercially available zener diodes have been tested as “high-temperature” dosimeters. They were heated above 50°C, and irradiated with 10-Me V electron beams and60Co γ-rays. For both radiations, the radiation-induced change in breakdown voltage of the zener diode when it is kept around 100°C have shown good linearity as a function of irradiated dose. It can be concluded from the present experiment that the zener diodes are promising candidates for dosimetry at temperatures above 50°C.
Germinating seeds of Glycine max (L.) cultivar. L-65 (Dr. W.G, variety) were treated with3H-thymidine at various times after seed soaking began at 25°C and the shoot apical meristem was squashed on slides. Then, microf luorography was carried out. The tritiumlabeled nuclei and mitoses were examined through the microscope. Consequently, it was suggested that most shoot apical meristem cells begin the DNA synthesis at 22-24 h after soaking of seed and lasts for 5 h, while mitosis starts at 26-28 h and the period is about 2.5 h. It was further supposed that shoot apical meristem cells stays at G0orG1period in the dormant seed.
Experiments were made to determine the energy dependence of CO3-3signal intensity in ESR dosimetry of tooth enamel. Packages containing 100 mg of mixed tooth enamel of particle size of 500-850μm were irradiated by X- or gamma-rays of various effective energies up to an exposure of about 1290×10-4 C/kg (500 R) . The irradiated tooth enamel samples were then subject to the ESR dosimetry and the relative response was determined as a function of effective photon energy. The response curve has a maximum at about 35 keV and is almost flat above 200 keV.