A radon monitor using thin plastic scintillation detector was developed and tested. A thin plastic scintillator was used because of its high detection efficiency for a particles of radon daughters but low efficiency for a particles or y ray of environmental radiation. A photomultiplier tube (PMT) was used with minus high voltage which was applied on photocathode of the PMT. The minus high voltage collects the positive charged radon daughters such as unattached 218Po atoms in the chamber. Using the developed radon monitor, energy peaks for radon daughters were clearly observed. A variations of radon concentration in several days were also obtained. These results indicate that the developed radon monitor is promising for earthquake prediction or estimation of internal exposure by radon daughters.
After tritiated steam-vapor was introduced into oxide superconductors (YBCO), radioactive YBCO was measured by Radio-Gas Analyzer Method. In this case, YBCO materials was prepared, then absorption period and temperature of tritium was varied properly. The position of tritium desorption peak was determined experimently. As a result, in absorption at low temperature, longer absorption period resulted in the shift of tritium desorption peaks toward higher temperature. On the other hand, in absorption at high temperature two desorption peaks were found. By analysis of the both, tritium desorption quantity at high temperature is twice as large as that at low temperature.
Realization of macroscopic and nanoscopic physico-chemical phenomena of several gels is proved to be due to the hydration and/or the liberation of water molecules, and dynamical properties of water cluster and their complex phase, and that they have an essential role in the biochemical mechanisms, since many of mechanisms are interpreted by the interaction between water molecules and hydrophilic polymer chains. Several behaviors of hydrogels and hydrogols such as poly (N-isopropylacrylamide), polyvinylalchol hydrogels, carrageenan, ovalbumin, and gelatin gels are discussed in terms of variations of lifetime of orhto-positronium because they reflect the behavior of radius size and numerical concentration of free volume, and its size distribution. The states of water molecules are divided into three categories — free water, associated water, and physically bound water by the present study.
Backscattered photons from slab phantoms were analyzed to investigate the effects of phantom size and material on calibration of dosimeters. The backscatter factor estimated by measurement with an ionization chamber was compared for three different phantoms ; a 40× 40×15 cm3polymethyl methacrylate (PMMA) phantom, a 30×30×15 cm3PMMA phantom and a water-filled phantom recommended by the International Organization for Standardization (ISO) . Monte Carlo calculations using EGS4 code were also performed to examine the measured results and to analyze the effect of phantom size and material on the dosimeter calibration. It was found that the ISO phantom could give up to 10% higher value of calibration factor than the 40×40×15 cm3 PMMA phantom, now commonly used in Japan, for photons of 60 keV.