The energy fluence of air irradiated with 300 keV electron beam (EB) was calculated using a Monte Garbo electron transport code named as EGS4-SPG code, which simulates 3-dimensional traverse of electrons in media. For evaluation of the effectiveness of the calculation, the results were compared with the energy fluenece rates measured by a calorimeter for the distances of 4.5-16.2 cm from the irradiation window of an irradiation vessel. As a result, the tendency of the calculated results as a function of depth in air agreed with the experimental results within the errors of ±1.3%. The calculated results also show that the overlap of energy fluenece rate distributions in air below each filament is sufficient at the depth deeper than 4.5 cm to provide the uniform energy fluence rate independently of the position of the calorimeter. In general, the measurement of an energy fluence rate distribution in air is difficult for electrons with their kinetic energy lower than 300 keV. Once the agreement between the calculation and the measurement is confirmed, even at one position, one can estimate an energy fluence rate distribution under similar irradiation geometry by only calculation.
A lot of earthquakes caused by Mt. Iwate's volcanic activities occurred in its surrounding area in 1998. Authorities of Meteorological agency pointed out a possibility of Mt. Iwate's eruption and we started the observation of many factors at Takizawa laboratory, located near Mt. Iwate, in order to find awakening sings of the eruption. We have collected several samples of the spring waters and the hot spring wasters from surrounding area of Mt. Iwate for measurement of their temperatures, conductivities, pH values, trace elemental concentrations and radon concentrations since 1998. The trace elemental concentrations were measured using ordinary vacuum PIXE at Nishina Memorial Cyclotron Center and the radon concentration was measured following to “The measurement manual of radon in hot spring water”. Spring water temperatures are about 10 °C and hot spring water temperatures range between 30 °C and 40 °C. Spring water conductivities are 10-20 mS/m (one point excepted: 70 mS/m) and hot spring water conductivities are 150-250 mS/m (one point excepted: 70 mS/m) . The pH values of all samples are almost 7. Mg, Na, Si, S, Cl, K, Ca, Fe, Br and Sr are detected in all samples using PIXE (0.01-1000 ppm) . The radon concentrations are not different between in spring water samples and in hot spring water samples (0.5-7.0 Bq/L) . At this stage there seem no significant indications of the relations between Mt. Iwate's volcanic activities and the fluctuations of temperatures, conductivities, pH values, trace elemental concentrations and radon concentrations in the sampled waters.
Possibility of reduction and removal of heavy metal ions Ag+, Zn2+, Cu2+, and Co2+from water by irradiation of γ ray was investigated. No concentration change was found when aqueous solutions of the metal ions were irradiated with γ ray either directly, or after bubbling with He gas. On the other hand, the metal ions were reduced to lower oxidation states by the irradiation in the presence of Na2SO3. Precipitates were observed in all the irradiated solutions of 4 metal ions of Ag+, Zn2+, Cu2+, and Co2+. Ag+was found to be reduced to metallic Ag.