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- Author or Editor: K. Masumoto x
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Abstract
Neutron emission from the d-d nuclear fusion reaction, D/d,n/3He, in and on titanium metals /titanium sponge and the mixture of titanium powder/ trapped deuterium at about 1 atm has been ascertained by using a high resolution liquid scintillation detector. The neutron emissions from 11 samples which were provided under wide varieties of conditions were measured by temperature change in the range of liquid nitrogen temperature to 350 °C. As a result, it was proved that the neutron emission observed can be divided into two types, such as cooling and heating, by the evolved conditions. Moreover, by estimating the neutron emission efficiencies of samples, it was suggested that the neutron emission reactions are closely related to the deuterium trapped in the surface of titanium metal.
Abstract
A highly sensitive determination of fluorine in standard rocks by photon activation using the19F(
,n)18F reaction combined with pyrohydrolysis for the separation of18F has been reported. The irradiation energy was operated at 20 MeV to avoid the interference from Na, because Na is one of the major element in rocks and18F is also produced from Na via23Na(,
n)18F reaction above its threshold energy, 20.9 MeV. After irradiation, fluorine was extracted by pyrohydrolysis and separated as LaF3 precipitate. It was ascertained that the average recovery of fluorine in standard rocks was about 90% and the precipitate was of high radiochemical purity. This method was applied to the analysis of ten GSJ rock reference samples and two USGS standard rocks issued by the Geological Survey of Japan and the United States Geological Survey, respectively. The detection limit of this method was 0.02 
g/g, and the results obtained by this method were in good agreement with the recommended values. This method was easily applied to the determination of a few ppm level of fluorine in rock samples, such as ultrabasic rock and feldspar.
Abstract
Gold activation detectors were placed at nine positions on the inner wall of the KEK neutrino target station, and were exposed to secondary particles during approximately one month of machine operation. After exposure, the production rates of 19 spallation nuclides, which were produced in the Au activation detectors by nuclear reactions with different threshold energies, were determined by γ-ray spectrometry. Thus, it was indicated that the Au activation detector is a novel tool for obtaining the distribution of various secondary particles with high intensity and high energy.
Abstract
In order to estimate the total radioactivity induced in a concrete shield by thermal neutron-capture reactions at high-energy accelerator facilities, the observed activity of 36Cl in the concrete is expected to serve as an indicator of the thermal neutron fluence. Since 36Cl can also be produced from K and Ca by spallation reactions, we measured these production rates in order to clarify the contribution of each reaction. The Cl, K, and Ca targets were irradiated with neutrons having a maximum energy of 500 MeV. As a result, the production rates of 36Cl from Cl were only two orders higher than those from K and Ca. It was found that the 36Cl production ratios from Cl, K, and Ca were 6.7%, 6.8%, and 86.5%, respectively, and Ca was the main source of 36Cl production.
