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36Cl is a long-lived radioisotope, which, because it is created mainly through a thermal neutron capture process by 35Cl, may be used to estimate the strength of thermal neutron flux from A-bombs or nuclear fuel facilities. The 36Cl contents in granite samples from the Hiroshima A-bomb site have been measured by the Cl-36 accelerator mass spectrometry (AMS) system at the University of Tsukuba. The 36Cl/Cl ratios deduced from the 36Cl measurements are compared with independent evaluations based upon the Dosimetry System 2002 (DS02) of the radiation doses received by the survivors of the Hiroshima A-bomb. The measurements corresponded well up to a ground distance of 1100 m, which proved the effectiveness of the DS02. Measurements of the 36Cl/Cl ratio of unexposed granite samples were 1.92 × 10-13 on average, and because the measured ratio for samples at a ground distance of 1163 m was 2.50 × 10-13, the assessment of the neutron flux by the 36Cl measurements of samples beyond about 1100 m is not practical. This limitation arises from the inability to distinguish bomb-induced Cl-36 from activation due to ambient sources. [Copyright &y& Elsevier]

Abstract: Ionization cross sections for Cu K-shell by positron impact in the energy range between 10 and 30keV have been calculated using the three-body classical trajectory Monte Carlo method and the binary encounter model. We have found that the classical treatment of the collision describes reasonably well the ionization cross sections measured recently. [Copyright &y& Elsevier]

Abstract: We have measured the 36Cl/Cl ratio of uncultivated surface soil samples collected from 11 areas distributed throughout Japan to determine the undisturbed value of the ratio. The ratio was found to be on the order of 10−13 except for the Tokai-mura area, where four research reactors, two commercial nuclear power plants and a nuclear fuel reprocessing plant have been operated. The observed ratio in the Tokai-mura area was higher than 10−12. Notably, soil samples collected from a site of commercial BWR nuclear power plants in Fukushima prefecture showed no significant increase in 36Cl/Cl ratio. The 36Cl/Cl ratio depth profiles of soil samples collected at both of Makabe-town and Tokai-mura were also measured. Since Makabe-town is located about 50km apart from Tokai-mura, we do not expect it to be affected by the nuclear facilities. No large variations were observed in the Makabe depth profile; the measured ratios ranged from ∼3 to ∼5×10−13. The result obtained for Tokai-mura is significantly different in that from the surface to about 80cm depth, the measured ratios, ∼10−12, are much higher than any at Makabe. At depth below 80cm, the Tokai-mura ratios are lower and become indistinguishable from those at Makabe. The 36Cl/Cl ratio in unaffected areas of Japan is estimated to be 3–4×10−13. [Copyright &y& Elsevier]

Abstract: The mystery of 26Al origin has made the nuclide important in the astrophysics. It was proposed that the reaction, 14N(16O,α)26Al, may be one of the origin of the source of 26Al in the cosmic. In his work, the 26Al was measured with AMS by using full-stripping method, and the cross-sections of these reactions for around sub-barrier energies were deduced. The experiment details are described and the results represented. [Copyright &y& Elsevier]

Abstract: The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10–30 years of operation were in the range of 1012–1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5–15cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400MeV and 12GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities. [Copyright &y& Elsevier]