[en] The uncertainty in the calculation of atmospheric neutrino fluxes is studied. The absolute value of atmospheric neutrino fluxes is sensitive to variation of the primary cosmic ray flux model and/or the interaction model. However, the ratios between different kind of neutrinos stay almost unchanged with these variations. It is unlikely that the anomalous ratio (ν_μ/ν_e)_obs/(ν_μ/ν_e)_MC reported by Kamiokande and Super Kamiokande is caused by the uncertainty of predicted atmospheric neutrino fluxes

[en] A large amount of the radioactive iodine isotopes 131I (t1/2 = 8.01 d) and 129I (t1/2 = 1.57×107 y) were released into the environment during the Fukushima Dai-ichi nuclear power plant (FDNPP) accident on March 2011. Radioactive iodine is one of the key fission products to be monitored due to the tendency of accumulation in the thyroid gland. There is an ethical obligation of science to serve society, and to help Japanese to better understand what happened, how it happened and why, even though public trust in science was lost in the aftermath of the accident. The study of radioactive iodine from the accident can fulfill this obligation. Information of environmental radiation monitoring was required in the initial phase of the FDNPP accident in making rational assessment of the radiological consequences to the public. However, in reality, it was not available at that time since monitoring system did not function due to the loss of power supply. Part of the on-site release characteristics and transportation mechanisms have been estimated via long-lived 129I in environmental samples. Two key questions of the macroscopic and microscopic dynamics of 129I have been investigated with large-scale soil and terrestrial water sampling. The results from these studies will be presented in the seminar. (author)

[en] The simulation of cosmic-ray propagation in the Galactic magnetic fields is presented in the energy region of 10 to the 16th - 10 to the 18th eV, where the gyroradius and the scale of the irregularity of the magnetic field are considered to be comparable. The diffusion tensor is calculated as a function of the ratio of the gyroradius (Rg) and the scale of the magnetic field irregularity (L0). The Rg dependence of the diffusion tensor in the region Rg greater than L0 is different from that in the region Rg less than L0. In the region Rg less than L0, the stochastic nature of the magnetic field suggested by Jokipii and Parker (1969) controls the process. In the region Rg greater than L0, like many other diffusion processes, the process can be understood in terms of the scattering centers and mean free path. 13 references

[en] Statistical techniques for determining cosmic-ray nuclide production rates in meteorites are described and demonstrated. Observed data on spallation products are compiled and systematized for the case of Fe meteorites and then applied to chondrites, using commonly defined shielding indices for irons and stones and for both stable and radioactive nuclides. Particular attention is given to methods based on single-element and multielement target systems; the production of He isotopes in Fe meteorites; metal-phase sampling; He-3, Al-26, and Ne isotopes in chondritic and multielement targets; the reference production rate of Ne-21 in chondrites; and products in the Ca and Fe systems. Extensive tables and graphs are provided. 30 references

[en] Based on experimental analysis, the overall point spread function (PSF) of the digital subtraction angiography (DSA) system can be described using three different kinds of PSFs, as follows: (1) a long-range PSF caused by scattered x-ray, (2) a medium-range PSF caused by the veiling glare, and (3) a narrow-range PSF caused by the other elements. The authors have developed the optimum construction method to design a spatial filter for correction of DSA images which were degraded by the narrow-range PSF. In this method, the salient preprocessing feature is that the components caused by the scattered x-ray and the veiling glare are connected before correction is carried out for the narrowing-range PSF. They applied the filter to practical DSA images and confirmed that the spatial resolution was visually improved without introducing extra artifacts

[en] The authors have developed an adaptive filtering method for scattered x-ray correction in a digital subtraction angiographic system, based on the following experimental results: (1) When the x-ray grid was applied in front of the image intensifier, the configuration of point spread function (PSF) for scattered radiation was independent of the water phantom thickness (5-25 cm) and the distance between the phantom and the image intensifier (0-25 cm); The distribution of the scattered x-ray (S) was represented by S = (a . P/sup n/ + b . P) * (PSF), where * denotes convolution, P is the primary distribution, and a, n and b are estimated from exposure conditions; (3) The original image (T) is described by T = P + S. A practical method of scatter correction and its pertinence for clinical imaging is presented

[en] The possibility of measuring the intergalactic magnetic field between an extragalactic ultrahigh-energy (UHE) gamma-ray source and the Galaxy is considered. It is found that, if there is a strong UHE gamma-ray source at a distance of less than about 100 kpc, the magnetic field between the Galaxy and the source can be studied by UHE gamma-ray observations. If the field strength is less than 10 to the -12th G, the gamma-ray flux for E(gamma) greater than or equal to 10 to the 15th is enhanced about 10 times over that expected from the source energy spectrum and the absorption with the 3 K microwave background photons alone. 15 refs

[en] The potential between the monopole and the antimonopole is studied by Monte Carlo simulation in the U(1) lattice system. It can be well understood by assuming a string between the monopole and the antimonopole in the β > 1 region. (orig.)

[en] A magnetic monopole is observed in a lattice gauge-Higgs system by Monte Carlo simulations. The distribution of magnetic charge assigned to a cube shows an obvious peak at M approx. equal to 2π/e. (orig.)

[en] The Ca-phosphate phases in the Allende CV3 meteorite were selectively dissolved in ammoniacal EDTA solution and measured for abundances of the rare earth elements (REE) by radiochemical neutron activation and mass-spectrometric isotope dilution analyses. The REE abundances in CA-phosphates of Allende are remarkably different from those of ordinary chondrites. All the REE except Eu were observed to be enriched by factors of 50-100 relative to the Cl values. This is 3-4 times lower than concentrations of REE in the ordinary-chondrite phosphates. Allende phosphates have a small positive Eu anomaly, in contrast to the large negative Eu anomaly in phosphates from ordinary chondrites. Though the positive Eu anomaly in Allende Ca-phosphates is puzzling, the lack of a negative Eu anomaly in Allende Ca-phosphates suggests that they never have been in equilibrium with Allende coarse-grained Ca, Al-rich inclusions or their precursor materials. 42 references