No abstract available

No abstract available

[en] We found that the effect of electric fields on deposit energy by electrons is obtainable from the electron range in a space with no electric field for low-energy electrons in weak electric fields. We calculated the effect of the electric field on the signal current from parallel-plate and cylindrical free-air ionization chambers by the EGS4 using an optional program for electric field and from the range of electrons in a space without an electric field. Photoelectrons emitted in a cylindrical ionization chamber gain or lose more than 0.3% of energy for photons with energy in a certain range. The net effect of the electric field for a signal current is usually small for both parallel-plate and cylindrical free-air ionization chambers because the gain and loss of energy usually compensate for each other. (S.Y.)

No abstract available

[en] In this study, diamond-like carbon (DLC) films were prepared by ion beam assisted deposition (IBAD), and micro-indentation tests were performed to evaluate the raw hardness that was independent of both the film thickness and the substrate hardness. As a result, the hardness constant proportional to the square root of the product of the Vickers hardness and elastic modulus was defined by analyzing the loading curves. Then, the raw hardness of the DLC films on tungsten carbide (WC) or high-speed steel (HSS) was evaluated by using the hardness constant. The effects of ion species in IBAD and the substrates with the different hardness were discussed. It was concluded that the evaluation by using the hardness constant proposed in the present study was useful for determination of the raw hardness of DLC films prepared by IBAD

[en] The geometry description of radiation shielding codes, such as QAD-CG and MORSE-CG, is often written by the combinatorial geometry (CG) method. However any EGS4/PRESTA user code with the CG method is not yet reported. Since the macro, called $CALL-HOWNEAR, is necessary to use the PRESTA algorithm on EGS4, it is difficult to write complicated geometries on EGS4/PRESTA. Then we developed an EGS4/PRESTA user code, which can be written by 3 dimensional CG method and it did the way that can evaluate influence of the step size for low energy electrons and influence of a calculative geometry. This paper described an user code using the CG method, named PRESTA-CG. Furthermore we reported comparison of the response of an ionization chamber with the UCSAMPCG which is employed the CG description for original EGS4. (author)

[en] Fe-doped high purity GaAs crystals have been grown using a vertical-type liquid-phase epitaxial technique and have been studied as room temperature gamma-ray spectrometric detectors for nuclear fuel safeguards. To improve the detector gamma-ray counting efficiency, a double-epitaxial-layer detector was studied

[en] It is often required in neutron calibration fields to determine the dose of gamma-rays produced in a neutron source and in the surroundings, because some neutron detectors are sensitive both to neutrons and gamma-rays. As a first step estimating neutron and gamma-ray energy spectra and fluences simultaneously in a neutron field, the gamma-ray response function for a ³He proportional counter was calculated using EGS4/PRESTA code. In the simulation, the gas multiplication factor, which depends on the detection position in the gas region along an anode wire, was taken into account to obtain the precise response function. For comparison, we measured response functions using different reference gamma-ray sources such as ²⁴¹Am, ¹³⁷Cs, and ⁶⁰Co, which were located vertically 55 mm away from the center of the anode wire. Calculated response functions agreed well with experimental ones. Monte Carlo code EGS4 is thus useful for the simulation of gamma response functions for neutron counters

[en] In order to establish the highly reliable design of heat exchanger and circulator in VHTR and the nuclear steel making system, seismic response calculations were conducted. First, the numerical calculation by the finite element method and the model experiment for the seismic analysis in heat exchanger tubes of helical type and structure of three dimensional frame to support the heat exchanger and other equipments were carried out. A real-sized model was used for the experiment in the heat exchanger and 1 : 9 scale model was used in the supporting structure. It was found that the calculated values agreed well with the experimental values. Next, transient response of the circulator rotor supported in water-lubricated hydrostatic journal bearings to seismic input was investigated numerically by Runge-Kutta-Gill procedure. Numerical results for the rotor which is equivalent to helium circulator for high temperature helium test loop with heat exchanging capacity 1.5 MWt are presented and the effects of operating conditions of the bearing on rotor response are discussed

[en] The thermoluminescence (TL) detection methods for irradiated spices were compared using spice samples obtained on the Japanese market, irradiated at doses of 1, 5, 10 and 30 kGy and stored for 1 year before analysis. The TL intensities of irradiated spices were stable for 1 year after irradiation. Measurement with whole samples failed to identify irradiated samples. Minerals were separated from spices in sodium tungstate saturated solution and/or sodium polytungstate solution. The TL intensity of minerals which had undergone irradiation was significantly increased for all samples. However, the ranges of TL intensity of irradiated and unirradiated samples overlapped. Clear discrimination has been obtained between the TL ratios of irradiated and unirradiated spices by using normalized measurement with reirradiation. The detection limit in terms of irradiation dose is 1 kGy even in a sample that has been irradiated 1 year prior to analysis. Normalization is the best technique currently available for thermoluminescence analysis to identify irradiated spices