A Si(Li)-Pb shower calorimeter for p-p collider experiments

A silicon/lead sandwich calorimeter with 38 cm² in active area and 10 radiation lengths in depth has been constructed. The performance has been investigated for incoming electrons of 250 to 750 MeV. The calorimeter shows a good linearity over the electron energy region and the energy resolution was well expressed by σ(rms)/E = (16.5 ± 0.5)/√E(GeV) %. Also, it is shown that the deposited energy and energy resolution do not change greatly even when the incident beam position is very close to the detector edge. The agreement between these results and a Monte Carlo simulation is quite satisfactory.     

Development of high strength low alloy TRIP‐aided steels with annealed martensite matrix

Formable high‐strength low‐alloy TRIP‐aided sheet steels with annealed martensite matrix or TRIP‐aided annealed martensitic steel were developed for automotive applications. The steels possessed a large amount of plate‐like retained austenite along annealed martensite lath boundary, the stability of which against the strain‐induced transformation was higher than that of the conventional TRIP‐aided dual‐phase steel with polygonal ferrite matrix. In a tensile strength range between 600 and 1000 MPa, the TRIP‐aided annealed martensitic steels exhibited superior large elongation and reduction of area. In addition, the steels possessed the same excellent stretch‐flangeability and bendability as TRIP‐aided bainitic steel with bainitic ferrite matrix. These properties were discussed by matrix structure, a strength ratio of second phase to matrix, retained austenite stability, internal stress in matrix and so on.     

Impact of PHITS spallation models on the neutronics design of an accelerator-driven system

The impact of different spallation models and parametrisation of nucleon–nucleus interactions in the particle transport code PHITS on the nuclear characteristics of an accelerator-driven system (ADS) is investigated. Cut-off neutrons below 20 MeV calculated using the default option of the current spallation model (i.e. Liège intranuclear cascade (INC) model version 4.6, INCL4.6) are found to be 14% less than those calculated by the old spallation model (i.e. Bertini INC model). This decrease increases the proton beam current that drives the 800-MW thermal power and impacts various ADS parameters, including material damage, nuclear heating of the proton beam window and the inventory of spallation products. To validate these options based on the ADS neutronics design, we conduct benchmark calculations of the total and non-elastic cross sections, thick target neutron yields and activation reaction rate distributions. The results suggest that Pearlstein–Niita systematics, which is a default option of the nucleon–nucleus interaction parametrisation, would be the best option and that Bertini INC is better suited for cut-off neutrons than INCL4.6. However, because of the difficulty in making a definite conclusion on the spallation models, we conclude that relatively large uncertainty in the cut-off neutrons, which is the difference between the two spallation models (i.e. 14%), should be considered.     

Experimental study and kinetic analysis on sodium oxide–silica reaction

ABSTRACT

In a sodium-cooled fast reactor (SFR), if considering hypothetical severe accidental condition such as the steel liner failure of structural concrete caused by intensive leakage of liquid sodium (Na) coolant, the liquid sodium–concrete reaction (SCR) may take place. The major consequences of SCR are hydrogen release, energy release and concrete ablation. Thus, it is important to understand the phenomenology and kinetic behavior of SCR. As a part of a series of studies on SCR, this study focused on the reaction between sodium oxide (Na₂O) and silica (SiO₂), which is dealt with possible formation of Na₂O as the result of sodium–water reaction in the initial stage of SCR. Through thermoanalytical and X-ray diffraction measurements, it was revealed that Na₂O–SiO₂ reaction to form sodium orthosilicate (Na₄SiO₄) occurs at significantly lower temperature in comparison with Na–SiO₂ reaction. The reaction is kinetically characterized as a largely overlapping multistep reaction, which is composed of at least three reaction steps. On the basis of the observations, the impact of Na₂O–SiO₂ reaction in the overall SCR and the significance of the conventional kinetic analysis using the Kissinger method are discussed.     

A microprogrammable real-time video signal processor (VSP) formotion compensation

A video signal processor (VSP) LSI circuit with a three pipelined architecture has been developed for pattern matching, which is fundamental for the motion compensation necessary for teleconferencing systems. A high-speed arithmetic logic unit with absolute-value calculation capability and a minimum/maximum value detector, which are essential to pattern matching, have been integrated on the VSP LSI. The chip was fabricated with a 2.5-μm CMOS and double-layer metallization technology. The number of MOSFETs integrated on the 9.91×9.50-mm ² chip is about 48000. It operates at a 14.3-MHz clock frequency with a single 5-V power supply and typically consumes 240 mW. An experimental video signal processing system, using a single VSP LSI chip, is discussed     

Precise estimation of linewidth reduction in wavelength-detuned DFBsemiconductor lasers

The linewidth reduction of DFB semiconductor lasers due to the wavelength detuning is estimated precisely. Firstly, the Schawlow-Townes linewidth, which excludes the enhancement due to the carrier effect, is determined from the AM noise spectrum. Secondly, the actual linewidth including the carrier effect is measured. Lastly, the contribution from the carrier effect is determined from both of the linewidths. The experimental result shows that the linewidth enhancement due to the carrier effect is four times larger in a 1.3 μm laser with a positive detuning (Δλ=+15 nm) than in a laser with a negative detuning (Δλ=-15 nm)     

Origin of residual semiconductor-laser linewidth in high-powerlimit

The FM noise spectrum and the spectral width of semiconductor lasers are measured in the high-power state up to 20 mW. The FM noise spectrum consists of the white noise and the 1/f noise. The spectral density of the white noise is suppressed by the increase in the output power, whereas that of the 1/f noise is kept constant. This fact means that the residual linewidth in the high-power limit is caused by the 1/f noise rather than the white noise     

Attenuation of ambient dose equivalent from neutrons by thick concrete, cast iron and composite shields for high energy proton, He, Ca and U ions on Cu targets for shielding design

Data on neutron dose attenuation by thick concrete, cast iron, and cast iron plus concrete composite shields for heavy ions and protons having high energies (200-1000 MeV/u) are necessary for shielding designs of high-powered heavy ion accelerator facilities. Neutron production source terms, shield material attenuation lengths, and neutron dose rate reduction effectiveness of the bulk shielding in the angular range from 0° to 125° were determined by the Particle and Heavy Ion Transport Code (PHITS) for beams of 300 and 550 MeV/u ⁴⁸Ca ions, 200 and 400 MeV/u ²³⁸U ions, 800 MeV/u ³He and 1 GeV protons. Calculated results of interaction lengths of concrete and cast iron were also compared with similar work performed by Agosteo et al., and to experimental and other calculated data on interaction lengths. The agreement can be regarded as acceptable.     

Basic design guideline for the preliminary engineering design of PIE facilities in IFMIF/EVEDA

The international fusion materials irradiation facility (IFMIF) is an accelerator-based intense 14 MeV neutron source for testing fusion reactor materials. Under broader approach (BA) agreement between EURATOM and Japan, the engineering validation and engineering design activity (EVEDA) were started from 2007. The IFMIF needs the post irradiation examination (PIE) facilities to generate a materials irradiation database for the design and licensing of fusion DEMO reactors. In this study we examined and discussed about the safety such as remote handling, hot cell design, and the equipments and apparatus of hot cells, and we summarized a basic design guideline for the preliminary engineering design of the PIE facilities.     

SHORI COAL LIQUEFACTION AND ITS CO-PROCESSING WITH PETROLEUM RESIDUE

Shori coal from China shows an excellent applicability to liquefaction. The reactivity to liquefaction of Shori coal is proved to show higher temperature-dependence than those of Wandoan coal and Battle River coal. Anthracene oil has an excellent solvent effect as a vehicle oil. However, Shori petroleum residue shows a comparable effect as a vehicle oil to anthracene oil at 450°c. Hydrogen contents in the hexane-soluble fraction produced from co-processing with Shori petroleum residue are higher than the hydrogen contents in the hexane-soluble fraction produced when anthracene oil was used. Shori petroleum residue seems to be associated with the lowering of the nitrogen content and oxygen content in the hexane-soluble fraction. But the sulfur in Shori petroleum residue was transferred to the hexane-soluble fraction.