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The irradiation of a free electron laser at Tokyo University of Science (FEL-TUS) to β-propiolactone molecules in the gas phase has efficiently induced the infrared multiple photon dissociation of the compound in the wavenumber regions of 1000–1100 and 1700–2000 cm−1. The products were carbon dioxide and ethylene at equal amounts, where carbon dioxide was enriched with 13C under selected irradiation conditions. The relative yields of products and the selectivity of 13C were examined under various experimental conditions; the maximum 13C atom fraction of 59% was achieved when 2.5 Torr β-propiolactone was irradiated by FEL pulses at 1750 cm−1 with a fluence of 5.8 J cm−2. One of the reasons of this high selectivity is a large isotope shift of ∼47 cm−1 for the C O stretching vibration around 1880 cm−1, which is larger than the energy resolution of FEL-TUS. Another possible factor may be a shorter micropulse interval (∼350 ps) of FEL-TUS than the collisional frequency of β-propiolactone molecules in the gas phase, which prevents the collisional energy transfer from 13C molecules to 12C molecules during successive micropulses.

Optimization of the cooling system of the helium gas circuit was studied for the purpose of reducing the power consumption of a cryogenic system for a fusion device. Cooling the helium gas with a chemical heat pump is effective to save the total power consumption because the chemical heat pump does not require so much energy for cooling. We confirmed that the waste heat from the oil circuit of the high stage compressor is enough to drive the adsorption chiller, and the cooling power of the adsorption chiller is enough to cool down the temperature of the helium gas circuit. We also confirmed that about 7% of power consumption can be saved when we apply this new system to a large scaled helium compressor which would be fitted to the ITER project.

The Japan-Proton Accelerator Research Complexes (J-PARC) requires thick carbon stripper foils (250–500 μg/cm 2 ) to strip electrons from the H − beam supplied by the linac before injection into the Rapid Cycling Synchrotron (RCS). The 200 MeV H − beam from the linac has a pulse length of 0.5 ms with a repetition rate of 25 Hz and an average beam current of 335 μA. For this high-energy and high-intensity beam, conventional carbon stripper foils will break in a very short time and even a diamond foil will be ruptured at around 1800 K by the MW class accelerator. Thus, thick carbon stripper foils with high durability at 1800 K produced by energy deposition in the foil are indispensable for this accelerator. For this purpose, we have been developing carbon stripper foils of 350 μg/cm 2 by means of both the controlled DC and AC/DC arc-discharge methods. Recently, we have successfully developed hybrid type thick boron-doped carbon stripper foils, which showed a drastic improvement not only with respect to the lifetime, but also with respect to thickness reduction and shrinkage at high temperature during long beam irradiation. In this report the preparation procedure and lifetime measurements with a 3.2 MeV, Ne + beam are presented.

The effect of amorphous carbon underlayer thickness on the microstructure of the Co/Pd multilayer perpendicular magnetic recording media was investigated. From the magnetic force microscopy observation in the AC-demagnetized state of the Co/Pd multilayer media, the magnetic cluster size was observed to effectively decrease with an increase in carbon underlayer thickness, where the higher coercivity and the higher S / N ratio of the Co/Pd multilayer media were obtained with the thicker underlayer. Furthermore, the distribution of [1 1 1] orientation of FCC-Pd became broader, and the grain size decreased with an increase in the carbon underlayer thickness. These effects caused the magnetic exchange decoupling of Co/Pd multilayer media. We suggested that the change of microstructure was directly related to the surface roughness of the amorphous carbon underlayer.

Amorphous C and Si films were sputter-deposited as underlayers of Co/Pd multilayer perpendicular magnetic recording media. The magnetic properties of the media were significantly affected by the underlayer thickness; namely, the values of coercivity H c and nucleation field − H n increased and the value of α decreased with merely increasing the thickness of C or Si underlayer, where α is the derivative of M – H loop at the value of coercivity. The coercivity was not always affected by magnetic anisotropy constant K u for the Co/Pd media. In read–write experiments, the higher S/N ratio was obtained for the media with the thicker C or Si underlayer, which exhibited low α and high H c . In the time decay experiments of magnetization, the Co/Pd multilayer media with C or Si underlayer possessed good thermal stability. This study demonstrated that the introduction of C or Si underlayer greatly improves magnetic properties, read–write characteristics, and thermal stability of Co/Pd multilayer perpendicular magnetic recording media.

Signal and noise characteristics of Co/Pd multilayer perpendicular magnetic recording media are discussed based upon MFM analysis. The noise of the Co/Pd multilayer media is originated mainly from irregularities in the magnetic transition regions, and can be drastically suppressed by increasing the thickness of the carbon underlayer although a large number of reversed magnetic domains between the magnetic transitions still exist. The fine magnetic clusters formed in the medium with a thick carbon underlayer result in clear magnetic transition boundaries of recorded bits in the high recording density region. By examining the profile of the M – H loops, the decrement in the α value, which is defined as the slope of M – H loop at the value of coercivity, improves the signal to noise ( S / N ) ratio for the Co/Pd multilayer media.

We have observed flares of TeV-gamma rays from Mrk501 in 1997 using three telescopes of the Utah Seven Telescope Array at Dugway, Utah. Determination of the energy spectrum from such Active Galactic Nuclei (AGN) is very important, because the gamma-ray spectrum is expected to steepen around 10 TeV from objects like Mrk501 by the interaction of the infrared photons. We have developed the method to estimate energies of the gamma rays by stereoscopic analysis using multiple telescopes. The differential index of the energy spectrum obtained is well expressed by −2.5 between 700 GeV and 3 TeV. This spectrum seems to become steeper above several TeV.

This paper presents the latest design work of high speed adder logic based on Josephson elements. The Josephson adder uses a novel exclusive-OR logic and performs high speed carry propagation technique. The idea of directionality is also undertaken to avoid the necessary distortion in carry signal. The principle of operation with salient feature of simulation of the adder are presented in full detail. Necessary checks for carry skip and other fabrication parameters are investigated using detailed model of the device based on its highly miniaturized size. The results of the simulation show that the nominal delay of the adder logic is 20 ps/stage and average power dissipation is 47 μW/stage. Authors have mainly stressed upon how to obtain ultra fast speed at the cost of very low power dissipation of the presented adder with its small size.