[en] We developed a dual-frequency eddy-current NDE system based on High-T_c RF superconducting quantum interference devices. This method could be used to decrease the unwanted signals caused by the variance of lift-off, to estimate the depth of crack flaw or to detect the thickness of metal structures by choosing appropriate excitation frequencies

[en] By optimizing the designing, we made a small size and low noise high-T_c DC SQUID readout electronics with the modulation frequency of 80 kHz. The white flux noise was about 30 μPHI₀/√Hz when Sumitomo high-T_c DC SQUID sensor was used. We also proved mobile high-T_c DC SQUID magnetometer was feasible. By using a special compensation method, the SQUID magnetometer could keep locking when it swung about 20 degree sign in the earth field. Using this system and eddy-current nondestructive evaluation method, we successfully detected the defect in ferromagnetic material

[en] We developed a high-T_c DC SQUID system cooled by pulse-tube cooler. To avoid the influence of the wire resistance between SQUID and preamplifier, and to reduce the influence of the temperature fluctuation of pulse-tube cooler, DC coupling between SQUID chip and preamplifier was used and the flux locked loop worked in modulation mode. We also developed a temperature controller, using the DC SQUID as temperature sensor, to control and stabilize the operating temperature of the pulse-tube cooler. With the temperature controller, the DC SQUID system could remain locked for over 8 h

[en] The dynamical evolution of two-component star clusters, each of which is enclosed within a perfectly reflecting sphere, is investigated by numerically solving moment equations derived from the Boltzmann equation. One of the two adopted model clusters evolves, starting from a state of no mass segregation, toward an equilibrium state at a quite slow rate. The other one evolves away from an equilibrium state and its central density increases without limit. The different evolutionary behaviours of the model clusters are explained by the fact that there exists no equilibrium state for such clusters if the total energy is less than a certain critical value. The critical value increases with increasing total mass fraction of the heavier stars. This is qualitatively the same as Spitzer's theorem (1969) expressed in another way. (Auth.)

[en] A measuring system for the field of a quadrupole magnet with a small bore radius in a drift tube linac is fabricated. The induced voltage at a rotating coil, the rotating axis of which is adjusted to the magnet axis, is analysed by a Fast Fourier Transformer (FFT). The measuring time can be made shorter with the use of an FFT. By calibration in a uniform field, the field gradient can be evaluated without the use of coil dimension. The accuracy of the measurement is better than +-8%. This system is applied to a permanent quadrupole magnet and its field gradient and sextupole components are measured to be 2.1 kG/cm and 0.81 G/cm₂. (author)

[en] We have grown the single crystal of the bi-layered manganaites La_2-2xSr_1+2xMn₂O₇ for x=0.525 by the optical floating zone furnace. The quality of obtained sample was evaluated by X-ray diffraction measurement. The electric and magnetic properties were also evaluated by the resistivity (ρ) and magnetic susceptibility (χ) measurements, respectively. A clear anomaly was observed around 210 K in both ρ and χ measurements. These results are compared with previous studies done by other groups, from the view of the oxygen concentration

[en] This paper is dedicated to design and prepare the experimental equipment for momentum cooling at TARN (Test Accumulation Ring for Numatron, attached to the SF cyclotron at the Institute for Nuclear Study, University of Tokyo). Stochastic cooling has been the subject of many theoretical and experimental works, and recently this method has been applied to accumulate anti-protons. The application of this method to the beam stacked in TARN was planned, and the equipment for longitudinal momentum cooling with a filter has been set up. In the paper, the authors first review momentum cooling theory. Next, the beam pick-up, the kicker and the notch filter are described. Coupling impedance and total gain, and the parameters and performance of the travelling wave helix are discussed. As for the notch filter, a coaxial cable and the resistor dependence are investigated. The effect of notch gain shape on the beam distribution is discussed. The revolution frequency of the particles is 1.1 MHz, and the revolution time is 0.88 μs. The consideration for the network is briefly reported. The data taking system such as a spectrum analyzer and a computer is also described. (Wakatsuki, Y.)

[en] For eddy-current NDE, due to the big permeability of ferromagnetic material, low testing frequency is needed to detect defects in it. SQUID has advantages in low frequency eddy current NDE. But the large magnetic field produced by ferromagnetic material often exceeds the dynamic range of general SQUID system. We developed a mobile high-T_C SQUID system, with which, the dc and low-frequency magnetic field could be compensated well. Using our mobile SQUID system, the magnetic field produced by the cast iron could be compensated well and the defect in it could be successfully detected

[en] Beam profile monitors have been constructed to examine characteristics of the TARN; the profile and the orbit of an injected beam and the displacement of the beam orbit due to the sweep of RF frequency. We prepared two kinds of sensers, i.e. a multiwire chamber and a single rod, in which the beam is stopped. A beam stopper is also prepared to measure the intensity of the injected beam. Each senser is attached to a driving apparatus with a pulse motor operated remotely in the control room. A read-out circuit is prepared for the multiwire monitor. As well as the construction of the monitor system, the characteristics of the TARN obtained by the monitors are briefly described. (author)

[en] Beam test of a slow extraction by utilizing the 3rd order resonance has been performed to investigate the characteristics of the extraction system at TARNII and to develop a new technique with the slow extraction. High extraction efficiency was obtained by the extraction without accelerating beam. Time dependence of the profile of the extracted beam and micro-structure of the beam spill were measured. Furthermore we succeeded to extract the beam by a new method utilizing the emittance growth of the circulating beam in the ring. (author)