[en] The plutonium fuel production factories (PFPF) (Tokai Japan) having two production lines for mixed oxide fuel: a production line for FBR fast breeder reactor fuel and a line (under construction) for ATR fuel is described

[en] We have studied the driving-field dependent transport of ions trapped below the free surface of superfluid ³He-B. For small driving fields, the velocity of ions is a linear function of the field. At high electric fields, the velocity is observed to be a nonlinear function of the field. The onset velocity of the nonlinearity is consistent in magnitude with the Landau critical velocity. This implies that the nonlinear behavior is caused by the pair-breaking effect of the moving ions

[en] An Inner Drift Chamber (IDC) has been constructed for the TOPAZ e⁺e^- experiment at TRISTAN. The IDC has a cylindrical shape with dimensions of 20 cm in inner diameter, 60 cm in outer diameter and 150 cm long. The IDC is equipped with 1024 anode wires grouped into 10 layers. For the position readout along the anode wires, eight delay-line layers are placed on coaxial cylinders made of Normex honeycomb. The chamber is operated with a gas mixture of Ar(89 %)/CO₂(10 %)/CH₄(1 %) at an atmospheric pressure. In this paper, details of the mechanical structure and the fabrication procedures are described. (author)

[en] A TOPAZ inner drift chamber (IDC) is designed (1) as a fast triggering element for charged particles and (2) as a tracking element closest to the beam crossing area. The sensitive area of the IDC is shown in Fig.1. The inner diameter and the outer diameter of the IDC are 200 mm and 590 mm, respectively. Its length in the beam direction is 1510 mm. The end-plate of the IDC is schematically shown in Fig.2. Ten layers of anode wires are placed co-cylindrically, where neighbouring two layers are staggered to solve the left-right ambiguity. Inner four layers have 64 anode wires each and outer six layers have 128 anode wires each. As shown in Fig.2, each pair of layers are separated with the cathode cylinder made of paper-honeycomb structures. The z-information in the IDC is obtained from the zig-zag delay line placed on both surfaces of the honeycomb cylinder. As we intend to extract both the drift time information and the cathode-induced signal information with good accuracy, the wire configuration should be carefully studied. Also the IDC will be used under the magnetic field of 10 kG, the geometry of the wire configuration would have much effect on the space-time relation and on the spatial resolution of the drift chamber. We have studied two possible patterns of the wire configuration under the magnetic field of 6 kG. (author)

[en] Nanoparticles of Cu were formed in the zinc oxide (ZnO) substrate by negative ion implantation. Zinc oxide was chosen, because of its possibility for photonic applications, as a semiconductor with high radiation resistance. Negative Cu ions of 60 keV were implanted to (0 0 0 1) oxygen-face single crystal. The total dose varied in a range of 1 x 10¹⁵-1 x 10¹⁷ ions/cm². After implantation and after post-irradiation annealing, optical absorption was measured in a UV-IR range and the radiation damage was evaluated by XRD and RBS. The formation of Cu nanoparticle was verified by a surface plasmon resonance peak in absorption spectra. The crystallinity of ZnO was kept well below the tolerance dose of 1 x 10¹⁶ ions/cm², which is large in comparison with other semiconductors. It is concluded that ZnO is a promising candidate for nanoparticle-dispersed optical materials, together with functionality of semiconductor

[en] The authors investigated a conductivity dip of the surface-state electrons on a quench-condensed hydrogen-film surface. The dip appears when about 10 atomic layers of helium are adsorbed onto the hydrogen surface. It depends on the degree of the surface roughness and also on the electron density n_s and/or the applied electric field. The other experimental parameters, like temperature, and driving frequency and voltage of the ac-conductivity measurement were found to be irrelevant for the phenomenon. Electron scattering from ripplons and a ripplonic polaron were considered as possible candidates for the interpretation of the conductivity dip. It was found that scattering from ripplons alone as treated by Paalanen and Iye, in order to explain the phenomenon, is not sufficient to interpret the present experimental results. Likewise, assuming the formation of a ripplonic polaron does not completely account for the data because the energy gained by forming the polaron state is estimated to be an order of magnitude smaller than the thermal energy in the experiment

[en] Metallic V nanoparticles (NPs) were formed in silica glass by implantation with V⁺ ions of 60 keV to a fluence of 1.0 × 10¹⁷ ions/cm². Annealing in oxygen gas at 800 °C transformed the metallic NPs to oxide NPs. While the mean diameter of the metal V NPs was 8.4 nm in the as-implanted state, the diameters steeply increased during oxidation, with some exceeding 100 nm. Since at least 15 different composition phases, such as V₂O₃, V₃O₇, V₆O₁₃, V₉O₁₇, etc., are known for vanadium oxides, identification of the oxide phase of the NPs was not easy. X-ray diffraction (XRD) was not a powerful tool for phase identification of the NPs, because the diffraction peaks were broad due to the nanometric sizes of the particles and readily shift due to stress effects. The temperature dependence of the optical absorption spectrum was measured. The observed spectra were almost unchanged between 3.3 and 370 K. Combining the spectral result and the XRD results, the candidates were narrowed down to three phases, V₂O₅, V₄O₉, and V₇O₁₃, from the 15 candidates. Among the three, the V₂O₅ phase is the most probable because the absorption spectrum and the oxygen partial pressure for its formation were both consistent. - Highlights: ► Vanadium nanoparticles of 8.4 nm in mean diameter are formed by ion implantation. ► V₂O₅ nanoparticles are formed by thermal oxidation of metallic vanadium NPs in SiO₂. ► V₂O₅ phase is determined from 15 candidate phases. ► Phase identification is made by optical spectroscopy and X-ray diffraction. ► Temperature dependent spectroscopy is used for identification of multiple oxide phases.

[en] We have measured the mobility of surface state electrons (SSE) on liquid ³He, μ₃, aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ₃ below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in ³He down to 100 mK. We observe an abrupt decrease of μ₃, due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid ⁴He

[en] Localization properties of third sound were studied experimentally in one-dimensional random lattices. Transmission spectra were measured and compared with those in periodic, Fibonacci, and Thue-Morse lattices. Not only the resonant transmission but also the phase-velocity renormalization of third sound was observed in the random lattices

[en] An experimental technique is developed to study acoustic transmission in one and two dimensional modulated structures by employing third sound of a superfluid helium film. In particular, the Penrose lattice, which is a two dimensional quasiperiodic structure, is studied. In two dimensions, the scattering of third sound is weaker than in one dimension. Nevertheless, the authors find that the transmission spectrum in the Penrose lattice, which is a two dimensional prototype of the quasicrystal, is observable if the helium film thickness is chosen around 5 atomic layers. The transmission spectra in the Penrose lattice are explained in terms of dynamical theory of diffraction