Diffraction of slow neutrons by nanoparticle-polymer composite gratings has been observed. By carefully choosing grating parameters such as grating thickness and spacing, a three-port beam splitter operation for cold neutrons - splitting the incident neutron intensity equally into the plus-minus first and zeroth diffraction orders - was realized. As a possible application, a Zernike three-path interferometer is briefly discussed.

J. Klepp Y. Tomita C. Pruner J. Kohlbrecher M. Fally

We experimentally demonstrate how to solve the phase problem of diffraction using multi-wave interference with standard diffraction experimental setups without the need for taking any auxiliary data. In particular, we show that the phases of the Fourier components of a periodic structure can be fully recovered by deliberately choosing a probe wavelength of the diffracting radiation much smaller than the lattice constant. In the course of the demonstration, we accurately determine the refractive index profile of nanocomposite phase gratings by light and neutron diffraction measurements.

M. Fally Y. Tomita A. Fimia R. F. Madrigal J. Guo J. Kohlbrecher J. Klepp

The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V, R, and I surface photometry, optical low-resolution spectroscopy, and 12CO (J=1-0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-formation activities, indicating that the environment does not affect these galaxy properties. Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.

A. Tomita H. Maehara T. T. Takeuchi K. Nakanishi M. Honma Y. Tutui Y. Sofue

A {\it weak selection} on $\mathbb{R}$ is a function $f: [\mathbb{R}]^2 \to \mathbb{R}$ such that $f(\{x,y\}) \in \{x,y\}$ for each $\{x,y\} \in [\mathbb{R}]^2$. In this article, we continue with the study (which was initiated in \cite{ag}) of the outer measures $\lambda_f$ on the real line $\mathbb{R}$ defined by weak selections $f$. One of the main results is to show that $CH$ is equivalent to the existence of a weak selection $f$ for which: \[ \mathcal \lambda_f(A)= \begin{cases} 0 & \text{if $|A| \leq \omega$,}\\ \infty & \text{otherwise.} \end{cases} \] Some conditions are given for a $\sigma$-ideal of $\mathbb{R}$ in order to be exactly the family $\mathcal{N}_f$ of $\lambda_f$-null subsets for some weak selection $f$. It is shown that there are $2^\mathfrak{c}$ pairwise distinct ideals on $\mathbb{R}$ of the form $\mathcal{N}_f$, where $f$ is a weak selection. Also we prove that Martin Axiom implies the existence of a weak selection $f$ such that $\mathcal{N}_f$ is exactly the $\sigma$-ideal of meager subsets of $\mathbb{R}$. Finally, we shall study pairs of weak selections which are "almost equal" but they have different families of $\lambda_f$-measurable sets.

S. García-Ferreira A. H. Tomita Y. F. Ortiz-Castillo

We investigate collective Thomson scattering (CTS) in two-stream non-equilibrium plasmas analytically, numerically and experimentally. In laboratory astrophysics, CTS is a unique tool to obtain local plasma diagnostics. While the standard CTS theory assumes plasmas to be linear, stationary, isotropic and equilibrium, it is often nonlinear, non-stationary, anisotropic, and non-equilibrium in high energy phenomena relevant to laboratory astrophysics. We theoretically calculate and numerically simulate the CTS spectra in two-stream plasmas as a typical example of non-equilibrium system in space and astrophysical plasmas. The simulation results show the feasibility to diagnose two-stream instability directly via CTS measurements. In order to confirm the non-equilibrium CTS analysis, we have been developing experimental system with high repetition rate table top laser for laboratory astrophysics.

K. Sakai S. Isayama N. Bolouki M. S. Habibi Y. L. Liu Y. H. Hsieh H. H. Chu J. Wang S. H. Chen T. Morita K. Tomita R. Yamazaki Y. Sakawa S. Matsukiyo Y. Kuramitsu

We constructed a parametrized family of Mordell curves with the rank of at least three.

Seiji Tomita

In this paper, we proved that there are infinitely many integer solutions of $X^6 - Y^6 = W^n - Z^n,\ n=2,3,4$.

Seiji Tomita

We present high-resolution central-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies. We discuss their general characteristics, particularly their central behavior, as well as dependencies on morphological types, activity, and peculiarity. The rotation curves generally show a steep nuclear rise, and high-velocity central rotation, followed by a broad maximum in the disk and then by a flat rotation due to the massive halo. Since the central high velocity and steep rise are common to all massive galaxies, it cannot be due to non-circular motions. Disk rotation curves of barred galaxies show larger dispersion than those of normal galaxies which is probably due to non-circular motions. Interacting galaxies show often perturbed outer rotation curves, while their central rotation shows no particular peculiarity. Also, central activities, such as starbursts and AGN, appear to show no particular correlation with the property of rotation curves. This would suggest that the central activities are triggered by a more local effect than the global dynamical property.

Y. Sofue Y. Tutui M. Honma A. Tomita T. Takamiya J. Koda Y. Takeda

We have developed a 4-channel multi-anode MCP-PMT, SL10, which exhibits a performance of sigma_TTS ~ 30 ps for single photons with G ~ 10^6 and QE=20% under a magnetic field of B <= 1.5 T. The cross-talk among anodes has been extensively studied. We have taken two measures to suppress it: one is to configure the SL10 to an effectively independent 4 small pieces of MCP-PMT's by segmenting an electrode of the second MCP-layer; the other is to use a constant fractional discriminator. Remarkable improvement has been achieved.

K. Inami T. Mori T. Matsumura K. Kurimoto S. Hasegawa Y. Suzuki T. Murase Y. Yurikusa M. Akatsu Y. Enari T. Hokuue A. Tomita N. Kishimoto T. Ohshima T. Ihara H. Nishizawa

A novel secure communication network with quantum key distribution in a metropolitan area is reported. Different QKD schemes are integrated to demonstrate secure TV conferencing over a distance of 45km, stable long-term operation, and application to secure mobile phones.

M. Sasaki M. Fujiwara H. Ishizuka W. Klaus K. Wakui M. Takeoka A. Tanaka K. Yoshino Y. Nambu S. Takahashi A. Tajima A. Tomita T. Domeki T. Hasegawa Y. Sakai H. Kobayashi T. Asai K. Shimizu T. Tokura T. Tsurumaru M. Matsui T. Honjo K. Tamaki H. Takesue Y. Tokura J. F. Dynes A. R. Dixon A. W. Sharpe Z. L. Yuan A. J. Shields S. Uchikoga M. Legre S. Robyr P. Trinkler L. Monat J. -B. Page G. Ribordy A. Poppe A. Allacher O. Maurhart T. Langer M. Peev A. Zeilinger