[en] We study the structure of the monopole configuration in U(2) non-commutative super Yang-Mills theory. Our analysis consists of two steps: solving the BPS equation and then the eigenvalue equation in the non-commutative space. Calculation to the first non-trivial order in the non-commutativity parameter theta shows that the monopole exhibits a certain non-locality. This structure is precisely the one expected from the recent predictions by the brane-configuration technique. (author)

[en] We construct a 1/4 BPS soliton solution in N=4 non-commutative super Yang-Mills theory to the first order in the non-commutativity parameter θ₍i_j). We then solve the non-commutative eigenvalue equations for the scalar fields. The Callan-Maldacena interpretation of the eigenvalues precisely reproduces the expected string junction picture: the string junction is tilted against the D3-branes with angle θ₍i_j). (author)

[en] A preliminary result of the solar axion search experiment at the University of Tokyo is presented. We searched for axions which could be produced in the solar core by exploiting the axion helioscope. The helioscope consists of a superconducting magnet with field strength of 4 Tesla over 2.3 meters. From the absence of the axion signal we set a 95% confidence level upper limit on the axion coupling to two photons g_aγγ < 6.0 x 10^-10GeV^-1 for the axion mass m_a < 0.03 eV. This is the first solar axion search experiment whose sensitivity to g_aγγ exceeds the limit inferred from the solar age consideration

[en] The XMASS project utilizes ultrapure liquid xenon and aims to detect pp and ⁷Be solar neutrinos by means of ν+e scatterings. Our goal is a 10 t scale detector in which an ultralow background can be realized in a fiducial volume. Since it requires extremely low background, it will give great opportunities for us to search for dark matter and double beta decay signals with high sensitivity. Here we will discuss a detector design common for solar neutrino and dark matter detection and a new design devoted for the double beta decay experiment. The status of the current 100 kg xenon detector will also be shown. (author)

[en] In the recent gyrotron development in JT-60U ECRF system, 1.5 MW for 1 s of the world highest power oscillation (> 0.1 sec) has been achieved at 110 GHz. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellow, and a low-loss DC break enabled this achievement. Moreover as a development step to realize a reliable ECRF system in future fusion experiments, long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved. It has been confirmed that the temperature of cooled components are saturated and no evidence of damage were found in the waveguides and antenna without forced cooling. As a forced cooling antenna for longer pulse in future, an innovative antenna having relatively wide range of beam steering capability with linearly-moving-mirror concept has been designed. Beam profile and mechanical strength analysis shows the feasibility of the antenna. (author)

[en] An X-ray detector for a solar axion search was developed. The detector is operated in a cryostat of a superconducting magnet. Special care was paid to microphonic noise tolerance and mechanical tightness against thermal contraction. The detector consists of an array of 16 PIN photodiodes and tailor made preamplifiers. The size of each PIN photodiode is 11x11x0.5 mm³. The detector consists of two parts, the front-end part being operated at a temperature of 60 K and the main part at room temperature. Under these circumstances, the detector achieved an energy resolution of 1.0 keV in FWHM, a threshold of 2.5 keV and a background level of 6x10^-5 counts s^-1 keV^-1 cm^-2

No abstract available

[en] Lead molybdate (PbMoO₄) is found to be an efficient scintillator when cooled down to liquid nitrogen temperature. The scintillation light of PbMoO₄ excited by γ-rays amounts to as much as 16% of that of NaI(Tl) in the wavelength range between 180 nm and 650 nm and the decay time is as long as 11 μs if it is cooled below 100 K. Since ¹⁰⁰Mo, whose natural abundance is 9,6%, is a double β decay nuclide, the PbMoO₄ can be useful for the double β decay experiment. (orig.)

[en] Unwanted X-mode behavior in the fundamental harmonic electron cyclotron (EC) wave launching from the low field side with an oblique toroidal injection angle is experimentally studied on JT-60U by changing the poloidal injection angle. It is found that there is a critical region in the poloidal injection angle to cause the rise in vacuum pressure at the NBI port adjacent to the ECRF antenna port. The typical EC beam power is about 1 MW and the pulse length is 3 s in this experiment. The ray-trace calculation indicates that the X-mode launched from the low field side is guided into the NBI port after reflection at the cut-off layer for the critical poloidal injection angle. The results suggest that the O-mode injection with quite high mode purity, that is, with a very low fraction of X-mode is required for the avoidance of the overheat of the in-vessel components due to the reflected X-mode in the case of the EC beam launching from the low field side, especially for long pulse operation

[en] We have proposed a ceramics-free antenna feeder line employing a ridged waveguide as a local support for IC antenna of next-generation tokamaks. One fourth mock-up model of the all metal waveguide designed for the ITER ICRF system is fabricated and electrical characteristics of the model including the coaxial line - waveguide converter are measured. Power reflection coefficient of the model including the coax-waveguide converter to the input coaxial line is estimated to be less than 15% below the cut-off frequency of 107 MHz and less than 3% above the cut-off frequency. It is found that this ceramics-free antenna support employing a ridged waveguide is quite available for IC antenna of next-generation tokamaks. (author)