T. Ohsugi

Early Phase Obserbations of Extermely Luminous Type Ia Supernova 2009dc

We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of the light curve is ?m 15(B) = 0.65 ? 0.03, which is one of the slowest among SNe Ia. The peak V-band absolute magnitude is estimated to be MV = ?19.90 ? 0.15?mag if no host extinction is assumed. It reaches MV = ?20.19 ? 0.19?mag if we assume the host extinction of AV = 0.29?mag. SN 2009dc belongs to the most luminous class of SNe Ia, like SNe 2003fg and 2006gz. Our JHKs -band photometry shows that this SN is also one of the most luminous SNe Ia in near-infrared wavelengths. We estimate the ejected 56Ni mass of 1.2 ? 0.3 M ? for the no host extinction case (and of 1.6 ? 0.4 M ? for the host extinction of AV = 0.29?mag). The C II ?6580 absorption line remains visible until a week after the maximum brightness, in contrast to its early disappearance in SN 2006gz. The line velocity of Si II ?6355 is about 8000?km?s?1 around the maximum, being considerably slower than that of SN 2006gz. The velocity of the C II line is similar to or slightly less than that of the Si II line around the maximum. The presence of the carbon line suggests that the thick unburned C+O layer remains after the explosion. Spectropolarimetric observations by Tanaka et?al. indicate that the explosion is nearly spherical. These observational facts suggest that SN 2009dc is a super-Chandrasekhar mass SN Ia.

Capacitances in silicon microstrip detectors

Abstract We present an analysis of the capacitances which are important for the operation of double-sided, AC-coupled silicon microstrip detectors. From frequency dependent measurements we extract interstrip, body and coupling capacitances of the strips, using SPICE simulations. Using electrostatic simulations we calculate the geometry dependence of interstrip and body capacitances and of depletion voltages. We evaluate the radiation hardness and the noise contribution of different strip geometries.

Systematic shifts of evaluated charge centroid for the cathode read-out multiwire proportional chamber☆

Abstract We have investigated the systematic error associated with the charge centroid evaluation for the cathode read-out multiwire proportional chamber. Correction curves for the systematic error according to six centroid finding algorithms have been obtained by using the charge distribution calculated in a simple electrostatic model. They have been experimentally examined and proved to be essential for the accurate determination of the irradiated position.

Wide-field one-shot optical polarimeter: HOWPol

For prompt optical polarimetry of gamma-ray burst (GRB) afterglow, we require wide-field imaging polarimeter which can produce both Stokes Q and U parameters from only a single exposure, as well as quickly-moving telescope and enclosure system. HOWPol is an optical imaging polarimeter which provides four linearly polarized images at position angles of 0°, 45°, 90° and 135°, i.e., Stokes I, Q, U, simultaneously. The key device is the wedged double Wollaston prism described by Oliva (1997)1 and Pernechele et al. (2003).2 The images are focused on two 2k×4k fully depleted CCDs. We report the design and development of the optical devices of HOWPol, which will be mounted to the 1.5-m Kanata telescope at Hiroshima University and stand by the GRB alert.

Detection of Polarimetric Variations Associated with the Shortest Time-Scale Variability in S5 0716+714

We present the result of near-infrared and optical observations of the BL Lac object S5 0716

Measurement of R and search for new heavy quarks in e+e- annihilation at 50 and 52 GeV centre-of-mass energies

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Micro-discharge at strip edge of silicon microstrip sensors

714 carried out by the KANATA telescope. S5 0716

Proton irradiation on p-bulk silicon strip detectors using 12 GeV PS at KEK

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Double-sided microstrip sensor for the barrel of the SDC silicon tracker

714 has both a long term high-amplitude variability and a short-term variability within a night. The shortest variability (microvariability) time-scale is important for understanding the geometry of jets and magnetic field, because it provides a possible minimum size of variation sources. Here, we report the detection of 15-min variability in S5 0716

Bayesian Approach to Find a Long-Term Trend in Erratic Polarization Variations Observed in Blazars

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