477 research outputs found

    Identifications and SEDs of the detected sources from the AKARI Deep Field South

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    In order to find counterparts of the detected objects in the AKARI Deep Field South (ADFS) in all available wavelengths, we searched public databases (NED, SIMBAD and others). Checking 500 sources brighter than 0.0482 Jy in the AKARI Wide-S band, we found 114 sources with possible counterparts, among which 78 were known galaxies. We present these sources as well as our first attempt to construct spectral energy distributions (SEDs) for the most secure and most interesting sources among them, taking into account all the known data together with the AKARI measurements in four bands.Comment: 4 pages, 10 figures, To appear in: the proceedings of the conference "AKARI, a light to illuminate the misty Universe", February 16-19 2009, Toky

    Monolithic Ge:Ga Detector Development for SAFARI

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    We describe the current status and the prospect for the development of monolithic Ge:Ga array detector for SAFARI. Our goal is to develop a 64x64 array for the 45 -- 110 um band, on the basis of existing technologies to make 3x20 monolithic arrays for the AKARI satellite. For the AKARI detector we have achieved a responsivity of 10 A/W and a read-out noise limited NEP (noise equivalent power) of 10^-17 W/rHz. We plan to develop the detector for SAFARI with technical improvements; significantly reduced read-out noise with newly developed cold read-out electronics, mitigated spectral fringes as well as optical cross-talks with a multi-layer antireflection coat. Since most of the elemental technologies to fabricate the detector are flight-proven, high technical readiness levels (TRLs) should be achieved for fabricating the detector with the above mentioned technical demonstrations. We demonstrate some of these elemental technologies showing results of measurements for test coatings and prototype arrays.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies". Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche

    CSIP - a Novel Photon-Counting Detector Applicable for the SPICA Far-Infrared Instrument

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    We describe a novel GaAs/AlGaAs double-quantum-well device for the infrared photon detection, called Charge-Sensitive Infrared Phototransistor (CSIP). The principle of CSIP detector is the photo-excitation of an intersubband transition in a QW as an charge integrating gate and the signal amplification by another QW as a channel with very high gain, which provides us with extremely high responsivity (10^4 -- 10^6 A/W). It has been demonstrated that the CSIP designed for the mid-infrared wavelength (14.7 um) has an excellent sensitivity; the noise equivalent power (NEP) of 7x10^-19 W/rHz with the quantum efficiency of ~2%. Advantages of the CSIP against the other highly sensitive detectors are, huge dynamic range of >10^6, low output impedance of 10^3 -- 10^4 Ohms, and relatively high operation temperature (>2K). We discuss possible applications of the CSIP to FIR photon detection covering 35 -- 60 um waveband, which is a gap uncovered with presently available photoconductors.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies". Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche

    Density Matrix Renormalization Group Study of the Disorder Line in the Quantum ANNNI Model

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    We apply Density Matrix Renormalization Group methods to study the phase diagram of the quantum ANNNI model in the region of low frustration where the ferromagnetic coupling is larger than the next-nearest-neighbor antiferromagnetic one. By Finite Size Scaling on lattices with up to 80 sites we locate precisely the transition line from the ferromagnetic phase to a paramagnetic phase without spatial modulation. We then measure and analyze the spin-spin correlation function in order to determine the disorder transition line where a modulation appears. We give strong numerical support to the conjecture that the Peschel-Emery one-dimensional line actually coincides with the disorder line. We also show that the critical exponent governing the vanishing of the modulation parameter at the disorder transition is βq=1/2\beta_q = 1/2.Comment: 4 pages, 5 eps figure
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