http://hdl.handle.net/2289/101 Search the Channel search http://dspace.rri.res.in:8080/jspui/simple-search http://hdl.handle.net/2289/3894 Title: Development of THz waveguide NbTiN HEB mixers<br/><br/>Authors: Jiang, Ling; Shiba, S.; Shimbo, Ken; Sakai, Nami; Yamakura, Tetsuya; Sugimura, Mika; Ananthasubramanian, P.G.; Maezawa, H.; Irimajiri, Y.<br/><br/>Abstract: In this paper, we present the development of the waveguide niobium titanium nitride (NbTiN) superconducting hot electron bolometer (HEB) mixers, cryogenically cooled by a 4 K close-cycled refrigerator. The NbTiN thin film is formed on a crystalline quartz substrate by sputtering an NbTi target with the Ar and N2 gas at room temperature. The HEB mixer element is fabricated by using the 12 nm NbTiN film, and is mounted on a waveguide block. Measurement of a Fourier transform spectrometer shows that the response of the mixer is centered near 810 GHz with a bandwidth of about 500 GHz. The uncorrected DSB receiver noise temperature is measured to be 500 K, and the noise bandwidth is to be 1.4 GHz at 810 GHz. The present result shows that a good noise performance can be obtained for the NbTiN HEB mixer even with a relatively thick film (12 nm) fabricated at the room temperature.<br/><br/>Description: Open Access Fri, 29 May 2009 22:58:59 GMT http://hdl.handle.net/2289/3890 Title: The Murchison widefield arrary: design overview<br/><br/>Authors: Lonsdale, C.J.; Deshpande, A.A.; Gopalakrishna, M.R.; Kamini, P.A.; Kumar, Deepak; Madhavi, S.; Prabu, T.; Roshi, D.Anish; Udaya Shankar, N.; Srivani, K.S.; and 33 co-authors<br/><br/>Abstract: The Murchison Widefield Array is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations but is initially focused on three key science projects: detection and characterization of three-dimensional brightness temperature fluctuations in the 21 cm line of neutral hydrogen during the epoch of reionization (EoR) at redshifts from six to ten; solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources; and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broadband active dipoles, arranged into 512 ldquotilesrdquo comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5 km in diameter, with a small number of outliers extending to 3 km. All tile-tile baselines are correlated in custom field-programmable gate array based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment, allowing full exploitation of the instrumental capabilities.<br/><br/>Description: Open Access. Wed, 29 Jul 2009 22:58:59 GMT http://hdl.handle.net/2289/3885 Title: Orbital evolution and super-orbital flux variations in X-ray binary pulsars.<br/><br/>Authors: Raichur, Harsha<br/><br/>Description: Open Access Wed, 29 Oct 2008 22:58:59 GMT http://hdl.handle.net/2289/3884 Title: Long term X-ray intensity variations of Cen X-3<br/><br/>Authors: Paul, Biswajit; Raichur, Harsha<br/><br/>Description: Open Access Wed, 29 Oct 2008 22:58:59 GMT