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De Visser, P.J. (author), Yates, S.J.C. (author), Guruswamy, T. (author), Goldie, D.J. (author), Withington, S. (author), Neto, A. (author), Llombart, N. (author), Baryshev, A.M. (author), Klapwijk, T.M. (author), Baselmans, J.J.A. (author)We have measured the absorption of terahertz radiation in a BCS superconductor over a broad range of frequencies from 200 GHz to 1.1 THz, using a broadband antenna-lens system and a tantalum microwave resonator. From low frequencies, the response of the resonator rises rapidly to a maximum at the gap edge of the superconductor. From there on,...journal article 2015
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De Visser, P.J. (author), Goldie, D.J. (author), Diener, P. (author), Withington, S. (author), Baselmans, J.J.A. (author), Klapwijk, T.M. (author)In a superconductor, absorption of photons with an energy below the superconducting gap leads to redistribution of quasiparticles over energy and thus induces a strong nonequilibrium quasiparticle energy distribution. We have measured the electrodynamic response, quality factor, and resonant frequency of a superconducting aluminium microwave...journal article 2014
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De Visser, P.J. (author), Withington, S. (author), Goldie, D.J. (author)A model is presented for readout-power heating in kinetic inductance detectors. It is shown that the power dissipated by the readout signal can cause the temperature of the quasiparticle system in the superconducting resonator to switch between well-defined states. At low readout powers, only a single solution to the heat balance equation exists...journal article 2010
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Mauskopf, P. (author), Morozov, D. (author), Glowacka, D. (author), Goldie, D. (author), Withington, S. (author), Bruijn, M. (author), De Korte, P. (author), Hoevers, H. (author), Ridder, M. (author), Van der Kuur, J. (author), Gao, J.R. (author)We describe the optimization of transition edge superconducting (TES) detectors for use in a far-infrared (FIR) Fourier transform spectrometer (FTS) mounted on a cryogenically cooled space-borne telescope (e.g. SPICA). The required noise equivalent power (NEP) of the detectors is approximately 10?19 W/ ?Hz in order to be lower than the photon...conference paper 2008
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Smith, H. (author), Buckle, J. (author), Hills, R. (author), Bell, G. (author), Richer, J. (author), Curtis, E. (author), Withington, S. (author), Leech, J. (author), Williamson, R. (author), Klapwijk, T.M. (author)This paper describes the key design features and performance of HARP, an innovative heterodyne focal-plane array receiver designed and built to operate in the submillimetre on the James Clerk Maxwell Telescope (JCMT) in Hawaii. The 4x4 element array uses SIS detectors, and is the first sub-millimetre spectral imaging system on the JCMT. HARP...conference paper 2008