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Author Hoevers, H. F. C.; Bento, A. C.; Bruijn, M. P.; Gottardi, L.; Korevaar, M. A. N.; Mels, W. A.; de Korte, P. A. J.
Title Thermal fluctuation noise in a voltage biased superconducting transition edge thermometer Type Journal Article
Year 2000 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume (down) 77 Issue 26 Pages 4421-4424
Keywords TES; bolometer; thermal fluctuation noise; TFN
Abstract The current noise at the output of a microcalorimeter with a voltage biased superconducting transition edge thermometer is studied in detail. In addition to the two well-known noise sources: thermal fluctuation noise from the heat link to the bath and Johnson noise from the resistive thermometer, a third noise source strongly correlated with the steepness of the thermometer is required to fit the measured noise spectra. Thermal fluctuation noise, originating in the thermometer itself, fully explains the additional noise. A simple model provides quantitative agreement between the observed and calculated noise spectra for all bias points in the superconducting transition.
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Call Number RPLAB @ gujma @ Serial 759
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Author Tol, J. van; Brunel, L.-C.; Wylde, R. J.
Title A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz Type Journal Article
Year 2005 Publication Rev. Sci. Instrum. Abbreviated Journal Rev. Sci. Instrum.
Volume (down) 76 Issue 7 Pages 074101 (1 to 8)
Keywords Schottky, noise temperature
Abstract A new multifrequency quasioptical electron paramagnetic resonance (EPR) spectrometer is described. The superheterodyne design with Schottky diode mixer/detectors enables fast detection with subnanosecond time resolution. Optical access makes it suitable for transient EPR (TR-EPR) at 120 and 240 GHz. These high frequencies allow for an accurate determination of small g-tensor anisotropies as are encountered in excited triplet states of organic molecules like porphyrins and fullerenes. The measured concentration sensitivity for continuous-wave (cw) EPR at 240 GHz and at room temperature without cavity is 1013 spins/cm3 (15 nM) for a 1 mT linewidth and a 1 Hz bandwidth. With a Fabry-Perot cavity and a sample volume of 30 nl, the sensitivity at 240 GHz corresponds to [approximate]3×109 spins for a 1 mT linewidth. The spectrometer's performance is illustrated with applications of transient EPR of excited triplet states of organic molecules, as well as cw EPR of nitroxide reference systems and a thin film of a colossal magnetoresistance material.
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Notes Actually, noise spectral density is given (3e-19 W/Hz) Approved no
Call Number Serial 588
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Author Yagoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Svechnikov, S.; Gershenzon, E.
Title Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies Type Journal Article
Year 1998 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume (down) 73 Issue 19 Pages 2814-2816
Keywords NbN HEB mixers, noise temperature, local oscillator power
Abstract In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55–1.1 THz frequency range. The best results of the double-sideband <cd><2018>DSB<cd><2019> noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path causes significant contribution to the measured receiver noise temperature around 1.1 THz. The devices are made from 3-nm-thick NbN film on high-resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are typically 0.2Ï«2 um. The amount of local oscillator power absorbed in the bolometer is less than 100 nW.
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Call Number Serial 911
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Author Burke, P. J.; Schoelkopf, R. J.; Prober, D. E.; Skalare, A.; Karasik, B. S.; Gaidis, M. C.; McGrath, W. R.; Bumble, B.; Leduc, H. G.
Title Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers Type Journal Article
Year 1998 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume (down) 72 Issue 12 Pages 1516-1518
Keywords HEB mixer; thermal fluctuation noise; TFN
Abstract A systematic study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot-electron bolometers is presented. We have measured the spectrum of the output noise as well as the conversion efficiency over a very broad intermediate frequency range (from 0.1 to 7.5 GHz) for devices varying in length from 0.08 μm to 3 μm. Local oscillator and rf signals from 8 to 40 GHz were used. For a device of a given length, the spectrum of the output noise and the conversion efficiency behave similarly for intermediate frequencies less than the gain bandwidth, in accordance with a simple thermal model for both the mixing and thermal fluctuation noise. For higher intermediate frequencies the conversion efficiency decreases; in contrast, the noise decreases but has a second contribution which dominates at higher frequency. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, between 120 and 530 K (double side band).
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Call Number RPLAB @ gujma @ Serial 760
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Author Karasik, B. S.; Elantiev, A. I.
Title Noise temperature limit of a superconducting hot-electron bolometer mixer Type Journal Article
Year 1996 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume (down) 68 Issue 6 Pages 853-855
Keywords HEB mixer noise temperature, Johnson noise, thermal fluctuation noise, noise bandwidth
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Call Number Serial 260
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