Performance of Mo/Au TES microcalorimeters
08 Mar 2002-Vol. 605, Iss: 1, pp 203-206
TL;DR: In this paper, a transition-edge-sensor (TES) thermometer is used for X-ray calorimeters to meet the specifications of the Constellation-X mission.
Abstract: We are developing X-ray calorimeters to meet the specifications of the Constellation-X mission. Each calorimeter consists of a transition-edge-sensor (TES) thermometer, which is suspended on a silicon-nitride membrane. Our TES thermometers are Mo/Au bilayer films that are biased in the sharp phase transition between the superconducting and normal-metal states. These calorimeters have demonstrated very good energy resolutions: 2.4 eV at 1.5 keV and 3.7 eV at 3.3 keV. The energy resolutions are limited by thermal noise and Johnson noise (which are intrinsic to any resistive calorimeter) plus excess noise. The excess noise, which is several times larger than the Johnson noise, is consistent with frequency-independent voltage noise in the TES. Detailed measurements of one Mo/Au TES demonstrate that the excess noise is independent of the voltage applied to the TES over a range of biases at the same TES resistance. The magnitude of the excess noise is smallest at the high-resistance end of the phase transition. We also compared noise in square Mo/Au TES’s ranging in size from 300 microns to 600 microns to learn how the excess noise is affected by the geometry of the TES.
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TL;DR: In this article, the authors measured the complex impedance of a Mo/Au superconducting transition-edge-sensor (TES) calorimeter and obtained measurements of unprecedented accuracy of the heat capacity and the gradient of resistance with respect to temperature and current.
Abstract: We describe a method for measuring the complex impedance of transition-edge-sensor (TES) calorimeters. Using this technique, we measured the impedance of a Mo/Au superconducting transition-edge-sensor calorimeter. The impedance data are in good agreement with our linear calorimeter model. From these measurements, we obtained measurements of unprecedented accuracy of the heat capacity and the gradient of resistance with respect to temperature and current of a TES calorimeter throughout the phase transition. The measurements probe the internal state of the superconductor in the phase transition and are useful for characterizing the calorimeter.
121 citations
TL;DR: In this article, the fundamental noise processes contributing to transition edge sensor (TES) microcalorimeters and bolometers and their effect on device performance are reviewed. But the authors do not consider the effect of external noise on TES.
Abstract: Microcalorimeters and bolometers are noise-limited devices, therefore, a proper understanding of all noise sources is essential to predict and interpret their performance. In this paper, I review the fundamental noise processes contributing to Transition Edge Sensor (TES) microcalorimeters and bolometers and their effect on device performance. In particular, I will start with a simple, monolithic device model, moving to a more complex one involving discrete components, to finally move to today's more realistic, comprehensive model. In addition to the basic noise contribution (equilibrium Johnson noise and phonon noise), TES are significantly affected by extra noise, which is commonly referred to as “excess noise”. Different fundamental processes have been proposed and investigated to explain the origin of this excess noise, in particular near equilibrium non-linear Johnson noise, flux-flow noise, and internal thermal fluctuation noise. Experimental evidence shows that all three processes are real and contribute, at different levels, to the TES noise, although different processes become important at different regimes. It is therefore time to discard the term “excess noise” and consider these terms part of the “fundamental noise processes” instead.
18 citations
Cites background from "Performance of Mo/Au TES microcalor..."
...behavior of thermistor-based devices [2], as soon as research groups started modeling the behavior of TES devices it was clear the presence of additional noise, dubbed “excess noise” [8]–[10]....
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TL;DR: In this paper, the authors studied the origin of excess noise in superconducting transition-edge sensors (TES) with several different detector designs and showed that most of the observed noise and complex impedance features can be explained by a thermal model consisting of three bodies.
Abstract: We have studied the origin of excess noise in superconducting transition-edge sensors (TES) with several different detector designs. We show that most of the observed noise and complex impedance features can be explained by a thermal model consisting of three bodies. We suggest that one of the thermal blocks and the corresponding thermal fluctuation noise arises due to the high-frequency thermal decoupling of the normal and superconducting phase regions inside the TES film. Our results are also consistent with the prediction that in thin bilayer proximitized superconductors, the jump in heat capacity at the critical temperature is smaller than the universal BCS theory result.
16 citations
TL;DR: In this article, the authors studied the origin of excess noise in superconducting transition-edge sensors (TES) with several different detector designs and showed that most of the observed noise and complex impedance features can be explained by a thermal model consisting of three bodies.
Abstract: We have studied the origin of excess noise in superconducting transition-edge sensors (TES) with several different detector designs. We show that most of the observed noise and complex impedance features can be explained by a thermal model consisting of three bodies. We suggest that one of the thermal blocks and the corresponding thermal fluctuation noise arise due to the high-frequency thermal decoupling of the normal and superconducting phase regions inside the TES film. Our results are also consistent with the prediction that in thin bilayer proximitized superconductors, the jump in heat capacity at the critical temperature is smaller than the universal BCS theory result.
15 citations
01 Jan 2008
TL;DR: In this article, the performance of light detectors for the CRESST-II experiment has been investigated, focusing on their sensitivity and energy dependence of their energy resolution in the relevant signal range.
Abstract: The CRESST-II experiment attempts to detect hypothetical Weakly Interacting Massive Particles (WIMPS) via elastic scattering off nuclei in a scintillating CaWO4 crystal. Efficient discrimination of the searched nuclear recoil signal from the dominant gamma and beta background is achieved by simultaneously measuring a heat signal in the CaWO4 crystal, operated as a cryogenic calorimeter, and the amount of the scintillation light with a separate small cryogenic calorimeter optimized for light detection. Since the energy emitted in the form of scintillation light is typically only a few percent of the energy deposited in the target crystal, the discrimination efficiency depends strongly on the sensitivity and the resolution of the light detector.
This work reports on the performance of cryogenic light detectors developed for the CRESST-II experiment.
Particular attention is given to the investigation of their sensitivity and to the energy dependence of their energy resolution in the relevant signal range.
13 citations
Cites background from "Performance of Mo/Au TES microcalor..."
...understood, but it is quite common for SPTs and many experimental groups have observed large noise when detectors are operated in the lower part of the transition (see for example [Lindeman et al., 2002][Fujimoto et al....
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