A large number of low temperature detectors may be read out via few wires using frequency division multiplexing. In this scheme, each detector is biased by a sine wave with a unique carrier ...frequency. Numerous carriers can be combined in a single pair of wires. However, the combined signals occasionally result in large peak amplitudes in the bias or the readout. This stresses the capabilities of the electronics. We developed an efficient algorithm to optimize the phases and frequencies of the carriers in order to obtain a low crest factor. We also find that more regularly spaced carrier frequencies result in a lower crest factor, compared to irregularly spaced carriers.
TiAu-based micro-calorimeters for space applications Dirks, B.P.F.; Popescu, M.; Bruijn, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2009, Volume:
610, Issue:
1
Journal Article
Peer reviewed
We present the latest results of the performance of micro-calorimeters based on transition edge sensors (TESs) for space applications. Sensors based on TiAu superconductive layers with Cu/Bi ...absorbers are discussed and have been characterized. Different coupling schemes between absorber and TES have been tested leading to an optimal (preferred) design for a new batch of arrays. We discuss the progress on array development for the International X-ray Observatory (IXO) in terms of pixel uniformity and filling factor. Inter-pixel cross-talk is discussed as well.
We present results of the analysis of electrical noise in a transition edge sensor (TES) as a resistively shunted conducting junction (the RSJ model). We derive an expression for the spectral density ...of voltage fluctuations taking into account weak superconductivity of a TES. We analyse and discuss differences in voltage noise in a TES compared to the familiar situation for the Josephson junction. The spectral density of voltage noise in the RSJ model has a unique analytical structure and cannot be reduced to the expression for the nonlinear Johnson noise near equilibrium.
Transition-edge-sensor (TES) bolometers are the chosen detector technology for the SAFARI Imaging Spectrometer on the SPICA telescope. For this mission, SRON is developing bolometers, each consisting ...of a TiAu TES that is weakly coupled to the thermal bath through thin legs of silicon nitride. In order to understand and optimize the bolometer and to verify our detector models, we characterize the devices using a series of complex impedance measurements. We apply equivalent bolometer analysis (EBA) in combination with model fitting to these data. From this analysis, we obtain important parameters that give us confidence in our understating of the response and noise of these sensitive detectors.
Seven microcalorimeters with different geometries have been tested and their performance is compared. The study, for TiAu TESs with a Cu absorber, indicates the presence of so-called constant voltage ...noise and internal thermal fluctuation noise. The constant voltage noise is not changed by a normal metal pattern on the TES, or by a magnetic field. The energy resolution of the detectors, having different heat capacities, is 2.5 and 5.0 eV (at 5.9 keV).
Drug-induced liver injury (DILI) is the leading cause of acute liver failure. Currently, no adequate predictive biomarkers for DILI are available. This study describes a translational approach using ...proteomic profiling for the identification of urinary proteins related to acute liver injury induced by acetaminophen (APAP). Mice were given a single intraperitoneal dose of APAP (0-350 mg/kg bw) followed by 24 h urine collection. Doses of ≥275 mg/kg bw APAP resulted in hepatic centrilobular necrosis and significantly elevated plasma alanine aminotransferase (ALT) values (p<0.0001). Proteomic profiling resulted in the identification of 12 differentially excreted proteins in urine of mice with acute liver injury (p<0.001), including superoxide dismutase 1 (SOD1), carbonic anhydrase 3 (CA3) and calmodulin (CaM), as novel biomarkers for APAP-induced liver injury. Urinary levels of SOD1 and CA3 increased with rising plasma ALT levels, but urinary CaM was already present in mice treated with high dose of APAP without elevated plasma ALT levels. Importantly, we showed in human urine after APAP intoxication the presence of SOD1 and CA3, whereas both proteins were absent in control urine samples. Urinary concentrations of CaM were significantly increased and correlated well with plasma APAP concentrations (r = 0.97; p<0.0001) in human APAP intoxicants, who did not present with elevated plasma ALT levels. In conclusion, using this urinary proteomics approach we demonstrate CA3, SOD1 and, most importantly, CaM as potential human biomarkers for APAP-induced liver injury.
SRON is developing an electronic read-out system for an array of Transition-Edge Sensors (TES) which combines the techniques of Frequency Domain Multiplexing (FDM) with Base-Band FeedBack (BBFB). Its ...potential astronomical applications are in the read-out of soft X-ray microcalorimeters of the XMS instrument on the International X-ray Observatory (IXO) and the far-IR bolometers of the SAFARI instrument on the Japanese-European mission SPICA. In this paper we focus on the experimental verification of the system, demonstrating for 16 pixels that simultaneous read-out does not degrade the noise performance, and that crosstalk between pixels is close to the requirements for IXO. A detailed analysis of the BBFB system is presented, identifying its limitations and routes for improvement to the levels required for implementation on both missions.
We fabricated and characterized a low thermal conductance ( G ) transition edge sensor (TES). The device is based on a superconducting Ti/Au bilayer deposited on a suspended SiN membrane. The ...critical temperature of the device is 155 mK. The low thermal conductance is realized by using narrow SiN ring-like supporting structures. All measurements were performed having the device in a light-tight box, which to a great extent eliminates the loading of the background radiation. We measured the current-voltage (IV) characteristics of the device in different bath temperatures and determine the thermal conductance ( G ) to be equal to 1.66 pW/K. This value corresponds to a noise equivalent power (NEP) of 1×10 -18 W/√Hz. The current noise and complex impedance are also measured at different bias points at 25 mK bath temperature. The measured electrical (dark) NEP is 2×10 -18 W/√Hz, which is about a factor of 2 higher than what is expected from the thermal conductance that comes out of the IV curves analysis. We also measured the complex impedance of the same device at several bias points. Fitting a simple first order thermal-electrical model to the measured data, we find an effective time constant of about 62 μs and a thermal capacity of 3 fJ/K.
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