High aspect ratio rectangular pixels may increase the resolution of X-ray telescopes
DOI: 10.1063/10.0002862
High aspect ratio rectangular pixels may increase the resolution of X-ray telescopes lead image
Transition Edge Sensors (TESs) use the temperature dependence of superconducting transitions to measure the energy of individual photons. Because of their outstanding energy resolving ability, TESs may help improve the capability of next-generation X-ray space telescopes. De Wit et al. demonstrate how redesigning TES pixels might lead to more robust X-ray imaging.
A TES telescope would contain thousands of TES pixels whose readouts are combined and processed using a technique known as multiplexing. Many TES systems use time domain multiplexing (TDM), which uses a DC-bias to readout each TES. The authors explored an alternative readout technique known as frequency domain multiplexing (FDM), which uses AC-bias.
Both TDM and FDM require pixels specifically designed to match the readout. The authors explored different TES designs to optimize FDM readout performance. They examined Ti/Au bilayers of various dimensions, ranging from a long and narrow 120-by-20 micrometers to a squat 80-by-40.
They observed how the critical temperature of the superconducting transition and thermal conductance depend on the pixel dimensions. Among their tested devices, the one with the highest aspect ratio was able to measure 5.9 keV X-rays with an energy resolution of 1.63±0.17 eV, the highest resolution ever achieved using FDM, and comparable with the best TDM pixels.
Although further research is required to integrate thousands of FDM pixels into a detector array, de Wit said, “From a single pixel point of view, we have finally managed to bridge the gap between FDM and TDM in this paper.”
Source: “High aspect ratio transition edge sensors for x-ray spectrometry,” by M. de Wit, L. Gottardi, E. Taralli, K. Nagayoshi, M. L. Ridder, H. Akamatsu, M. P. Bruijn, M. D’Andrea, J. van der Kuur, K. Ravensberg, D. Vaccaro, S. Visser, J.R. Gao, and J.-W.A. den Herder, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/5.0029669 .
