Collin Arocho
14 December 2020

Scientists at the Netherlands Institute for Space Research (SRON) have developed five new pixel designs for X-ray telescopes. The designs will be used in ESA’s upcoming Athena space telescope, allowing it to study X-ray emissions from galaxies and enable unprecedented energy resolutions, including the ability to distinguish a rainbow of up to 2,000 distinct colors. Researchers determined the pros and cons of each design based on the goal of specific X-ray missions and have recently published their findings in the Journal of Applied Physics

Optical microscope picture of transition-edge sensors (TES). The central yellow area is the TES itself, with two ears where the absorber is connected. The reddish lines are the niobium leads. The blueish squares show the outline of the silicon nitride membrane on which the TES is grown to decouple it from the thermal bath. Credit: SRON

The pixels of Athena’s X-ray cameras use transition-edge sensors (TES), which measure the energy of individual photons by balancing on the verge of being superconducting. When a TES absorbs a photon, this causes a small change in temperature leading to a dramatic reduction of the superconducting state and therefore a large increase in the resistance of the TES, proportional to the energy of the measured photon. Athena will be equipped with nearly 4,000 TES pixels. Scientists at SRON have optimized the frequency domain multiplexing (FDM), where all pixels are combined into a single readout chain using only one amplifier for simultaneous readout by using alternating currents at different frequencies and greatly reducing power consumption.