Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

TL;DR

This paper discusses the development of superconducting Transition-edge sensor microcalorimeters and their Frequency Domain Multiplexing read-out for the Athena X-ray observatory's X-IFU instrument, aiming for high-resolution X-ray spectroscopy.

Contribution

It presents the design, physics, and current advancements of TES-based detectors and FDM read-out technology for the Athena mission's X-IFU instrument.

Findings

TES detectors achieve 2.5 eV energy resolution at 5.9 keV

FDM read-out enables MHz bandwidth multiplexing of thousands of TESs

Design optimizes filling-factor, quantum efficiency, and count-rate capability.

Abstract

The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3 -12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out.