Developing X-ray microcalorimeters based on TiAu TES for HUBS

G. Wang*, M. Bruijn, K. Nagayoshi, M. Ridder, E. Taralli, L. Gottardi, H. Akamatsu, J. W. Den Herder, J. R. Gao, W. Cui

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

2 Citations (Scopus)


Hot Universe Baryon Surveyor (HUBS), a Chinese space mission, is proposed to find a large fraction of the so-called missing baryons, which would help us to understand more about the structure formation and evolution of the universe. Both theoretical and experimental results show that developing a highly efficient soft X-ray spectrometer over a large field of view and with a high energy resolution is the key to detect the “missing baryons”. X-ray microcalorimeters based on a transition-edge sensor (TES) array is required for HUBS, which aims to have 1 deg2 field of view (FoV) with 1' angular resolution and 2 eV energy resolution optimized around 0.6 keV. Taking the high throughput X-ray optical focusing system on HUBS into account, the TES array is designed to have 60 x 60 pixels with an area of 1 mm2 for each pixel. The microcalorimeter consists of a TES, a weak thermal link to a heat bath, and a semi-metal or normal metal absorber to increase the X-ray absorption efficiency. When an X-ray photon with a given energy is absorbed, the temperature of the absorber increase, that can be monitored by measuring the resistance change of the TES. A bilayer of a superconductor and a normal metal is used to fabricate a TES with a critical temperature (Tc) of ~100 mK. The latter is set for the required energy resolution. For HUBS, both MoCu and TiAu TES technologies are considered in its development phase. Here we will focus on TiAu TES calorimeters designed and partially fabricated at SRON for HUBS. Recent demonstration of a resolution of 2.5 eV at 5.9 keV in an AC readout at SRON for X-IFU on board of Athena illustrates the promising of this technology. However, the challenging for the HUBS array is the large pixel size. We will report the design and fabrication of prototype HUBS calorimeters.

Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation 2020
Subtitle of host publicationUltraviolet to Gamma Ray
EditorsJan-Willem A. den Herder, Shouleh Nikzad, Kazuhiro Nakazawa
Number of pages9
ISBN (Electronic)9781510636750
Publication statusPublished - 2020
EventSpace Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray - Virtual, Online, United States
Duration: 14 Dec 202018 Dec 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSpace Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray
Country/TerritoryUnited States
CityVirtual, Online


  • BiAu absorber
  • HUBS
  • TiAu bilayer
  • Transition edge sensor
  • X-ray microcalorimeter


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