A Transition Edge Sensor (TES) is a kind of microcalorimeter or bolometer utilizing super-conducting film as a thermometer. Attached with an absorber of small heat capacitance at low temperature (< a few x 100 mK), a small heat input caused by an irradiated particle can be measured accurately. As an example, an energy resolution ΔE<2 eV for X-ray is achieved[1 and reference therein], and optical photon counting with 67 meV is reported[2]. This presentation will introduce many applications of this device that are being used and planned. After a sounding rocket experiment[3], future X-ray telescopes (ex. Athena[4], LEM[5]) and will adopt a TES microcalorimeter array and a Cosmic Microwave Background (CMB) mission LiteBIRD[6] will use TES bolometers. In particle physics, many dark matter search experiments (ex. CRESST[7], ALPS[8]) use TES high sensitivity and accurate energy determination by TES are required to measure energy levels in Kaonic atom[9] and 229 Th[10]. We conducted a Solar axion direct search experiment with a TES array with a57Fe absorber[12] and a test run was done in 2024.
To expand the field of application, a large format array and its readout method is essential. The original TES readout was done by a DC-SQUID amperemeter coupled with a TES. Multiplexing methods such as frequency-domain multiplexing (FDM) [13] and time-domain multiplexing (TDM) [14] are proposed to reduce the number of harnesses in refrigerators. ISAS and AIST collaborated to develop a microwave SQUID multiplexing (MWMUX) method with RF-SQUID and succeeded in reading 38 pixels by one channel[15]. These methods will be used in future applications, such as plasma diagnostics, and material analysis in combination with electron microscopes.
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[4] Barret, D. et al., Experimental Astronomy 55, 373 (2023)
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[6] Westbrook et al., Proc. SPIE Int. Soc. Opt. Eng. 11443, 11435Q (2020)
[7] Rothe, J et al. J. of Low Temp Phys, 193, 1160(2018)
[8] Gimeno, A. et al. NIM A, 1046, 167588 (2023)
[9] Hashimoto, S. et al., Phys. Rev. Lett, 128, 112503 (2022)
[10] Yamaguchi, A., et al., Phys. Rev. Lett, 123, 222501 (2019)
[12] Yagi, Y. et al., IEEE Tran. App. Supercon, 33(5), 2100805 (2023)
[13] Akamatsu, H. et al. Applied Physics Letters 119(18), 182601(2021)
[14] Doriese, W.B. et al. J. of Low Temp Phys, 184, 389(2016)
[15] Nakashima, Y. et al. App. Phys. Lett, 117 122601 (2020)
This work was supported by JSPS KAKENHI Grant Number 20H05857. Our research was partially preformed in the nano-electronics clean room in Institute of Space and Astronautical Institute (ISAS) and CRAVITY (Clean Room for Analog and digital superconductiVITY) at AIST.