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Journal of Low Temperature Physics

, Volume 193, Issue 3–4, pp 203–208 | Cite as

Optimization of Geomagnetic Shielding for MKIDs Mounted on a Rotating Cryostat

  • Hiroki Kutsuma
  • Makoto Hattori
  • Kenji Kiuchi
  • Satoru Mima
  • Taketo Nagasaki
  • Shugo Oguri
  • Junya Suzuki
  • Osamu Tajima
Article

Abstract

Superconducting detectors, such as microwave kinetic inductance detectors (MKIDs), are sensitive to the effects of ambient magnetic fields. There are two effects magnetic fields have on the response of MKIDs; the trapping of magnetic fields inside the superconducting materials degrades the resonator quality, and the time variation of the magnetic fields results in a baseline fluctuation. In the case of radio astronomy, this means the detector must be protected from the geomagnetic field. Here, we construct a test system to evaluate the effects described. We also evaluate the impact of the magnetic shield. We find that a shielding power of 47 dB is necessary in the case of application with a noise equivalent power of \(2.4 \times 10^{-16}\,\text {W}/\sqrt{\text {Hz}}\). We also confirm that the measured shielding power obtained using permalloy films is consistent with simulations based on the finite element method to an accuracy of 1 dB. We have designed magnetic shields for the GroundBIRD CMB telescope using these results. We achieve a sufficient shielding power of 55 dB.

Keywords

Microwave kinetic inductance detector Magnetic shield Cosmic Microwave Background Radiation 

Notes

Acknowledgements

This work was supported by Grants-in-Aid for Scientific Research from The Ministry of Education, Culture, Sports, Science and Technology, Japan (KAKENHI Grant Nos. 15H05743, 15H05448, 16J09435). I am deeply grateful to Koji Ishidoshiro, Keishi Hosokawa, and Atsushi Ohno of the Research Center for Neutrino Science, Tohoku University and Tomoka Okada of the Tohoku University Astronomical Institute.

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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Hiroki Kutsuma
    • 1
  • Makoto Hattori
    • 1
  • Kenji Kiuchi
    • 2
  • Satoru Mima
    • 3
  • Taketo Nagasaki
    • 4
  • Shugo Oguri
    • 3
  • Junya Suzuki
    • 4
  • Osamu Tajima
    • 5
  1. 1.Astronomical InstituteTohoku UniversitySendaiJapan
  2. 2.Department of PhysicsThe University of TokyoTokyoJapan
  3. 3.RIKENWakoJapan
  4. 4.High Energy Accelerator Research Organization (KEK)TsukubaJapan
  5. 5.Department of PhysicsKyoto UniversityKyotoJapan

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