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

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


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 2.4×10-16W/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.

Original languageEnglish
Pages (from-to)203-208
Number of pages6
JournalJournal of Low Temperature Physics
Issue number3-4
Publication statusPublished - 2018 Nov 1


  • Cosmic Microwave Background Radiation
  • Magnetic shield
  • Microwave kinetic inductance detector

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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