A 64-channel whole-head SQUID system in a superconducting magnetic shield

Authors
Ohta, H Matsui, T Aono, M Uchikawa, Y Kobayashi, K Tanabe, K Takeuchi, S Narasaki, K Tsunematsu, S Koyabu, Y Kamekawa, Y Nakayama, K Shimizu, T Koike, J Hoshino, K Kotaka, H Sudoh, E Takahara, H Yoshida, Y Shinada, K Takahata, M Yamada, Y Kamijo, K
Citation
H. Ohta et al., A 64-channel whole-head SQUID system in a superconducting magnetic shield, SUPERCOND S, 12(11), 1999, pp. 762-765
Citations number
4
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
ISSN journal
09532048 → ACNP
Volume
12
Issue
11
Year of publication
1999
Pages
762 - 765
Database
ISI
SICI code
0953-2048(199911)12:11<762:A6WSSI>2.0.ZU;2-P
Abstract
A superconducting magnetic shield of high-T-c superconductor Bi(Pb)-Sr-Ca-C u-O-x has been constructed whose diameter is 65 cm and length is 160 cm. We have successfully observed magnetic fields from somatosensory-evoked human brains in the superconducting magnetic shield by stimulating the median ne rves of patients by current pulses. We made a 64-channel whole-head SQUID m agnetometer of superconductor/normal metal/superconductor (SNS) junctions w hich do not show low-frequency telegraph noise. The sensitivities of the de SQUID mesoscopic SNS junctions are around 5 fT Hz(-1/2) even in rather unf avourable surroundings. The magnetic shield can reduce a magnetic field by around -80 dB or a factor of 10(-4) even at as low a frequency as 0.05 Hz. Therefore SQUIDs of SNS junctions and a superconducting magnetic shield are a good combination.