A superconducting magnetic shield of high-T_csuperconductor Bi(Pb)-Sr-Ca-Cu-O_x has been constructed whosediameter is 65 cm and length is 160 cm. We have successfullyobserved magnetic fields from somatosensory-evoked humanbrains in the superconducting magnetic shield by stimulating themedian nerves of patients by current pulses. We made a 64-channelwhole-head SQUID magnetometer of superconductorormalmetal/superconductor (SNS) junctions which do not show low-frequency telegraph noise. The sensitivities of the dc SQUIDmesoscopic SNS junctions are around 5 fT Hz~-1/2 even in ratherunfavourable surroundings. The magnetic shield can reduce amagnetic field by around -80 dB or a factor of 10~-4 even at aslow a frequency as 0.05 Hz. Therefore SQUIDs of SNS junctionsand a superconducting magnetic shield are a good combination.
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机译：构造了高T_c超导体Bi（Pb）-Sr-Ca-Cu-O_x的超导磁屏蔽，其直径为65 cm，长度为160 cm。通过用电流脉冲刺激患者的theme神经，我们已经成功地观察了超导磁屏蔽中体感诱发的人脑的磁场。我们制作了不显示低频电报噪声的超导体/标准金属/超导体（SNS）结的64通道全头SQUID磁力计。即使在不利的环境中，直流SQUID介观SNS结的灵敏度约为5 fT Hz〜-1 / 2。即使在低至0.05 Hz的频率下，电磁屏蔽也可以将磁场降低-80 dB左右或10〜-4倍。因此，SNS结的SQUID和超导磁屏蔽是很好的组合。
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