摘要
A dual-washer superconducting quantum interference device （SQUID） with a loop inductance of 350 pH and two on- washer integrated input coils is designed according to conventional niobium technology. In order to obtain a large SQUID flux-to-voltage transfer coefficient, the junction shunt resistance is selected to be 33 Ω. A vertical SQUID gradiometer module with a baseline of 100 mm is constructed by utilizing such a SQUID and a first-order niobium wire-wound antenna. The sensitivity of this module reaches about 0.2 fT/（cm.Hz1/2） in the white noise range using a direct readout scheme, i.e., the SQUID is directly connected to an operational amplifier, in a magnetically shielded room. Some magnetocardiography （MCG） measurements with a sufficiently high signal-to-noise ratio （SNR） are demonstrated.
A dual-washer superconducting quantum interference device （SQUID） with a loop inductance of 350 pH and two on- washer integrated input coils is designed according to conventional niobium technology. In order to obtain a large SQUID flux-to-voltage transfer coefficient, the junction shunt resistance is selected to be 33 Ω. A vertical SQUID gradiometer module with a baseline of 100 mm is constructed by utilizing such a SQUID and a first-order niobium wire-wound antenna. The sensitivity of this module reaches about 0.2 fT/（cm.Hz1/2） in the white noise range using a direct readout scheme, i.e., the SQUID is directly connected to an operational amplifier, in a magnetically shielded room. Some magnetocardiography （MCG） measurements with a sufficiently high signal-to-noise ratio （SNR） are demonstrated.
基金
Project supported by the Main Direction Program of Knowledge Innovation of the Chinese Academy of Sciences(Grant No.KGCX2-EW-105)
the "100 Talents Project" of the Chinese Academy of Sciences and Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB04020200)
