A SQUID gradiometer module with large junction shunt resistors  

作　　者：邱阳 刘超 张树林 张国峰 王永良 李华 曾佳 孔祥燕 谢晓明 

机构地区：[1]State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT),Chinese Academy of Sciences (CAS) [2]Joint Research Laboratory on Superconductivity and Bioelectronics, Collaboration between CAS-Shanghai [3]University of Chinese Academy of Sciences

出　　处：《Chinese Physics B》2014年第8期622-624,共3页中国物理B（英文版）

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)

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.

关 键 词：SQUID GRADIOMETER MAGNETOCARDIOGRAPHY 

分 类 号：O413[理学—理论物理]