A SQUID gradiometer with trimmable additional positive feedback
Youichi Takada; Keiji Tsukada; Akira Adachi; Youichi Takada; Superconducting Sensor Laboratory, 2-1200 Muzaigakuendai Inzai, Chiba 270-13, Japan; Keiji Tsukada; Superconducting Sensor Laboratory, 2-1200 Muzaigakuendai Inzai, Chiba 270-13, Japan; Akira Adachi; Superconducting Sensor Laboratory, 2-1200 Muzaigakuendai Inzai, Chiba 270-13, Japan
Журнал:
Superconductor Science and Technology
Дата:
1996-04-01
Аннотация:
A SQUID gradiometer with a glass package and trimmable additional positive feedback (APF) is developed to achieve a low equivalent flux noise over a wide range of bias current. The noise characteristics of a SQUID with APF are investigated by varying the APF gain and the bias current. We found the most suitable APF parameter to achieve low equivalent flux noise over a wide range of bias current. When a SQUID with APF has a co-planar first-order coil whose effective area is , a typical gradiometer noise level of at 100 Hz and at 1 Hz is achieved.
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