Optimization of pick-up coils for weakly damped SQUID gradiometers

Yang Kang^{1, 2, 3}, Wang Jialei^{1, 2, 3}, Kong Xiangyan^{1, 2, 3, †}, Yang Ruihu^{1, 2, 3}, Chen Hua^{1, 2, 3}

(color online) (a) Layout of the SQUID. (b) The first-order gradiometer with baseline of 50 mm. (c) Four-channel verification system in MSR.