title: Note: low temperature superconductor superconducting quantum interference device system with wide pickup coil for detecting small metallic particles.
abstract: A one-channel low temperature superconductor superconducting quantum interference device system comprising a second-order axial gradiometer with a sensing area of 10 mm × 190 mm was developed. The gradiometer was mounted in a liquid-helium dewar (450-mm diameter; 975-mm length), with a gap of 12 mm between the pickup coil and the dewar-tail surface. The magnetic field sensitivity was measured to be 16 fT/Hz(1/2) in the white noise regime above 2 Hz. The system was used to measure stainless steel particles of different sizes passing through the sensing area. A 100-μm diameter SUS304 particle was readily detected passing at different positions underneath the large pickup coil by measuring its 1.3-pT magnetic field. Thus, the system was shown to be applicable to quality control of lamination sheet products such as lithium ion batteries.
authors.affiliation: Central Research Laboratory, Hitachi, Ltd., 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan. akihiko.kandori.vc@hitachi.com
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kandori
authors.forename: Kuniomi
authors.initials: K
authors.lastname: Ogata
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Kawabata
authors.forename: Sayaka
authors.initials: S
authors.lastname: Tanimoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Seki