The design of a 7-channel DC-SQUID gradiometer system for brain research is discussed. The system is based on high-quality DC-SQUIDs made by IBM. The flux transformer system consists of seven identical wire-wound asymmetric axial first order gradiometers in a hexagonal array. The pickup loop diameter is 20 mm, and the base length 60 mm. The lower ends of the gradiometers are on the curved bottom surface of a dewar with a 125 mm radius of curvature. The diameter of the active measurement area is 94 mm. The DC-SQUIDs are matched to FET preamplifiers using superconducting resonant transformers. The preamplifiers are connected to detector/controller units located in a separate RF-shielded cabinet outside of the magnetically shielded room. The digitized outputs of the detectors are sent to a set of signal processors via a fiber optic link.
|Title of host publication||Proceedings of the International Cryogenic Engineering Conference, ICEC 11|
|Editors||Gustav Klipping, Ingrid Klipping|
|Number of pages||5|
|Publication status||Published - 1 Dec 1986|
|MoE publication type||A4 Article in a conference publication|