MAGNETOCARDIOGRAMS TAKEN INSIDE A SHIELDED ROOM WITH A SUPERCONDUCTING POINT-CONTACT MAGNETOMETER

Abstract
A point‐contact (SQUID) magnetometer was used inside a shielded room to record the magnetic field of the human heart, without noise‐averaging. The resulting magnetocardiograms, with the peak signal at about 3 × 10−7 G had a noise level of about 1 × 10−9 G (rms, per root cycle). They approach good medical electrocardiograms in clarity, and are an order‐of‐magnitude improvement in sensitivity over previous magnetic detectors of the heart. These results suggest new medical uses for this magnetometer.