Simplified magnetically shielded cylinder using flexible magnetic sheets for high-T-c superconducting quantum interference device magnetocardiogram systems

A small and simple magnetic-shielding cylinder using a new high-permeabilit y sheet, developed for magnetic shielding, can reduce the amount of effort expended on taking magnetocardiogram (MCG) measurements. This sheet is made of a nanocrystalline soft-magnetic material (an Fe-Cu-Nb-Si-B alloy) and i s flexible and easy to handle. Moreover, magnetostriction of the material i s nearly zero, unlike that of the materials used in conventional magnetic s hielding. The shielding cylinder is made up of three tubes of various diame ters (but having the same length), placed one inside the other. The shieldi ng cylinder is 1.0 m in diameter and 2.0 m long, and it has a shielding fac tor of about 35 dB at 1 Hz. The shielding cylinder was tested by measuring MCGs using a high-T-c superconducting quantum interference device (SQUID) g radiometer.