Superconducting instrument systems

Abstract

Some recently developed superconducting instrument systems which are based upon the use of a highly reliable thin-film superconducting quantum interference device (SQUID) are discussed in detail. These SQUID's, which are shown to have a noise temperature of less than 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> K, are capable of measuring: 1) magnetic flux with a sensitivity of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> Gċcm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> rms/√Hz; 2) magnetic field with a sensitivity of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> G rms/√Hz; 3) magnetic field gradient with a sensitivity of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> (G/cm) rms/√Hz. We present construction details and performance data on systems capable of making the above measurements.