Accession Number : ADA194237

Title :   CyroSQUID: A SQUID-Based Magnetic Field Sensor.

Descriptive Note : Technical rept. no. 3 (Final), 15 Aug 84-30 Nov 87,

Corporate Author : NEW YORK UNIV NY NEUROMAGNETISM LAB

Personal Author(s) : Williamson, S J ; Kaufman, Lloyd

PDF Url : ADA194237

Report Date : 15 Mar 1988

Pagination or Media Count : 16

Abstract : A new type of neuromagnetometer has been developed to enhance the capability for measuring the magnetic field of the human brain. This system - known as CryoSQUID - results from the marriage of two advanced technologies: a refrigerator incorporating closed-cycle operation of a pair of cryocoolers and a sensor incorporating the superconducting quantum interference device (SQUID). The apparatus is relatively small and requires no supply of liquid helium for initial cooling or operation. Only a source of electrical power is needed. Each sensor relies on a detection coil wound in the geometry of a second-order gradiometer so as to minimize the effects of ambient magnetic noise found in typical unshielded environments. The intrinsic noise level of CryoSQUID is comparable to a magnetic field sensitivity of 20 femtotesla within a one-hertz bandwidth. Residual noise at 1.2 Hz and its harmonics, contributed by the displacer in the Gifford-McMahon cooler, is virtually eliminated in real time by an adaptive filter run on a personal computer.

Descriptors :   *AMBIENT NOISE, *BRAIN, *INTERFERENCE, *MAGNETIC FIELDS, *REFRIGERATION SYSTEMS, *SUPERCONDUCTIVITY, ADAPTIVE FILTERS, CLOSED CYCLE SYSTEMS, COILS, COOLING, COOLING AND VENTILATING EQUIPMENT, CRYOGENICS, DETECTION, ELECTRIC POWER, ENVIRONMENTS, HARMONICS, HUMANS, LIQUID HELIUM, MAGNETIC PROPERTIES, MARRIAGE, MICROCOMPUTERS, NOISE, OPERATION, POWER SUPPLIES, QUANTUM THEORY, REAL TIME, RESIDUALS, SENSITIVITY, SHIELDING

Subject Categories : Anatomy and Physiology
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE