skip to main content

Title: High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2 fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.
Authors:
;  [1] ;  [2] ; ;  [3] ;  [3] ;  [4] ;  [1]
  1. College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061 (China)
  2. (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany)
  3. Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany)
  4. (Korea, Republic of)
Publication Date:
OSTI Identifier:
22392244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DESIGN; KHZ RANGE; MAGNETIC FIELDS; NUCLEAR MAGNETIC RESONANCE; SENSITIVITY; SIGNALS; SQUID DEVICES; SWITCHES