Construction and use of a pulsed copper nuclear magnetic resonance thermometer

✍ Scribed by M.I. Aalto; P.M. Berglund; H.K. Collan; G.J. Ehnholm; R.G. Gylling; M. Krusius; G.R. Pickett

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 779 KB
• Volume: 12
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(72)90083-5

✦ Synopsis

A pulsed nuclear magnetic resonance thermometer, constructed for temperature measurements below O. 5 K, is described. The nuclear free precession signal of copper nuclei is recorded with a gated low noise amplifier and with a phase sensitive detector gated to integrate the signal over an adjustable number of periods. The physical significance of the signal is discussed. A comparison of the resonance thermometer against a slurry type cerium magnesium nitrate (CMN) thermometer for the temperature region lO mK to lOO mK is presented. The deviation A = TNM R --TCMN, representing the departure of the CMN thermometer from a Curie law behaviour, was measured as (0.5 +-0.2) mK. In experiments with a nuclear refrigeration cryostat the resonance thermometer was calibrated against a nuclear orientation thermometer which provided an independent absolute temperature standard. At the low temperature end, from 1 mK to 10 mK, the linearity of the thermometer in T "1 was confirmed by measurements of the nuclear spin-lattice relaxation time.