HE-3 MELTING CURVE THERMOMETRY IN A NUCLEAR-POLARIZATION EXPERIMENT

Temperature measurement and control are important in brute force polarization experiments. We discuss the installation and use of He-3 melting curve thermometers in a cryostat used to polarize a TiH2 target. Comparison is made between the melting curve thermometers and the (CoCo)-Co-60 nuclear orientation thermometer, which is often used in such experiments. The melting curve thermometers provide increased temperature resolution and sensitivity, and were used in a feedback heating system to control temperature to +/- 5.5 muK at 16.5 mK. The He-3 melting curve and the (CoCo)-CO-60 temperature scales are found to agree within 2% at 15 mK. The present status of the melting curve scale and the effect of a magnetic field on melting curve thermometry am also discussed.