DEVELOPMENT OF MAGNETIC-RESONANCE-IMAGING TECHNIQUE FOR ULTRA-LOW TEMPERATURE PHYSICS

We have developed a Magnetic Resonance Imaging (MRI) technique applica ble for ultra low temperature physics. In contrast to conventional MRI for general use where a pulsed-field gradient method is commonly used , toe used a steady-field gradient method to avoid an eddy current hea ting due to metallic parts around the sample cell. We applied the MRI for He-3 - He-4 mixture liquid with a critical concentration below 1 K and visualized the shape of the phase-separated boundary. We obtained two-dimensional space resolution of a few 10 mu m. We extracted the i nterfacial tension of the boundary which was in good agreement with re ported values. The contact angle of the boundary to the cell wall was small at low temperature and increased toward 90 degrees near the crit ical temperature.