Ultrasonic attenuation in sodium at low temperatures

The ultrasonic attenuation in a wire sample of sodium was measured by pulse-echo and resonant techniques over a temperature range of 2°–77°K at frequencies of 150–300 kc in order to investigate the effects of the martensitic transformation and the electron-lattice interaction. The onset of the transformation into the low temperature h.c.p. structure was indicated by an increase in the attenuation which then decreased as absolute zero was...