Elastic constants of bcc 4He

Longitudinal and transverse sound velocities have been measured in single crystals of bcc 4He at a molar volume of 21.00 cm3. The samples were grown at nearly constant pressure in a plastic freezing cell by lowering the temperature of the copper freezing tip from just above the melting temperature to a temperature a few mK above the bcc→hcp phase transition. Data were taken on 61 crystals. A weighted least-squares fitting of the velocity data yielded the elastic constants. (Auth.)