velocity of second sound om 4He at 0.86K is 23.00 m/sec (Ref Table 12, page
239, Experimental Superfluidity by R. J. Donnelly. Chicago, 1967). Could
not find lower value. Karl
Dr. Karl I. Trappe Desk Phone: (512) 471-4152
Physics Dept, Mail Stop C-1600 Demo Office: (512) 471-5411
The University of Texas at Austin Home Phone: (512) 264-1616
Austin, Texas 78712-1081