EVALUATION OF VELOCITY OF ZERO-SOUND IN LIQUID-HE-4

The experimental value 238 m/s for the velocity of zero-sound in liqui d He-4 by solving the equation for phonon frequency in two methods has been reproduced. In one method, we have developed a scheme for BE dis tribution function which has one to one correspondence with FD distrib ution and other is a more direct method of evaluation. We have calcula ted the value of Bose velocity equal to 65 m/s and Bose energy equal t o 0.92 K for liquid He-4 analogous to Fermi velocity of 165;35 m/s and Fermi energy equal to 4.96 K for liquid He-3.