SUPERFLUID VORTICITY AND 1 F NOISE IN MELTING OF SOLID HE-4/

One of the ways to reach a zero-vorticity state in superfluid He-4 is to melt solid helium slowly at temperatures well below T-lambda. This method takes advantage of the small density difference between the liq uid and solid phases and of the high critical velocities for vortex fo rmation at low T. However, pinning of the liquid-solid interface on th e walls, revealed by 1/f-like pressure fluctuations of up to 1-10 mu b ar in our setup, has consistently led to remanent vortex line densitie s of similar to 4 . 10(3) lines per cm(2).