Pressure-driven mass flow in solid 4He

We report on two experiments that explore pressure-driven flow in solid 4He. In the first experiment, two pancake-shaped chambers are connected by a narrow slit. The pressure in one chamber is varied periodically at 2 mHz and we look for a superfluid pressure response in the second chamber. When the cell is filled with liquid, we observe a large pressure signal in the second chamber as expected for superfluid flow. In solid helium, no pressure response is detected outside the noise level. In a second experiment, we generate an oscillating pressure in a torsional oscillator by blocking an annulus. We expect the pressure difference to drive the supersolid component through a radial channel orthogonal to the rotational motion of the oscillator.