SUSPENSION OF SUPERFLUID-HELIUM USING CESIUM-COATED SURFACES

We report results of an experiment which demonstrates that a layer of superfluid helium can be suspended over a cesium-coated orifice. By me asuring the layer thickness with a capacitance bridge, we have shown i n two runs that fluid layers up to 2 mm thick were suspended over a 70 -mu m-diam cesium-coated orifice in a platinum foil for over 2 h in a cryostat held at 1.2 K. The effect depends on the recently established fact that superfluid helium does not wet cesium-coated surfaces. As a consequence, superfluid helium is expected to form a stable meniscus across such a cesium-coated hole. The observed depths of suspended hel ium are consistent with a simple theoretical model based an this pictu re. We briefly discuss the possible application of this method to the performance of a proposed experiment to study quantum coherence in sup erfluid helium by directing pulsed beams of helium atoms at such a sus pended layer of fluid.