ANDREEV REFLECTION OF A BEAM OF BALLISTIC QUASI-PARTICLE EXCITATIONS INCIDENT ON A STATIC B-A PHASE INTERFACE IN SUPERFLUID HE-3

We have attempted to observe the Andreev reflection of a beam of balli stic quasiparticle excitations as it impinges on a static B-A phase in terface. The beam is created, and the Andreev reflected component meas ured, by the quasiparticle equivalent of a blackbody radiator. The A-p hase is stabilized at low temperature and pressure by a magnetic field which is generated by a miniature superconducting solenoid, situated next to the radiator orifice and which provides the necessary 0.34 T f ield in a small, localized region. Preliminary results indicate that w e can observe Andreev reflection both from the high-field distorted B- phase energy gap and from the larger equatorial A-phase energy gap.