ULTRASONIC VELOCITY DETERMINATION OF THE PHASE-DIAGRAM OF UPT3

We report ultrasonic velocity measurements on two UPt3 samples with three different field orientations (H-perpendicular-to-c, H-parallel-to-c and H-tripple-over-that-c = 45-degrees). Velocity changes are observed at constant temperatures, as the field is swept, at the upper critical fiel H(c2) and at the flux lattice transition H(fl). Velocity changes are also observed at T(c)+ the upper transition temperature and T(c)- the lower transition temperature as the temperature is swept at constant fields. Complete phase diagrams for UPt3 obtained by a single measurement technique on the same samples in the H-T plane are presented.