Possibility of a Phase Transition in the Pure Helium Isotope of Mass 3

Abstract

Sydoriak, Crilly and Hammel¹ have reported the preparation and separation of the pure helium isotope of mass 3. They have succeeded in condensing it and have determined its vapour pressure in the temperature range 1·21°–3·34° K. (the critical temperature) and its boiling point at 3·20° K. These vapour pressure measurements appear to have interesting consequences with regard to the possibility of a phase transition in the pure helium isotope of mass 3. They provide evidence for such a transition at 1·9° K. In this communication, the possibility of this transition is first examined, the vapour pressure equations in the two ranges 1·2–1·9° K. and 1·9–3·20° K. are given, and a few remarks are made about the theoretical implications of the existence of a phase transition in the pure helium isotope of mass 3.