Order of theHe4II-He4I Transition under Rotation

Abstract

Purely thermodynamic considerations show that the volume discontinuity at the ${\mathrm{He}}^4$II → ${\mathrm{He}}^4$I transition under rotation reported by Andronikashvili and Tsakadze cannot correspond to a transition between thermodynamic equilibrium states if ${\left(\frac{\partial P}{\partial T_{\lambda }}\right)}_{\omega }<0\mathrm{}$. Experimental results are presented which show that at the transition $\left|\Delta H\right|<~6\times {10}^{-4\mathrm{}}$ J/mole and $\left|\Delta V\right|<~3\times {10}^{-5\mathrm{}}$ cc/mole at $\omega =30\mathrm{}$ ${\sec }^{-1\mathrm{}}$. Thus, within these limits, the transition is of higher than first order.