Comment on ``Measurement of the $^3$He mass diffusion coefficient in   superfluid $^4$He over the 0.45--0.95 K temperature range
  The role of 3He-3He collisions in our diffusion experiment is addressed and shown to not be relevant to the measurement of 3He diffusion against phonons in superfluid helium. 
S.K. Lamoreaux and R. Golub