Temperature Independent Nucleation of Solid Helium 4 Below 1K

Nucleation of solid helium in superfluid helium was studied in a temperature range between 50mK and 1K. Pulsed electrostatical compression was employed to initiate nucleation in a slightly overpressurized superfluid helium. The nucleation rate w was estimated from a distribution of the overpressure Peffrequired for nucleation. The temperature dependence of Peffat constant ω was essentially flat between 50mK and 1K. The ln ω was almost linear in Peffwithin the resolution of our data.