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 P_effrequired for nucleation. The temperature dependence of P_effat constant was essentially flat between 50mK and 1K. The ln was almost linear in P_effwithin the resolution of our data.