Cluster with GEANT4

Is there available a cluster with GEANT4 installed with at least 256 cores to speed up a simulation of radioactive particle tracking.
I am making simulations of radioactive particle decays in different positions (2000 aprox) to estimate the detector response for straigth trajectory.
With a Intel Core i-7, simulation takes 18 hours. I wanna increase the speed to have a large data set for machine learning algorithms.
The cluster has to be free. Perhaps, a collaboration would be great!