  GZKFast is a low-cost astrophysical event generator designed to simulate
photohadron processes resulting from ultra high energy cosmic ray fluxes.
GZKFast is an easy to use event generator which specifically addresses issues
relevant to cosmogenic neutrinos and the ultra high energy (UHE) neutrino
spectrum. GZKFast injects UHE particles into a simulated cosmic microwave
background (CMB) using a Monte Carlo approach. The interaction of each particle
is simulated and the resulting detectable events are spooled to log files.
Although GZKFast uses a simplified particle physics model and limited
accelerator data it generates event distributions which are comparable with
more thorough simulations such as the event generator SOPHIA
