set the simulation_duration
        see: http://www.gsshawiki.com/Project_File:Required_Inputs

def set_simulation_duration(self, simulation_duration):
        """
        set the simulation_duration
        see: http://www.gsshawiki.com/Project_File:Required_Inputs
        """
        self.project_manager.setCard('TOT_TIME', str(simulation_duration.total_seconds()/60.0))
        super(EventMode, self).set_simulation_duration(simulation_duration)
        self.simulation_duration = simulation_duration