def METHOD_NAME( ap_mass , lhe, detector ) :
    """Example configuration for producing dark brem interactions in the target.
    This configures the sim to fire a 4 GeV electron upstream of the
    tagger tracker.  The dark-photon production cross-section is biased up in
    the target.  Only events that result in a dark-photon being produced in the
    target are kept.
    Parameters
    ----------
    ap_mass : float
        The mass of the A' in MeV.
    lhe : str
        The path to the directory containing LHE files to use as events of the dark brem.
    detector : str
        Name of detector to simulate in
    Return
    ------
    Instance of the sim configured for dark-brem production in the target.
    Example
    -------
    Here we use the example vertex library. This should not be used
    for large (>50k) event samples.
        from LDMX.SimCore import makePath
        target_ap_sim = target.dark_brem(1000., makePath.makeLHEPath(1000.), 'ldmx-det-v12')
    In general, the second argument should be the full path to the LHE event library.
        target_ap_sim = target.dark_brem(1000, 'path/to/lhe', 'ldmx-det-v12')
    """
    sim = simulator.simulator( "target_dark_brem_" + str(ap_mass) + "_MeV" )
    sim.description = "One e- fired far upstream with Dark Brem turned on and biased up in target"
    sim.setDetector( detector , True )
    sim.generators.append( generators.single_4gev_e_upstream_tagger() )
    sim.beamSpotSmear = [ 20., 80., 0. ] #mm
    #Activiate dark bremming with a certain A' mass and LHE library
    from LDMX.SimCore import METHOD_NAME
    db_model = METHOD_NAME.G4DarkBreMModel(lhe)
    db_model.threshold = 2. #GeV - minimum energy electron needs to have to dark brem
    db_model.epsilon   = 0.01 #decrease epsilon from one to help with Geant4 biasing calculations
    sim.METHOD_NAME.activate( ap_mass , db_model )
    #Biasing dark brem up inside of the target
    sim.biasing_operators = [
            bias_operators.DarkBrem.target(sim.METHOD_NAME.ap_mass**2 / db_model.epsilon**2)
            ]
    sim.actions.extend([
        #make sure electron reaches target with 3.5GeV
        filters.TaggerVetoFilter(3500.),
        #make sure dark brem occurs in the target where A' has at least 2GeV
        filters.TargetDarkBremFilter(2000.),
        #keep all prodcuts of dark brem(A' and recoil electron)
        util.TrackProcessFilter.METHOD_NAME()
        ])
    return sim