def projection_x(th2d):
    """
    create the projection on the x axis of a th2d
    :param th2d:
    :return: TH1D of the projected data on the x axis
    """
    xproj = th2d.ProjectionX('Projection on ToF axis')
    xproj.SetXTitle("Time Of Flight")
    xproj.SetYTitle("Nb of Counts")
    return xproj