def findTimes(num_sweep):
    """
    Finds the times at the beginning and at the end of each sweep. Information
    comes from the elapsed time since the beginning of the volume scan, from
    the Rad4Alp: Specifications/ Request for Proposal (RFP) document.
    Inputs
    ------
    num_sweep: int
        rank of the sweep
    Returns
    -------
    elapsed_times[num_sweep][0]: float
        the elapsed time since the beginning of the volume scan at the
        beginning of the sweep
    elapsed_times[num_sweep][1]: float
        the elapsed time since the beginning of the volume scan at the end of
        the sweep
    """
    elapsed_times = {(9): [0, 11.4], (7): [11.4, 22.8], (5): [22.8, 39.2],
        (3): [39.3, 60.5], (1): [60.5, 84.7], (19): [84.7, 97.2], (17): [
        97.2, 109.6], (15): [109.6, 121.6], (13): [121.6, 133.1], (11): [
        133.1, 144.4], (10): [144.4, 155.8], (8): [155.8, 172.2], (6): [
        172.2, 188.6], (4): [188.6, 204.9], (2): [204.9, 229.4], (20): [
        229.4, 241.9], (18): [241.9, 254.4], (16): [254.4, 266.6], (14): [
        266.6, 278.3], (12): [278.3, 289.9]}
    return elapsed_times[num_sweep][0], elapsed_times[num_sweep][1]
