def ev_to_s(offset_us, source_to_detector_m, array):<EOL>
<EOL>time_s = np.sqrt(<NUM_LIT> / (array * <NUM_LIT>)) * source_to_detector_m / <NUM_LIT><EOL>time_record_s = time_s - offset_us * <NUM_LIT><EOL>return time_record_s<EOL>
convert energy (eV) to time (us)

    Parameters:
    ===========
    array: array (in eV)
    offset_us: float. Delay of detector in us
    source_to_detector_m: float. Distance source to detector in m

    Returns:
    ========
    time: array in s