Tutorial 3: Stripping Ratios Calibration

Database Setup

This tool is for estimating the stripping ratios for an airborne gamma-ray spectrometer using data specifically acquired for this purpose. Spectra (lines) are acquired at ground level over each of four calibration pads (K, U Th and a background pad). The database should contain at least four lines. You also need to know the radioelement concentrations of the calibration pads. These are contained in a pad concentrations file – see the example file in the "demo_data\airborne_cal_pads" directory.

Use either Intrepid or Oasis Montaj to set up all the input database fields required by the tool. You will see which fields are required at Step 3 below. Of course, for an Intrepid database, the line number, flight number and fiducial fields must also always be present in the database – with prescribed names as indicated in the "Preparing The Database" section.

Processing Steps

    1. Open a database from the Main Window – File|Open. For the demonstration dataset select "demo_data\airborne_spectrometry\stripping_ratios\PAD_CALIBRATION..DIR" (or the Oasis Montaj equivalent).
    2. Launch the tool – Calibration| Pad Calibration.
    3. Set the database aliases and tool parameters – File|Set Aliases and Parameters. Click the Load From File button and select the "aliases_and_params_stripping_ratios.pc" control file from the working directory. For an explanation of the aliases and parameters click the Help button. Click Save And Return.
    4. Read the calibration spectra from the database. Do this by selecting each of the Select buttons next to the charts – in this database the K spectrum (line) is line 3000, the U spectrum is line 2000, the Th spectrum is line 4000, and the background line is line 9000. 
    5. Read the pad concentrations from file – File|Read Pad Concentrations File. Select the "pad_concentrations.con" file in the working directory.
    6. Click the Calculate button to estimate the stripping ratios. A summary of results are displayed in the tool window.
    7. View the log file (File|View User Log File) to see the full results.
    8. Click Save to save the stripping ratios to a temporary file in a form suitable for cutting/pasting into a control file for airborne processing.