Tutorial 14: Portable Pad Calibration

Data Setup

The Portable Calibration tool operates on ASCII text files. See the example file in the "demo_data\portable_cal_pads directory". Note that the spectra are formatted as columns. Spectra are acquired using a portable spectrometer over each of four calibration pads (K, U, Th and a background pad). The ASCII text file should contain at least five spectra. The fifth spectrum is an over-water spectrum to estimate background radiation. 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 the "demo_data\portable_cal_pads" directory.

Processing Steps

    1. Launch the tool – Portable|Portable Pad Calibration.
    2. Open the spectra file – File:Open ASCII Spectra File. Navigate to the "demo_data\portable_spectrometry\portable_cal_pads" directory and select the "spectra_padcal_portable.txt" file. The spectra are loaded into memory and displayed in the chart windows. The textBoxes to the left of each chart specify the column number for that spectrum in the file. The default sequence of the spectra in the input file are column 1 – K, column 2 – U, column 3 – Th, column 4 – Background pad and column 5 – over-water spectrum. By default, they are inserted into the chart windows in that order. If your spectra are not in that order (eg. you can see the K spectrum is in the Th window), then use the textBoxes to the left of the charts to specify the column numbers of each of the relevant spectra in the input file.
    3. Set the processing parameters – File|Set Parameters. Click the Load From File button and select the "parameters_processing_portable.pc" control file from the working directory. For an explanation of the parameters click the Help button. Click Save And Return.
    4. Read the pad concentrations from file – File|Read Pad Concentrations From File. Select the "pad_concentrations.con" file in the working directory.
    5. Process the calibration spectra. Click the Calculate button. The results are displayed in the Results listBox.
    6. Save the new calibration parameters to a text file. Click the Save button. The format in the file is suitable for a copy/paste to construct a control file for the processing of portable spectrometer data.
    7. View the log file (File|View User Log File) to see the full results.