3. Calibration files
Calibration files with extension MCF (Medusa Calibration File) contain:
· Standard spectra;
· Information on the gain stabilization of the detector system;
· information on the supplier and owner of the tool;
· Date of the calibration.
The most important information inside the detector file is the information about the standard spectra. In the full spectrum analysis implemented in Gamman, the standard spectra are used tofit the measured spectrum. A standard spectrum is nuclide, detector and geometry specific; and it is defined as "a detector's response to a source of unit activity in a given geometry". An example is shown in the figure below.
Example of a set of standard spectra. In yellow: 137Cs; red: 40K; green: 238U; blue: 232Th. System: 4x4x16 CsI in a borehole geometry.
Calibration files are unique for a detector-acquisition system used in a certain geometry. This means that for each geometry, a separate calibration file is needed. The reason for this is that both the shape and the intensity of the standard spectra differ with the geometry of the source being measured.
The name of the MCF file is made up of the ID of the detector (serial number, or type id, etc), then a single character determining the geometry and the extension MCF. For example; ssu472.a.mcf is a calibration file for a detector named ssu472, calibrated for use in an airborne application (".a").
Calibration files are stored in the Gamman program directory, and cannot be moved to another location on your computer.
Note The Gamman installation comes with a single Gamman calibration file. This calibration file (SCB095.MCF) contains a set of calibration spectra for a 4x4x16 inch cesium iodide detector and was added for instructive purposes only.