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====== Calibration ======
Calibrations contain information regarding energy, full width at half maximum (FWHM) and efficiency calibrations. They must be selected and loaded for analyses (see [[Analysis Parameters]]). In //LVis// / //GammaVision// calibrations (''.CLB'' files) or any calibrated //LVis// measurement file (''.LVM'' files) can be used as a source of calibration. 

In each //LVis// measurement, the calibration is presented in its own tab (see as well [[Changing a Calibration in an .LVM file]]). 

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The accurate measurement values of individual calibrations can be shown and edited in a calibration table. There you can find (if known) the reference source (on the left side), as well as optionally the respective nodes and fit information of the energy and FHWM calibration or the efficiency calibration.

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To change peak fit parameters, click on the Spectrum tab to access the peak editor.

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Several ways exist to create and edit calibrations. For example it is possible, to manually calibrate each already existing measurement (''.LVM'' file) using the peak editor (See [[Detector Calibration]]). It is also possible to change an already existing calibration by changing the data in the calibration table.

However, //LVis// usually automatically takes care of all calibrations using its own detector-specific calibration parameter sets (see [[Detector Calibration]]). The calibration data obtained is automatically assigned to the detector or measurement parameter sets to ensure that the most up-to-date calibrations are used at all times.
In principle, energy and FWHM calibration (channel-energy relation and channel-resolution relation) as well as efficiency calibration (energy - efficiency relation) are performed in two separate steps. The energy calibration as detector-specific calibration is saved under the detector (or better, the electronic measurement equipment); efficient calibrations can be assigned to individual parameter sets. If such calibrated parameter set is used, LVis automatically combines the current internal energy calibration of the detector with the efficiency calibration stored in the parameter set for analysis.

Automatic calibrations are based on [[reference sources]], which contain all necessary nuclide information ([[library]]) and activity data (certificate file). In order to use the automatic LVis calibration function, you must create your calibration sources as reference sources in //LVis//. Without reference sources it is not possible to create calibration measurements in LVis. Therefore, in the event that no reference source is available in the calibration parameter set, you will be requested to enter one prior to analysis.

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===== Detector Calibration =====
Calibration parameter sets (one each for energy/FWHM calibration and efficiency calibration) can be created, changed and started from the context menu of a detector (Energy/Efficiency calibration parameters). Parameter sets for energy/FWHM calibration and efficiency calibration only differ in one field for the reference data and contain, in addition, the measuring time, peak analysis parameters and the reference source to be used (nuclides, peaks and possibly activity and reference date).

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Selecting //New Energy/Efficiency calibration// in the detector menu starts a new parameterized calibration measurement. //Calibration using current spectrum// lets you use an already existing (manually started) spectrum for calibration.

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==== Creation of an Energy Calibration for a Detector ====
In order to create an energy calibration for a detector, a spectrum with respective calibration parameter set must be evaluated. This can either be done by selecting //Execute energy calibration// (starts a new parameterized calibration measurement) or by selecting //Energy calibration based on current measurement//, if a spectrum has already been recorded using the calibration source.

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In this case, the corresponding calibration table does not contain any information except the entries from the reference source on the left side.

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When //Auto calibration// is ''clicked'', //LVis// will try to find the peaks specified in the reference source, and then accordingly calibrate the spectrum.

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**Important**\\
The [[nuclide library]] used for creating the reference source should be absolutely unique. It should only contain nuclides specified in the corresponding certificate. If energies are present in the reference source, which, for example, cannot be found in the spectra (e.g., due to the short half-life of the corresponding nuclide), problems may occur during automatic calibration.
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Next the calibration will be displayed in the respective tab. Clicking on the //Calibration table// button takes you to detailed calibration information.

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Corresponding nodes and fit results of the automatic calibration can now be found and, if necessary, edited in the calibration table (simply by clicking on the respective entry in the calibration table). All identified peaks used for calibration from the reference source are marked with an asterisk (*) in the calibration table (in the reference source data are displayed in the left table).

Double-clicking on peak energy in the left column of the calibration table takes you automatically to the respective peak in the spectrum. There you can display the fit in detail by clicking on //Peak editor//. You can also change the fit and apply the changes to the calibration.

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**Important**\\
The fit displayed in the peak editor always depends on the fit display modus selected on the spectra view. If no fits were shown in the spectrum, //LVis// will fit the peak for the display in peak editor. This result may differ from the //GammaVision// analysis or peak search.
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If the calibration is saved, //LVis// will then ask whether to assign this energy calibration to the detector. 

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This ensures that each spectrum newly recorded using this detector will automatically be furnished with the current energy calibration. For this purpose, this energy calibration is stored in the electronic measurement equipment and will not be lost, once //LVis// is exited or the electronic measurement equipment is switched off.

You can always review the measurement corresponding to the currently active energy calibration of a detector by selecting //Open last energy calibration// in the context menu of the detector.

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If you would like to delete the internally stored energy calibration, then select //Delete energy calibration// in the context menu.