Automatically loaded entries
After creating a new evaluation, or selecting an existing one, the spectrum peak evaluator window appears. HyperLab now loads all necessary entries of the peak evaluation from the database:
the measurement entry;
its spectrum entries (e.g. a Normal and an LFC-corrected spectrum part in case of Dual LFC measurements);
latest FWHM calibration for the spectrum entries;
latest energy calibration for the spectrum entries, together with nonlinearity calibration, if that is selected by the user on the Energy calibration editor window;
efficiency curve for the measurement setup, if existing. This may be used for efficiency-corrected peak area calculations in the output reports.
Usage of latest FWHM and energy calibrations
Although you can save several independent peak evaluations for a specific measurement, when you re-load them later, the latest FWHM and energy calibration will be loaded. If you have modified these calibrations in the meantime, saving of the peak list may result in slightly different peak positions or peak fits. This way the exact reproduction of previous fitting results also requires the restoring of previous calibrations.
Ensuring automatic loading of the efficiency curve
HyperLab is able to automatically determine which detector efficiency curve belongs to a particular measurement. If such an efficiency curve is found, it will be automatically loaded by the peak evaluator, and efficiency corrected peak list reports may be generated.
To check if the efficiency analysis is successfully loaded, change to the Messages panel after you started the peak evaluator, and search for a message about the status of the efficiency loading.
In order to ensure the automatic determination of the efficiency curve belonging to a specific measurement, you must perform the following two steps before starting the peak evaluator.
Create a quality efficiency curve, where the relative uncertainty of the full-energy absolute detector efficiency is around the precision of your calibrated radioactive sources. For example, if you have taken measurements of absolutely calibrated radioactive sources with 1-2% activity uncertainty, then the efficiency value calculated from the efficiency curve is also expected to have 1-2% uncertainty. Store this efficiency analysis into your database.
Assign the efficiency analysis to the measurement setup entry where the measurements were taken. Do not forget to set the validity start date. HyperLab will automatically use this efficiency calibration for all the measurements, which were taken after this validity date (and before the validity start date of the next assigned efficiency curve). When multiple efficiency curves are assigned to the same measurement setup, their validity start dates will determine the one to be applied for a specific acquisition.
Creating reports with efficiency corrected peak areas
Saving of efficiency-corrected peak areas may be achieved in several ways:
Select the File / Create report menu item, and select a report template where the description of the report shows “efficiency correction”.
Select File / Export to CSV file menu item, and you will get a report which can be immediately loaded into a spreadsheet application.
The reports will contain the efficiency value at the energy of the peak centroid, relative uncertainty of the efficiency, as well as the efficiency corrected peak area together with its uncertainty (combined from the uncertainty of the peak area and the uncertainty of the efficiency curve at the centroid).