Click
on the picture for a larger versionThis calibration section of the program enables FitzPeaks Gamma Analysis Software to perform the full quantitative analysis of spectral data files that consist of only raw channel data. It provides the facility to calibrate for energy, peak shape and efficiency.
Throughout the calibration, use is made of source data files to eliminate the need to enter peak energies and calibration source details each time a calibration is performed. When the energy calibration is performed, the program selects and matches the appropriate peaks out of those found by the peak search with the energies read from an energy list data file. The user can select to use a 1st or 2nd order function and is presented with a list of entered and fitted energies and their differences. This is also displayed in graphical form, which in addition, displays the amount of non-linearity. The peak energies used for the calibration are also saved in the detector calibration data file to facilitate a subsequent auto energy re-calibration operation.
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on the picture for a larger version
When the peak shape calibration is performed, the program determines parameters for the peak width and the amount of low energy tailing, with the option of determining the amount of high energy tailing. Again, the user can select to use 1st or 2nd order functions when fitting these measured parameters and is presented with a graphical display showing how well they were fitted.
Click
on the picture for a larger version
When the efficiency calibration is performed, the user can select to use a single, or a dual exponential function with a crossover energy. The order of each of these functions and the crossover energy can be adjusted to give the best fit of the measured efficiency values. A new option of using a linear instead of an exponential energy function has recently been added. This is an example of the display that is obtained when an efficiency calibration is being performed:-
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on the picture for a larger version
As an alternative to the above method of efficiency calibration using a single, or a dual exponential function, a new option of using a non-linear interpolated function has recently been added. This is an example of an efficiency calibration using this method:-
Click
on the picture for a larger version
There is an option to perform a sample density correction during the analysis. A counting geometry would be calibrated for two or more standards of different weights, resulting in a series of efficiency curves. During the analysis, the efficiency value for a sample at the required energy is calculated by referring to these efficiency curves in turn, and producing a function of efficiency versus weight as shown in the following display:-
Click
on the picture for a larger version
There is also an auto energy re-calibration function that can be used regularly to make minor adjustments to the energy calibration to compensate for any drift etc.
This software has been under development for over 6 years and is under constant review, the opinions and findings of current users are being taken into account. As a result of this, the program has a reasonable initial purchase price which includes one year of upgrades, after which an upgrade continuation contract can be agreed.
Jim Fitzgerald, JF Computing Services, 17 Chapel Road,
STANFORD IN THE VALE, Oxfordshire, SN7 8LE
Tel: +44 (0)1367
710543 Fax: +44 (0)8700 521900
E-mail:
jim@jimfitz.demon.co.uk
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Copyright © Jim
Fitzgerald 1991-2007
Last updated 23rd March 2007