Nucleonica’s GSG & GSGPro: limitation of the number of mixture components

June 16th, 2022
by Joseph Magill

Every nuclide mixture, regardless of the number of components, is now accepted by the applications GSG and GSGPro.
When the number of components exceeds the limit of currently 30 nuclides, the application selects the top 30 strongest gamma emitters from the nuclide inventory to compute the spectrum, no matter if the inventory is the originally submitted mixture, or the result of an internal decay calculation of the application.
The nuclides are selected based on the emitted gamma energy given by:
SumEEP = Σi ( Ei · EPi )
where Ei is the energy of the photon i emitted with the probability EPi during a decay reaction. The sum is built over all photons (gamma, x or annihilation) emitted by the nuclide.
This emitted photon energy (per decay) is then multiplied by the activity of the nuclide if decay is not taken into account otherwise by the number of decays of that nuclide during the measurement time.

The advantages of the new approach are multiple and important for the user:
* The same mixture can be used in different applications, regardless of the maximum supported number of components which may be 30 for the GSG/GSGPro, 400 for the BetaDoseRate, or unlimited as for the most of the applications.
* The user has no longer to delete components of a mixture which may be time consuming, and it is not really easy to select the right nuclides.
* The number of mixtures can be reduced
* When the maximum number of nuclides changes or when another approach is used to reduce the computation time the user has nothing to do but benefits directly from the improvement.

Notices:
* One may also consider the full set of emitted photons and then select the strongest lines independently from the emitting parent and their total number.
* In the Options tab, you can change (Administrators only) the maximum number of nuclides taken into account and compare the accuracy of the resulting spectra as well as the consumed CPU time.

See the related post
Gamma Spectrum Generator for large nuclide inventories

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