Photon Evaporation dataset Ac 228

Physics Lists
1

Hello,

I am currently working on isotope simulations and I saw that the Radioactive Decay and Photon Evaporation datasets are based on the Evaluated Nuclear Structure Data File (ENSDF) from the National Nuclear Data Center.

While comparing results obtained with Geant4 v11.1.1 and v11.3.0, I observed that the differences between the PhotonEvaporation datasets (PhotonEvaporation-5.7 for Geant4 11.1.1 and PhotonEvaporation-6.1.2 for Geant4 11.3.0) for Ac-228 lead to the following changes in the resulting spectrum of Ra 228:

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Neither dataset includes the gamma intensities (Iγ) for the transitions at Eγ ≈ 12.75 keV (12.88 keV in the Geant4 datasets) and Eγ ≈ 26.4 keV in agreement with ENSDF. In particular, for the 26.4 keV transition, I could not find any available Iγ value in ENSDF.

Additionally, I observed that in other cases Geant4 provides values (e.g., for internal conversion coefficients) even when corresponding data is not explicitly available in ENSDF.

I would appreciate clarification on the following points:

  • How frequently are the Geant4 radioactive decay and photon evaporation datasets updated?

  • When nuclear data (such as gamma intensities or conversion coefficients) is missing in ENSDF, what procedure or assumptions does Geant4 follow to fill in these values?

Thank you in advance for your help.

Geant4 Version: 11.3.0, 11.1.1

2

Hello,

thanks for the post. The recent conversion of nuclear gamma/electrons transitions and radioactive decay was done for 11.3. New data are in datasets PhotonEvaporation6.1.X and RadioactiveDecay6.1.X. these datasets are obtained by direct conversion of ENDF data for cases when data exist inside ENDF and from additional sources of information.

The procedure is long and within Geant4 collaboration there is no manpower to control every number. Our current approach to improve the data is to react on external experts. The procedure is following: experts submit Bugzilla bug reports, we consider all reports for some interval of time and produce patches to datasets. Just now we collect bug reports for the new version 6.1.3.

In some bug reports there are concerns also to Geant4 code, not only for the data. We are trying to address reported problem. It is why we ask experts, who submit bug report, if possible to work with the recent Geant4 - some problems are fixed there. Recommended version of today is Geant4 11.4.1 .

VI