Hi, I see incorrect gamma branching ratios in the decay of 133-Ba. The ratios are incorrect by up to 9% for some gammas. Here are the intensities from Geant4 simulation, compared to literature values: E_lit | I_lit | I_sim | (I_sim - I_lit) / I_lit 53.16 | 2.14 ± 0.03 | 2.08 ± 0.01 | -2.8 ± 1.6 79.61 | 2.65 ± 0.05 | 2.41 ± 0.02 | -9.0 ± 1.8 81.00 | 32.95 ± 0.33 | 33.30 ± 0.06 | 1.1 ± 1.0 160.61 | 0.64 ± 0.01 | 0.62 ± 0.01 | -2.8 ± 1.5 223.24 | 0.45 ± 0.00 | 0.44 ± 0.01 | -3.3 ± 1.6 276.40 | 7.16 ± 0.05 | 6.83 ± 0.03 | -4.6 ± 0.7 302.85 | 18.34 ± 0.06 | 18.00 ± 0.04 | -1.8 ± 0.4 356.01 | 62.05 ± 0.19 | 59.80 ± 0.08 | -3.6 ± 0.3 383.85 | 8.94 ± 0.06 | 8.78 ± 0.03 | -1.8 ± 0.8 where: E_lit = gamma energy from literature I_lit = gamma intensity from literature I_sim = gamma intensity from Geant4 The literature values above are from ENSDF and the Nuclear Data Sheets for A=133, which was published in 2011. I'm using Geant4.9.3.p01, with the PhotonEvaporation2.0 and RadioactiveDecay3.2 data files. I think the discrepancies are due to slightly incorrect values in the data files -- maybe the G4 data files are based on older ENSDF data? There don't seem to be any updates to the newer PhotonEvaporation2.2 and RadioactiveDecay3.4 files for 133-Ba, though. Is there any documentation of which ENSDF versions were used to generate data files in the PhotonEvaporation and RadioactiveDecay packages? Thank you, Alexis
Created attachment 180 [details] Gamma lines fron Bs133 decay with g4.9.5 and new database
Dear Alexis, Thanks for the report! I have developed an automatic procedure for rebuilding the photo-evaporation database from nudat2. The new database will be released soon. Attached is the results of Ba13 decay lines obtained with G4.9.5 and the new database compared to nudat2. As you see the agreement is excellent! I also attach the new evaporation data file z55.a133 and z56.a133 used for this computation. Please try them and tell meif you get better results. Best Laurent
Created attachment 181 [details] z55.a133
Created attachment 182 [details] z56.a133
(In reply to comment #2) > Dear Alexis, > > Thanks for the report! > I have developed an automatic procedure for rebuilding the photo-evaporation > database from nudat2. The new database will be released soon. > Attached is the results of Ba13 decay lines obtained with G4.9.5 and the new > database compared to nudat2. As you see the agreement is excellent! > I also attach the new evaporation data file z55.a133 and z56.a133 used for > this computation. > Please try them and tell meif you get better results. > > Best > > Laurent Dear Laurent, Thanks for the quick reply. I tested the files, but now I see a distorted energy spectrum of gammas emitted in the decay, and the branching ratios are not correct. Attached are the spectra from 5E6 decays of 133-Ba, before and after the new files. I am studying decays of the 133-Ba ground state, so I think only the z55.a133 evaporation file is being used. I now see these branching ratios: 41.789 +/- 0.029 % BR for 81-keV peak 13.709 +/- 0.017 % BR for 356-keV peak The updated PhotonEvaporation2.0/z55.a133 file has slightly different level energies than RadioactiveDecay3.2/z56.a133. Could this contribute to the problem? Are you updating RadioactiveDecay in addition to PhotonEvaporation? Thanks, Alexis
Created attachment 183 [details] 133-Ba spectrum from RadioactiveDecay3.2 and PhotonEvaporation2.0
Created attachment 184 [details] 133-Ba spectrum from RadioactiveDecay3.2 and patched PhotonEvaporation files
Dear Alexis, > > Dear Laurent, > > Thanks for the quick reply. I tested the files, but now I see a distorted > energy spectrum of gammas emitted in the decay, and the branching ratios are > not correct. Attached are the spectra from 5E6 decays of 133-Ba, before and > after the new files. It seems that the simulation conditions in term of physics model selection are not the same in your two simulation cases. Why does the continuous gamma spectra appear in the new simulation but not in the old one? I do not believe that this difference come from the fact that you have use another evaporation file! Am I wrong? Can you explain me more how you exactly make your simulation? In my case I am only generating Ba133 decay, switching off atomic relaxation such that I get only the discrete lines! Do you make the same? As far as I know you obtain your results with 4.9.3! Is that correct? If yes you should first migrate to 4.9.5 to be sure that the problem does not come from any old bug that has been corrected with new versions. > I am studying decays of the 133-Ba ground state, so I > think only the z55.a133 evaporation file is being used. > Yes that is correct! > I now see these branching ratios: > 41.789 +/- 0.029 % BR for 81-keV peak > 13.709 +/- 0.017 % BR for 356-keV peak Very strange? As you may see in my simulation results the BR that I get for these lines are in agreement with nudat2. > > The updated PhotonEvaporation2.0/z55.a133 file has slightly different level > energies than RadioactiveDecay3.2/z56.a133. Could this contribute to the > problem? Are you updating RadioactiveDecay in addition to PhotonEvaporation? Yes but that is more tricky! > > Thanks, > Alexis Best Laurent
Hi Laurent, My two tests use the same simulation settings. I think the issue is because I am using Geant4.9.3, which has a problem with the formatting of the PhotonEvaporation files. In the standard PhotonEvaporation2.0 files, the polarity in column 4 is written as the spin variation of the transition followed by the parity of the transition, e.g. +1. In your new z55.a133 file this is reversed, e.g. 1+. Using the new file gives a continuous gamma energy distribution from 4.9.3.p01, but if I change the polarity order to match the old format the energies are discrete. By switching the polarity order and making no other changes I can switch back and forth between the continuous and discrete distributions. You are right, I should upgrade to 4.9.5! Using your new file with Geant4.9.3.p01 and the polarity modification, I see these branching ratios from 5M decays of 133-Ba: 53.16 keV | 2.131 +/- 0.007 % BR 79.61 keV | 2.625 +/- 0.007 % BR 80.99 keV | 33.444 +/- 0.026 % BR 160.61 keV | 0.634 +/- 0.004 % BR 223.24 keV | 0.439 +/- 0.003 % BR 276.39 keV | 6.952 +/- 0.012 % BR 356.01 keV | 60.206 +/- 0.035 % BR 383.85 keV | 8.613 +/- 0.013 % BR So this looks better, especially for the 79.6-keV gamma. For the simulations I am interested in, the ratio of the 356-keV to 81-keV peaks is important. With the new z55.a133 file, this is 55.55 +/- 0.054%, compared to the NDS value of 53.10 +/- 0.5%. Things were similar with the old z55.a133 file: 55.75 +/- 0.03%. So maybe there are some parameters in RadioactiveDecay/z56.a133 that are a little off. If you do make updates for RadioactiveDecay, I would be very interested in using them. Thank you, Alexis
This should now be fixed with the recent update to ENSDF 2012. Please upgrade to Geant4 version 10 and use the most recent radioactive decay database, RadioactiveDecay4.0.
