Created attachment 177 [details] The resulting spectra we acquire following excitation of the 12710-keV level of carbon-12 in geant4.8.2 and geant4.9.5. Our code references the G4PhotonEvaporation class to obtain the reaction products of de-excitation of the nucleus following nuclear excitation, and we are seeing strange results in the de-excitation pattern that is simulated. When we simulate excitation of carbon-12 nuclei to the 12710-keV energy level, following the excitation our simulations using geant4.8.2 show that the nucleus decays primarily (79% of the time) by emitting 12703 keV gamma-rays, with the emission of 8268 keV gamma-rays occurring less often (21% of the time). This branching ratio reflects what we find in the 'z6.a12' file in the 'PhotonEvaporation2.0/' data directory. However, when we simulate the same scenario in geant4.9.5, the excited nucleus decays by emitting 8268 keV gamma-rays 100% of the time. Using the 'strace' Linux command we find that the 'z6.a12' file in the 'PhotonEvaporation2.2/' data directory is being accessed by the simulation, though that file contains the correct branching ratios. Modifying the data for these two excitation pathways in the 'z6.a12' file also does not change the results. Unless if both the lines containing de-excitation data for the 12710-keV level in the data file are deleted entirely, then all possible de-excitation pathways are simulated from the 12710-keV level. When using the increased verbosity option in the 'G4PhotonEvaporation' class, we find that the two simulations (geant4.8.2 and geant4.9.5) first differ in the 'G4VGammaDeexcitation::GenerateGamma' function: geant4.9.5 prints: "G4DiscreteGammaDeexcitation::CanDoTransition - Halflife 3.64e-08, Calling from RDM True , Max-HL = 1000 G4DiscreteGammaDeexcitation::CanDoTransition - CanDo: True G4VGammaDeexcitation::GenerateGamma - Edeexc(MeV)= 8.27109 ** left Eexc(MeV)= 4.43891" and geant4.8.2 prints: "G4DiscreteGammaDeexcitation::CanDoTransition - Halflife 3.64e-08, Calling from RDM True Max-HL = 1000 G4DiscreteGammaDeexcitation::CanDoTransition - CanDo: True G4VGammaDeexcitation::GenerateGamma - Gamma energy 12.703 ** New excitation 0.007" . It seems that there may be a bug in the 'G4VGammaDeexcitation' or 'G4PhotonEvaporation' classes. In addition, we are seeing a similar problem for de-excitation from the 1511-keV level in carbon-12, i.e., the direct transition from 1511-keV to the ground state is not simulated in geant4.9.5, although we expect it to occur 92% of the time from the 'PhotonEvaporation2.2/z6.a12' file. However, the branching is simulated correctly in geant4.9.5 from the 3448.41-keV state in iron-56, i.e., we see peaks at 3448 keV, 2601 keV, and 846 keV in the expected 3 to 1 to 1 proportion based on the 'PhotonEvaporation2.2/z26.a56' file. We have attached a MATLAB figure showing the resulting spectra we acquire following excitation of the 12710-keV level of carbon-12 in geant4.8.2 and geant4.9.5.
Hello, Unfortunately, it is not easy to follow the problem. More information needed: 1) What Physics List is used? 2) is it possible to get tar file with the application? 3) plot in attachment is not readable, can it be sent in pdf or png? 4) Excited C12 not easy to get in ordinary test; if one starts with low-energy neutron in carbon media, then excited C13 is created and it is possible to follow decay channels; it seems that there are problems but I need more clarification what lines should be seen with what intensity and with what Physics list. VI
(In reply to comment #1) > Hello, > > Unfortunately, it is not easy to follow the problem. More information needed: > > 1) What Physics List is used? > 2) is it possible to get tar file with the application? > 3) plot in attachment is not readable, can it be sent in pdf or png? > 4) Excited C12 not easy to get in ordinary test; if one starts with low-energy > neutron in carbon media, then excited C13 is created and it is possible to > follow decay channels; it seems that there are problems but I need more > clarification what lines should be seen with what intensity and with what > Physics list. > > VI Hi Vladimir, We have used a custom physics list that you can find in the zip file with the application at this link: http://www.duke.edu/~mnl7/For_Vladimir/nuclear_resonance_fluorescence.zip . Be sure to source the file "NRFenv.csh" before running the executable. Here is the plot I tried to attach the first time instead in png format: http://www.duke.edu/~mnl7/For_Vladimir/spectra.png . In that model, the incident gamma rays will cause the C-12 nuclei in the sample to be excited to the 12710-keV state, upon which the de-excitation should show lines at 12703, 8268 and 4439 keV. Manu
Hello, It seems that the bug is fixed. Would you like to test the fix privately - it is only one file, which may be sent. VI
Hi Vladimir, thank you so much for fixing the bug. I am eager to test the fix privately. Can you send me the updated file? Manu (In reply to comment #3) > Hello, > > It seems that the bug is fixed. Would you like to test the fix privately - it > is only one file, which may be sent. > > VI
