|Message: Re: problems with G4RadioactiveDecay in geant4.9.4||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
I am looking right now at the different problems that you describe below. When I have some answers I let you know. Could you please in the mean time post your message as a bug report, if not already done. The problem that you list below will then officially be recognized as a Geant4 bug to solve!
On Mon, 28 Mar 2011 08:04:58 GMT, Susana Cebrian wrote:
> Dear all, > > We are interested in the simulation of radioactive decays of isotopes > inside a detector, that is, all the emissions generated are relevant for > us. We encountered problems in the past using the Radioactive Decay > Model mainly due to the missing energy in beta- and EC emitters, as > reported in problem report #1001( > http://bugzilla-geant4.kek.jp/show_bug.cgi?id=1001 ). When using the > last available version 4.9.4.p01, many of these problems have been > solved, although some remain and also some new issue has appeared. > > Our particular doubts, using the last version, are the following: > > 1) From the sequence of isotopes in the natural radioactive chains, > there are still problems for 228Ra (from 232Th chain) and 227Ac (from > 235U chain), both beta- emitters with Q around 45 keV. In an ideal > detector registering all the emissions, we expect a superposition of > several beta spectra starting at the energies of the excited levels of > daughters, but this expectation is not acomplished. Beta shapes start in > some cases below the level energies, so it seems that there is still > some missing energy (I attach the spectrum obtained for 227Ac). > > 2) Concerning the electron energy spectrum for a beta- decay, I would > like to know if as stated in the forum post ( > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/hadronprocess/766.html > ) and as it seems having a glance at the code in G4RadioactiveDecay.cc, > LoadDecayTable(), case BetaMinus:, the considered shape is still always > that of allowed transitions, and if the correction implemented in > version 4.9.4 at G4RadioactiveDecay.cc suggested in the problem report > #1068 ( http://bugzilla-geant4.kek.jp/show_bug.cgi?id=1068 ) is > exclusively for 40K isotope. Our problem here is the following. The beta > spectrum shape obtained for 40K with previous version (9.3.p02) agreed > very well with the spectral information obtained from the book "Table of > Isotopes" (Wiley, 1999) coming apparently from calculation having into > account the order of forbiddenness, while after the specific correction > for 40K implemented in the new version (9.4.p01) the agreement is much > worse. The following table shows the comparisons: > > energy range (keV) % Simulation (geant4.9.3.p02) % Tables % Simulation > (geant4.9.4.p01) 0 a 10 0.49 0.495 0.403 10 a 20 0.51 0.51 0.41 20 a 40 > 1.1 1.1 0.87 40 a 100 3.9 3.9 3.02 100 a 300 18.0 17.9 13.8 300 a 600 > 32.0 32 27.4 600 a 1300 33.3 33.4 43.4 >1300 0.001 0.000326 0.0016 <E> > 453.9 455 525.8 > > Mean energy <E> is calculated over 40K decays (not over electrons > emitted in beta decays). We have checked that for other isotope (210Bi, > first-forbidden transition) the agreement of the simulated beta spectrum > with the information on Tables is also very good with the previous > version. Are we misunderstanding anythig? > > 3) It seems that the decay of 234Th (from 238U chain) is not properly > reproduced in version 4.9.4.p01. * According to tables of isotopes, the > beta decay ends almost always to the metastable state of 234Pa at 73.92 > keV, either directly (70.3%, according to /RadioactiveDecay3.3/z90.a234 > file) or through excited states with higher energy. The 234mPa decays > beta- (mainly to the ground state of 234U, 98.2% from > /RadioactiveDecay3.3/z91.a234 file) having a negligible probability of > IT to the ground state of 234Pa (0.16%). * From the simulation, however, > I encounter that in many cases (roughly, 70%) 234Pa[0.0], that is the > ground state, is produced. Its beta- decay is very different from that > of the metastable state, giving rise to the emission of a lot of gamma > lines from 234U deexcitation. This problem was not present in previous > version (I checked 9.3.p02) where 234Pa[73.9] state was correctly > produced. Are you aware of this problem? Can be avoided in some way? > > Many thanks for your help in any of these questions, Susana Cebrian > > Attachment: > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2011/03/28/00.57-60078-SimulacionClara_ac227.txt >
|Inline Depth:||Outline Depth:||Add message:|