|Message: Neutron Angular Distribution with LElastic Model||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 having a problem with a neutron simulation at 30 MeV and I wondered if anyone else had had a similar problem and knew of a solution? I am doing a simulation of a detector module of liquid scintillator made from hydrogen and carbon, and I am looking at what happens to the neutron after it scatters inside the detector. I get an angular distribution for the neutrons that is peaked at forward angles and decays exponetially with increasing angle (as expected). However, there is a large peak in the distribution at theta = 16 deg., followed by a hole in the distribution immediately following the peak at around 20 deg. This peak is not there at very low energies (< 2 MeV), begins to appear around 3 MeV and then moves from 90 degs. toward 0 degs. as energy increases. As one approaches 100 MeV, however, the peak disappears. The peak does not appear if I use in the simulation a "detector" of pure hydrogen and it does not appear if I do not add the Elastic Scattering Model (LElastic) to the neutrons. If I only add the LElastic model (and do not use any other models with the neutron), the peak is there.
Attached is the Physics List I am currently using (for the neutrons): pManager = G4Neutron::Neutron()->GetProcessManager();
// Create Pointers for Neutron nuclear processes
G4HadronElasticProcess* N_LE_ElasticProcess = new G4HadronElasticProcess(); G4HadronCaptureProcess* N_LE_CaptureProcess = new G4HadronCaptureProcess(); G4HadronFissionProcess* N_LE_FissionProcess = new G4HadronFissionProcess(); G4NeutronInelasticProcess* Neutron_InelasticProcess = new G4NeutronInelasticProcess();
// Neutron Nuclear Scattering Models
G4LElastic* N_LE_Elastic = new G4LElastic(); G4LCapture* N_LE_Capture = new G4LCapture(); G4LFission* N_LE_Fission = new G4LFission();
// Choose Inelastic Interaction!!! // Pre-Compound Model - from Hadronic Physics
G4ExcitationHandler *theHandler = new G4ExcitationHandler(); G4PreCompoundModel *thePreCompModel = new G4PreCompoundModel(theHandler);
// Bertini Cascade Model // G4CascadeInterface *theCascade = new G4CascadeInterface();
G4NeutronInelasticCrossSection* the_Neutron_IE_Cross_Section_Data = new G4NeutronInelasticCrossSection();
// // Add neutron processes // N_LE_ElasticProcess->RegisterMe(N_LE_Elastic);
N_LE_CaptureProcess->RegisterMe(N_LE_Capture); N_LE_FissionProcess->RegisterMe(N_LE_Fission); Neutron_InelasticProcess->RegisterMe(thePreCompModel); // Neutron_InelasticProcess->RegisterMe(theCascade);
pManager->AddDiscreteProcess(N_LE_ElasticProcess); pManager->AddDiscreteProcess(N_LE_CaptureProcess); pManager->AddDiscreteProcess(N_LE_FissionProcess); pManager->AddDiscreteProcess(Neutron_InelasticProcess); // End attached code
Has anyone else had a similar problem and can suggest a solution? Thanks for the help. B.R.
|Inline Depth:||Outline Depth:||Add message:|