|Message: Re: Alpha n reactions in geant4||Not Logged In (login)|
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Hi all, let me add a comment, in the sense that has already been done several times in in the past. Given the very low energies, and masses your reaction will proceed via very simple equilibrium de_excitation mechanisms, which in Binary cascade is Fermi-BreakUp (if A<17, as in your case) or evaporation (A>17). Bertini uses its own version of equilibrium de_excitation models, as did INCL in the past (now it uses the same de_excitation models as Binary). But in any case those models are intended as final de-excitation stages after string or cascade models (starting at much higher energies, above GeV) have done their job. By no means they are intended as "doorway" models. Fermi Break-Up model considers the different possible partitions of the excited nuclear system (13C in your case, if target is 9Be), and samples them according to probability distribution coming from phase space availability arguments. Just a theoretical model. If it comes out (as it seems that happens in your case) that the partitions with 1n+ residuals (or residuals) never "win" (or even are simply forbidden by the model).. you end up without neutrons. Just a model. Even if, just by simulating many, many particles, you get some neutrons, you shouldn't expect to reproduce experimental data at such low energies and light systems. The same applies to alphas on quartz at these energies. You should resort to evaluated data, which is what G4ParticleHP (under development) is intended for. regards Jose Manuel On 10/09/2014 05:04 PM, Neha Dokania wrote: > *** Discussion title: Hadronic Processes > > Hi, > > I have used Hadr03 Physics list with Geant4.9.5.p01. But I don't see any > neutrons being produced as secondaries from 2-20MeV alpha on Be. Same > happened with QGSP_BERT, QGSP_BIC physics lists. > > Any help will be much appreciated. > > On Fri, 18 Apr 2014 09:03:10 GMT, michel maire wrote: > >> On Wed, 16 Apr 2014 17:09:10 GMT, Zachary Babbitt wrote: >> >>> Hello, >>> >>> I am attempting to simulate an (alpha, n) reaction in Geant4 and I cannot >>> figure out how to do this. I have registered the QGSP_BERT_HP physics list >>> as well as the QGSP_BIC_HP physics list and no neutrons are showing up in >>> the process. Do I need to fully implement my own physics list to do this, >>> and if so, are there any examples I can reference? I'm working with alpha >>> particles that are from 5-20 MeV range which are being thrown into a >>> cylinder of quartz. Thank you. >>> >> Your list of physics must include one of the physics constructors in >> source/physics_lists/constructors/ions >> >> In attachement an example of Hadr03 run. See the PhysicsList.cc of this example. >> >> Attachment: >> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/18/01.59-47917-ion.mac.txt >> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/04/18/01.59-11631-ion.log.txt >> > ------------------------------------------------------------- > Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at: > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/hadronprocess/1395/1/1.html > -- José Manuel Quesada Molina Departamento de Física Atómica, Molecular y Nuclear Facultad de Física Universidad de Sevilla Apartado 1065 41080 Sevilla, España Tel:+34.954559508 Fax:+34.954554445 http://personal.us.es/quesada/