|Message: Re: Anti-Proton Physics||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)|
Dear Dipanwita, For the G4QCaptureAtRest process, it is the CHIPS model which is handling the interactions. As with any model you can look at the description in the Physics Reference Manual; in this case you should also refer to the original papers by M. Kossov, P. Degtiarenko and H.P. Wellisch circa 2002-03 for a description of the underlying model. You seem to hope to adapt the implementation/code which exists. This is possible, since the source code is available. However it is likely very difficult to make changes to the model and corresponding changes to the code without care and expert advice. I suggest to contact its author M. Kossov via his CERN email, in case he is able and willing to give you guidance in this regard. Since a physics model has several parameters, it can be hard for someone who is not very-very familiar with the model and code to do this - e.g. to decide on the appropriate range of parameters for tuning and to compare to the relevant data for constraining and fixing these parameters, if such data exists. However it would likely be more productive to use instead a new version of Geant4, with an FTFP-based physics list. I suggest using Geant4 9.6 patch 02 with the FTFP_BERT physics list, which is the recommended list for several domains, including HEP and nuclear physics. It may be, though, that your requirements cannot be met by our current models - there are limits both to their underlying assumptions and to the calculations/tuning which the authors were able to undertake. In this case I would suggest to seek alternative approaches, either modeling or parameterising data which you have been able to measure, in case this would allow you to fulfill your application's requirements. Best regards, John Apostolakis On 7/5/13 9:01 AM, Dipanwita Banerjee wrote: > *** Discussion title: Physics List > > Hello > > I am trying to look into the tracks of the secondaries produced by > antiproton annihilations. In principle I am just interested in the > mesons produced as a result of the annihilation. My beam energy would be > <1kev. I am using G4QCaptureAtRest for the process which is giving me > the pions but also other particles as a result of the nuclear > fragmentation that's a part of the QCapture algorithm. I would like to > get rid of this part and just have the pions, as a part of the pions are > being absorbed by the nucleus of the target which is causing the > fragmentation and that's causing me to loose few pions in the result. I > don't want that. My geometry is fairly simple. It has a 2mm titanium > target followed by a tracker with Argon Gas. > > Can anyone tell me if there's a better process that can give me the > correct production rate of the pions? Or maybe I can change the > G4QCaptureAtRest process to meet my requirements. I would like to have > the explanation of the code in G4QCaptureAtRest as I am a little > confused how they have defined the annihilation and the fragmentation. > Can anyone please tell me where I can find the explanation or maybe give > me an idea how they have defined the code? > > Thanks, > > Dipanwita > > ------------------------------------------------------------- > Visit this GEANT4 at hypernews.slac.stanford.edu message (to reply or unsubscribe) at: > http://hypernews.slac.stanford.edu/HyperNews/geant4/get/phys-list/749/2.html