|Message: Re: Negative Current Interaction Length with Photonuclear interaction, and other problems||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)|
On Mon, 6 Jun 2005, Giles Reid wrote: > *** Discussion title: Event and Track Management > Email replies to PublicHyperNews@slac.stanford.edu must include: > In-Reply-To: <"/eventtrackmanage/338"@geant4-hn.slac.stanford.edu> > Subject: ...change this to be about your reply. > > Hello, > > I'm trying to simulate magnetic monopoles in GEANT. I am currently using > a modified mu+ with charge 68.5 and mass of around 300GeV. > > I've been trying to get the Photonuclear interaction process to work, > using the base of the MuonProcess example, but when I add the process I > get the following error: > > *** G4Exception : Negative currentInteractionLength > issued by : G4VProcess::SubtractNumberOfInteractionLengthLeft() > > All of the PostStepDoIt outputs above this error contain nans for > various parameters like momentum and total energy. > > So my first question is, can the Muon Photonuclear code be expected to > work for high charges and masses, or would it need to be rewritten? > > I have been able to modify the PairProduction model to include extra > factors of the monopole charge and this appears to give reasonable > results. I have also found that the MuIoni process doesn't work very > well, but the hIoni one does. The problem is, I can't make pair > production and ionisation work simultaneously, because when I use hIoni > with the Muon along with Pair Production I get a segmentation fault in > the line: > > theDEDXTable->GetFlag(i) > > in G4VEnergyLossProcess.cc. > > I realise that having hadronic and muon processes may be causing the > problem. However, in order to make the simulations realistic I need to > have the Pair Production and Photonuclear Processes working, and as far > as I can tell there is no hadronic equivalent to these processes in > GEANT. > > Any help would be greatly appreciated. > > Giles Reid. > Hello, There is little information to make a conclusion but too many things changed in official processes/particles, so I am not suprised that it crashes. Few obvious advices: 1) Never modify official code of G4. If you need to change something - make a copy of G4 class, rename it , introduce your changes and use in your application. 2) Muon example has specific - all secondary particles are killed, because it intends not for simulation of all processes but only to demonstrate muon cross sections and energy loss. If one needs simulation of secondaries, PHysicsList should be extended by including hadron processes. 3) Both ionisation models muIoni and hIoni are not adequate to monopole, because monopole ionisation is different. However, if one defines mass and change of heavy particle they have to work, if PhysicsList is written correctly. VI
|Inline Depth:||Outline Depth:||Add message:|