|Message: Re: How can I Restart a Stopped Track?||Not Logged In (login)|
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On Thu, 9 Feb 2006, Tom Roberts wrote: > *** Discussion title: Event and Track Management > Email replies to PublicHyperNews@slac.stanford.edu must include: > In-Reply-To: <"/eventtrackmanage/440/1/1"@geant4-hn.slac.stanford.edu> > Subject: ...change this to be about your reply. > > Yes,indeed, the electric field is dynamic: it is zero until most of the > mu+ stop (or are quite low energy). Then after ~1/4 decay time the E > field is rapidly ramped up to accelerate them out of the material. > > I really want the full Geant4 tracking, energy loss, multiple > scattering, etc. for tracking these, as I want the simulation to be as > realistic as possible. > > I'm thinking that my new Process should replace G4StepLimiter on this > particle, and never actually stop it. My new Process should ensure the > particle always has ~1/40 eV KE, so it can specify a step length of a > micron or so, keeping the time interval of each step ~1 ns while waiting > for the E field to come on. Whenever the particle's KE is too low, it > would kick it in a random direction. > > For my purposes, errors of a few eV and a few dozen microns are not > important. That 1/40 eV is of course not arbitrary, and perhaps these > random kicks are not really "errors" anyway. So I'm not terribly > concerned how accurate the other physics processes are at such a low > energy, just that they behave reasonably. > > This way the particles never actually stop. > Hello Tom, In that case I would propose to try following: 1) make you field time dependent 2) create a new you own AtRest process for mu+ and include it into PhysicsList this process should have a method AtRestGetPhysicalInteractionLength which should return t = delay_time_of_field, as a result, you will sample a competition between mu+ decay and this process. in the AtRestDoIt method the process need to do following: - change mu+ status from fStopButAlive to fKilled - create a new track of mu+ with the time and point in space exactly as the previous one - give to this new mu+ a very small kinetic energy (for example, 10 eV) Please, try and report if any problem. VI
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