|Message: Re: How can I Restart a Stopped Track?||Not Logged In (login)|
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On Wed, 8 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"@geant4-hn.slac.stanford.edu> > Subject: ...change this to be about your reply. > > I literally do want to restart the tracking of a track that has stopped. > Physically we put low-energy mu+ into a gas absorber in which they range > out, but before they can decay we turn on a large electric field to > accelerate them. (mu- are problematical as they get captured, so ignore > them for now) > > What I want to do is use a new process to keep stepping the track while > stopped; it looks to me that I can simply implement the > AtRestGetPhysicalInteractionLength() function to return the time step I > want, and the track will simply make multiple steps while at rest (until > it decays). > > The part I don't understand is how to convince the transportation > process to resume tracking once the electric field has come on and given > it a kinetic energy above the threshold. What I think I can do is > implement AtRestDoit() to get the global field at the current point of > the track (includes time), and basically integrate the equation of > motion myself until it gets above threshold -- hopefully the real > transportation process will then resume tracking it. > > Some questions: > a) will transportation automatically resume tracking, or do I > need to do something explicit? > b) how do I know when it does (so I stop tracking myself)? > c) how do I determine the K.E. threshold in the current volume > (material)? > Hello, Starting from the end: by default (If no user limits) there is no thresholds - tracking is performed until particle stop. If electric field is permanent, then there may be only reflection point - mu+ loses energy for ionizzation then is accelerated by field. If it is the case it should work even now. But in your experiment field is dynamic (is it?) - it is switched on after some time, which is smaller than the decay time. Is it correct? Before going to further discussion, please, confirm your physics. VI
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