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Question particle bouncing back-and-forth 

Forum: Event and Track Management
Date: 30 Sep, 2004
From: Daniel Barna <Daniel Barna>


I encountered a problem in a relatively simple setup: low-energy particles are emitted in a vacuum, and accelerated towards a copper surface by an electric field. I have setup a global electric field as shown in the example at with one trick: I derived my electric field class from G4MagneticField (and overwrote the DoesFieldChangeEnergy function to return true), because otherwise the program did not compile (see This field seemed to work well, with one problem: in some events the simulation seemed to be stuck, one event was processed for several minutes. Setting the /tracking/verbose level I traced the problem back to particles bouncing back and forth in the copper surface (one step from world to copper, next step from copper to world, and so forth), with 0 (or negligible) step size. If I switched off the electric field globally, or only at the surface of the copper, then the problem disappeared. Has anybody encountered the same problem?

Thank you, Daniel

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1 Angry: Re: particle bouncing back-and-forth   (stacey - 06 Apr, 2006)
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