Message: Re: Electrons not affected by electric field?  Not Logged In (login) 
Dear John,
thanks for your quick reply. I've implemented your remarks. Now sometimes I get the following messages:
1)// ** G4MagIntegrationDriver: found case of zero momentum. iteration= 0 h= 1.07306 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 1 h= 0.107306 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 2 h= 0.0107306 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 3 h= 0.00107306 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 4 h= 0.000107306 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 5 h= 1.07306e005 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 6 h= 1.07306e006 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 7 h= 1.07306e007 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 8 h= 1.07306e008 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 9 h= 1.07306e009 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 10 h= 1.07306e010 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 11 h= 1.07306e011 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 12 h= 1.07306e012 ** G4MagIntegrationDriver: found case of zero momentum. iteration= 13 h= 1.07306e013 G4MagIntegratorDriver::OneGoodStep: Stepsize underflow in Stepper Step's start x=968.516 and end x= 968.516 are equal !! Due to stepsize= 1.07306e014 . Note that input step was 1.07306 // 2)// ********************************************************************************************************* * G4Track Information: Particle = e, Track ID = 2, Parent ID = 1 *********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 0 18.3 10.5 5.44 1.5e005 0 0 0 Gas_in_cylinder_tube initStep 1 18 11 5.6 1.5e005 0 20.1 20.1 Gas_in_cylinder_tube eIoni 2 18.6 11 5.55 1.5e005 0 3.51 23.6 Gas_in_cylinder_tube msc 3 19.1 10.9 5.5 1.5e005 0 3.51 27.1 Gas_in_cylinder_tube msc 4 19.6 10.9 5.45 1.5e005 0 3.51 30.7 Gas_in_cylinder_tube msc 5 20.1 10.9 5.4 1.5e005 0 3.51 34.2 Gas_in_cylinder_tube msc 6 1.#J 1.#J 1.#J 1.#R 0 3.51 37.7 Gas_in_cylinder_tube msc // where in this case the program is not responding anymore. I suppose case 2 is when an electron leaves the cylinder and goes to "infinity"? 3)// ********************************************************************************************************* * G4Track Information: Particle = e, Track ID = 2, Parent ID = 1 *********************************************************************************************************
Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 0 14.5 12.9 117 1.5e005 0 0 0 Gas_in_cylinder_tube initStep 1 17.1 11.5 110 0.000387 0 20.1 20.1 Gas_in_cylinder_tube eIoni 2 17 0.597 109 17.8 0 10.9 31 Gas_in_cylinder_tube msc 3 11.9 0.659 107 822 0 6.96 38 Long_cylinder_tube Transportation 4 10.8 0.635 107 822 2.61e008 1.08 39.1 Long_cylinder_tube msc 5 9.19 0.601 107 1.61e+006 3.87e008 1.61 40.7 World Transportation G4MagIntegratorDriver::OneGoodStep: Stepsize underflow in Stepper Step's start x=1007 and end x= 1007 are equal !! Due to stepsize= 2.19296e014 . Note that input step was 2.19296 G4MagIntegratorDriver::OneGoodStep: Stepsize underflow in Stepper Step's start x=1007 and end x= 1007 are equal !! Due to stepsize= 2.19296e014 . Note that input step was 2.19296 G4MagIntegratorDriver::OneGoodStep: Stepsize underflow in Stepper Step's start x=1008 and end x= 1008 are equal !! Due to stepsize= 4.21789e014 . Note that input step was 1.19296 6 1e+003 1.23 109 3.99e+024 2.14e028 1.01e+003 1.05e+003 OutOfWorld Transportation // In this case here, the voltage is set to +1V, and I've seen the same if the voltage is set to 0V. The incoming photon has a energy of 35eV, the electron after photoionization has 15eV (with approx. 20eV being the Neon ionization potential). However, the kinetic energy of the electrons after 12 steps is more than 10 MeV, with a wire potential of 1V...
For testing purposes I've altered my GetFieldValue function to the following code: // void B7ElectricField::GetFieldValue(const G4double Point[3],G4double *Efield) const { Efield[2] = 0.; //z component of electrical field is zero
G4double X=Point[0], Y=Point[1]; G4double U=1.*volt;
Efield[0]=0; Efield[1]=U/1.6*cm; } // and the output is of the form in cases 13. Do you have any idea, where the error may lie? Thanks & best regards, Robert

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