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Forum: Fast Simulation, Transportation & Others
Re: None Problems with transportation with spin (Tom Roberts)
Date: 15 Mar, 2012
From: Tom Roberts <Tom Roberts>

On Thu, 15 Mar 2012 20:50:42 GMT, Tom Roberts wrote:
> 3. The constructor of G4Mag_SpinEqRhs takes a G4MagneticField, not a
>    G4ElectroMagneticField. As a result, the particles do not see any electric
>    field -- neither spin nor momentum are changed by an E field.

I just stumbled across G4EqEMFieldWithSpin. It appears to resolve this -- a quick test shows that a mu+ moves in a constant E field just as for the usual equation of motion without spin, and the spin precessed a little bit.

In my class derived from G4ElectroMagneticField, I simply replaced
    G4EquationOfMotion *e = new G4Mag_SpinEqRhs((G4MagneticField*)this);
    pStepper = new G4ClassicalRK4(e,12);
with
    G4EquationOfMotion *e = new G4EqEMFieldWithSpin(this);
    pStepper = new G4ClassicalRK4(e,12);

Tom Roberts

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