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Forum: Fast Simulation, Transportation & Others
Re: None Problems with transportation with spin (Tom Roberts)
Date: 20 Mar, 2012
From: Tom Roberts <Tom Roberts>

On Thu, 15 Mar 2012 20:50:42 GMT, Tom Roberts wrote:
 > 1. The G4Track global time is not updated. [...]

This problem has disappeared, using G4EqEMFieldWithSpin for the equation of motion.

I have plotted the precession of a single mu+'s spin for the BNL g-2 experiment, and it agrees with the experiment to 4-digit accuracy over 45 turns (no real fit was performed, which is needed to get better accuracy; this is just computing the period from an eyeball estimate of the 45th zero crossing).

In PreUserTrackingAction() my code now sets the anomaly for electrons and muons, and I have documented that spin tracking only applies to them. So #2 is handled.

Problem #3 was resolved by using G4EqEMFieldWithSpin.

So the only remaining problem is #4, the magnetic moment does not respond to a B-field gradient. Any suggestions?

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