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This has the result that you cannot reliably swim the Track to a given point. Although Because the reference point for the track is 0, the Swimmer claims that the tracklength to the origin is not 00. However, since the Track has been instantiated from a particle that did not originate at the IP, the track parameters do not actually correspond to the origin.
In other words: The POCA on the track to the IP results in the wrong point.
The result of this can be seen in fig. (). Note that this is the distance to swim the track to the origin, which should be independent of the impact parameter. 
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A new Track
Interface Design goals:
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