Given a straight line track and a helical track, we can combine them to
improve the helix parameter measurements as we did for the helix
to helix linking^{}.
Again the pivots should be chosen at a common space point:
the best choice is the intersection of the straight line track with
the boundary of the two regions.
We then correct the error matrix of the straight line track for
multiple scattering.
Then the to minimize is defined by

(24) |

(25) |