Track Linking

  There are two ways to link tracks to improve the precision of track parameter measurements. The first method is to combine track parameters and their error matrices obtained by individual tracking devices. In the second method, we go all way back to hit points and refit them to a single track consisting of several track segments. Apparently the second is more powerful, since it uses all of the available information. Unlike the first method, this, however, heavily depends on the nature of the coordinate information from each tracking divice. Thus, we will review the first method here.