Hi,

    Manuel indicated that in order to satisfy the muon Level 1 trigger and the
    STT, he would like to change the anchor layer for the CFT equations from A
    to D or E. That means we would receive the hit fibers in layers D (or E)
    and H instead of A and H. I have computed the width of the roads spanned
    by a fiber in layer H and any other layer. You can find a short document
    on the web:
     http://www-d0.fnal.gov/~heintz/public_html/d0_private/stt/CFT_roads.ps

    In a nutshell: the road pointing gets worse (as expected) if the A layer
    hit is replaced by a D layer hit. Quantitatively, the width of the roads
    increase by
        * 20% in any SMT layer, for impact parameter = 0 
        *  8% in SMT layer 1 (innermost), for impact parameter < 2mm
        * 36% in SMT layer 8 (outermost), for impact parameter < 2mm
    The momentum resolution from the two fiber hits and the point closest to
    the center of the detector gets worse by 16% if the inner fiber changes
    from layer A to D.

                                   Ulrich