Intermediate Tracker

We have focused so far on the measurement of the imi)act parameters, especially in the coordinate. The vertex detector, how( ver, will also improve the measurement of the momentum for high-momentum tracks considerably l)y ( xtending the lever arm of the measurements in the central drift chamber (CDC), which begins at 22.5 cm. In order to achieve both the d( sired impact j)aramet( r resolution and the improvement in momentum resolution, a vertex tletc ctor with two or tlin c laytus ( xtemding from close to the beampipe out to approximately 8 cm in raelius we)ulel l)c satisfactory. Tins we)ulel lea e the space from 8 te 20 cm uninstruine iite el. 

Additional iiieasure inents in this region have little inii)act e)ii the measurement of high momentum trae ks, but can la ve iy useful for e)ther ])ui])oses sue-h as  

Section 2.6 contains a brief discussion of a straw tube intermi fliate trax ker that remains a possible choice for tins function. The straw tul)c design is also ea,sily adaptable for u.se in the trigger. 

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We also include a description of a low-mass straw tube design for the intermediate tracker. The inclusion of this device would allow reduction of the silicon strip system to three or four layers. The straw tube system can be designed to provide track angle information in the r — plane for use in the trigger. 

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