DELPHI Very Forward Tracker (VFT)
Technical description
The Very Forward Tracker is located on both sides A and C of the new 1996
vertex detector. On each side it is built from two layers of mini strip and
two layers of pixel detectors. The VFT covers the polar angle from 10 to 25
degrees.
All mini strip modules are installed with about 24.500 readout channels.
In 1996 there is 5/8 of the pixel detectors were installed. In 1997 the
pixel upgrade was completed, with about 1.2 million
detector elements (pixels). The sector AD is equipped with two pixel layers.
The VFT Pixel Detector
Each layer of the Pixel Detector is built from two crowns of modules which are
rotated against each others to cover the holes between the modules. The crowns
on side A have an odd numbering and the ones on side C an even numbering.
In 1996 the crowns 1,3,5,7 and 0,2 were installed, and crowns 5 and 7 were only
equipped by half (sector AD). In 1997 the upgrade was completed.
A pixel detector crown is built from 18 or 20 modules which are arranged on a
cone as inicated in the following graphics. Each module has about 8000 detector
elements.
The VFT Mini Strip Detector
Each layer of the mini strip detector is built from two half rings with 6
detector modules each surrounding the beam pipe. Each module is formed by two
single-sided strip detectors which are assembled back to back with
perpendicular strip orientation. In total there are 48 mini strip modules
consisting of 96 detectors.
