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.

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