Detector structure and naming conventions

   Barrel  →  Half Shell  →  Layer  →  Ladder  →  Module
↑                                 ↓
  Pixel                               ROC
  ↓                                 ↑
   Endcap → Half Cylinder → Half Disk → Blade → Panel → Module

Pixel detector

The Pixel detector consists of a central barrel and two endcaps at both ends (?<i>z</i>) of the barrel. Together, the endcaps are known as the forward Pixel or Pixel Endcap.

Figure: Diagram of the Pixel detector.


Physically, the barrel is separated vertically (<i>y</i>-axis) to give two half-barrels. For the purpose of DAQ and DCS (but not for alignment), each half-barrel is considered to be made of two half-shells joined at <i>z</i> = 0. Therefore, the Pixel Barrel consists of four half-shells denoted as BmI, BmO, BpI, BpO, where 'p' stands for "plus" (+<i>z</i>), 'm' for "minus" (−<i>z</i>), 'I' for "Inner" (+<i>x</i>), 'O' for "Outer" (−<i>x</i>).

Figure: Schematic of Pixel Barrel showing the half-shells.

half-barrel.png half-barrel.jpg
Figure: (Left) computer-aided drawing of a half-barrel in upright position. (Right) photograph of a half-barrel lying down.

Half shell

Each half-shell has 3 layers numbered as 1, 2, 3 in increasing radii. Logically, it is useful to divide each half-shell into 8 sectors in <i>φ</i>, Sector1 to Sector8, where the numbering increases from top to bottom (see figure).

Figure: r-φ view of Pixel Barrel showing the sector numbers.


Layer1 (considering a semi-circular surface) has 10 (so-called) ladders arranged symmetrically in <i>φ</i>, while Layer2 has 16 and Layer3 has 22. Due to the separation in <i>y</i>, the top and bottom ladders are actually half-ladders, but most of the time, we will simply refer to all as ladders.

Figure: r-φ view of the first layers of Pixel Barrel (2 half-shells together) showing the arrangement of the ladders.

Figure: Photograph of Layer1 of a half-barrel.


A ladder consists of 8 modules joined end to end along the length of the barrel, four on the -z side and four on the +z side. To be precise, sometimes the letter 'F' or 'H' is used to indicate a full- or half-ladder in a label.


A module (or sensor) of the Pixel Barrel has either 8 or 16 readout chips (ROC) arranged in a 1 8 (for half-ladders) or 2 8 (for full-ladders) configuration.

module.png module.jpg
Figure: (Left) computer-aided drawing of a 2 8 barrel module. (Right) photograph of a 2 8 barrel module.

Readout chip (ROC)

The readout chip is an array of 80 52 pixels, each of size 100 μm 150 μm.

ROC.png ROC.jpg
Figure: Computer-aided drawing (left) and photograph (right) of a ROC.

-- BalintRadics - 2011-03-02

Topic attachments
I Attachment History Action Size Date Who Comment
Jpgjpg ROC.jpg r1 manage 109.3 K 2011-03-02 - 22:25 BalintRadics  
Pngpng ROC.png r1 manage 724.4 K 2011-03-02 - 22:24 BalintRadics  
Pngpng barrel.png r1 manage 24.0 K 2011-03-02 - 21:41 BalintRadics  
Jpgjpg half-barrel.jpg r1 manage 45.5 K 2011-03-02 - 21:43 BalintRadics  
Pngpng half-barrel.png r1 manage 386.0 K 2011-03-02 - 21:42 BalintRadics  
Jpgjpg layer1.jpg r1 manage 206.4 K 2011-03-02 - 22:21 BalintRadics  
Pngpng layer1.png r1 manage 7.1 K 2011-03-02 - 22:20 BalintRadics  
Jpgjpg module.jpg r1 manage 41.0 K 2011-03-02 - 22:24 BalintRadics  
Pngpng module.png r1 manage 281.0 K 2011-03-02 - 22:24 BalintRadics  
Pngpng pixel.png r1 manage 207.6 K 2011-03-02 - 21:35 BalintRadics  
Pngpng sectors.png r1 manage 133.5 K 2011-03-02 - 22:18 BalintRadics  
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Topic revision: r2 - 2011-04-10 - RadicsBalint
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