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name="Pixel" |
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.
Barrel
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. 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.
Layer
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.
Ladder
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.
Module
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.
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.
Figure: Computer-aided drawing (left) and photograph (right) of a ROC.
-- BalintRadics - 2011-03-02
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