// Creates the "ladder" = silicon sensor + 5 chips.
// All parts are implemented as TGeoBBox and inserted
// into a container which is the return value of this method.
- // This will allow to replicate this object many times, as required
- // for the implementation of half-staves.
// The sizes of the components come from drawings
- // of the Technical office of INFN Padova
+ // of the Technical office of INFN Padova.
+ // Due to the requirement to specify the sensitive volume separately from the rest,
+ // the sensor is implemented as the sum of a central sensitive part + a guard ring.
+ // Also the bump-bondings are added in form of small cylinders.
// ---
// Arguments:
// - the layer which will own this ladder (MUST be 1 or 2)
// ** CRITICAL CHECK **
// layer number can be ONLY 1 or 2
- if (layer != 1 && layer != 2) AliFatal("Required that layer number be 1 or 2");
+ if (layer != 1 && layer != 2) AliFatal("Layer number MUST be 1 or 2");
// instantiate all required media
- TGeoMedium *medVacuum = mgr->GetMedium("VACUUM");
+ TGeoMedium *medAir = mgr->GetMedium("Air");
TGeoMedium *medSPDSiChip = mgr->GetMedium("SPD SI CHIP");
- TGeoMedium *medSi = mgr->GetMedium("SI");
+ TGeoMedium *medSi = mgr->GetMedium("Si");
+ TGeoMedium *medBumpBond = mgr->GetMedium("BumpBond");
- // define sizes:
+ // ** Define sizes **
// they are expressed in mm in the drawings so they require conversion
- // 'widths' are in the direction of the detector length (Z axis)
+ // 'length' is in the direction of the detector length (Z axis)
// 'thickness' is obvious
- // 'heights' are in the direction orthogonal to 'width' and 'thickness'
- Double_t chipThickness = fgkmm * 0.15;
- Double_t chipWidth = fgkmm * 15.95;
- Double_t chipLength = fgkmm * 13.60;
- Double_t chipSpacing = fgkmm * 0.40;
- Double_t chipBorder = fgkmm * 0.56;
- Double_t sensThickness = fgkmm * 0.20;
- Double_t sensWidth = fgkmm * 13.92;
- Double_t sensLength = fgkmm * 70.72;
-
- // create the container, bounded exactly around the limits of the ladder size
- // the 'thickness' is the sum of both thicknesses
- // the 'height' is the chip's one, which is larger
- // the 'width' is the one of the sensor, which contains all chips + a border
- // the name depends on the chosen layer number,
- // in order to respect ALICE sensitive volumes naming conventions
- thickness = sensThickness + chipThickness;
- width = chipWidth;
- length = sensLength;
- TGeoVolume *container = mgr->MakeBox(Form("LAY%d_LADDER", layer), medVacuum, 0.5*thickness, 0.5*width, 0.5*length);
+ // 'width' is in the direction orthogonal to 'width' and 'thickness'
+
+ // for the chip, also the spacing between them is required
+ Double_t chipThickness = fgkmm * 0.150;
+ Double_t chipWidth = fgkmm * 15.950;
+ Double_t chipLength = fgkmm * 13.600;
+ Double_t chipSpacing = fgkmm * 0.400;
+
+ // for the sensor, we define the area of sensitive volume
+ // while the guard ring is added as a separate piece
+ Double_t sensThickness = fgkmm * 0.200;
+ Double_t sensLength = fgkmm * 69.600;
+ Double_t sensWidth = fgkmm * 13.920;
+ Double_t guardRingWidth = fgkmm * 0.560;
+
+ // bump bond is defined as a small stripe of height = 0.012 mm
+ // and a suitable width to keep the same volume it has
+ // before being compressed (a line of spheres of 0.025 mm radius)
+ Double_t bbLength = fgkmm * 0.042;
+ Double_t bbWidth = sensWidth;
+ Double_t bbThickness = fgkmm * 0.012;
+ Double_t bbPos = 0.080; // Z position w.r. to left pixel edge
- // create two volume boxes which describe the two involved objects:
- // - the sensor (large box, used once)
- // - the chip (small box, used 5 times)
- TGeoVolume *volSens = mgr->MakeBox("SENSOR", medSi, 0.5*sensThickness, 0.5*sensWidth, 0.5*sensLength);
+ // ** Create volumes **
+ // the container is the return value, and is built as a box
+ // whose edges exactly enclose the stuff we inserted here, filled with air.
+ // Its name depends on the layer number.
+ width = chipWidth;
+ length = sensLength + 2.0*guardRingWidth;
+ thickness = sensThickness + chipThickness + bbThickness;
+ TGeoVolume *container = mgr->MakeBox(Form("LAY%d_LADDER", layer), medAir, 0.5*thickness, 0.5*width, 0.5*length);
+
+ // the chip is a simple box:
TGeoVolume *volChip = mgr->MakeBox("CHIP", medSPDSiChip, 0.5*chipThickness, 0.5*chipWidth, 0.5*chipLength);
+
+ // the sensor is the union of a box and a border, to separate sensitive part from the rest
+ // the sensitive volume (inner part) is named according to the owner layer.
+ // To compute the shape subtraction which is needed for this we create two shapes,
+ // which are two boxes with the same center.
+ // The smaller one is then used to define the sensor, while the subtraction of the two
+ // is used for the guard ring.
+ TGeoBBox *shSens = new TGeoBBox(0.5*sensThickness, 0.5*sensWidth, 0.5*sensLength);
+ TGeoBBox *shIn = new TGeoBBox(sensThickness, 0.5*sensWidth, 0.5*sensLength);
+ TGeoBBox *shOut = new TGeoBBox(0.5*sensThickness, 0.5*sensWidth + guardRingWidth, 0.5*sensLength + guardRingWidth);
+ shIn->SetName("innerBox");
+ shOut->SetName("outerBox");
+ TGeoCompositeShape *shBorder = new TGeoCompositeShape("", "outerBox-innerBox");
+ TGeoVolume *volSens = new TGeoVolume(Form("LAY%d_SENSOR", layer), shSens, medSi);
+ TGeoVolume *volBorder = new TGeoVolume("GUARD_RING", shBorder, medSi);
+
+ // one line of bumpbonds
+ TGeoVolume *volBB = mgr->MakeBox("BB", medBumpBond, 0.5*bbThickness, 0.5*bbWidth, 0.5*bbLength);
+
+ // set colors of all objects for visualization
volSens->SetLineColor(kYellow + 1);
volChip->SetLineColor(kGreen);
+ volBorder->SetLineColor(kYellow + 3);
- // translation for the sensor box: direction of width (moved to edge of container) and thickness (moved up)
- Double_t x = 0.5 * (thickness - sensThickness);
- Double_t y = 0.5 * (width - sensWidth);
- Double_t z = 0.0;
- TGeoTranslation *trSens = new TGeoTranslation(x, y, z);
// translations for the chip box: direction of length and thickness (moved down)
TGeoTranslation *trChip[5] = {0, 0, 0, 0, 0};
- x = 0.5 * (chipThickness - thickness);
- y = 0.0;
+ Double_t x = 0.5 * (chipThickness - thickness);
+ Double_t y = 0.0;
+ Double_t z = 0.0;
Int_t i;
for (i = 0; i < 5; i++) {
- z = -0.5*length + chipBorder + (Double_t)i*chipSpacing + ((Double_t)(i) + 0.5)*chipLength;
+ z = -0.5*length + guardRingWidth + (Double_t)i*chipSpacing + ((Double_t)(i) + 0.5)*chipLength;
trChip[i] = new TGeoTranslation(x, y, z);
}
+ // translation for the sensor parts: direction of width (moved to edge of container) and thickness (moved up)
+ x = 0.5 * (thickness - sensThickness);
+ y = 0.5 * (width - sensWidth - 2.0*guardRingWidth);
+ z = 0.0;
+ TGeoTranslation *trSens = new TGeoTranslation(x, y, z);
+
+ // translation for the bump bonds:
+ // keep same y used for sensors, but change the Z
+ TGeoTranslation *trBB[160];
+ //x = 0.5 * (thickness - bbThickness) + 0.5*sensThickness;
+ x = 0.5 * (thickness - bbThickness) - sensThickness;
+ z = -0.5 * sensLength + guardRingWidth + fgkmm*0.425 - bbPos;
+ for (i = 0; i < 160; i++) {
+ trBB[i] = new TGeoTranslation(x, y, z);
+ switch(i) {
+ case 31:
+ case 63:
+ case 95:
+ case 127:
+ z += fgkmm * 0.625 + fgkmm * 0.2;
+ break;
+ default:
+ z += fgkmm * 0.425;
+ }
+ }
+
// add nodes to container
container->AddNode(volSens, 1, trSens);
+ container->AddNode(volBorder, 1, trSens);
+ for (i = 0; i < 160; i++) container->AddNode(volBB, i, trBB[i]);
for (i = 0; i < 5; i++) container->AddNode(volChip, i + 2, trChip[i]);
// return the container
git://git.uio.no / u / mrichter / AliRoot.git / commitdiff