make stave width explicit variable and use it to constrain its placement, rather than sensor width: this allowed for potential small ex/intrusions.

Author: JustusRudolph

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/include/FT3Simulation/FT3Module.h

@@ -86,8 +86,8 @@ class FT3Module
 
   // Helper functions
   void fill_stave_greedy(
-    PosNegPositionTypes& y_positions, double Rin, double Rout,
-    double x_left, unsigned kSensorStack, PositionRangeType y_range,
+    PosNegPositionTypes& y_positions, unsigned kSensorStack,
+    PositionRangeType y_range,
     std::pair<double, double>& absAllowedYRange);
 
   PositionTypes fill_stave_exact(const std::vector<Constants::StaveFill>& fills);

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/include/FT3Simulation/FT3ModuleConstants.h

@@ -47,7 +47,7 @@ namespace o2::ft3::ModuleConstants
 // First set all layout constants for the rest of the function
 const double single_sensor_width = 2.5;
 const double single_sensor_height = 2.9;
-const double inactive_width = 0.2;
+const double inactive_width = 0.15;
 const double sensor2x1_gap = 0.015;    // gap between L&R sensors in 2x1, and between sensors in a stack
 const double stackGap = 0.035;         // gap between 2xN module stacks
 
@@ -111,8 +111,9 @@ const double effectiveCarbonThickness_Stave = 0.02; // foam + shell
 const double staveOpeningAngle = 60 * TMath::DegToRad();
 const double sinTheta = TMath::Sin(staveOpeningAngle / 2);
 const double alpha = TMath::Pi() / 2 - staveOpeningAngle / 2; // bottom angles
-const double staveSensorGap = 0.1;                            // 2mm padding on each side when sensor is glued
-const double staveTriangleHeight = (sensor2x1_width + 2 * staveSensorGap) / 2.0 / tan(staveOpeningAngle / 2.0);
+const double staveSensorGap = 0.1025;                         // 1025µm padding on each side: 52.2mm stave width
+const double staveWidth = sensor2x1_width + 2 * staveSensorGap;
+const double staveTriangleHeight = staveWidth / 2.0 / tan(staveOpeningAngle / 2.0);
 /*
  * Now describe the offset of every other stave in z to avoid overlaps
  * ______      ______

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/src/FT3Layer.cxx

@@ -423,8 +423,10 @@ void FT3Layer::createLayer(TGeoVolume* motherVolume)
     double z_local_offset = z_layer_thickness / 2.0;
     // ensure staves fully encapsulated in the layer volume,
     // but don't cross out of max nominal radii of 38.5cm & 71.5cm respectively (3.5cm tolerance)
+    // Allow 9cm inward for OT:
+    double innerRadiusForAirTube =  mIsMiddleLayer ? mInnerRadius : mInnerRadius - 9.0;
     // MvL: try 70.5 // 2.5 cm tolerance instead
-    TGeoTube* layer = new TGeoTube(mInnerRadius - 0.2, mOuterRadius + 2.49, z_layer_thickness / 2);
+    TGeoTube* layer = new TGeoTube(innerRadiusForAirTube - 0.2, mOuterRadius + 2.49, z_layer_thickness / 2);
     layerVol = new TGeoVolume(mLayerName.c_str(), layer, medAir);
 
     if (ft3Params.drawReferenceCircles) {

Detectors/Upgrades/ALICE3/TRKFT3/FT3/simulation/src/FT3Module.cxx

@@ -83,17 +83,14 @@ std::pair<double, double> calculate_y_range(
  * y_positions: a pair of vectors, where each vector contains pairs of
  *              y position and stack height for the positive and negative y positions respectively.
  *              This argument will be appended with the new sensor positions and stack heights.
- * Rout: the outer radius of the layer
- * Rin: the inner radius of the layer
- * x_left: the x position of the left edge of the sensor to be placed
  * kSensorStack: the number of sensors to be stacked on top of each other
  * y_ranges: the y positions to start and end placing sensors,
  *           for positive and negative y respectively
  * absAllowedYRange: the absolute y range allowed for placing sensors,
  *                   used to cut placement if they go past allowed tolerances
  */
-void FT3Module::fill_stave_greedy(PosNegPositionTypes& y_positions, double Rin, double Rout,
-                                  double x_left, unsigned kSensorStack, PositionRangeType y_ranges,
+void FT3Module::fill_stave_greedy(PosNegPositionTypes& y_positions, unsigned kSensorStack,
+                                  PositionRangeType y_ranges,
                                   std::pair<double, double>& absAllowedYRange)
 {
   // start with upper half of the stave, then mirror to the bottom half
@@ -648,10 +645,10 @@ void FT3Module::build_staves_greedy(
      * (2) The inner tolerance is large enough to allow stave placement as wished
      *    a) AND the given stave midpoint is above the inner radius
      */
-    double x_left = staveConfig.x_midpoints[i_stave] - Constants::sensor2x1_width / 2;
-    double x_right = x_left + Constants::sensor2x1_width;
+    double x_left_stave = staveConfig.x_midpoints[i_stave] - Constants::staveWidth / 2;
+    double x_right_stave = x_left_stave + Constants::staveWidth;
     std::pair<double, double> absAllowedYRange =
-      calculate_y_range(x_left, x_right, Rin, Rout);
+      calculate_y_range(x_left_stave, x_right_stave, Rin, Rout);
 
     /*
      * Shift allowed range by tolerance. Note that both values in the range must
@@ -679,9 +676,8 @@ void FT3Module::build_staves_greedy(
     // now add the sensor positions on the stave
     for (unsigned i_kSens = 0; i_kSens < Constants::kSensorsPerStack.size(); i_kSens++) {
       unsigned nModulesCurr = y_positionsPosNeg.back().first.size() + y_positionsPosNeg.back().second.size();
-      fill_stave_greedy(y_positionsPosNeg.back(), Rin, Rout, x_left,
-                        Constants::kSensorsPerStack[i_kSens], y_ranges,
-                        absAllowedYRange);
+      fill_stave_greedy(y_positionsPosNeg.back(), Constants::kSensorsPerStack[i_kSens],
+                        y_ranges, absAllowedYRange);
       unsigned nModulesAdded = y_positionsPosNeg.back().first.size() + y_positionsPosNeg.back().second.size() - nModulesCurr;
       nSensorStackCountPerStave[i_stave][i_kSens] = nModulesAdded;
       nSensorStackTotal[i_kSens] += nModulesAdded;
@@ -820,12 +816,12 @@ void FT3Module::create_layout_staveGeo(double mZ, int layerNumber, int direction
           double z_mid = z_offset_to_silicon * z_offset_multiplier + z_stave_shift;
           addSingleSensorVolume(
             motherVolume, layerNumber, direction, i_stave, sensor_count,
-            x_mid - Constants::sensor2x1_width / 2,
+            x_mid - Constants::sensor2x1_gap / 2 - Constants::active_width / 2,
             y_mid, z_mid, true);
           // right single sensor of the 2x1: place left edge half of sensor gap from center
           addSingleSensorVolume(
             motherVolume, layerNumber, direction, i_stave, sensor_count + 1,
-            x_mid + Constants::sensor2x1_width / 2,
+            x_mid + Constants::sensor2x1_gap / 2 + Constants::active_width / 2,
             y_mid, z_mid, false);
           // ------------ (2) Epoxy glue layer between silicon and copper (FPC) ------------
           z_mid = z_offset_to_glue_Si * z_offset_multiplier + z_stave_shift;