Add functionality for the user to enforce a strict cut on module placement to remain within nominal radii. Also remove initial placement of sensor stack before calling fill_stave, moving to using y_start instead.

Author: JustusRudolph

Detectors/Upgrades/ALICE3/FT3/base/include/FT3Base/FT3BaseParam.h

@@ -40,6 +40,9 @@ struct FT3BaseParam : public o2::conf::ConfigurableParamHelper<FT3BaseParam> {
   Float_t etaOut = 1.5;
   Float_t Layerx2X0 = 0.01;
 
+  // override values from FT3ModuleConstants
+  bool cutStavesOnNominalRadius = false;
+
   O2ParamDef(FT3BaseParam, "FT3Base");
 };
 

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

@@ -66,8 +66,7 @@ class FT3Module
 
   // Helper functions
   void fill_stave(PosNegPositionTypes& y_positions, double Rout,
-                  double Rin, double x_left,
-                  unsigned kSensorStack, double tolerance,
+                  double x_left, unsigned kSensorStack, double tolerance,
                   std::pair<double, double> y_start);
   void addDetectorVolume(
     TGeoVolume* motherVolume, std::string volumeName, int color, unsigned* sensor_count,

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

@@ -52,6 +52,9 @@ namespace o2::ft3::ModuleConstants
   const double sensor2x1_width = 2 * single_sensor_width;
   const double sensor2x1_active_width = 2 * active_width;
   const double sensor2x1_height = single_sensor_height;
+  const unsigned kSensorsPerStack = 1;
+  const double sensor_stack_height = kSensorsPerStack * sensor2x1_height +
+                                    (kSensorsPerStack - 1) * sensor2x1_gap;
 
   const double carbonFiberThickness = 0.01;
   const double foamSpacingThickness = 1.0;
@@ -66,6 +69,7 @@ namespace o2::ft3::ModuleConstants
   // First define midpoints of staves that would overlap with inner disc
   // EXCEPTION: Assumed mirrored around x-axis
   // map from Stave ID (1-indexed from other documents) to midpoint
+  // Do NOT add any zero midpoints, this is taken off separately
   const std::map<int, double> staveID_to_y_midpoint = {
     {-2, 39.0},
     {-1, 41.4},
@@ -101,8 +105,6 @@ namespace o2::ft3::ModuleConstants
     return staveIdx - nStavesOneSide + isRight;
   }
 
-  const unsigned kSensorsPerStack = 1;
-
   // material properties
   const double siliconThickness = 0.01;
   const double copperThickness = 0.006;

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

@@ -13,6 +13,7 @@
 /// \brief Implementation of the FT3Module class
 
 #include "FT3Simulation/FT3Module.h"
+#include "FT3Base/FT3BaseParam.h"
 #include <TGeoManager.h>
 #include <TGeoMaterial.h>
 #include <TGeoMedium.h>
@@ -102,8 +103,7 @@ double calculate_y_circle(double x, double radius)
  *          for positive and negative y respectively
  */
 void FT3Module::fill_stave(PosNegPositionTypes& y_positions, double Rout,
-                           double Rin, double x_left,
-                           unsigned kSensorStack, double tolerance,
+                           double x_left, unsigned kSensorStack, double tolerance,
                            std::pair<double, double> y_start={0, 0})
 {
   // start with upper half of the stave, then mirror to the bottom half
@@ -314,6 +314,7 @@ void FT3Module::create_layout_scopingV3(double mZ, int layerNumber, int directio
             << layerNumber << ", Direction " << direction;
 
   FT3Module::initialize_materials();
+  auto& ft3Params = o2::ft3::FT3BaseParam::Instance();
 
   // initialise all y_positions, vector over all staves
   std::vector<PosNegPositionTypes> y_positionsPosNeg;
@@ -322,28 +323,41 @@ void FT3Module::create_layout_scopingV3(double mZ, int layerNumber, int directio
     y_positionsPosNeg.emplace_back(PosNegPositionTypes{PositionTypes{}, PositionTypes{}});
 
     double y_midpoint = 0.;
+    // default positive and negative starting points has a gap around x-axis
+    std::pair<double, double> y_start{0., Constants::sensor2x1_gap};
     const int staveID = Constants::staveIdxToID(i_stave);
     auto y_midpoint_it = Constants::staveID_to_y_midpoint.find(staveID);
-    if ( y_midpoint_it != Constants::staveID_to_y_midpoint.end() ) { // there is a defined midpoint for this stave
+    if ( y_midpoint_it != Constants::staveID_to_y_midpoint.end() ) {
+      // there is a defined midpoint for this stave, use this for starting points
       y_midpoint = y_midpoint_it->second;  // avoid double map lookup
       double y_start_pos = y_midpoint - Constants::y_lengths[i_stave] / 2;
-      // currently we have the same positions on positive and negative x
-      // place the first sensor tile, assume it fits
-      y_positionsPosNeg.back().first.emplace_back(y_start_pos, Constants::kSensorsPerStack);  // positive
-      y_positionsPosNeg.back().second.emplace_back(-y_start_pos, Constants::kSensorsPerStack);  // negative
-    } else {
-      // midpoint is zero, i.e., the start point for x>0 & y>0 is y=0
-      // while y_start for x>0, y<0 is -Constants::sensor2x1_gap
-      y_positionsPosNeg.back().first.emplace_back(0, Constants::kSensorsPerStack);  // positive
-      y_positionsPosNeg.back().second.emplace_back(-Constants::sensor2x1_gap, Constants::kSensorsPerStack);  // negative
     }
+
     double x_left = Constants::x_midpoints[i_stave] - Constants::sensor2x1_width / 2;
-    // fill_stave(y_positionsPosNeg, Rout, Rin, x_left, Constants::kSensorsPerStack, -3);
-    LOG(info) << "FT3Module: Filling Stave " << staveID << " (x = " << Constants::x_midpoints[i_stave]
-              << ") with sensors. Starting y positions: "
-              << y_positionsPosNeg.back().first.front().first << " (positive), "
-              << y_positionsPosNeg.back().second.front().first << " (negative).";
-    fill_stave(y_positionsPosNeg.back(), Rout, Rin, x_left, 1, -1);  // easiest: just do with 2x1 for now
+    double x_right = x_left + Constants::sensor2x1_width;
+    double tolerance = -Constants::sensor_stack_height;  // allow one sensor placement beyond
+    // cut staves on nominal inner radius if specified
+    if (ft3Params.cutStavesOnNominalRadius) {
+      double min_y_at_x;
+      if (x_left * x_right < 0) {
+        // stave crosses y-axis, so we start at y=Rin
+        min_y_at_x = Rin;
+      } else if (x_left > 0) {
+        // stave is on the right side, so minimum y is at x_left
+        min_y_at_x = calculate_y_circle(x_left, Rin);
+      } else {
+        // stave is on the left side, so minimum y is at x_right
+        min_y_at_x = calculate_y_circle(x_right, Rin);
+      }
+      y_start = {min_y_at_x, -min_y_at_x};
+      tolerance = 0.; // no tolerance in case of cutting at nominal radius
+    }
+    // fill_stave(y_positionsPosNeg, Rout, x_left, Constants::kSensorsPerStack, -3);
+    LOG(info) << "FT3Module: Filling Stave " << staveID << " (x = "
+              << Constants::x_midpoints[i_stave] << ") with sensors. Starting y positions: "
+              << y_start.first << " (positive), " << y_start.second << " (negative).";
+    fill_stave(y_positionsPosNeg.back(), Rout, x_left, Constants::kSensorsPerStack,
+               tolerance, y_start);
   }
 
   unsigned sensor_count = 0;