AliceO2Group · njacazio · Mar 31, 2026 · Apr 3, 2026
@@ -10,4 +10,5 @@
 # or submit itself to any jurisdiction.
 
 add_subdirectory(base)
-add_subdirectory(simulation)
+add_subdirectory(simulation)
+add_subdirectory(macros)
@@ -0,0 +1,13 @@
+# Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+# See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+# All rights not expressly granted are reserved.
+#
+# This software is distributed under the terms of the GNU General Public
+# License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+#
+# In applying this license CERN does not waive the privileges and immunities
+# granted to it by virtue of its status as an Intergovernmental Organization
+# or submit itself to any jurisdiction.
+
+o2_add_test_root_macro(defineIOTOFGeo.C
+                       LABELS alice3)
@@ -0,0 +1,128 @@
+#include <TCanvas.h>
+#include <TGraph.h>
+#include <TArc.h>
+#include <TH2F.h>
+#include <TMath.h>
+#include <TLatex.h>
+#include <TStyle.h>
+#include <algorithm>
+#include <cmath>
+
+void defineIOTOFGeo(const double rAvg = 21,              // cm, average radius of the layer (used for stave size calculations)
+                    const int nStaves = 24,              // Number of staves
+                    const double staveWidth = 5.42,      // cm, Stave width (arc length at avg radius at 0 degrees)
+                    const double staveHeightX2X0 = 0.02, // Stave height (radial at 0 degrees)
+                    const double staveTilt = 10          // Stave tilt angle in degrees
+)
+{
+  const double Si_X0 = 9.5f; // cm, radiation length of silicon
+  const double staveHeight = staveHeightX2X0 * Si_X0;
+
+  // 1. Define inner and outer radii for the disk.
+  //    The radius corresponds to the distance of the center of the stave to the origin
+  const double rInner = rAvg - staveHeight / 2.0;
+  const double rOuter = rAvg + staveHeight / 2.0;
+
+  const double alpha = staveTilt * TMath::DegToRad(); // Tilt angle in radians
+  const double H = staveHeight;
+  const double W = staveWidth;
+
+  // 2. Analytical calculation of Inscribed and Outscribed Radii
+  //    We project the global origin (0,0) into the local, unrotated coordinate
+  //    system of a single stave centered at (0,0).
+  const double u0 = -rAvg * TMath::Cos(alpha);
+  const double v0 = rAvg * TMath::Sin(alpha);
+
+  // Inscribed Radius: Distance to the closest point on the stave rectangle
+  const double uc = std::max(-H / 2.0, std::min(H / 2.0, u0));
+  const double vc = std::max(-W / 2.0, std::min(W / 2.0, v0));
+  const double rInscribed = TMath::Sqrt((uc - u0) * (uc - u0) + (vc - v0) * (vc - v0));
+
+  // Outscribed Radius: Maximum distance to one of the 4 corners
+  double rOutscribed = 0;
+  const double uCorners[4] = {-H / 2.0, H / 2.0, H / 2.0, -H / 2.0};
+  const double vCorners[4] = {-W / 2.0, -W / 2.0, W / 2.0, W / 2.0};
+  for (int i = 0; i < 4; ++i) {
+    const double dist = std::hypot(uCorners[i] - u0, vCorners[i] - v0);
+    if (dist > rOutscribed) {
+      rOutscribed = dist;
+    }
+  }
+
+  // 3. Visualization
+  new TCanvas("DiskWithStaves", "Disk with Staves", 800, 800);
+  gPad->SetGrid();
+  gPad->SetLeftMargin(0.15);
+  gPad->SetBottomMargin(0.15);
+  gPad->SetRightMargin(0.05);
+  gPad->SetTopMargin(0.05);
+
+  const double maxR = std::max(rOuter, rOutscribed) * 1.5;
+  gPad->DrawFrame(-maxR, -maxR, maxR, maxR, ";X (cm);Y (cm)");
+
+  // Draw Inner and Outer Disk Radii (Reference)
+  TArc* arcInner = new TArc(0, 0, rInner);
+  arcInner->SetLineStyle(2);
+  arcInner->SetLineColor(kGray + 1);
+  arcInner->SetFillStyle(0);
+  arcInner->Draw("same");
+
+  TArc* arcOuter = new TArc(0, 0, rOuter);
+  arcOuter->SetLineStyle(2);
+  arcOuter->SetLineColor(kGray + 1);
+  arcOuter->SetFillStyle(0);
+  arcOuter->Draw("same");
+
+  // Draw Inscribed and Outscribed circles
+  TArc* arcInscribed = new TArc(0, 0, rInscribed);
+  arcInscribed->SetLineColor(kBlue);
+  arcInscribed->SetLineWidth(2);
+  arcInscribed->SetFillStyle(0);
+  arcInscribed->Draw("same");
+
+  TArc* arcOutscribed = new TArc(0, 0, rOutscribed);
+  arcOutscribed->SetLineColor(kRed);
+  arcOutscribed->SetLineWidth(2);
+  arcOutscribed->SetFillStyle(0);
+  arcOutscribed->Draw("same");
+
+  // Generate and Draw Staves
+  for (int i = 0; i < nStaves; ++i) {
+    double phi = i * TMath::TwoPi() / nStaves;
+    double xPts[5], yPts[5];
+    for (int j = 0; j < 4; ++j) {
+      double u = uCorners[j];
+      double v = vCorners[j];
+      // Apply stave tilt (alpha) around its own center
+      double uRot = u * TMath::Cos(alpha) - v * TMath::Sin(alpha);
+      double vRot = u * TMath::Sin(alpha) + v * TMath::Cos(alpha);
+      // Move stave to rAvg and apply azimuthal rotation (phi)
+      double x_phi0 = rAvg + uRot;
+      double y_phi0 = vRot;
+      xPts[j] = x_phi0 * TMath::Cos(phi) - y_phi0 * TMath::Sin(phi);
+      yPts[j] = x_phi0 * TMath::Sin(phi) + y_phi0 * TMath::Cos(phi);
+    }
+    // Close the geometric polygon
+    xPts[4] = xPts[0];
+    yPts[4] = yPts[0];
+    TGraph* gStave = new TGraph(5, xPts, yPts);
+    gStave->SetFillColorAlpha(kGreen + 2, 0.4);
+    gStave->SetLineColor(kBlack);
+    gStave->SetLineWidth(1);
+    gStave->Draw("f same"); // Fill
+    gStave->Draw("l same"); // Outline
+  }
+
+  // 7. Add Legend / Parameter Text
+  TLatex* tex = new TLatex();
+  tex->SetNDC();
+  tex->SetTextSize(0.028);
+  tex->SetTextFont(42);
+  tex->SetTextColor(kBlack);
+  tex->DrawLatex(0.12, 0.88, Form("R_{inner} = %.1f, R_{outer} = %.1f", rInner, rOuter));
+  tex->DrawLatex(0.12, 0.84, Form("Staves: %d, Tilt: %.1f#circ", nStaves, staveTilt));
+  tex->SetTextColor(kBlue);
+  tex->DrawLatex(0.12, 0.80, Form("Inscribed Radius = %.2f", rInscribed));
+  tex->SetTextColor(kRed);
+  tex->DrawLatex(0.12, 0.76, Form("Outscribed Radius = %.2f", rOutscribed));
+}