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[ALICE3] IOTOF: Add geometry macros (#15257)
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‎Detectors/Upgrades/ALICE3/IOTOF/CMakeLists.txt‎

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# or submit itself to any jurisdiction.
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add_subdirectory(base)
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add_subdirectory(simulation)
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add_subdirectory(simulation)
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add_subdirectory(macros)

‎Detectors/Upgrades/ALICE3/IOTOF/macros/CMakeLists.txt‎

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# Copyright 2019-2020 CERN and copyright holders of ALICE O2.
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# See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
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# All rights not expressly granted are reserved.
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#
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# This software is distributed under the terms of the GNU General Public
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# License v3 (GPL Version 3), copied verbatim in the file "COPYING".
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#
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# In applying this license CERN does not waive the privileges and immunities
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# granted to it by virtue of its status as an Intergovernmental Organization
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# or submit itself to any jurisdiction.
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o2_add_test_root_macro(defineIOTOFGeo.C
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LABELS alice3)

‎Detectors/Upgrades/ALICE3/IOTOF/macros/defineIOTOFGeo.C‎

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

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