epic/src/BeamPipeTracking_geo.cpp

0001 // SPDX-License-Identifier: LGPL-3.0-or-later
0002 // Copyright (C) 2024 Simon Gardner
0003
0004 //==========================================================================
0005 //
0006 // Places a small sensitive disk of vacuum at the end of beam pipes
0007 //
0008 //==========================================================================
0009
0010 #include "DD4hep/DetFactoryHelper.h"
0011 #include "DD4hep/Printout.h"
0012 #include "TMath.h"
0013 #include <XML/Helper.h>
0014
0015 using namespace std;
0016 using namespace dd4hep;
0017
0018 static Ref_t create_detector(Detector& description, xml_h e, SensitiveDetector sens) {
0019
0020   using namespace ROOT::Math;
0021   xml_det_t x_det   = e;
0022   string det_name   = x_det.nameStr();
0023   int det_id        = x_det.id();
0024   Material m_Vacuum = description.material("Vacuum");
0025   string vis_name   = dd4hep::getAttrOrDefault<std::string>(x_det, _Unicode(vis), "BeamPipeVis");
0026
0027   sens.setType("tracker");
0028
0029   DetElement sdet(det_name, det_id);
0030   Assembly assembly(det_name + "_assembly");
0031
0032   // Grab info for beamline magnets
0033   for (xml_coll_t slice_coll(x_det, _Unicode(slice)); slice_coll; slice_coll++) { // pipes
0034
0035     string grandmotherName = slice_coll.attr<string>(_Unicode(grandmother));
0036     string motherName      = slice_coll.attr<string>(_Unicode(mother));
0037     bool detStart          = getAttrOrDefault<bool>(slice_coll, _Unicode(end), true);
0038     int pipe_id            = getAttrOrDefault<int>(slice_coll, _Unicode(pipe_id), 0);
0039     string slice_name      = slice_coll.attr<string>(_Unicode(name));
0040     DetElement mother      = description.detector(grandmotherName).child(motherName);
0041
0042     // Get the mother volume
0043     Volume mother_vol = mother.volume();
0044
0045     // Get mother volume shape as cone segment
0046     ConeSegment mother_shape = mother_vol.solid();
0047
0048     // Get the parameters of the mother volume
0049     double rOuter1 = mother_shape.rMax1();
0050     double rOuter2 = mother_shape.rMax2();
0051     double length  = 2 * mother_shape.dZ();
0052
0053     double sensitive_thickness = 0.1 * mm;
0054
0055     //Calculate R or cone after sensitive layer
0056
0057     double rEnd = rOuter2 - (rOuter2 - rOuter1) * sensitive_thickness / length;
0058     double zPos = length / 2.0 - sensitive_thickness / 2.0;
0059     if (detStart) {
0060       rEnd = rOuter1 - (rOuter1 - rOuter2) * sensitive_thickness / length;
0061       zPos = -length / 2.0 + sensitive_thickness / 2.0;
0062     }
0063
0064     ConeSegment s_start_disk(sensitive_thickness / 2, 0.0, rOuter2, 0.0, rEnd);
0065     Volume v_start_disk("v_start_disk_" + motherName, s_start_disk, m_Vacuum);
0066     v_start_disk.setSensitiveDetector(sens);
0067
0068     auto disk_placement = mother_vol.placeVolume(v_start_disk, Position(0.0, 0.0, zPos));
0069     disk_placement.addPhysVolID("end", detStart);
0070     disk_placement.addPhysVolID("pipe", pipe_id);
0071     disk_placement.addPhysVolID("system", det_id);
0072
0073     DetElement slice_element(sdet, slice_name, pipe_id);
0074
0075     slice_element.setPlacement(disk_placement);
0076     description.declareParent(slice_name, mother);
0077   }
0078
0079   auto pv_assembly = description.worldVolume().placeVolume(assembly, Position(0.0, 0.0, 0.0));
0080   pv_assembly.addPhysVolID("system", det_id);
0081   sdet.setPlacement(pv_assembly);
0082
0083   return sdet;
0084 }
0085
0086 DECLARE_DETELEMENT(BeamPipeTracking, create_detector)