epic/src/BeamPipeStop_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   string grandmotherName = x_det.attr<string>(_Unicode(grandmother));
0028   string motherName      = x_det.attr<string>(_Unicode(mother));
0029   bool detStart          = getAttrOrDefault<bool>(x_det, _Unicode(end), true);
0030   DetElement mother      = description.detector(grandmotherName).child(motherName);
0031
0032   DetElement sdet(det_name, det_id);
0033
0034   // Get the mother volume
0035   Volume mother_vol = mother.volume();
0036
0037   // Get mother volume shape as cone segment
0038   ConeSegment mother_shape = mother_vol.solid();
0039
0040   // Get the parameters of the mother volume
0041   double rOuter1 = mother_shape.rMax1();
0042   double rOuter2 = mother_shape.rMax2();
0043   double length  = 2 * mother_shape.dZ();
0044
0045   double sensitive_thickness = 100 * mm;
0046
0047   //Calculate R or cone after sensitive layer
0048   double rEnd = rOuter2 - (rOuter2 - rOuter1) * sensitive_thickness / length;
0049   double zPos = length / 2.0 - sensitive_thickness / 2.0;
0050   if (detStart) {
0051     rEnd = rOuter1 - (rOuter1 - rOuter2) * sensitive_thickness / length;
0052     zPos = -length / 2.0 + sensitive_thickness / 2.0;
0053   }
0054
0055   ConeSegment s_start_disk(sensitive_thickness / 2, 0.0, rOuter2, 0.0, rEnd);
0056   Volume v_start_disk("stop_disk_" + motherName, s_start_disk, m_Vacuum);
0057
0058   v_start_disk.setLimitSet(description, "kill_limits");
0059
0060   auto disk_placement = mother_vol.placeVolume(v_start_disk, Position(0.0, 0.0, zPos));
0061
0062   sdet.setPlacement(disk_placement);
0063   description.declareParent(det_name, mother);
0064
0065   return sdet;
0066 }
0067
0068 DECLARE_DETELEMENT(BeamPipeStop, create_detector)