//==========================================================================
// Forward Ring Imaging Cherenkov Detector
//--------------------------------------------------------------------------
//
// Author: C. Peng (ANL)
// Date: 09/30/2020
//
//==========================================================================
#include <XML/Helper.h>
#include "TMath.h"
#include "TString.h"
#include "ref_utils.h"
#include "Math/Point2D.h"
#include "DDRec/Surface.h"
#include "DDRec/DetectorData.h"
#include "DD4hep/OpticalSurfaces.h"
#include "DD4hep/DetFactoryHelper.h"
#include "DD4hep/Printout.h"
using namespace std;
using namespace dd4hep;
using namespace dd4hep::rec;
// create the detector
static Ref_t createDetector(Detector& desc, xml::Handle_t handle, SensitiveDetector sens)
{
xml::DetElement detElem = handle;
std::string detName = detElem.nameStr();
int detID = detElem.id();
DetElement det(detName, detID);
xml::Component dims = detElem.dimensions();
xml::Component rads = detElem.child(_Unicode(radiator));
xml::Component mir = detElem.child(_Unicode(mirror));
xml::Component mcp = detElem.child(_Unicode(mcppmt));
xml::Component tank = detElem.child(_Unicode(tank));
// dimensions
double z0 = dims.z0();
double length = dims.length();
double rmin = dims.rmin();
double rmax0 = dims.attr<double>(_Unicode(rmax0));
double rmax1 = dims.attr<double>(_Unicode(rmax1));
double rmax2 = dims.attr<double>(_Unicode(rmax2));
double snout_length = dims.attr<double>(_Unicode(snout_length));
// mirror setting
auto mThick = mir.thickness();
auto mirZ = mir.attr<double>(_Unicode(z0));
// mcppmt setting
auto pRmin = mcp.rmin();
auto pRmax = mcp.rmax();
auto pThick = mcp.thickness();
auto pSize = mcp.attr<double>(_Unicode(module_size));
auto pGap = mcp.attr<double>(_Unicode(module_gap));
auto pTol = mcp.attr<double>(_Unicode(rtol));
auto pZ = mcp.attr<double>(_Unicode(z0));
// tank parameters
double tank_length = length - snout_length;
// materials
auto mirMat = desc.material(mir.materialStr());
auto gasMat = desc.material(rads.materialStr());
auto mcpMat = desc.material(mcp.materialStr());
double front_offset = snout_length+tank_length/2.0;
// constants
auto richCenterAngle = std::atan((rmin + (rmax1 - rmin)/2.)/(front_offset+mirZ));
//std::cout << richCenterAngle*180./M_PI << std::endl;
// an envelope for the detector
// use a complicated shape to avoid conflict with the other parts
// cone for radiator and the first set of mirrors
double halfLength = length/2.;
Cone env1(snout_length/2.0, rmin, rmax0, rmin, rmax1);
// envelope for detection plane
// Cone env2(halfLength - pZ/2., rmin, pRmax, rmin, rmax2);
Tube env2(rmin, pRmax + pTol + pGap + 1.0*cm, tank_length/2., 0., 2*M_PI);
UnionSolid envShape(env2, env1, Position(0., 0., -tank_length/2.-snout_length/2));
Volume envVol(detName + "_envelope", envShape, gasMat);
envVol.setVisAttributes(desc.visAttributes(detElem.visStr()));
// ---------------
// spherical mirrors inside it
int ilayer = 1;
// optical surface
OpticalSurfaceManager surfMgr = desc.surfaceManager();
OpticalSurface mirSurf = surfMgr.opticalSurface("MirrorOpticalSurface");
// mirror slices
int imod = 1;
for (xml::Collection_t sl(mir, _Unicode(slice)); sl; ++sl, ++imod) {
auto focus = sl.attr<double>(_Unicode(focus));
auto wphi = sl.attr<double>(_Unicode(phiw));
auto rotZ = sl.attr<double>(_Unicode(rotz));
auto mRmin = sl.attr<double>(_Unicode(rmin));
auto mRmax = sl.attr<double>(_Unicode(rmax));
double curve = 0.;
if (sl.hasAttr(_Unicode(curve))) {
curve = sl.attr<double>(_Unicode(curve));
}
// geometry of mirror slice
PlacedVolume mirPV;
Volume mirVol(Form("mirror_v_dummy%d", imod));
mirVol.setMaterial(mirMat);
mirVol.setVisAttributes(desc.visAttributes(mir.visStr()));
// spherical mirror
if (curve > 0.) {
// somehow geant4 does not support -wphi/2. to wphi/2., so additonal rotation in Z
double mTheta1 = std::asin(mRmin/curve);
double mTheta2 = std::asin(mRmax/curve);
double rotY = -std::asin(focus/curve);
mirVol.setSolid(Sphere(curve, curve + mThick, mTheta1, mTheta2, 0., wphi));
// action is in a reverse order
Transform3D tr = Translation3D(0., 0., mirZ - front_offset) // move for z position
* RotationZ(rotZ) // rotate phi angle
* RotationY(rotY) // rotate for focus point
* RotationX(180*degree)
* Translation3D(0., 0., -curve) // move spherical shell to origin
* RotationZ(-wphi/2.); // center phi angle to 0. (-wphi/2., wphi/2.)
mirPV = envVol.placeVolume(mirVol, tr);
// plane mirror
} else {
mirVol.setSolid(Tube(mRmin, mRmax, mThick/2.0, 0., wphi));
Transform3D tr = Translation3D(0., 0., mirZ - front_offset) // move for z position
* RotationZ(rotZ) // rotate phi angle
* RotationZ(-wphi/2.); // center phi angle to 0. (-wphi/2., wphi/2.)
mirPV = envVol.placeVolume(mirVol, tr);
}
mirPV.addPhysVolID("layer", ilayer).addPhysVolID("module", imod);
DetElement mirDE(det, Form("Mirror_DE%d", imod), imod);
mirDE.setPlacement(mirPV);
SkinSurface mirSurfBorder(desc, mirDE, Form("RICHmirror%d", imod), mirSurf, mirVol);
mirSurfBorder.isValid();
}
ilayer++;
// ---------------
// photo-detector unit
// Fill the photo-detection plane with square shape MCP-PMTs
Box mcpShape1(pSize/2.0, pSize/2.0, pThick/2.0);
Volume mcpVol1("mcppmt_v_material", mcpShape1, mcpMat);
// a thin layer of cherenkov gas for accepting optical photons
Box mcpShape(pSize/2.0, pSize/2.0, pThick/2.0 + 0.1*mm);
Volume mcpVol("mcppmt_v", mcpShape, gasMat);
mcpVol.placeVolume(mcpVol1, Position(0., 0., -0.1*mm));
mcpVol.setVisAttributes(desc.visAttributes(mcp.visStr()));
sens.setType("photoncounter");
mcpVol.setSensitiveDetector(sens);
// photo-detector plane envelope
for (size_t ipd = 0; ipd < 6; ++ipd) {
double phmin = -M_PI/6.5; // added 0.5 to make it smaller
double phmax = M_PI/6.5;
Tube pdEnvShape(pRmin - pTol - pGap, pRmax + pTol + pGap, pThick/2.0 + 0.1*cm, phmin, phmax);
Volume pdVol("pd_envelope", pdEnvShape, desc.material("AirOptical"));
auto points = ref::utils::fillSquares({0., 0.}, pSize + pGap, pRmin + pTol + pGap, pRmax + pTol + pGap, phmin, phmax);
for (size_t i = 0; i < points.size(); ++i) {
auto pt = points[i];
auto mcpPV = pdVol.placeVolume(mcpVol, Position(pt.x(), pt.y(), 0.));
mcpPV.addPhysVolID("layer", ilayer).addPhysVolID("module", i + 1);
DetElement mcpDE(det, Form("MCPPMT_DE%d_%d", ipd + 1, i + 1), i + 1);
mcpDE.setPlacement(mcpPV);
}
Transform3D tr = Translation3D(0., 0., -front_offset + pZ + pThick/2.0) // move for z position
* RotationZ(ipd*M_PI/3.) // rotate phi angle
* RotationY(-richCenterAngle); // rotate to perpendicular position
auto pdPV = envVol.placeVolume(pdVol, tr);
pdPV.addPhysVolID("layer", ilayer).addPhysVolID("piece", ipd + 1);
}
Volume motherVol = desc.pickMotherVolume(det);
PlacedVolume envPV = motherVol.placeVolume(envVol, Position(0, 0, z0 + halfLength));
envPV.addPhysVolID("system", detID);
det.setPlacement(envPV);
return det;
}
//@}
// clang-format off
DECLARE_DETELEMENT(refdet_ForwardRICH, createDetector)