ForwardDetLayer.cc

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#include "TrackingTools/DetLayers/interface/ForwardDetLayer.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "DataFormats/GeometrySurface/interface/SimpleDiskBounds.h"
#include "DataFormats/GeometrySurface/interface/BoundingBox.h"
#include "FWCore/Utilities/interface/Likely.h"

using namespace std;

ForwardDetLayer::~ForwardDetLayer() {}

//--- Extension of the interface
void ForwardDetLayer::setSurface(BoundDisk* cp) { theDisk = cp; }

bool ForwardDetLayer::contains(const Local3DPoint& p) const { return surface().bounds().inside(p); }

void ForwardDetLayer::initialize() { setSurface(computeSurface()); }

BoundDisk* ForwardDetLayer::computeSurface() {
  LogDebug("DetLayers") << "ForwaLayer::computeSurface callded";
  vector<const GeomDet*> comps = basicComponents();

  vector<const GeomDet*>::const_iterator ifirst = comps.begin();
  vector<const GeomDet*>::const_iterator ilast = comps.end();

  // Find extension in R
  float theRmin = components().front()->position().perp();
  float theRmax = theRmin;
  float theZmin = components().back()->position().z();
  float theZmax = theZmin;
  for (vector<const GeomDet*>::const_iterator deti = ifirst; deti != ilast; deti++) {
    vector<GlobalPoint> corners = BoundingBox().corners(dynamic_cast<const Plane&>((**deti).surface()));
    for (vector<GlobalPoint>::const_iterator ic = corners.begin(); ic != corners.end(); ic++) {
      float r = ic->perp();
      LogDebug("DetLayers") << "corner.perp(): " << r;
      float z = ic->z();
      theRmin = min(theRmin, r);
      theRmax = max(theRmax, r);
      theZmin = min(theZmin, z);
      theZmax = max(theZmax, z);
    }

    // in addition to the corners we have to check the middle of the
    // det +/- length/2
    // , since the min (max) radius for typical fw dets is reached there

    float rdet = (**deti).position().perp();
    float len = (**deti).surface().bounds().length();
    float width = (**deti).surface().bounds().width();

    GlobalVector xAxis = (**deti).toGlobal(LocalVector(1, 0, 0));
    GlobalVector yAxis = (**deti).toGlobal(LocalVector(0, 1, 0));
    GlobalVector perpDir = GlobalVector((**deti).position() - GlobalPoint(0, 0, (**deti).position().z()));

    double xAxisCos = xAxis.unit().dot(perpDir.unit());
    double yAxisCos = yAxis.unit().dot(perpDir.unit());

    LogDebug("DetLayers") << "in ForwardDetLayer::computeSurface(),xAxisCos,yAxisCos: " << xAxisCos << " , "
                          << yAxisCos;
    LogDebug("DetLayers") << "det pos.perp,length,width: " << rdet << " , " << len << " , " << width;

    if (fabs(xAxisCos) > fabs(yAxisCos)) {
      theRmin = min(theRmin, rdet - width / 2.F);
      theRmax = max(theRmax, rdet + width / 2.F);
    } else {
      theRmin = min(theRmin, rdet - len / 2.F);
      theRmax = max(theRmax, rdet + len / 2.F);
    }
  }

  LogDebug("DetLayers") << "creating SimpleDiskBounds with r range" << theRmin << " " << theRmax << " and z range "
                        << theZmin << " " << theZmax;

  // By default the forward layers are positioned around the z axis of the
  // global frame, and the axes of their local frame coincide with
  // those of the global grame (z along the disk axis)
  float zPos = (theZmax + theZmin) / 2.;
  PositionType pos(0., 0., zPos);
  RotationType rot;

  return new BoundDisk(pos, rot, new SimpleDiskBounds(theRmin, theRmax, theZmin - zPos, theZmax - zPos));
}

pair<bool, TrajectoryStateOnSurface> ForwardDetLayer::compatible(const TrajectoryStateOnSurface& ts,
                                                                 const Propagator& prop,
                                                                 const MeasurementEstimator&) const {
  if UNLIKELY (theDisk == nullptr)
    edm::LogError("DetLayers") << "ERROR: BarrelDetLayer::compatible() is used before the layer surface is initialized";
  // throw an exception? which one?

  TrajectoryStateOnSurface myState = prop.propagate(ts, specificSurface());
  if UNLIKELY (!myState.isValid())
    return make_pair(false, myState);

  // check z;  (are we sure?????)
  // auto z = myState.localPosition().z();
  // if ( z<bounds().minZ | z>bounds().maxZ) return make_pair( false, myState);

  // check r
  auto r2 = myState.localPosition().perp2();
  if ((r2 > rmin() * rmin()) & (r2 < rmax() * rmax()))
    return make_pair(true, myState);

  // take into account the thickness of the layer
  float deltaR = 0.5f * bounds().thickness() * myState.localDirection().perp() / std::abs(myState.localDirection().z());

  // and take into account the error on the predicted state
  const float nSigma = 3.;
  if (myState.hasError()) {
    LocalError err = myState.localError().positionError();
    // ignore correlation for the moment...
    deltaR += nSigma * sqrt(err.xx() + err.yy());
  }

  // check r again;
  auto ri2 = std::max(rmin() - deltaR, 0.f);
  ri2 *= ri2;
  auto ro2 = rmax() + deltaR;
  ro2 *= ro2;
  return make_pair((r2 > ri2) & (r2 < ro2), myState);
}