DriftLengthEstimator Struct Reference

Helper construct implementing the (re)estimation of the drift length for various hit objects. More...

#include <DriftLengthEstimator.h>

Classes
struct	FacetDriftLengthCache
	Memory for the results of a facet drift length update that do not depend on the right left passage hypothesis of the middle hit. More...

Public Member Functions
void	exposeParameters (ModuleParamList *moduleParamList, const std::string &prefix)
	Add the parameters of the estimator to the module.
double	updateDriftLength (TrackingUtilities::CDCRecoHit2D &recoHit2D)
	Update the drift length of the reconstructed hit in place.
double	updateDriftLength (TrackingUtilities::CDCRecoHit3D &recoHit3D, double tanLambda)
	Update the drift length of the reconstructed hit in place.
void	updateDriftLength (TrackingUtilities::CDCFacet &facet)
	Re-estimate the drift length of all three contained drift circles.
void	updateDriftLength (TrackingUtilities::CDCFacet &facet, FacetDriftLengthCache &cache)
	Re-estimate the drift lengths like updateDriftLength(facet), sharing the results that do not depend on the middle right left passage hypothesis via the given cache.
void	updateDriftLength (TrackingUtilities::CDCSegment2D &segment)
	Update the drift length of the contained reconstructed hit in place.
void	updateDriftLength (TrackingUtilities::CDCSegment3D &segment, double tanLambda)
	Update the drift length of the contained reconstructed hit in place.
void	updateDriftLength (TrackingUtilities::CDCTrack &track, double tanLambda)
	Update the drift length of the contained reconstructed hit in place.

Public Attributes
bool	m_param_useAlphaInDriftLength = true
	Parameter : Switch to serve the alpha angle to the drift length translator.
double	m_param_tofMassScale = NAN
	Parameter : Mass to estimate the velocity in the flight time to the hit.

Private Member Functions
CDC::RealisticTDCCountTranslator &	getTDCCountTranslator ()
	Getter for the drift time translator constructing it on first use.

Private Attributes
std::shared_ptr< CDC::RealisticTDCCountTranslator >	m_tdcCountTranslator
	Drift time translator constructed lazily on first use.

Detailed Description

Helper construct implementing the (re)estimation of the drift length for various hit objects.

Definition at line 43 of file DriftLengthEstimator.h.

Member Function Documentation

exposeParameters()

void exposeParameters	(	ModuleParamList *	moduleParamList,
		const std::string &	prefix )

Add the parameters of the estimator to the module.

Definition at line 49 of file DriftLengthEstimator.cc.

{
  moduleParamList->addParameter(prefixed(prefix, "useAlphaInDriftLength"),
                                m_param_useAlphaInDriftLength,
                                "Switch to serve the alpha angle to the drift length translator",
                                m_param_useAlphaInDriftLength);
 
  moduleParamList->addParameter(prefixed(prefix, "tofMassScale"),
                                m_param_tofMassScale,
                                "Mass to estimate the velocity in the flight time to the hit",
                                m_param_tofMassScale);
}

getTDCCountTranslator()

CDC::RealisticTDCCountTranslator & getTDCCountTranslator ( )

inlineprivate

Getter for the drift time translator constructing it on first use.

The translator cannot be constructed together with the estimator, which usually happens during module construction, since it requires the geometry to be present.

Definition at line 121 of file DriftLengthEstimator.h.

      {
        if (not m_tdcCountTranslator) {
          m_tdcCountTranslator = std::make_shared<CDC::RealisticTDCCountTranslator>();
        }
        return *m_tdcCountTranslator;
      }

updateDriftLength() [1/7]

void updateDriftLength

(

TrackingUtilities::CDCFacet &

facet

)

Re-estimate the drift length of all three contained drift circles.

Using the additional flight direction information the accuracy of the drift length can be increased a lot helping the filters following this step

Definition at line 93 of file DriftLengthEstimator.cc.

{
  CDC::RealisticTDCCountTranslator& tdcCountTranslator = getTDCCountTranslator();
 
  const UncertainParameterLine2D& line = facet.getFitLine();
  ROOT::Math::XYVector flightDirection = line->tangential();
  ROOT::Math::XYVector centralPos2D = line->closest(facet.getMiddleWire().getRefPos2D());
  double alpha = ROOT::Math::VectorUtil::DeltaPhi(centralPos2D, flightDirection);
  if (not m_param_useAlphaInDriftLength) {
    alpha = 0;
  }
 
  auto doUpdate = [&](CDCRLWireHit & rlWireHit, ROOT::Math::XYVector recoPos2D) {
    const CDCWire& wire = rlWireHit.getWire();
    const CDCHit* hit = rlWireHit.getWireHit().getHit();
    const bool rl = rlWireHit.getRLInfo() == ERightLeft::c_Right;
    const double beta = 1;
    double flightTimeEstimate = FlightTimeEstimator::instance().getFlightTime2D(recoPos2D, alpha, beta);
    double driftLength = tdcCountTranslator.getDriftLength(hit->getTDCCount(),
                                                           wire.getWireID(),
                                                           flightTimeEstimate,
                                                           rl,
                                                           wire.getRefZ(),
                                                           alpha);
    rlWireHit.setRefDriftLength(driftLength);
  };
 
  doUpdate(facet.getStartRLWireHit(), facet.getStartRecoPos2D());
  doUpdate(facet.getMiddleRLWireHit(), facet.getMiddleRecoPos2D());
  doUpdate(facet.getEndRLWireHit(), facet.getEndRecoPos2D());
 
  // More accurate implementation
  // double startDriftLength = updateDriftLength(facet.getStartRecoHit2D());
  // facet.getStartRLWireHit().setRefDriftLength(startDriftLength);
 
  // double middleDriftLength = updateDriftLength(facet.getMiddleRecoHit2D());
  // facet.getMiddleRLWireHit().setRefDriftLength(middleDriftLength);
 
  // double endDriftLength = updateDriftLength(facet.getEndRecoHit2D());
  // facet.getEndRLWireHit().setRefDriftLength(endDriftLength);
}

updateDriftLength() [2/7]

void updateDriftLength	(	TrackingUtilities::CDCFacet &	facet,
		FacetDriftLengthCache &	cache )

Re-estimate the drift lengths like updateDriftLength(facet), sharing the results that do not depend on the middle right left passage hypothesis via the given cache.

On the first call the cache is filled from a full update. Subsequent calls must be made with facets that differ from the first one only in the right left passage hypothesis of the middle hit and with unchanged base drift lengths, and only recompute the drift length of the middle hit.

Definition at line 135 of file DriftLengthEstimator.cc.

{
  CDC::RealisticTDCCountTranslator& tdcCountTranslator = getTDCCountTranslator();
 
  auto computeDriftLength = [&](const CDCRLWireHit & rlWireHit, double flightTimeEstimate, double alpha) {
    const CDCWire& wire = rlWireHit.getWire();
    const CDCHit* hit = rlWireHit.getWireHit().getHit();
    const bool rl = rlWireHit.getRLInfo() == ERightLeft::c_Right;
    return tdcCountTranslator.getDriftLength(hit->getTDCCount(),
                                             wire.getWireID(),
                                             flightTimeEstimate,
                                             rl,
                                             wire.getRefZ(),
                                             alpha);
  };
 
  const double beta = 1;
  if (not cache.valid) {
    // Full update like updateDriftLength(facet) filling the cache on the way
    const UncertainParameterLine2D& line = facet.getFitLine();
    ROOT::Math::XYVector flightDirection = line->tangential();
    ROOT::Math::XYVector centralPos2D = line->closest(facet.getMiddleWire().getRefPos2D());
    double alpha = ROOT::Math::VectorUtil::DeltaPhi(centralPos2D, flightDirection);
    if (not m_param_useAlphaInDriftLength) {
      alpha = 0;
    }
 
    double startFlightTime =
      FlightTimeEstimator::instance().getFlightTime2D(facet.getStartRecoPos2D(), alpha, beta);
    double startDriftLength = computeDriftLength(facet.getStartRLWireHit(), startFlightTime, alpha);
    facet.getStartRLWireHit().setRefDriftLength(startDriftLength);
 
    double middleFlightTime =
      FlightTimeEstimator::instance().getFlightTime2D(facet.getMiddleRecoPos2D(), alpha, beta);
    double middleDriftLength = computeDriftLength(facet.getMiddleRLWireHit(), middleFlightTime, alpha);
    facet.getMiddleRLWireHit().setRefDriftLength(middleDriftLength);
 
    double endFlightTime =
      FlightTimeEstimator::instance().getFlightTime2D(facet.getEndRecoPos2D(), alpha, beta);
    double endDriftLength = computeDriftLength(facet.getEndRLWireHit(), endFlightTime, alpha);
    facet.getEndRLWireHit().setRefDriftLength(endDriftLength);
 
    cache.fitLine = line;
    cache.alpha = alpha;
    cache.middleFlightTime = middleFlightTime;
    cache.startDriftLength = startDriftLength;
    cache.endDriftLength = endDriftLength;
    cache.valid = true;
  } else {
    // Only the middle hit depends on its right left passage hypothesis
    facet.setFitLine(cache.fitLine);
    facet.getStartRLWireHit().setRefDriftLength(cache.startDriftLength);
    double middleDriftLength =
      computeDriftLength(facet.getMiddleRLWireHit(), cache.middleFlightTime, cache.alpha);
    facet.getMiddleRLWireHit().setRefDriftLength(middleDriftLength);
    facet.getEndRLWireHit().setRefDriftLength(cache.endDriftLength);
  }
}

updateDriftLength() [3/7]

double updateDriftLength

(

TrackingUtilities::CDCRecoHit2D &

recoHit2D

)

Update the drift length of the reconstructed hit in place.

Definition at line 62 of file DriftLengthEstimator.cc.

{
  CDC::RealisticTDCCountTranslator& tdcCountTranslator = getTDCCountTranslator();
 
  ROOT::Math::XYVector flightDirection = recoHit2D.getFlightDirection2D();
  ROOT::Math::XYVector recoPos2D = recoHit2D.getRecoPos2D();
  double alpha = ROOT::Math::VectorUtil::DeltaPhi(recoPos2D, flightDirection);
  const double beta = 1;
  double flightTimeEstimate = FlightTimeEstimator::instance().getFlightTime2D(recoPos2D, alpha, beta);
 
  const CDCWire& wire = recoHit2D.getWire();
  const CDCHit* hit = recoHit2D.getWireHit().getHit();
  const bool rl = recoHit2D.getRLInfo() == ERightLeft::c_Right;
 
  if (not m_param_useAlphaInDriftLength) {
    alpha = 0;
  }
 
  double driftLength = tdcCountTranslator.getDriftLength(hit->getTDCCount(),
                                                         wire.getWireID(),
                                                         flightTimeEstimate,
                                                         rl,
                                                         wire.getRefZ(),
                                                         alpha);
  if (driftLength > -2 and driftLength < 16) {
    bool snapRecoPos = true;
    recoHit2D.setRefDriftLength(driftLength, snapRecoPos);
  }
  return driftLength;
}

updateDriftLength() [4/7]

double updateDriftLength	(	TrackingUtilities::CDCRecoHit3D &	recoHit3D,
		double	tanLambda )

Update the drift length of the reconstructed hit in place.

Definition at line 201 of file DriftLengthEstimator.cc.

{
  CDC::RealisticTDCCountTranslator& tdcCountTranslator = getTDCCountTranslator();
 
  ROOT::Math::XYVector flightDirection = recoHit3D.getFlightDirection2D();
  const ROOT::Math::XYZVector& recoPos3D = recoHit3D.getRecoPos3D();
  const ROOT::Math::XYVector& recoPos2D = VectorUtil::getXYVector(recoPos3D);
  double alpha = ROOT::Math::VectorUtil::DeltaPhi(recoPos2D, flightDirection);
  const double beta = 1;
  double flightTimeEstimate = FlightTimeEstimator::instance().getFlightTime2D(recoPos2D, alpha, beta);
 
  if (std::isnan(tanLambda)) {
    tanLambda = recoPos3D.z() / recoPos3D.Rho();
  }
  const double theta = M_PI / 2 - std::atan(tanLambda);
  flightTimeEstimate *= hypot2(1, tanLambda);
 
  const CDCWire& wire = recoHit3D.getWire();
  const CDCHit* hit = recoHit3D.getWireHit().getHit();
  const bool rl = recoHit3D.getRLInfo() == ERightLeft::c_Right;
  double driftLength =
    tdcCountTranslator.getDriftLength(hit->getTDCCount(),
                                      wire.getWireID(),
                                      flightTimeEstimate,
                                      rl,
                                      recoPos3D.z(),
                                      alpha,
                                      theta,
                                      hit->getADCCount());
  if (driftLength > -2 and driftLength < 16) {
    bool snapRecoPos = true;
    recoHit3D.setRecoDriftLength(driftLength, snapRecoPos);
  }
  return driftLength;
}

updateDriftLength() [5/7]

void updateDriftLength

(

TrackingUtilities::CDCSegment2D &

segment

)

Update the drift length of the contained reconstructed hit in place.

Definition at line 194 of file DriftLengthEstimator.cc.

{
  for (CDCRecoHit2D& recoHit2D : segment) {
    updateDriftLength(recoHit2D);
  }
}

updateDriftLength() [6/7]

void updateDriftLength	(	TrackingUtilities::CDCSegment3D &	segment,
		double	tanLambda )

Update the drift length of the contained reconstructed hit in place.

Definition at line 239 of file DriftLengthEstimator.cc.

{
  for (CDCRecoHit3D& recoHit3D : segment3D) {
    updateDriftLength(recoHit3D, tanLambda);
  }
}

updateDriftLength() [7/7]

void updateDriftLength	(	TrackingUtilities::CDCTrack &	track,
		double	tanLambda )

Update the drift length of the contained reconstructed hit in place.

Definition at line 247 of file DriftLengthEstimator.cc.

{
  for (CDCRecoHit3D& recoHit3D : track) {
    updateDriftLength(recoHit3D, tanLambda);
  }
}

Member Data Documentation

m_param_tofMassScale

double m_param_tofMassScale = NAN

Parameter : Mass to estimate the velocity in the flight time to the hit.

Definition at line 112 of file DriftLengthEstimator.h.

m_param_useAlphaInDriftLength

bool m_param_useAlphaInDriftLength = true

Parameter : Switch to serve the alpha angle to the drift length translator.

Definition at line 109 of file DriftLengthEstimator.h.

m_tdcCountTranslator

std::shared_ptr<CDC::RealisticTDCCountTranslator> m_tdcCountTranslator

private

Drift time translator constructed lazily on first use.

Definition at line 130 of file DriftLengthEstimator.h.

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The documentation for this struct was generated from the following files:

• tracking/trackFindingCDC/eventdata/utils/include/DriftLengthEstimator.h
• tracking/trackFindingCDC/eventdata/utils/src/DriftLengthEstimator.cc