#include <GsfMultipleScatteringUpdator.h>

Inheritance diagram for GsfMultipleScatteringUpdator:

Public Member Functions
virtual GsfMultipleScatteringUpdator *	clone () const
	GsfMultipleScatteringUpdator (float mass)
	constructor with explicit mass
Protected Member Functions
virtual bool	newArguments (const TrajectoryStateOnSurface &, const PropagationDirection) const
virtual void	storeArguments (const TrajectoryStateOnSurface &, const PropagationDirection) const
Private Member Functions
virtual void	compute (const TrajectoryStateOnSurface &, const PropagationDirection) const
	Computation: generates vectors of weights, means and standard deviations.
Private Attributes
float	theLastDz
float	theLastP
PropagationDirection	theLastPropDir
float	theLastRadLength

Detailed Description

Description of multiple scattering with two Gaussian components as described in HEPHY-PUB 724-99. Gaussians as a function of x/X0 are parametrized as polynomials. The mixture is parametrized as a function of the thickness, velocity and Xs=X0*h(Z).

Definition at line 14 of file GsfMultipleScatteringUpdator.h.

Constructor & Destructor Documentation

GsfMultipleScatteringUpdator::GsfMultipleScatteringUpdator ( float mass ) [inline]

constructor with explicit mass

Definition at line 25 of file GsfMultipleScatteringUpdator.h.

Referenced by clone().

                                           :
    GsfMaterialEffectsUpdator(mass),
    theLastDz(0.),
    theLastP(0.),
    theLastPropDir(alongMomentum),
    theLastRadLength(0.) {}

Member Function Documentation

virtual GsfMultipleScatteringUpdator* GsfMultipleScatteringUpdator::clone ( void ) const [inline, virtual]

Implements GsfMaterialEffectsUpdator.

Definition at line 32 of file GsfMultipleScatteringUpdator.h.

References GsfMultipleScatteringUpdator().

  {
    return new GsfMultipleScatteringUpdator(*this);
  }

void GsfMultipleScatteringUpdator::compute	(	const TrajectoryStateOnSurface &	TSoS,
		const PropagationDirection	propDir
	)		const `[private, virtual]`

Computation: generates vectors of weights, means and standard deviations.

Implements GsfMaterialEffectsUpdator.

Definition at line 10 of file GsfMultipleScatteringUpdator.cc.

References h, TrajectoryStateOnSurface::localMomentum(), funct::log(), PV3DBase< T, PVType, FrameType >::mag(), GsfMaterialEffectsUpdator::mass(), Surface::mediumProperties(), AlCaHLTBitMon_ParallelJobs::p, PV3DBase< T, PVType, FrameType >::perp(), funct::pow(), MediumProperties::radLen(), mathSSE::sqrt(), storeArguments(), TrajectoryStateOnSurface::surface(), GsfMaterialEffectsUpdator::theDeltaCovs, GsfMaterialEffectsUpdator::theDeltaPs, GsfMaterialEffectsUpdator::theWeights, w2, PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), PV3DBase< T, PVType, FrameType >::z(), and z.

{
  //
  // clear cache
  //
  theWeights.clear();
  theDeltaPs.clear();
  theDeltaCovs.clear();
  //
  // Get surface and check presence of medium properties
  //
  const Surface& surface = TSoS.surface();
  //
  // calculate components
  //
  if ( surface.mediumProperties() ) {
    LocalVector pvec = TSoS.localMomentum();
    double p = TSoS.localMomentum().mag();
    pvec *= 1./p;
    // thickness in radiation lengths
    double rl = surface.mediumProperties()->radLen()/fabs(pvec.z());
    // auxiliary variables for modified X0
    const double z = 14;                 // atomic number of silicon
    const double logz = log(z);
    const double h = (z+1)/z*log(287*sqrt(z))/log(159*pow(z,-1./3.));
    double beta2 = 1./(1.+mass()*mass()/p/p);
    // reduced thickness
    double dp1 = rl/beta2/h;
    double logdp1 = log(dp1);
    double logdp2 = 2./3.*logz + logdp1;
    // means are always 0
    theDeltaPs.push_back(0.);
    theDeltaPs.push_back(0.);
    // weights
    double w2;
    if ( logdp2<log(0.5) )  
      w2 = 0.05283+0.0077*logdp2+0.00069*logdp2*logdp2;
    else
      w2 =-0.01517+0.1151*logdp2-0.00653*logdp2*logdp2;
    double w1 = 1.-w2;
    theWeights.push_back(w1);
    theWeights.push_back(w2);
    // reduced variances
    double var1 = 0.8510+0.03314*logdp1-0.001825*logdp1*logdp1;
    double var2 = (1.-w1*var1)/w2;
    for ( int ic=0; ic<2; ic++ ) {
      // choose component and multiply with total variance
      double var = ic==0 ? var1 : var2;
      var *= 225.e-6*dp1/p/p;
      AlgebraicSymMatrix55 cov;
      // transform from orthogonal planes containing the
      // momentum vector to local parameters
      double sl = pvec.perp();
      double cl = pvec.z();
      double cf = pvec.x()/sl;
      double sf = pvec.y()/sl;
      cov(1,1) = var*(sf*sf*cl*cl + cf*cf)/(cl*cl*cl*cl);
      cov(1,2) = var*(cf*sf*sl*sl        )/(cl*cl*cl*cl);
      cov(2,2) = var*(cf*cf*cl*cl + sf*sf)/(cl*cl*cl*cl);
      theDeltaCovs.push_back(cov);
    }
  }
  else {
    theWeights.push_back(1.);
    theDeltaPs.push_back(0.);
    theDeltaCovs.push_back(AlgebraicSymMatrix55());
  }
  //
  // Save arguments to avoid duplication of computation
  //
  storeArguments(TSoS,propDir); 
}

bool GsfMultipleScatteringUpdator::newArguments	(	const TrajectoryStateOnSurface &	TSoS,
		const PropagationDirection	propDir
	)		const `[protected, virtual]`

Reimplemented from GsfMaterialEffectsUpdator.

Definition at line 88 of file GsfMultipleScatteringUpdator.cc.

References TrajectoryStateOnSurface::localMomentum(), PV3DBase< T, PVType, FrameType >::mag(), Surface::mediumProperties(), MediumProperties::radLen(), TrajectoryStateOnSurface::surface(), theLastDz, theLastP, theLastPropDir, theLastRadLength, Vector3DBase< T, FrameTag >::unit(), and PV3DBase< T, PVType, FrameType >::z().

                                                                                      {
  return TSoS.localMomentum().unit().z()!=theLastDz ||
    TSoS.localMomentum().mag()!=theLastP || propDir!=theLastPropDir ||
    TSoS.surface().mediumProperties()->radLen()!=theLastRadLength;
}

void GsfMultipleScatteringUpdator::storeArguments	(	const TrajectoryStateOnSurface &	TSoS,
		const PropagationDirection	propDir
	)		const `[protected, virtual]`

Reimplemented from GsfMaterialEffectsUpdator.

Definition at line 97 of file GsfMultipleScatteringUpdator.cc.

References TrajectoryStateOnSurface::localMomentum(), PV3DBase< T, PVType, FrameType >::mag(), Surface::mediumProperties(), MediumProperties::radLen(), TrajectoryStateOnSurface::surface(), theLastDz, theLastP, theLastPropDir, theLastRadLength, Vector3DBase< T, FrameTag >::unit(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by compute().

                                                                                             {
  theLastDz = TSoS.localMomentum().unit().z();
  theLastP = TSoS.localMomentum().mag();
  theLastPropDir = propDir;
  theLastRadLength = TSoS.surface().mediumProperties()->radLen();
}