PaTPar Class Reference

Trajectory parameters. More...

#include <PaTPar.h>

Public Member Functions
float &	operator() (const int i, const int j=0)
	Access to individual trajectory parameters and it's covariance matrix by "()" operator.
double	Dip (bool in_deg=false) const
	Dip angle.
double	Azi (bool in_deg=false) const
	Azi angle.
double	Phi (bool in_deg=false) const
	$\phi$ angle.
double	Theta (bool in_deg=false) const
	$\Theta$ angle.
double	DirCos (char axis) const
	return direction cosine (axis = 'x','y','z' for COSx, COSy, COSz)
void	DirVector (TVector3 &vec) const
	return track direction unit vector "vec"
double	Mom () const
	return \|P\|
int	Q () const
	return charge
double	qP () const
	return \|P\|*charge
double	Pt () const
	return Pt
double	Pos (int i) const
	returns X if i == 0, Y if i == 1 and Z if i == 2
TVector3	Pos () const
	returns X,Y,Z as TVector3
double	X () const
	X of the trajectory.
double	Y () const
	Y of the trajectory.
double	Z () const
	Z (fixed) where trajectory parameters are defined.
double	dXdZ () const
	dX/dZ (horizontal slope) of the trajectory
double	dYdZ () const
	dY/dZ (vertical slope) of the trajectory
TVector3	Mom3 () const
	returns 3-vector of momentum components
TLorentzVector	LzVec (double mass) const
	returns Lorentz vector for specified mass
TVector	ParVect () const
	returns parameters as TVector
TMatrix	CovMatrix () const
	returns covariance matrix as TMatrix
bool	IsEmpty () const
	"true" it's empty (not defined) trajectory params
bool	HasEmptyCov () const
	true" if covariance matrix is not defined
bool	HasMom () const
	"true" if momentum had been defined
void	Print (int level=0, string comment="") const
	Print.
void	Rotate (double ca, double sa, PaTPar &Pout) const
	Rotate to "wire reference system".
double	Dist (PaTPar &P) const
	Straight line distance from "this" PaTPar (X,Y,Z) to PaTPar P.
void	AddNoise (float x, float RadLen, bool reverse_ms=false)
	Add multiple scattering "noise" to covariance matrix after propagation through a material.
bool	Extrapolate (double Z, PaTPar &Hout, bool useMatMap=true, bool reverse_ms=false) const
	Propagate charged particle trajectory parameters.
bool	ExtrapNeutral (double Z, PaTPar &Hout) const
	Propagate neutral particle trajectory parameters.
double	Path () const
	Returns trajectory length of previouse extrapolation.
double	RadLenFr () const
	Returns fractions of radiation length passed in previouse extrapolation.
bool	FindCDA (PaTPar &H, float Z0=0, float Zmin=-1000, float Zmax=+1000, bool neutral1=false, bool neutral2=false)
	Find closest distance of approach for "this" PaTPar and PaTPar "H".
bool	Update (PaTPar &H1, PaTPar &Hout, double &Chi2)
	do Kalman update of "this" state vector by "H1"
bool	Update (const PaHit &h, PaTPar &Hout)
	do Kalman update of "this" state vector by measurment (hit) "h"
double	HitChi2 (PaHit &h)
	calculate $\chi^2$ increment for "this" state vector by measurment "h" (object of PaHit class)
void	Set (double &x, PaMtx &V, PaMtx &M)
	Pack vector and matrix into helix.
void	Get (double &x, PaMtx &V, PaMtx &M) const
	Upack helix to vector and matrix.

Detailed Description

Trajectory parameters.

Class for charged particle trajectory parameters (X, Y, dX/dZ, dY/dZ, q/|P| at fixed Z position with corresponding covariance matrix.

Read and write access to parameters is provided by means of overloaded "operator ()".
E.g. if p is an object of this class, p(i) are references to parameters, p(i,j) - are references to covariance matrix elements.
i,j=1,2,3,4,5 and corresponds to X,Y,X',Y',q/|P| .
For example: p(0) is "fixed parameter" (i.e. Z position where trajectory parameters are defined), p(1) is X, p(3) is dX/dY, p(5) is q/P etc.

This class also could be used to store neutral particles parameters, assuming that 5-th parameter is just 1/P
(Warning: Do not use Extrapolate() in this case. Use ExtrapNeutral() instead.)

Author:: Sergei.Gerassimov@cern.ch

Member Function Documentation

void PaTPar::AddNoise	(	float	x,
		float	RadLen,
		bool	reverse_ms = `false`
	)

Add multiple scattering "noise" to covariance matrix after propagation through a material.

Parameters:

	x	- thickness of material traversed
	RadLen	- radiation length of material traversed
	reverse_ms	- if set to true", "noise" will be _subtracted_ (for very special purposes)

Referenced by Extrapolate(), and PaTrack::FullKF().

double PaTPar::Azi ( bool in_deg = false ) const

Azi angle.

Angle between projection of $\vec P$ on plane X0Z and Z (rad/deg depending on parameter)

TMatrix PaTPar::CovMatrix ( ) const

returns covariance matrix as TMatrix

Warning:: Returns matrix "by value". Avoid to use in CPU time consumings code

double PaTPar::Dip ( bool in_deg = false ) const

Dip angle.

Angle between $\vec P$ and it's projection on plane X0Z (rad/deg depending on parameter)

bool PaTPar::ExtrapNeutral	(	double	Z,
		PaTPar &	Hout
	)			const

Propagate neutral particle trajectory parameters.

Perform straight line extrapolation of neutral particle parameters to specified "Z"
Result is stored in "Hout".

References Dist().

bool PaTPar::Extrapolate	(	double	Z,
		PaTPar &	Hout,
		bool	useMatMap = `true`,
		bool	reverse_ms = `false`
	)			const

Propagate charged particle trajectory parameters.

Parameters:

	Z	- z-coordinate of desired destination point of the propagation
	Hout	- resulting trajectory parameters at Z (if Z had been reached)
	useMatMap	- set to "false"to ignore multiple scattering and energy losses effects
	reverse_ms	- special purpose mode. Please always leave default (false).

Function returns "false" is Z had not been reached.

Warning:: Do not use it for neutral particles extrapolation. Use ExtrapNeutral() instead.

References AddNoise(), Dist(), PaMaterialMaps::getdE(), PaMaterialMaps::getdEStraggling(), PaMaterialMaps::getRadLength(), HasMom(), PaSetup::MaterialMaps(), Mom(), Path(), and PaSetup::Ref().

Referenced by PaTrack::CanBeMuon(), PaAlgo::CrossCells(), PaTrack::CrossYokeSM2(), PaTrack::Extrapolate(), PaTrack::FullKF(), PaTrack::GetSmoothed(), and PaTrack::PointsHodoscopes().

bool PaTPar::FindCDA	(	PaTPar &	H,
		float	Z0 = `0`,
		float	Zmin = `-1000`,
		float	Zmax = `+1000`,
		bool	neutral1 = `false`,
		bool	neutral2 = `false`
	)

Find closest distance of approach for "this" PaTPar and PaTPar "H".

Function find such Z (within specified range) that distance between 2 trajectories propagated to this Z is minimal.

At the exit, "this" PaTPar and PaTPar "H" has it's values at the Z where they have minimal distance.

Parameters:

	H	- 2-d input PaTPar (first one is "this")
	Z0	- starting value for minimization
	Zmin	- lower limit
	Zmax	- upper limit
	neutral1	- to be set to "true" if PaTPar "this" is of neutral particle
	neutral2	- to be set to "true" if PaTPar "H" is of neutral particle

Returns:: "false" if minimization did not converged or had reached one of 2 limits

Warning:

Function changes both "this" object and H!
What is minimized is not the distance in space but the distance at the plane Z=const.
Extrapolations of charged particles are used inside by default. Use "neutral1" and "neutral2" flags to force straight line extrapolations.

double PaTPar::HitChi2 ( PaHit & h )

calculate $\chi^2$ increment for "this" state vector by measurment "h" (object of PaHit class)

Returns:: $\Delta\chi^2$

Referenced by PaTrack::FullKF(), and PaTrack::QuickKF().

float & PaTPar::operator()	(	const int	i,
		const int	j = `0`
	)

Access to individual trajectory parameters and it's covariance matrix by "()" operator.

If "p" is an object of class PaTPar, then

p(0) is Z position where trajectory parameters are defined
p(1) is X
p(2) is Y
p(3) is dX/dZ
p(4) is dY/dZ
p(5) is q/|P|

p(i,j) is $COV_{i,j}$ , where i,j = 1,2,3,4,5

double PaTPar::Phi ( bool in_deg = false ) const

$\phi$ angle.

Angle between projection of $\vec P$ on plane X0Y and X (rad/deg depending on parameter)

References DirCos().

void PaTPar::Print	(	int	level = `0`,
		string	str = `""`
	)			const

Print.

Print trajectory parameters

Parameters:

	level	if > 0 full cov. matrix is printed
	str	comment to be printed

References Mom3().

Referenced by PaTrack::FullKF(), PaTrack::GetSmoothed(), PaMCtrack::Print(), PaTrack::QuickKF(), and Update().

void PaTPar::Rotate	(	double	ca,
		double	sa,
		PaTPar &	Pout
	)			const

Rotate to "wire reference system".

Rotate trajectory parameters (together with cov. matrix) to reference system rotation of which is defined by matrix:

   cos(a)  sin(a)   0      0     0
  -sin(a)  cos(a)   0      0     0
     0      0     cos(a) sin(a)  0
     0      0    -sin(a) cos(a)  0
     0      0       0      0     1

Parameters:

	ca	- cos(a)
	sa	- sin(a)
	Pout	- resulting trajectory parameters.

Referenced by Update().

double PaTPar::Theta ( bool in_deg = false ) const

$\Theta$ angle.

Angle between $\vec P$ and Z (rad/deg depending on parameter)

bool PaTPar::Update	(	const PaHit &	h,
		PaTPar &	Hout
	)

do Kalman update of "this" state vector by measurment (hit) "h"

Result is stored to "Hout".

References PaDetect::Ca(), PaHit::DetRef(), Print(), Rotate(), PaDetect::Sa(), PaHit::U(), and PaHit::V().

bool PaTPar::Update	(	PaTPar &	H1,
		PaTPar &	Hout,
		double &	Chi2
	)

do Kalman update of "this" state vector by "H1"

Result is stored to "Hout". At the same time $\chi^2$ increment is returned in "Chi2"

References Get(), PaMtx::i(), PaMtx::Print(), and Set().

Referenced by PaTrack::FullKF(), PaTrack::GetSmoothed(), and PaTrack::QuickKF().

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

lib/PaTPar.h
lib/PaTPar.cc
lib/PaTParAddNoise.cc
lib/PaTParExtrap.cc
lib/PaTParExtrapolate.cc
lib/PaTParFindCDA.cc
lib/PaTParHitChi2.cc
lib/PaTParUpdate.cc

PaTPar Class Reference

Public Member Functions

Detailed Description

Member Function Documentation