#include <StFmsClusterFitter.h>

Inheritance diagram for FMSCluster::StFmsClusterFitter:

Public Member Functions
	StFmsClusterFitter (Int_t detectorId, Float_t xw, Float_t yw, Float_t scaleShowerShapeLarge, Float_t scaleShowerShapeSmall, Int_t ShowerShapeWithAngle, Int_t MergeSmallToLarge, double vertexZ)

	StFmsClusterFitter ()

virtual	~StFmsClusterFitter ()

TF2 *	showerShapeFunction ()

void	setTowers (StFmsTowerCluster::Towers *towers)

Double_t	fitNPhoton (const std::vector< double > &parameteres, const std::vector< double > &steps, const std::vector< double > &lower, const std::vector< double > &up, PhotonList *photons)

Double_t	fitNPhoton (const std::vector< double > &parameters, const std::vector< double > &lower, const std::vector< double > &up, PhotonList *photons)

Int_t	fit2Photon (const std::array< double, 7 > &parameters, const std::array< double, 7 > &steps, const std::array< double, 7 > &lower, const std::array< double, 7 > &upper, PhotonList *photons)

Static Public Member Functions
static Double_t	energyDepositionInTowerOLD (Double_t x, Double_t y, Double_t *par)

static Double_t	energyDepositionInTower (Double_t x, Double_t par)

static Double_t	energyDepositionInTower (Double_t x, Double_t y, Double_t xun, Double_t yun, Double_t *parmeters, Int_t MergeSmallToLarge, double vertexz)

static Double_t	energyDepositionInTowerSingleLayer (Double_t x, Double_t y, Double_t *parameters)

static int	maxNFittedPhotons ()

Detailed Description

Photon shower-shape fitting routine for FMS clusters.

Fits tower clusters with the photon energy-deposition shower-shape distribution function i.e. how a photon hitting the FMS distributes its energy over towers. This serves to:

find the best-fit photon properties for a cluster.
distinguish clusters made by a single photon from those made by two nearby photons merging into a single cluster, which can frequently happen at the far-forward rapidity of the FMS.

Todo:: It may be safer to make StFmsClusterFitter a singleton class, or something like that. The shower shape fit function is shared across all objects (by necessity, in order to interface with TMinuit), but each object updates the function itself with different parameters. Therefore bad things would happen if there were more than one object in existence at any time. There isn't ever more than one instance created in this code, but I think it would be good to enforce that.

Definition at line 95 of file StFmsClusterFitter.h.

Constructor & Destructor Documentation

FMSCluster::StFmsClusterFitter::StFmsClusterFitter	(	Int_t	detectorId,
		Float_t	xw,
		Float_t	yw,
		Float_t	scaleShowerShapeLarge,
		Float_t	scaleShowerShapeSmall,
		Int_t	ShowerShapeWithAngle,
		Int_t	MergeSmallToLarge,
		double	vertexZ
	)

Constructor using detector geometry for a single sub-detector

Definition at line 194 of file StFmsClusterFitter.cxx.

FMSCluster::StFmsClusterFitter::StFmsClusterFitter ( )

inline

Default constructor.

Todo:: Actually initialize things!

Definition at line 106 of file StFmsClusterFitter.h.

FMSCluster::StFmsClusterFitter::~StFmsClusterFitter ( )

virtual

Destructor

Definition at line 213 of file StFmsClusterFitter.cxx.

Member Function Documentation

Double_t FMSCluster::StFmsClusterFitter::energyDepositionInTower	(	Double_t *	x,
		Double_t *	par
	)

static

adding 6 slices aong z with angle taken into account

Definition at line 354 of file StFmsClusterFitter.cxx.

Double_t FMSCluster::StFmsClusterFitter::energyDepositionInTowerOLD	(	Double_t	x,
		Double_t	y,
		Double_t *	par
	)

inlinestatic

Energy-deposition shower-shape function, for use with a TF2.

Yields the fraction of energy deposited in a tower by a photon, as a function of the distance from the photon to the tower center. Arguments:

x: array with x[0] = x distance from tower center, x[1] = y distance.
par: array of fit parameters (fixed, derived from FMS studies).

Integrates F(x, y) over a tower, with F(x, y) defined as here: https://drupal.star.bnl.gov/STAR/blog/leun/2010/aug/02/fms-meeting-20100802

Todo:: Provide LaTeX math function in documentation

Definition at line 296 of file StFmsClusterFitter.h.

Int_t FMSCluster::StFmsClusterFitter::fit2Photon	(	const std::array< double, 7 > &	parameters,
		const std::array< double, 7 > &	steps,
		const std::array< double, 7 > &	lower,
		const std::array< double, 7 > &	upper,
		PhotonList *	photons
	)

Specialized fit function for exactly 2-photon fit.

Argument meanings are as for fitNPhoton(). However as this is for 2-photon fits only, the input arrays should always have 7 (3 * 2 photons + 1) elements. Additionally each element has a different meaning here:

0: Still a constant parameter, should be set to 2 for 2-photon fitting.
1: x-position of pi⁰.
2: y-position of pi⁰.
3: Distance between 2 photons.
4: Theta angle of displacement vector from photon 2 to photon 1.
5: z_gg, from -1 to +1, so we do not set E1 > E2.
6: Total energy of two photons.

Returns the χ² of the fit.

Definition at line 308 of file StFmsClusterFitter.cxx.

Double_t FMSCluster::StFmsClusterFitter::fitNPhoton	(	const std::vector< double > &	parameteres,
		const std::vector< double > &	steps,
		const std::vector< double > &	lower,
		const std::vector< double > &	up,
		PhotonList *	photons
	)

Fit photons to the list of towers.

All array arguments are of size 3N+1 for an N-photon fit:

par: initial guess values for each fit variable.
step: step size when fitting (if empty use default values).
low: lower bound on each fit variable.
up: upper bound on each fit variable.

In each 3N+1D array, the first element is the number of photons to fit. Each subsequent triplet is the x position, y position and energy of a photon. e.g.

for a 1-photon fit: [1, x0, y0, E0]
for a 2-photon fit: [2, x0, y0, E0, x1, y1, E1]

Returns the χ² of the fit.

Definition at line 219 of file StFmsClusterFitter.cxx.

Referenced by fitNPhoton().

Double_t FMSCluster::StFmsClusterFitter::fitNPhoton	(	const std::vector< double > &	parameters,
		const std::vector< double > &	lower,
		const std::vector< double > &	up,
		PhotonList *	photons
	)

Calls fitNPhoton() with default step sizes

Definition at line 269 of file StFmsClusterFitter.cxx.

References fitNPhoton().

int FMSCluster::StFmsClusterFitter::maxNFittedPhotons ( )

static

Maximum number of photons that can be fit at once.

Definition at line 400 of file StFmsClusterFitter.cxx.

void FMSCluster::StFmsClusterFitter::setTowers ( StFmsTowerCluster::Towers * towers )

Set the tower list to fit when calling fitNPhoton() or fit2Photon()

Definition at line 549 of file StFmsClusterFitter.cxx.

TF2 * FMSCluster::StFmsClusterFitter::showerShapeFunction ( )

Return the shower shape function.

The shower shape gives the fractional energy deposition by a photon in a tower as a function of the distance of the photon from the tower center.

Definition at line 215 of file StFmsClusterFitter.cxx.

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

StFmsUtil/StFmsClusterFitter.h
StFmsUtil/StFmsClusterFitter.cxx

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation