RegionCutFinder Namespace Reference

Finding regions by fitting a two-component mixture to the scatter. More...

Functions
RegionFit	FitMixture (TH2F *scatter, Int_t reac, Double_t x_lo, Double_t x_hi, Double_t y_lo, Double_t y_hi)
	Fit the two-component mixture to one strip's scatter.
TCutG *	EllipseCut (const char *name, const Gauss2D &g, Double_t nsigma, Int_t npts=64)
	Closed polygon of a component's Mahalanobis contour.
RegionFit	FitBeam (TH2F *scatter, Int_t reac, Double_t x_lo, Double_t x_hi, Double_t y_lo, Double_t y_hi)
	Fit the beam component alone, with no reaction component.
Double_t	AboveRidge (const Gauss2D &beam, Double_t x, Double_t y)
	How far a point sits above the beam ridge, in conditional sigma.
TCutG *	RidgeBandCut (const char *name, const Gauss2D &beam, Double_t nsig_lo, Double_t nsig_hi, Double_t x_lo, Double_t x_hi, Double_t y_lo, Double_t y_hi)
	Closed polygon of a band above the beam ridge.
Double_t	CountInside (TH2F *scatter, TCutG *cut, const RegionFit &fit)
	Count scatter events inside a cut.
void	SaveFigures (TH2F *scatter, Int_t reac, const RegionFit &fit, TCutG *an, TCutG *aa, const TString &subdir)
	Save the diagnostic figures for a strip's regions.

Detailed Description

Finding regions by fitting a two-component mixture to the scatter.

This is ApJ 983:142's "two Gaussian peaks" carried into two dimensions. The two populations separate along the beam ridge's diagonal, which 1-D projections wash out, and the reaction island is a few times 1e-4 of the scatter.

The fit is staged accordingly: the beam-like component is pinned from its own core, the reaction component is seeded at the first local maximum above the ridge, and the mixture is fitted only above the core, so that the island rather than the 1e5-count peak decides the second component.

Function Documentation

AboveRidge()

Double_t RegionCutFinder::AboveRidge	(	const Gauss2D &	beam,
		Double_t	x,
		Double_t	y )

How far a point sits above the beam ridge, in conditional sigma.

The residual of y about the ridge line, in units of the beam's conditional width sigma_y * sqrt(1 - rho^2).

Parameters

beam	Fitted beam component.
x	Point x.
y	Point y.

Returns

The height in sigma; negative below the ridge.

Definition at line 468 of file RegionCuts.cpp.

Referenced by FitMixture().

CountInside()

Double_t RegionCutFinder::CountInside	(	TH2F *	scatter,
		TCutG *	cut,
		const RegionFit &	fit )

Count scatter events inside a cut.

Parameters

scatter	Scatter histogram.
cut	Region to count within.
fit	Fit supplying the window; only bins inside it are considered.

Returns

Summed contents of the bins whose centre lies inside cut.

Definition at line 528 of file RegionCuts.cpp.

Referenced by main().

EllipseCut()

TCutG * RegionCutFinder::EllipseCut	(	const char *	name,
		const Gauss2D &	g,
		Double_t	nsigma,
		Int_t	npts = 64 )

Closed polygon of a component's Mahalanobis contour.

Parameters

name	Name for the returned cut.
g	Component to contour.
nsigma	Contour level, in Mahalanobis sigma.
npts	Polygon vertices; more gives a smoother ellipse.

Returns

The cut. The caller owns it.

Definition at line 512 of file RegionCuts.cpp.

Referenced by main(), and SaveFigures().

FitBeam()

RegionFit RegionCutFinder::FitBeam	(	TH2F *	scatter,
		Int_t	reac,
		Double_t	x_lo,
		Double_t	x_hi,
		Double_t	y_lo,
		Double_t	y_hi )

Fit the beam component alone, with no reaction component.

Pinned from its core exactly as FitMixture() does, but returns a fit with has_reac == kFALSE. For the ridge-band region mode, where the (a,n) population is not a compact island and so cannot be modelled as a second Gaussian.

Parameters

scatter	Scatter histogram. Must not be null.
reac	Reaction strip index.
x_lo	Fit window, lower x.
x_hi	Fit window, upper x.
y_lo	Fit window, lower y.
y_hi	Fit window, upper y.

Returns

The beam-only fit.

Definition at line 473 of file RegionCuts.cpp.

Referenced by main().

FitMixture()

RegionFit RegionCutFinder::FitMixture	(	TH2F *	scatter,
		Int_t	reac,
		Double_t	x_lo,
		Double_t	x_hi,
		Double_t	y_lo,
		Double_t	y_hi )

Fit the two-component mixture to one strip's scatter.

Parameters

scatter	Scatter histogram for the strip. Must not be null.
reac	Reaction strip index.
x_lo	Fit window, lower x.
x_hi	Fit window, upper x.
y_lo	Fit window, lower y.
y_hi	Fit window, upper y.

Returns

The fit; check RegionFit::ok, and RegionFit::why when it is false.

Definition at line 311 of file RegionCuts.cpp.

Referenced by main().

RidgeBandCut()

TCutG * RegionCutFinder::RidgeBandCut	(	const char *	name,
		const Gauss2D &	beam,
		Double_t	nsig_lo,
		Double_t	nsig_hi,
		Double_t	x_lo,
		Double_t	x_hi,
		Double_t	y_lo,
		Double_t	y_hi )

Closed polygon of a band above the beam ridge.

The (a,n) region in AN_REGION_RIDGE_BAND mode. Spans the window in x and is clipped to the window in y.

Parameters

name	Name for the returned cut.
beam	Fitted beam component defining the ridge.
nsig_lo	Lower band edge, in conditional sigma above the ridge.
nsig_hi	Upper band edge.
x_lo	Window, lower x.
x_hi	Window, upper x.
y_lo	Window, lower y.
y_hi	Window, upper y.

Returns

The cut. The caller owns it.

Definition at line 491 of file RegionCuts.cpp.

Referenced by main().

SaveFigures()

void RegionCutFinder::SaveFigures	(	TH2F *	scatter,
		Int_t	reac,
		const RegionFit &	fit,
		TCutG *	an,
		TCutG *	aa,
		const TString &	subdir )

Save the diagnostic figures for a strip's regions.

The scatter with both regions drawn, then each projection with the fitted mixture's projection overlaid — so a region that landed somewhere silly is visible rather than merely wrong.

Parameters

scatter	Scatter histogram.
reac	Reaction strip index.
fit	Fit to overlay.
an	The (a,n) region.
aa	The (a,a') region.
subdir	Plot subdirectory under the plots base.

Definition at line 540 of file RegionCuts.cpp.

Referenced by main().