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[BeamSpot] fit 1D projections of PV distribution to get initial values for 3D fit parameters #10782

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merged 2 commits into from Aug 19, 2015
Merged

[BeamSpot] fit 1D projections of PV distribution to get initial values for 3D fit parameters #10782

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4d96d96
stabilised fit 3D PV distribution. Parameters are initialised from a …
rmanzoni Aug 13, 2015
49541a6
Merge remote branch 'cms/CMSSW_7_4_X' into CMSSW_7_4_X_stabilized3DFit
rmanzoni Aug 14, 2015
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62 changes: 34 additions & 28 deletions RecoVertex/BeamSpotProducer/src/PVFitter.cc
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Expand Up @@ -90,16 +90,15 @@ void PVFitter::initialize(const edm::ParameterSet& iConfig,

// preset quality cut to "infinite"
dynamicQualityCut_ = 1.e30;

hPVx = new TH2F("hPVx","PVx vs PVz distribution",200,-maxVtxR_, maxVtxR_, 200, -maxVtxZ_, maxVtxZ_);
hPVy = new TH2F("hPVy","PVy vs PVz distribution",200,-maxVtxR_, maxVtxR_, 200, -maxVtxZ_, maxVtxZ_);
}

PVFitter::~PVFitter() {

}


void PVFitter::readEvent(const edm::Event& iEvent)
{

Expand Down Expand Up @@ -147,7 +146,6 @@ void PVFitter::readEvent(const edm::Event& iEvent)
if ( pv->isFake() || pv->tracksSize()==0 ) continue;
if ( pv->ndof() < minVtxNdf_ || (pv->ndof()+3.)/pv->tracksSize()<2*minVtxWgt_ ) continue;
//---

hPVx->Fill( pv->x(), pv->z() );
hPVy->Fill( pv->y(), pv->z() );

Expand Down Expand Up @@ -341,28 +339,36 @@ bool PVFitter::runFitter() {

//bool fit_ok = false;

if ( ! do3DFit_ ) {
TH1F *h1PVx = (TH1F*) hPVx->ProjectionX("h1PVx", 0, -1, "e");
TH1F *h1PVy = (TH1F*) hPVy->ProjectionX("h1PVy", 0, -1, "e");
TH1F *h1PVz = (TH1F*) hPVx->ProjectionY("h1PVz", 0, -1, "e");
TH1F *h1PVx = (TH1F*) hPVx->ProjectionX("h1PVx", 0, -1, "e");
TH1F *h1PVy = (TH1F*) hPVy->ProjectionX("h1PVy", 0, -1, "e");
TH1F *h1PVz = (TH1F*) hPVx->ProjectionY("h1PVz", 0, -1, "e");

//Use our own copy for thread safety
TF1 gaus("localGaus","gaus");

h1PVx->Fit(&gaus,"QLM0");
h1PVy->Fit(&gaus,"QLM0");
h1PVz->Fit(&gaus,"QLM0");

TF1 *gausx = h1PVx->GetFunction("localGaus");
TF1 *gausy = h1PVy->GetFunction("localGaus");
TF1 *gausz = h1PVz->GetFunction("localGaus");

fwidthX = gausx->GetParameter(2);
fwidthY = gausy->GetParameter(2);
fwidthZ = gausz->GetParameter(2);
fwidthXerr = gausx->GetParError(2);
fwidthYerr = gausy->GetParError(2);
fwidthZerr = gausz->GetParError(2);

double estX = gausx->GetParameter(1);
double estY = gausy->GetParameter(1);
double estZ = gausz->GetParameter(1);
double errX = fwidthX*3.;
double errY = fwidthY*3.;
double errZ = fwidthZ*3.;

//Use our own copy for thread safety
TF1 gaus("localGaus","gaus");

h1PVx->Fit(&gaus,"QLM0");
h1PVy->Fit(&gaus,"QLM0");
h1PVz->Fit(&gaus,"QLM0");

TF1 *gausx = h1PVx->GetFunction("localGaus");
TF1 *gausy = h1PVy->GetFunction("localGaus");
TF1 *gausz = h1PVz->GetFunction("localGaus");

fwidthX = gausx->GetParameter(2);
fwidthY = gausy->GetParameter(2);
fwidthZ = gausz->GetParameter(2);
fwidthXerr = gausx->GetParError(2);
fwidthYerr = gausy->GetParError(2);
fwidthZerr = gausz->GetParError(2);
if ( ! do3DFit_ ) {

reco::BeamSpot::CovarianceMatrix matrix;
matrix(2,2) = gausz->GetParError(1) * gausz->GetParError(1);
Expand Down Expand Up @@ -390,9 +396,9 @@ bool PVFitter::runFitter() {
// fit parameters: positions, widths, x-y correlations, tilts in xz and yz
//
MnUserParameters upar;
upar.Add("x" , 0. , 0.02 , -10. , 10. ); // 0
upar.Add("y" , 0. , 0.02 , -10. , 10. ); // 1
upar.Add("z" , 0. , 0.20 , -30. , 30. ); // 2
upar.Add("x" , estX , errX , -10. , 10. ); // 0
upar.Add("y" , estY , errY , -10. , 10. ); // 1
upar.Add("z" , estZ , errZ , -30. , 30. ); // 2
upar.Add("ex" , 0.015 , 0.01 , 0. , 10. ); // 3
upar.Add("corrxy", 0. , 0.02 , -1. , 1. ); // 4
upar.Add("ey" , 0.015 , 0.01 , 0. , 10. ); // 5
Expand Down