for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) fProb[ispec] = -1.;
fLabels[0]=-1; fLabels[1]=-1; // most freq MC labels
fLabels[2]=0; // number of different labels for tracklet
- memset(fRefCov, 0, 3*sizeof(Double_t));
+ memset(fRefCov, 0, 7*sizeof(Double_t));
// covariance matrix [diagonal]
// default sy = 200um and sz = 2.3 cm
fCov[0] = 4.e-4; fCov[1] = 0.; fCov[2] = 5.3;
memcpy(target.fdEdx, fdEdx, kNslices*sizeof(Float_t));
memcpy(target.fProb, fProb, AliPID::kSPECIES*sizeof(Float_t));
memcpy(target.fLabels, fLabels, 3*sizeof(Int_t));
- memcpy(target.fRefCov, fRefCov, 3*sizeof(Double_t));
+ memcpy(target.fRefCov, fRefCov, 7*sizeof(Double_t));
memcpy(target.fCov, fCov, 3*sizeof(Double_t));
TObject::Copy(ref);
Double_t y, z;
if(!track->GetProlongation(fX0, y, z)) return kFALSE;
- UpDate(track);
+ Update(track);
return kTRUE;
}
for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) fProb[ispec] = -1.;
fLabels[0]=-1; fLabels[1]=-1; // most freq MC labels
fLabels[2]=0; // number of different labels for tracklet
- memset(fRefCov, 0, 3*sizeof(Double_t));
+ memset(fRefCov, 0, 7*sizeof(Double_t));
// covariance matrix [diagonal]
// default sy = 200um and sz = 2.3 cm
fCov[0] = 4.e-4; fCov[1] = 0.; fCov[2] = 5.3;
}
//____________________________________________________________________
-void AliTRDseedV1::UpDate(const AliTRDtrackV1 *trk)
+void AliTRDseedV1::Update(const AliTRDtrackV1 *trk)
{
// update tracklet reference position from the TRD track
- // Funny name to avoid the clash with the function AliTRDseed::Update() (has to be made obselete)
Double_t fSnp = trk->GetSnp();
Double_t fTgl = trk->GetTgl();
fPt = trk->Pt();
- fYref[1] = fSnp/TMath::Sqrt(1. - fSnp*fSnp);
- fZref[1] = fTgl;
+ Double_t norm =1./TMath::Sqrt(1. - fSnp*fSnp);
+ fYref[1] = fSnp*norm;
+ fZref[1] = fTgl*norm;
SetCovRef(trk->GetCovariance());
Double_t dx = trk->GetX() - fX0;
//____________________________________________________________________
-Float_t AliTRDseedV1::GetdQdl(Int_t ic) const
+Float_t AliTRDseedV1::GetdQdl(Int_t ic, Float_t *dl) const
{
// Using the linear approximation of the track inside one TRD chamber (TRD tracklet)
// the charge per unit length can be written as:
// BEGIN_LATEX
-// #frac{dq}{dl} = #frac{q_{c}}{dx * #sqrt{1 + #(){#frac{dy}{dx}}^{2}_{fit} + #(){#frac{dy}{dx}}^{2}_{ref}}}
+// #frac{dq}{dl} = #frac{q_{c}}{dx * #sqrt{1 + #(){#frac{dy}{dx}}^{2}_{fit} + #(){#frac{dz}{dx}}^{2}_{ref}}}
// END_LATEX
// where qc is the total charge collected in the current time bin and dx is the length
-// of the time bin. For the moment (Jan 20 2009) only pad row cross corrections are
-// considered for the charge but none are applied for drift velocity variations along
-// the drift region or assymetry of the TRF
+// of the time bin.
+// The following correction are applied :
+// - charge : pad row cross corrections
+// [diffusion and TRF assymetry] TODO
+// - dx : anisochronity, track inclination - see Fit and AliTRDcluster::GetXloc()
+// and AliTRDcluster::GetYloc() for the effects taken into account
//
+//Begin_Html
+//<img src="TRD/trackletDQDT.gif">
+//End_Html
+// In the picture the energy loss measured on the tracklet as a function of drift time [left] and respectively
+// drift length [right] for different particle species is displayed.
// Author : Alex Bercuci <A.Bercuci@gsi.de>
//
Float_t dq = 0.;
- if(fClusters[ic]) dq += TMath::Abs(fClusters[ic]->GetQ());
- if(fClusters[ic+kNtb]) dq += TMath::Abs(fClusters[ic+kNtb]->GetQ());
- if(dq<1.e-3 || fdX < 1.e-3) return 0.;
+ // check whether both clusters are inside the chamber
+ Bool_t hasClusterInChamber = kFALSE;
+ if(fClusters[ic] && fClusters[ic]->IsInChamber()){
+ hasClusterInChamber = kTRUE;
+ dq += TMath::Abs(fClusters[ic]->GetQ());
+ }else if(fClusters[ic+kNtb] && fClusters[ic+kNtb]->IsInChamber()){
+ hasClusterInChamber = kTRUE;
+ dq += TMath::Abs(fClusters[ic+kNtb]->GetQ());
+ }
+ if(!hasClusterInChamber) return 0.;
+ if(dq<1.e-3) return 0.;
+
+ Double_t dx = fdX;
+ if(ic-1>=0 && ic+1<kNtb){
+ Float_t x2(0.), x1(0.);
+ // try to estimate upper radial position (find the cluster which is inside the chamber)
+ if(fClusters[ic-1] && fClusters[ic-1]->IsInChamber()) x2 = fClusters[ic-1]->GetX();
+ else if(fClusters[ic-1+kNtb] && fClusters[ic-1+kNtb]->IsInChamber()) x2 = fClusters[ic-1+kNtb]->GetX();
+ else if(fClusters[ic] && fClusters[ic]->IsInChamber()) x2 = fClusters[ic]->GetX()+fdX;
+ else x2 = fClusters[ic+kNtb]->GetX()+fdX;
+ // try to estimate lower radial position (find the cluster which is inside the chamber)
+ if(fClusters[ic+1] && fClusters[ic+1]->IsInChamber()) x1 = fClusters[ic+1]->GetX();
+ else if(fClusters[ic+1+kNtb] && fClusters[ic+1+kNtb]->IsInChamber()) x1 = fClusters[ic+1+kNtb]->GetX();
+ else if(fClusters[ic] && fClusters[ic]->IsInChamber()) x1 = fClusters[ic]->GetX()-fdX;
+ else x1 = fClusters[ic+kNtb]->GetX()-fdX;
+
+ dx = .5*(x2 - x1);
+ }
+ dx *= TMath::Sqrt(1. + fYfit[1]*fYfit[1] + fZref[1]*fZref[1]);
+ if(dl) (*dl) = dx;
+ return dq/dx;
+}
+
+//____________________________________________________________
+Float_t AliTRDseedV1::GetMomentum(Float_t *err) const
+{
+// Returns momentum of the track after update with the current tracklet as:
+// BEGIN_LATEX
+// p=#frac{1}{1/p_{t}} #sqrt{1+tgl^{2}}
+// END_LATEX
+// and optionally the momentum error (if err is not null).
+// The estimated variance of the momentum is given by:
+// BEGIN_LATEX
+// #sigma_{p}^{2} = (#frac{dp}{dp_{t}})^{2} #sigma_{p_{t}}^{2}+(#frac{dp}{dtgl})^{2} #sigma_{tgl}^{2}+2#frac{dp}{dp_{t}}#frac{dp}{dtgl} cov(tgl,1/p_{t})
+// END_LATEX
+// which can be simplified to
+// BEGIN_LATEX
+// #sigma_{p}^{2} = p^{2}p_{t}^{4}tgl^{2}#sigma_{tgl}^{2}-2p^{2}p_{t}^{3}tgl cov(tgl,1/p_{t})+p^{2}p_{t}^{2}#sigma_{1/p_{t}}^{2}
+// END_LATEX
+//
- return dq/fdX/TMath::Sqrt(1. + fYfit[1]*fYfit[1] + fZref[1]*fZref[1]);
+ Double_t p = fPt*TMath::Sqrt(1.+fZref[1]*fZref[1]);
+ Double_t p2 = p*p;
+ Double_t tgl2 = fZref[1]*fZref[1];
+ Double_t pt2 = fPt*fPt;
+ if(err){
+ Double_t s2 =
+ p2*tgl2*pt2*pt2*fRefCov[4]
+ -2.*p2*fZref[1]*fPt*pt2*fRefCov[5]
+ +p2*pt2*fRefCov[6];
+ (*err) = TMath::Sqrt(s2);
+ }
+ return p;
}
+
//____________________________________________________________________
Float_t* AliTRDseedV1::GetProbability(Bool_t force)
{
// Output
// returns pointer to the probability array and 0x0 if missing DB access
//
-// Detailed description
+// Retrieve PID probabilities for e+-, mu+-, K+-, pi+- and p+- from the DB according to tracklet information:
+// - estimated momentum at tracklet reference point
+// - dE/dx measurements
+// - tracklet length
+// - TRD layer
+// According to the steering settings specified in the reconstruction one of the following methods are used
+// - Neural Network [default] - option "nn"
+// - 2D Likelihood - option "!nn"
-
- // retrive calibration db
AliTRDcalibDB *calibration = AliTRDcalibDB::Instance();
if (!calibration) {
AliError("No access to calibration data");
Double_t xr = fX0-x;
Double_t sy2 = fCov[0] +2.*xr*fCov[1] + xr*xr*fCov[2];
- Double_t sz2 = GetPadLength()*GetPadLength()/12.;
+ Double_t sz2 = fS2Z;
+ //GetPadLength()*GetPadLength()/12.;
// insert systematic uncertainties
if(fReconstructor){
cov[0] = (sy2+t2*sz2)*correction;
cov[1] = GetTilt()*(sz2 - sy2)*correction;
cov[2] = (t2*sy2+sz2)*correction;
+
+ //printf("C(%6.1f %+6.3f %6.1f) [%s]\n", 1.e4*TMath::Sqrt(cov[0]), cov[1], 1.e4*TMath::Sqrt(cov[2]), IsRowCross()?" RC ":"-");
}
//____________________________________________________________
return Det;
}
+//____________________________________________________________________
+UShort_t AliTRDseedV1::GetVolumeId() const
+{
+ Int_t ic=0;
+ while(ic<kNclusters && !fClusters[ic]) ic++;
+ return fClusters[ic] ? fClusters[ic]->GetVolumeId() : 0;
+}
+
+
//____________________________________________________________________
void AliTRDseedV1::Calibrate()
{
}
-// //____________________________________________________________________
-// Bool_t AliTRDseedV1::AttachClustersIter(AliTRDtrackingChamber *chamber, Float_t quality, Bool_t kZcorr, AliTRDcluster *c)
-// {
-// //
-// // Iterative process to register clusters to the seed.
-// // In iteration 0 we try only one pad-row and if quality not
-// // sufficient we try 2 pad-rows (about 5% of tracks cross 2 pad-rows)
-// //
-// // debug level 7
-// //
-//
-// if(!fReconstructor->GetRecoParam() ){
-// AliError("Seed can not be used without a valid RecoParam.");
-// return kFALSE;
-// }
-//
-// AliTRDchamberTimeBin *layer = 0x0;
-// if(fReconstructor->GetStreamLevel(AliTRDReconstructor::kTracker)>=7){
-// AliTRDtrackingChamber ch(*chamber);
-// ch.SetOwner();
-// TTreeSRedirector &cstreamer = *fReconstructor->GetDebugStream(AliTRDReconstructor::kTracker);
-// cstreamer << "AttachClustersIter"
-// << "chamber.=" << &ch
-// << "tracklet.=" << this
-// << "\n";
-// }
-//
-// Float_t tquality;
-// Double_t kroady = fReconstructor->GetRecoParam() ->GetRoad1y();
-// Double_t kroadz = GetPadLength() * .5 + 1.;
-//
-// // initialize configuration parameters
-// Float_t zcorr = kZcorr ? GetTilt() * (fZfit[0] - fZref[0]) : 0.;
-// Int_t niter = kZcorr ? 1 : 2;
-//
-// Double_t yexp, zexp;
-// Int_t ncl = 0;
-// // start seed update
-// for (Int_t iter = 0; iter < niter; iter++) {
-// ncl = 0;
-// for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
-// if(!(layer = chamber->GetTB(iTime))) continue;
-// if(!Int_t(*layer)) continue;
-//
-// // define searching configuration
-// Double_t dxlayer = layer->GetX() - fX0;
-// if(c){
-// zexp = c->GetZ();
-// //Try 2 pad-rows in second iteration
-// if (iter > 0) {
-// zexp = fZref[0] + fZref[1] * dxlayer - zcorr;
-// if (zexp > c->GetZ()) zexp = c->GetZ() + GetPadLength()*0.5;
-// if (zexp < c->GetZ()) zexp = c->GetZ() - GetPadLength()*0.5;
-// }
-// } else zexp = fZref[0] + (kZcorr ? fZref[1] * dxlayer : 0.);
-// yexp = fYref[0] + fYref[1] * dxlayer - zcorr;
-//
-// // Get and register cluster
-// Int_t index = layer->SearchNearestCluster(yexp, zexp, kroady, kroadz);
-// if (index < 0) continue;
-// AliTRDcluster *cl = (*layer)[index];
-//
-// fIndexes[iTime] = layer->GetGlobalIndex(index);
-// fClusters[iTime] = cl;
-// // fY[iTime] = cl->GetY();
-// // fZ[iTime] = cl->GetZ();
-// ncl++;
-// }
-// if(fReconstructor->GetStreamLevel(AliTRDReconstructor::kTracker)>=7) AliInfo(Form("iter = %d ncl [%d] = %d", iter, fDet, ncl));
-//
-// if(ncl>1){
-// // calculate length of the time bin (calibration aware)
-// Int_t irp = 0; Float_t x[2]={0., 0.}; Int_t tb[2] = {0,0};
-// for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
-// if(!fClusters[iTime]) continue;
-// x[irp] = fClusters[iTime]->GetX();
-// tb[irp] = iTime;
-// irp++;
-// if(irp==2) break;
-// }
-// Int_t dtb = tb[1] - tb[0];
-// fdX = dtb ? (x[0] - x[1]) / dtb : 0.15;
-//
-// // update X0 from the clusters (calibration/alignment aware)
-// for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
-// if(!(layer = chamber->GetTB(iTime))) continue;
-// if(!layer->IsT0()) continue;
-// if(fClusters[iTime]){
-// fX0 = fClusters[iTime]->GetX();
-// break;
-// } else { // we have to infere the position of the anode wire from the other clusters
-// for (Int_t jTime = iTime+1; jTime < AliTRDtrackerV1::GetNTimeBins(); jTime++) {
-// if(!fClusters[jTime]) continue;
-// fX0 = fClusters[jTime]->GetX() + fdX * (jTime - iTime);
-// break;
-// }
-// }
-// }
-//
-// // update YZ reference point
-// // TODO
-//
-// // update x reference positions (calibration/alignment aware)
-// // for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
-// // if(!fClusters[iTime]) continue;
-// // fX[iTime] = fX0 - fClusters[iTime]->GetX();
-// // }
-//
-// FitMI();
-// }
-// if(fReconstructor->GetStreamLevel(AliTRDReconstructor::kTracker)>=7) AliInfo(Form("iter = %d nclFit [%d] = %d", iter, fDet, fN2));
-//
-// if(IsOK()){
-// tquality = GetQuality(kZcorr);
-// if(tquality < quality) break;
-// else quality = tquality;
-// }
-// kroadz *= 2.;
-// } // Loop: iter
-// if (!IsOK()) return kFALSE;
-//
-// if(fReconstructor->GetStreamLevel(AliTRDReconstructor::kTracker)>=1) CookLabels();
-//
-// // load calibration params
-// Calibrate();
-// UpdateUsed();
-// return kTRUE;
-// }
-
//____________________________________________________________________
Bool_t AliTRDseedV1::AttachClusters(AliTRDtrackingChamber *chamber, Bool_t tilt)
{
- //
- // Projective algorithm to attach clusters to seeding tracklets
- //
- // Parameters
- //
- // Output
- //
- // Detailed description
- // 1. Collapse x coordinate for the full detector plane
- // 2. truncated mean on y (r-phi) direction
- // 3. purge clusters
- // 4. truncated mean on z direction
- // 5. purge clusters
- // 6. fit tracklet
- //
+//
+// Projective algorithm to attach clusters to seeding tracklets. The following steps are performed :
+// 1. Collapse x coordinate for the full detector plane
+// 2. truncated mean on y (r-phi) direction
+// 3. purge clusters
+// 4. truncated mean on z direction
+// 5. purge clusters
+//
+// Parameters
+// - chamber : pointer to tracking chamber container used to search the tracklet
+// - tilt : switch for tilt correction during road building [default true]
+// Output
+// - true : if tracklet found successfully. Failure can happend because of the following:
+// -
+// Detailed description
+//
+// We start up by defining the track direction in the xy plane and roads. The roads are calculated based
+// on tracking information (variance in the r-phi direction) and estimated variance of the standard
+// clusters (see AliTRDcluster::SetSigmaY2()) corrected for tilt (see GetCovAt()). From this the road is
+// BEGIN_LATEX
+// r_{y} = 3*#sqrt{12*(#sigma^{2}_{Trk}(y) + #frac{#sigma^{2}_{cl}(y) + tg^{2}(#alpha_{L})#sigma^{2}_{cl}(z)}{1+tg^{2}(#alpha_{L})})}
+// r_{z} = 1.5*L_{pad}
+// END_LATEX
+//
+// Author : Alexandru Bercuci <A.Bercuci@gsi.de>
+// Debug : level >3
+
Bool_t kPRINT = kFALSE;
if(!fReconstructor->GetRecoParam() ){
AliError("Seed can not be used without a valid RecoParam.");
}
// Initialize reco params for this tracklet
// 1. first time bin in the drift region
- Int_t t0 = 4;
+ Int_t t0 = 14;
Int_t kClmin = Int_t(fReconstructor->GetRecoParam() ->GetFindableClusters()*AliTRDtrackerV1::GetNTimeBins());
- Double_t syRef = TMath::Sqrt(fRefCov[0]);
+ Double_t s2yTrk= fRefCov[0],
+ s2yCl = 0.,
+ s2zCl = GetPadLength()*GetPadLength()/12.,
+ syRef = TMath::Sqrt(s2yTrk),
+ t2 = GetTilt()*GetTilt();
//define roads
- Double_t kroady = 1.;
- //fReconstructor->GetRecoParam() ->GetRoad1y();
- Double_t kroadz = GetPadLength() * 1.5 + 1.;
+ Double_t kroady = 1., //fReconstructor->GetRecoParam() ->GetRoad1y();
+ kroadz = GetPadLength() * 1.5 + 1.;
+ // define probing cluster (the perfect cluster) and default calibration
+ Short_t sig[] = {0, 0, 10, 30, 10, 0,0};
+ AliTRDcluster cp(fDet, 6, 75, 0, sig, 0);
+ Calibrate();
+
if(kPRINT) printf("AttachClusters() sy[%f] road[%f]\n", syRef, kroady);
// working variables
const Int_t kNrows = 16;
- AliTRDcluster *clst[kNrows][kNclusters];
- Double_t cond[4], dx, dy, yt, zt,
- yres[kNrows][kNclusters];
- Int_t idxs[kNrows][kNclusters], ncl[kNrows], ncls = 0;
+ const Int_t kNcls = 3*kNclusters; // buffer size
+ AliTRDcluster *clst[kNrows][kNcls];
+ Double_t cond[4], dx, dy, yt, zt, yres[kNrows][kNcls];
+ Int_t idxs[kNrows][kNcls], ncl[kNrows], ncls = 0;
memset(ncl, 0, kNrows*sizeof(Int_t));
- memset(clst, 0, kNrows*kNclusters*sizeof(AliTRDcluster*));
+ memset(yres, 0, kNrows*kNcls*sizeof(Double_t));
+ memset(clst, 0, kNrows*kNcls*sizeof(AliTRDcluster*));
// Do cluster projection
AliTRDcluster *c = 0x0;
AliTRDchamberTimeBin *layer = 0x0;
Bool_t kBUFFER = kFALSE;
- for (Int_t it = 0; it < AliTRDtrackerV1::GetNTimeBins(); it++) {
+ for (Int_t it = 0; it < kNtb; it++) {
if(!(layer = chamber->GetTB(it))) continue;
if(!Int_t(*layer)) continue;
-
+ // get track projection at layers position
dx = fX0 - layer->GetX();
yt = fYref[0] - fYref[1] * dx;
zt = fZref[0] - fZref[1] * dx;
- if(kPRINT) printf("\t%2d dx[%f] yt[%f] zt[%f]\n", it, dx, yt, zt);
+ // get standard cluster error corrected for tilt
+ cp.SetLocalTimeBin(it);
+ cp.SetSigmaY2(0.02, fDiffT, fExB, dx, -1./*zt*/, fYref[1]);
+ s2yCl = (cp.GetSigmaY2() + t2*s2zCl)/(1.+t2);
+ // get estimated road
+ kroady = 3.*TMath::Sqrt(12.*(s2yTrk + s2yCl));
+
+ if(kPRINT) printf(" %2d dx[%f] yt[%f] zt[%f] sT[um]=%6.2f sy[um]=%6.2f syTilt[um]=%6.2f yRoad[mm]=%f\n", it, dx, yt, zt, 1.e4*TMath::Sqrt(s2yTrk), 1.e4*TMath::Sqrt(cp.GetSigmaY2()), 1.e4*TMath::Sqrt(s2yCl), 1.e1*kroady);
- // select clusters on a 5 sigmaKalman level
+ // select clusters
cond[0] = yt; cond[2] = kroady;
cond[1] = zt; cond[3] = kroadz;
Int_t n=0, idx[6];
yres[r][ncl[r]] = dy;
ncl[r]++; ncls++;
- if(ncl[r] >= kNclusters) {
- AliWarning(Form("Cluster candidates reached limit %d. Some may be lost.", kNclusters));
+ if(ncl[r] >= kNcls) {
+ AliWarning(Form("Cluster candidates reached buffer limit %d. Some may be lost.", kNcls));
kBUFFER = kTRUE;
break;
}
if(ncl[ir] > 3) AliMathBase::EvaluateUni(ncl[ir], yres[ir], mean, syDis, Int_t(ncl[ir]*.8));
else {
mean = 0.; syDis = 0.;
+ continue;
}
+ if(fReconstructor->GetStreamLevel(AliTRDReconstructor::kTracker) > 3){
+ TTreeSRedirector &cstreamer = *fReconstructor->GetDebugStream(AliTRDReconstructor::kTracker);
+ TVectorD dy(ncl[ir], yres[ir]);
+ UChar_t stat(0);
+ if(IsKink()) SETBIT(stat, 0);
+ if(IsStandAlone()) SETBIT(stat, 1);
+ cstreamer << "AttachClusters"
+ << "stat=" << stat
+ << "det=" << fDet
+ << "pt=" << fPt
+ << "s2y=" << s2yTrk
+ << "dy=" << &dy
+ << "m=" << mean
+ << "s=" << syDis
+ << "\n";
+ }
+
// TODO check mean and sigma agains cluster resolution !!
- if(kPRINT) printf("\tr[%2d] m[%f %5.3fsigma] s[%f]\n", ir, mean, TMath::Abs(mean/syRef), syDis);
+ if(kPRINT) printf("\tr[%2d] m[%f %5.3fsigma] s[%f]\n", ir, mean, TMath::Abs(mean/syDis), syDis);
// select clusters on a 3 sigmaDistr level
Bool_t kFOUND = kFALSE;
for(Int_t ic = ncl[ir]; ic--;){
Calibrate();
// calculate dx for time bins in the drift region (calibration aware)
- Int_t irp = 0; Float_t x[2] = {0.,0.}; Int_t tb[2]={0,0};
- for (Int_t it = t0; it < AliTRDtrackerV1::GetNTimeBins(); it++) {
+ Float_t x[2] = {0.,0.}; Int_t tb[2]={0,0};
+ for (Int_t it = t0, irp=0; irp<2 && it < AliTRDtrackerV1::GetNTimeBins(); it++) {
if(!fClusters[it]) continue;
x[irp] = fClusters[it]->GetX();
- tb[irp] = it;
+ tb[irp] = fClusters[it]->GetLocalTimeBin();
irp++;
- if(irp==2) break;
}
Int_t dtb = tb[1] - tb[0];
fdX = dtb ? (x[0] - x[1]) / dtb : 0.15;
-
return kTRUE;
}
//____________________________________________________________________
-Bool_t AliTRDseedV1::Fit(Bool_t tilt, Int_t errors)
+Bool_t AliTRDseedV1::Fit(Bool_t tilt, Bool_t zcorr)
{
- //
- // Linear fit of the tracklet
- //
- // Parameters :
- //
- // Output :
- // True if successful
- //
- // Detailed description
- // 2. Check if tracklet crosses pad row boundary
- // 1. Calculate residuals in the y (r-phi) direction
- // 3. Do a Least Square Fit to the data
- //
+//
+// Linear fit of the clusters attached to the tracklet
+//
+// Parameters :
+// - tilt : switch for tilt pad correction of cluster y position based on
+// the z, dzdx info from outside [default false].
+// - zcorr : switch for using z information to correct for anisochronity
+// and a finner error parameterization estimation [default false]
+// Output :
+// True if successful
+//
+// Detailed description
+//
+// Fit in the xy plane
+//
+// The fit is performed to estimate the y position of the tracklet and the track
+// angle in the bending plane. The clusters are represented in the chamber coordinate
+// system (with respect to the anode wire - see AliTRDtrackerV1::FollowBackProlongation()
+// on how this is set). The x and y position of the cluster and also their variances
+// are known from clusterizer level (see AliTRDcluster::GetXloc(), AliTRDcluster::GetYloc(),
+// AliTRDcluster::GetSX() and AliTRDcluster::GetSY()).
+// If gaussian approximation is used to calculate y coordinate of the cluster the position
+// is recalculated taking into account the track angle. The general formula to calculate the
+// error of cluster position in the gaussian approximation taking into account diffusion and track
+// inclination is given for TRD by:
+// BEGIN_LATEX
+// #sigma^{2}_{y} = #sigma^{2}_{PRF} + #frac{x#delta_{t}^{2}}{(1+tg(#alpha_{L}))^{2}} + #frac{x^{2}tg^{2}(#phi-#alpha_{L})tg^{2}(#alpha_{L})}{12}
+// END_LATEX
+//
+// Since errors are calculated only in the y directions, radial errors (x direction) are mapped to y
+// by projection i.e.
+// BEGIN_LATEX
+// #sigma_{x|y} = tg(#phi) #sigma_{x}
+// END_LATEX
+// and also by the lorentz angle correction
+//
+// Fit in the xz plane
+//
+// The "fit" is performed to estimate the radial position (x direction) where pad row cross happens.
+// If no pad row crossing the z position is taken from geometry and radial position is taken from the xy
+// fit (see below).
+//
+// There are two methods to estimate the radial position of the pad row cross:
+// 1. leading cluster radial position : Here the lower part of the tracklet is considered and the last
+// cluster registered (at radial x0) on this segment is chosen to mark the pad row crossing. The error
+// of the z estimate is given by :
+// BEGIN_LATEX
+// #sigma_{z} = tg(#theta) #Delta x_{x_{0}}/12
+// END_LATEX
+// The systematic errors for this estimation are generated by the following sources:
+// - no charge sharing between pad rows is considered (sharp cross)
+// - missing cluster at row cross (noise peak-up, under-threshold signal etc.).
+//
+// 2. charge fit over the crossing point : Here the full energy deposit along the tracklet is considered
+// to estimate the position of the crossing by a fit in the qx plane. The errors in the q directions are
+// parameterized as s_q = q^2. The systematic errors for this estimation are generated by the following sources:
+// - no general model for the qx dependence
+// - physical fluctuations of the charge deposit
+// - gain calibration dependence
+//
+// Estimation of the radial position of the tracklet
+//
+// For pad row cross the radial position is taken from the xz fit (see above). Otherwise it is taken as the
+// interpolation point of the tracklet i.e. the point where the error in y of the fit is minimum. The error
+// in the y direction of the tracklet is (see AliTRDseedV1::GetCovAt()):
+// BEGIN_LATEX
+// #sigma_{y} = #sigma^{2}_{y_{0}} + 2xcov(y_{0}, dy/dx) + #sigma^{2}_{dy/dx}
+// END_LATEX
+// and thus the radial position is:
+// BEGIN_LATEX
+// x = - cov(y_{0}, dy/dx)/#sigma^{2}_{dy/dx}
+// END_LATEX
+//
+// Estimation of tracklet position error
+//
+// The error in y direction is the error of the linear fit at the radial position of the tracklet while in the z
+// direction is given by the cluster error or pad row cross error. In case of no pad row cross this is given by:
+// BEGIN_LATEX
+// #sigma_{y} = #sigma^{2}_{y_{0}} - 2cov^{2}(y_{0}, dy/dx)/#sigma^{2}_{dy/dx} + #sigma^{2}_{dy/dx}
+// #sigma_{z} = Pad_{length}/12
+// END_LATEX
+// For pad row cross the full error is calculated at the radial position of the crossing (see above) and the error
+// in z by the width of the crossing region - being a matter of parameterization.
+// BEGIN_LATEX
+// #sigma_{z} = tg(#theta) #Delta x_{x_{0}}/12
+// END_LATEX
+// In case of no tilt correction (default in the barrel tracking) the tilt is taken into account by the rotation of
+// the covariance matrix. See AliTRDseedV1::GetCovAt() for details.
+//
+// Author
+// A.Bercuci <A.Bercuci@gsi.de>
- if(!IsCalibrated()){
- AliWarning("Tracklet fit failed. Call Calibrate().");
- return kFALSE;
- }
+ if(!IsCalibrated()) Calibrate();
const Int_t kClmin = 8;
-
- // cluster error parametrization parameters
- // 1. sy total charge
- const Float_t sq0inv = 0.019962; // [1/q0]
- const Float_t sqb = 1.0281564; //[cm]
- // 2. sy for the PRF
- const Float_t scy[AliTRDgeometry::kNlayer][4] = {
- {2.827e-02, 9.600e-04, 4.296e-01, 2.271e-02},
- {2.952e-02,-2.198e-04, 4.146e-01, 2.339e-02},
- {3.090e-02, 1.514e-03, 4.020e-01, 2.402e-02},
- {3.260e-02,-2.037e-03, 3.946e-01, 2.509e-02},
- {3.439e-02,-3.601e-04, 3.883e-01, 2.623e-02},
- {3.510e-02, 2.066e-03, 3.651e-01, 2.588e-02},
- };
- // 3. sy parallel to the track
- const Float_t sy0 = 2.649e-02; // [cm]
- const Float_t sya = -8.864e-04; // [cm]
- const Float_t syb = -2.435e-01; // [cm]
-
- // 4. sx parallel to the track
- const Float_t sxgc = 5.427e-02;
- const Float_t sxgm = 7.783e-01;
- const Float_t sxgs = 2.743e-01;
- const Float_t sxe0 =-2.065e+00;
- const Float_t sxe1 =-2.978e-02;
-
- // 5. sx perpendicular to the track
-// const Float_t sxd0 = 1.881e-02;
-// const Float_t sxd1 =-4.101e-01;
-// const Float_t sxd2 = 1.572e+00;
-
// get track direction
Double_t y0 = fYref[0];
Double_t dydx = fYref[1];
Double_t dzdx = fZref[1];
Double_t yt, zt;
- // calculation of tg^2(phi - a_L) and tg^2(a_L)
- Double_t tgg = (dydx-fExB)/(1.+dydx*fExB); tgg *= tgg;
- //Double_t exb2= fExB*fExB;
-
//AliTRDtrackerV1::AliTRDLeastSquare fitterZ;
TLinearFitter fitterY(1, "pol1");
- // convertion factor from square to gauss distribution for sigma
- //Double_t convert = 1./TMath::Sqrt(12.);
+ TLinearFitter fitterZ(1, "pol1");
// book cluster information
Double_t qc[kNclusters], xc[kNclusters], yc[kNclusters], zc[kNclusters], sy[kNclusters];
- Int_t ily = AliTRDgeometry::GetLayer(fDet);
Int_t n = 0;
AliTRDcluster *c=0x0, **jc = &fClusters[0];
for (Int_t ic=0; ic<kNtb; ic++, ++jc) {
- //zRow[ic] = -1;
xc[ic] = -1.;
yc[ic] = 999.;
zc[ic] = 999.;
sy[ic] = 0.;
- //sz[ic] = 0.;
if(!(c = (*jc))) continue;
if(!c->IsInChamber()) continue;
if(c->GetNPads()>4) w = .5;
if(c->GetNPads()>5) w = .2;
- //zRow[fN] = c->GetPadRow();
+ // cluster charge
qc[n] = TMath::Abs(c->GetQ());
- // correct cluster position for PRF and v drift
+ // pad row of leading
+
+ // Radial cluster position
//Int_t jc = TMath::Max(fN-3, 0);
//xc[fN] = c->GetXloc(fT0, fVD, &qc[jc], &xc[jc]/*, z0 - c->GetX()*dzdx*/);
- //Double_t s2 = fS2PRF + fDiffL*fDiffL*xc[fN]/(1.+2.*exb2)+tgg*xc[fN]*xc[fN]*exb2/12.;
- //yc[fN] = c->GetYloc(s2, GetPadWidth(), xc[fN], fExB);
-
- // uncalibrated cluster correction
- // TODO remove
- Double_t x, y;
- //GetClusterXY(c, x, y);
- x = c->GetX(); y = c->GetY();
- xc[n] = fX0 - x;
- yc[n] = y;
- zc[n] = c->GetZ();
+ xc[n] = fX0 - c->GetX();
- // extrapolated y value for the track
+ // extrapolated track to cluster position
yt = y0 - xc[n]*dydx;
- // extrapolated z value for the track
zt = z0 - xc[n]*dzdx;
- // tilt correction
- if(tilt) yc[n] -= GetTilt()*(zc[n] - zt);
-
- // ELABORATE CLUSTER ERROR
- // TODO to be moved to AliTRDcluster
- // basic y error (|| to track).
- sy[n] = xc[n] < AliTRDgeometry::CamHght() ? 2. : sy0 + sya*TMath::Exp(1./(xc[n]+syb));
- //printf("cluster[%d]\n\tsy[0] = %5.3e [um]\n", fN, sy[fN]*1.e4);
- // y error due to total charge
- sy[n] += sqb*(1./qc[n] - sq0inv);
- //printf("\tsy[1] = %5.3e [um]\n", sy[fN]*1.e4);
- // y error due to PRF
- sy[n] += scy[ily][0]*TMath::Gaus(c->GetCenter(), scy[ily][1], scy[ily][2]) - scy[ily][3];
- //printf("\tsy[2] = %5.3e [um]\n", sy[fN]*1.e4);
-
- sy[n] *= sy[n];
-
- // ADD ERROR ON x
- // error of drift length parallel to the track
- Double_t sx = sxgc*TMath::Gaus(xc[n], sxgm, sxgs) + TMath::Exp(sxe0+sxe1*xc[n]); // [cm]
- //printf("\tsx[0] = %5.3e [um]\n", sx*1.e4);
- // error of drift length perpendicular to the track
- //sx += sxd0 + sxd1*d + sxd2*d*d;
- sx *= sx; // square sx
-
- // add error from ExB
- if(errors>0) sy[n] += fExB*fExB*sx;
- //printf("\tsy[3] = %5.3e [um^2]\n", sy[fN]*1.e8);
-
- // global radial error due to misalignment/miscalibration
- Double_t sx0 = 0.; sx0 *= sx0;
- // add sx contribution to sy due to track angle
- if(errors>1) sy[n] += tgg*(sx+sx0);
- // TODO we should add tilt pad correction here
- //printf("\tsy[4] = %5.3e [um^2]\n", sy[fN]*1.e8);
- c->SetSigmaY2(sy[n]);
-
- sy[n] = TMath::Sqrt(sy[n]);
- fitterY.AddPoint(&xc[n], yc[n], sy[n]);
+
+ // Recalculate cluster error based on tracking information
+ c->SetSigmaY2(fS2PRF, fDiffT, fExB, xc[n], zcorr?zt:-1., dydx);
+ sy[n] = TMath::Sqrt(c->GetSigmaY2());
+
+ yc[n] = fReconstructor->UseGAUS() ?
+ c->GetYloc(y0, sy[n], GetPadWidth()): c->GetY();
+ zc[n] = c->GetZ();
+ //optional tilt correction
+ if(tilt) yc[n] -= (GetTilt()*(zc[n] - zt));
+
+ fitterY.AddPoint(&xc[n], yc[n], TMath::Sqrt(sy[n]));
+ fitterZ.AddPoint(&xc[n], qc[n], 1.);
n++;
}
// to few clusters
fCov[2] = p[3]; // variance of dydx
// the ref radial position is set at the minimum of
// the y variance of the tracklet
- fX = -fCov[1]/fCov[2]; //fXref = fX0 - fXref;
- fS2Y = fCov[0] +2.*fX*fCov[1] + fX*fX*fCov[2];
+ fX = -fCov[1]/fCov[2];
// fit XZ
- if(IsRowCross()){
- // TODO pad row cross position estimation !!!
- //AliInfo(Form("Padrow cross in detector %d", fDet));
- fZfit[0] = .5*(zc[0]+zc[n-1]); fZfit[1] = 0.;
- fS2Z = 0.02+1.55*fZref[1]; fS2Z *= fS2Z;
+ if(IsRowCross()){
+/* // THE LEADING CLUSTER METHOD
+ Float_t xMin = fX0;
+ Int_t ic=n=kNclusters-1; jc = &fClusters[ic];
+ AliTRDcluster *c0 =0x0, **kc = &fClusters[kNtb-1];
+ for(; ic>kNtb; ic--, --jc, --kc){
+ if((c0 = (*kc)) && c0->IsInChamber() && (xMin>c0->GetX())) xMin = c0->GetX();
+ if(!(c = (*jc))) continue;
+ if(!c->IsInChamber()) continue;
+ zc[kNclusters-1] = c->GetZ();
+ fX = fX0 - c->GetX();
+ }
+ fZfit[0] = .5*(zc[0]+zc[kNclusters-1]); fZfit[1] = 0.;
+ // Error parameterization
+ fS2Z = fdX*fZref[1];
+ fS2Z *= fS2Z; fS2Z *= 0.2887; // 1/sqrt(12)*/
+
+ // THE FIT X-Q PLANE METHOD
+ Int_t ic=n=kNclusters-1; jc = &fClusters[ic];
+ for(; ic>kNtb; ic--, --jc){
+ if(!(c = (*jc))) continue;
+ if(!c->IsInChamber()) continue;
+ qc[n] = TMath::Abs(c->GetQ());
+ xc[n] = fX0 - c->GetX();
+ zc[n] = c->GetZ();
+ fitterZ.AddPoint(&xc[n], -qc[n], 1.);
+ n--;
+ }
+ // fit XZ
+ fitterZ.Eval();
+ if(fitterZ.GetParameter(1)!=0.){
+ fX = -fitterZ.GetParameter(0)/fitterZ.GetParameter(1);
+ fX=(fX<0.)?0.:fX;
+ Float_t dl = .5*AliTRDgeometry::CamHght()+AliTRDgeometry::CdrHght();
+ fX=(fX> dl)?dl:fX;
+ fX-=.055; // TODO to be understood
+ }
+
+ fZfit[0] = .5*(zc[0]+zc[kNclusters-1]); fZfit[1] = 0.;
+ // temporary external error parameterization
+ fS2Z = 0.05+0.4*TMath::Abs(fZref[1]); fS2Z *= fS2Z;
+ // TODO correct formula
+ //fS2Z = sigma_x*TMath::Abs(fZref[1]);
} else {
fZfit[0] = zc[0]; fZfit[1] = 0.;
fS2Z = GetPadLength()*GetPadLength()/12.;
}
-
-
-// // determine z offset of the fit
-// Float_t zslope = 0.;
-// Int_t nchanges = 0, nCross = 0;
-// if(nz==2){ // tracklet is crossing pad row
-// // Find the break time allowing one chage on pad-rows
-// // with maximal number of accepted clusters
-// Int_t padRef = zRow[0];
-// for (Int_t ic=1; ic<fN; ic++) {
-// if(zRow[ic] == padRef) continue;
-//
-// // debug
-// if(zRow[ic-1] == zRow[ic]){
-// printf("ERROR in pad row change!!!\n");
-// }
-//
-// // evaluate parameters of the crossing point
-// Float_t sx = (xc[ic-1] - xc[ic])*convert;
-// fCross[0] = .5 * (xc[ic-1] + xc[ic]);
-// fCross[2] = .5 * (zc[ic-1] + zc[ic]);
-// fCross[3] = TMath::Max(dzdx * sx, .01);
-// zslope = zc[ic-1] > zc[ic] ? 1. : -1.;
-// padRef = zRow[ic];
-// nCross = ic;
-// nchanges++;
-// }
-// }
-//
-// // condition on nCross and reset nchanges TODO
-//
-// if(nchanges==1){
-// if(dzdx * zslope < 0.){
-// AliInfo("Tracklet-Track mismatch in dzdx. TODO.");
-// }
-//
-//
-// //zc[nc] = fitterZ.GetFunctionParameter(0);
-// fCross[1] = fYfit[0] - fCross[0] * fYfit[1];
-// fCross[0] = fX0 - fCross[0];
-// }
-
+ fS2Y = fCov[0] +2.*fX*fCov[1] + fX*fX*fCov[2];
return kTRUE;
}
// Printing the seedstatus
//
- AliInfo(Form("Det[%3d] X0[%7.2f] Pad[L[%5.2f] W[%5.2f] Tilt[%+6.2f]]", fDet, fX0, GetPadLength(), GetPadWidth(), GetTilt()));
+ AliInfo(Form("Det[%3d] X0[%7.2f] Pad{L[%5.2f] W[%5.2f] Tilt[%+6.2f]}", fDet, fX0, GetPadLength(), GetPadWidth(), GetTilt()));
AliInfo(Form("N[%2d] Nused[%2d] Nshared[%2d] [%d]", GetN(), GetNUsed(), GetNShared(), fN));
+ AliInfo(Form("FLAGS : RC[%c] Kink[%c] SA[%c]", IsRowCross()?'y':'n', IsKink()?'y':'n', IsStandAlone()?'y':'n'));
Double_t cov[3], x=GetX();
GetCovAt(x, cov);
AliInfo(" | x[cm] | y[cm] | z[cm] | dydx | dzdx |");
AliInfo(Form("Fit | %7.2f | %7.2f+-%7.2f | %7.2f+-%7.2f| %5.2f | ----- |", x, GetY(), TMath::Sqrt(cov[0]), GetZ(), TMath::Sqrt(cov[2]), fYfit[1]));
- AliInfo(Form("Ref | %7.2f | %7.2f+-%7.2f | %7.2f+-%7.2f| %5.2f | %5.2f |", x, fYref[0]-fX*fYref[1], TMath::Sqrt(fRefCov[2]), fZref[0]-fX*fYref[1], TMath::Sqrt(fRefCov[2]), fYref[1], fZref[1]))
+ AliInfo(Form("Ref | %7.2f | %7.2f+-%7.2f | %7.2f+-%7.2f| %5.2f | %5.2f |", x, fYref[0]-fX*fYref[1], TMath::Sqrt(fRefCov[0]), fZref[0]-fX*fYref[1], TMath::Sqrt(fRefCov[2]), fYref[1], fZref[1]))
if(strcmp(o, "a")!=0) return;
}
return kTRUE;
}
+
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff