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Some fixes of the coding conventions.
[u/mrichter/AliRoot.git] / HMPID / AliHMPIDRecon.cxx
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d3da6dc4 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
16//////////////////////////////////////////////////////////////////////////
17// //
18// AliHMPIDRecon //
19// //
20// HMPID class to perfom pattern recognition based on Hough transfrom //
21// for single chamber //
22//////////////////////////////////////////////////////////////////////////
23
a591e55f 24#include "AliHMPIDRecon.h" //class header
25#include "AliHMPIDParam.h" //CkovAngle()
d3da6dc4 26#include "AliHMPIDCluster.h" //CkovAngle()
43400d2d 27#include <TMinuit.h> //FitEllipse()
a591e55f 28#include <TRotation.h> //TracePhot()
29#include <TH1D.h> //HoughResponse()
30#include <TClonesArray.h> //CkovAngle()
31#include <AliESDtrack.h> //CkovAngle()
d3da6dc4 32
33const Double_t AliHMPIDRecon::fgkRadThick=1.5;
34const Double_t AliHMPIDRecon::fgkWinThick=0.5;
35const Double_t AliHMPIDRecon::fgkGapThick=8.0;
d3da6dc4 36const Double_t AliHMPIDRecon::fgkWinIdx =1.5787;
37const Double_t AliHMPIDRecon::fgkGapIdx =1.0005;
38
d3da6dc4 39//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
40AliHMPIDRecon::AliHMPIDRecon():TTask("RichRec","RichPat"),
abb5f786 41 fRadNmean(1.292),
d3da6dc4 42 fPhotCnt(-1),
43 fCkovSigma2(0),
44 fIsWEIGHT(kFALSE),
45 fDTheta(0.001),
46 fWindowWidth(0.045),
47 fTrkDir(TVector3(0,0,1)),fTrkPos(TVector2(30,40))
48{
49// main ctor
50 for (Int_t i=0; i<3000; i++) {
51 fPhotFlag[i] = 0;
52 fPhotCkov[i] = -1;
53 fPhotPhi [i] = -1;
54 fPhotWei [i] = 0;
55 }
611e810d 56//hidden algorithm
57 fMipX=fMipY=fThTrkFit=fPhTrkFit=fCkovFit=-999;
58 fIdxMip=fNClu=0;
59 for (Int_t i=0; i<1000; i++) {
60 fXClu[i] = fYClu[i] = 0;
61 }
d3da6dc4 62}
63//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
a591e55f 64void AliHMPIDRecon::CkovAngle(AliESDtrack *pTrk,TClonesArray *pCluLst,Double_t nmean)
d3da6dc4 65{
66// Pattern recognition method based on Hough transform
59280a5a 67// Arguments: pTrk - track for which Ckov angle is to be found
68// pCluLst - list of clusters for this chamber
69// Returns: - track ckov angle, [rad],
a591e55f 70
71 AliHMPIDParam *pParam=AliHMPIDParam::Instance();
d3da6dc4 72
a591e55f 73 if(pCluLst->GetEntries()>pParam->MultCut()) fIsWEIGHT = kTRUE; // offset to take into account bkg in reconstruction
74 else fIsWEIGHT = kFALSE;
d3da6dc4 75
611e810d 76 Float_t xRa,yRa,th,ph;
a591e55f 77 pTrk->GetHMPIDtrk(xRa,yRa,th,ph); //initialize this track: th and ph angles at middle of RAD
a591e55f 78 SetTrack(xRa,yRa,th,ph);
611e810d 79
abb5f786 80 fRadNmean=nmean;
d3da6dc4 81
59280a5a 82 Float_t dMin=999,mipX=-1,mipY=-1;Int_t chId=-1,mipId=-1,mipQ=-1;
d3da6dc4 83 fPhotCnt=0;
84 for (Int_t iClu=0; iClu<pCluLst->GetEntriesFast();iClu++){//clusters loop
85 AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(iClu); //get pointer to current cluster
59280a5a 86 chId=pClu->Ch();
a591e55f 87 if(pClu->Q()>pParam->QCut()){ //charge compartible with MIP clusters
88 Float_t dX=fPc.X()-pClu->X(),dY=fPc.Y()-pClu->Y(),d =TMath::Sqrt(dX*dX+dY*dY); //distance between current cluster and intersection point
89 if( d < dMin) {mipId=iClu; dMin=d;mipX=pClu->X();mipY=pClu->Y();mipQ=(Int_t)pClu->Q();} //current cluster is closer, overwrite data for min cluster
90 }else{ //charge compatible with photon cluster
91 Double_t thetaCer,phiCer;
92 if(FindPhotCkov(pClu->X(),pClu->Y(),thetaCer,phiCer)){ //find ckov angle for this photon candidate
93 fPhotCkov[fPhotCnt]=thetaCer; //actual theta Cerenkov (in TRS)
b4ad85e9 94 fPhotPhi [fPhotCnt]=phiCer; //actual phi Cerenkov (in TRS): -pi to come back to "unusual" ref system (X,Y,-Z)
a591e55f 95 fPhotCnt++; //increment counter of photon candidates
96 }
59280a5a 97 }
d3da6dc4 98 }//clusters loop
a591e55f 99 Int_t iNacc=FlagPhot(HoughResponse()); //flag photons according to individual theta ckov with respect to most probable
100 pTrk->SetHMPIDmip(mipX,mipY,mipQ,iNacc); //store mip info
59280a5a 101
a591e55f 102 if(mipId==-1) {pTrk->SetHMPIDsignal(kMipQdcCut); return;} //no clusters with QDC more the threshold at all
103 if(dMin>pParam->DistCut()) {pTrk->SetHMPIDsignal(kMipDistCut); return;} //closest cluster with enough charge is still too far from intersection
104 pTrk->SetHMPIDcluIdx(chId,mipId); //set index of cluster
105 if(iNacc<1) pTrk->SetHMPIDsignal(kNoPhotAccept); //no photon candidates is accepted
106 else pTrk->SetHMPIDsignal(FindRingCkov(pCluLst->GetEntries())); //find best Theta ckov for ring i.e. track
611e810d 107
a591e55f 108 pTrk->SetHMPIDchi2(fCkovSigma2); //errors squared
d3da6dc4 109
43400d2d 110}//CkovAngle()
d3da6dc4 111//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
a591e55f 112Bool_t AliHMPIDRecon::FindPhotCkov(Double_t cluX,Double_t cluY,Double_t &thetaCer,Double_t &phiCer)
d3da6dc4 113{
114// Finds Cerenkov angle for this photon candidate
115// Arguments: cluX,cluY - position of cadidate's cluster
a591e55f 116// Returns: Cerenkov angle
d3da6dc4 117
a591e55f 118 TVector3 dirCkov;
119
67a1c24c 120 Double_t zRad= -0.5*fgkRadThick-0.5*fgkWinThick; //z position of middle of RAD
121 TVector3 rad(fTrkPos.X(),fTrkPos.Y(),zRad); //impact point at middle of RAD
122 TVector3 pc(cluX,cluY,0.5*fgkWinThick+fgkGapIdx); //mip at PC
a591e55f 123 Double_t cluR = TMath::Sqrt((cluX-fTrkPos.X())*(cluX-fTrkPos.X())+
124 (cluY-fTrkPos.Y())*(cluY-fTrkPos.Y()));//ref. distance impact RAD-CLUSTER
67a1c24c 125 Double_t phi=(pc-rad).Phi(); //phi of photon
a591e55f 126
b4ad85e9 127 Double_t ckov1=0;
67a1c24c 128 Double_t ckov2=0.75+fTrkDir.Theta(); //start to find theta cerenkov in DRS
b4ad85e9 129 const Double_t kTol=0.01;
d3da6dc4 130 Int_t iIterCnt = 0;
131 while(1){
a591e55f 132 if(iIterCnt>=50) return kFALSE;
d3da6dc4 133 Double_t ckov=0.5*(ckov1+ckov2);
67a1c24c 134 dirCkov.SetMagThetaPhi(1,ckov,phi);
a591e55f 135 TVector2 posC=TraceForward(dirCkov); //trace photon with actual angles
136 Double_t dist=cluR-(posC-fTrkPos).Mod(); //get distance between trial point and cluster position
137 if(posC.X()==-999) dist = - 999; //total reflection problem
138 iIterCnt++; //counter step
b4ad85e9 139 if (dist> kTol) ckov1=ckov; //cluster @ larger ckov
d3da6dc4 140 else if(dist<-kTol) ckov2=ckov; //cluster @ smaller ckov
a591e55f 141 else{ //precision achived: ckov in DRS found
142 dirCkov.SetMagThetaPhi(1,ckov,phi); //
143 RecPhot(dirCkov,thetaCer,phiCer); //find ckov (in TRS:the effective Cherenkov angle!)
144 return kTRUE;
145 }
d3da6dc4 146 }
147}//FindPhotTheta()
148//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
a591e55f 149TVector2 AliHMPIDRecon::TraceForward(TVector3 dirCkov)const
d3da6dc4 150{
a591e55f 151 //Trace forward a photon from (x,y) up to PC
152 // Arguments: dirCkov photon vector in LORS
153 // Returns: pos of traced photon at PC
154 TVector2 pos(-999,-999);
67a1c24c 155 Double_t thetaCer = dirCkov.Theta();
156 if(thetaCer > TMath::ASin(1./fRadNmean)) return pos; //total refraction on WIN-GAP boundary
157 Double_t zRad= -0.5*fgkRadThick-0.5*fgkWinThick; //z position of middle of RAD
158 TVector3 posCkov(fTrkPos.X(),fTrkPos.Y(),zRad); //RAD: photon position is track position @ middle of RAD
159 Propagate(dirCkov,posCkov, -0.5*fgkWinThick); //go to RAD-WIN boundary
160 Refract (dirCkov, fRadNmean,fgkWinIdx); //RAD-WIN refraction
161 Propagate(dirCkov,posCkov, 0.5*fgkWinThick); //go to WIN-GAP boundary
162 Refract (dirCkov, fgkWinIdx,fgkGapIdx); //WIN-GAP refraction
163 Propagate(dirCkov,posCkov,0.5*fgkWinThick+fgkGapThick); //go to PC
a591e55f 164 pos.Set(posCkov.X(),posCkov.Y());
165 return pos;
166}//TraceForward()
167//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
168void AliHMPIDRecon::RecPhot(TVector3 dirCkov,Double_t &thetaCer,Double_t &phiCer)
169{
170 //Theta Cerenkov reconstruction
171 // Arguments: (x,y) of initial point in LORS, dirCkov photon vector in LORS
172 // Returns: thetaCer theta cerenkov reconstructed
173// TVector3 dirTrk;
174// dirTrk.SetMagThetaPhi(1,fTrkDir.Theta(),fTrkDir.Phi());
175// Double_t thetaCer = TMath::ACos(dirCkov*dirTrk);
176 TRotation mtheta; mtheta.RotateY(- fTrkDir.Theta());
177 TRotation mphi; mphi.RotateZ(- fTrkDir.Phi());
178 TRotation mrot=mtheta*mphi;
179 TVector3 dirCkovTRS;
180 dirCkovTRS=mrot*dirCkov;
181 phiCer = dirCkovTRS.Phi(); //actual value of the phi of the photon
182 thetaCer= dirCkovTRS.Theta(); //actual value of thetaCerenkov of the photon
d3da6dc4 183}
184//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
185Double_t AliHMPIDRecon::FindRingArea(Double_t ckovAng)const
186{
187// Find area inside the cerenkov ring which lays inside PCs
a591e55f 188// Arguments: ckovAng - cerenkov angle
d3da6dc4 189// Returns: area of the ring in cm^2 for given theta ckov
190
d3da6dc4 191 const Int_t kN=100;
192 Double_t area=0;
193 for(Int_t i=0;i<kN;i++){
a591e55f 194 TVector2 pos1=TracePhot(ckovAng,Double_t(TMath::TwoPi()*i /kN));//trace this photon
195 TVector2 pos2=TracePhot(ckovAng,Double_t(TMath::TwoPi()*(i+1)/kN));//trace the next photon
196 area+=(pos1-fTrkPos)*(pos2-fTrkPos); //add area of the triangle...
d3da6dc4 197 }
198 return area;
199}//FindRingArea()
200//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
201Double_t AliHMPIDRecon::FindRingCkov(Int_t)
202{
203// Loops on all Ckov candidates and estimates the best Theta Ckov for a ring formed by those candidates. Also estimates an error for that Theat Ckov
204// collecting errors for all single Ckov candidates thetas. (Assuming they are independent)
205// Arguments: iNclus- total number of clusters in chamber for background estimation
206// Return: best estimation of track Theta ckov
207
208 Double_t wei = 0.;
209 Double_t weightThetaCerenkov = 0.;
210
211 Double_t ckovMin=9999.,ckovMax=0.;
212 Double_t sigma2 = 0; //to collect error squared for this ring
213
214 for(Int_t i=0;i<fPhotCnt;i++){//candidates loop
215 if(fPhotFlag[i] == 2){
a591e55f 216 if(fPhotCkov[i]<ckovMin) ckovMin=fPhotCkov[i]; //find max and min Theta ckov from all candidates within probable window
d3da6dc4 217 if(fPhotCkov[i]>ckovMax) ckovMax=fPhotCkov[i];
a591e55f 218 weightThetaCerenkov += fPhotCkov[i]*fPhotWei[i];
219 wei += fPhotWei[i]; //collect weight as sum of all candidate weghts
d3da6dc4 220
d3da6dc4 221 sigma2 += 1./Sigma2(fPhotCkov[i],fPhotPhi[i]);
222 }
223 }//candidates loop
224
225 if(sigma2>0) fCkovSigma2=1./sigma2;
226 else fCkovSigma2=1e10;
227
b4ad85e9 228 if(wei != 0.) weightThetaCerenkov /= wei; else weightThetaCerenkov = 0.;
d3da6dc4 229 return weightThetaCerenkov;
230}//FindCkovRing()
231//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
232Int_t AliHMPIDRecon::FlagPhot(Double_t ckov)
233{
234// Flag photon candidates if their individual ckov angle is inside the window around ckov angle returned by HoughResponse()
235// Arguments: ckov- value of most probable ckov angle for track as returned by HoughResponse()
236// Returns: number of photon candidates happened to be inside the window
237
a591e55f 238// Photon Flag: Flag = 0 initial set;
239// Flag = 1 good candidate (charge compatible with photon);
240// Flag = 2 photon used for the ring;
d3da6dc4 241
242 Int_t steps = (Int_t)((ckov )/ fDTheta); //how many times we need to have fDTheta to fill the distance between 0 and thetaCkovHough
243
244 Double_t tmin = (Double_t)(steps - 1)*fDTheta;
245 Double_t tmax = (Double_t)(steps)*fDTheta;
246 Double_t tavg = 0.5*(tmin+tmax);
247
248 tmin = tavg - 0.5*fWindowWidth; tmax = tavg + 0.5*fWindowWidth;
249
250 Int_t iInsideCnt = 0; //count photons which Theta ckov inside the window
251 for(Int_t i=0;i<fPhotCnt;i++){//photon candidates loop
252 if(fPhotCkov[i] >= tmin && fPhotCkov[i] <= tmax) {
253 fPhotFlag[i]=2;
254 iInsideCnt++;
255 }
256 }
257 return iInsideCnt;
258}//FlagPhot()
259//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
a591e55f 260TVector2 AliHMPIDRecon::TracePhot(Double_t ckovThe,Double_t ckovPhi)const
d3da6dc4 261{
262// Trace a single Ckov photon from emission point somewhere in radiator up to photocathode taking into account ref indexes of materials it travereses
a591e55f 263// Arguments: ckovThe,ckovPhi- photon ckov angles in DRS, [rad]
d3da6dc4 264// Returns: distance between photon point on PC and track projection
265 TRotation mtheta; mtheta.RotateY(fTrkDir.Theta());
266 TRotation mphi; mphi.RotateZ(fTrkDir.Phi());
267 TRotation mrot=mphi*mtheta;
a591e55f 268 TVector3 dirCkov,dirCkovTors;
269
270 dirCkovTors.SetMagThetaPhi(1,ckovThe,ckovPhi); //initially photon is directed according to requested ckov angle
271 dirCkov=mrot*dirCkovTors; //now we know photon direction in LORS
272 return TraceForward(dirCkov);
273}//TracePhot()
d3da6dc4 274//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
a591e55f 275void AliHMPIDRecon::Propagate(const TVector3 dir,TVector3 &pos,Double_t z)const
d3da6dc4 276{
277// Finds an intersection point between a line and XY plane shifted along Z.
278// Arguments: dir,pos - vector along the line and any point of the line
279// z - z coordinate of plain
280// Returns: none
281// On exit: pos is the position if this intesection if any
282 static TVector3 nrm(0,0,1);
283 TVector3 pnt(0,0,z);
284
285 TVector3 diff=pnt-pos;
286 Double_t sint=(nrm*diff)/(nrm*dir);
287 pos+=sint*dir;
288}//Propagate()
289//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
290void AliHMPIDRecon::Refract(TVector3 &dir,Double_t n1,Double_t n2)const
291{
292// Refract direction vector according to Snell law
293// Arguments:
294// n1 - ref idx of first substance
295// n2 - ref idx of second substance
296// Returns: none
297// On exit: dir is new direction
67a1c24c 298 Double_t sinref=(n1/n2)*TMath::Sin(dir.Theta());
d3da6dc4 299 if(sinref>1.) dir.SetXYZ(-999,-999,-999);
67a1c24c 300 else dir.SetTheta(TMath::ASin(sinref));
d3da6dc4 301}//Refract()
302//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
303Double_t AliHMPIDRecon::HoughResponse()
304{
305//
611e810d 306// fIdxMip = mipId;
307
d3da6dc4 308//
309 Double_t kThetaMax=0.75;
310 Int_t nChannels = (Int_t)(kThetaMax/fDTheta+0.5);
311 TH1D *phots = new TH1D("Rphot" ,"phots" ,nChannels,0,kThetaMax);
312 TH1D *photsw = new TH1D("RphotWeighted" ,"photsw" ,nChannels,0,kThetaMax);
313 TH1D *resultw = new TH1D("resultw","resultw" ,nChannels,0,kThetaMax);
314 Int_t nBin = (Int_t)(kThetaMax/fDTheta);
315 Int_t nCorrBand = (Int_t)(fWindowWidth/(2*fDTheta));
316
317 for (Int_t i=0; i< fPhotCnt; i++){//photon cadidates loop
318 Double_t angle = fPhotCkov[i]; if(angle<0||angle>kThetaMax) continue;
319 phots->Fill(angle);
320 Int_t bin = (Int_t)(0.5+angle/(fDTheta));
321 Double_t weight=1.;
322 if(fIsWEIGHT){
323 Double_t lowerlimit = ((Double_t)bin)*fDTheta - 0.5*fDTheta; Double_t upperlimit = ((Double_t)bin)*fDTheta + 0.5*fDTheta;
324 Double_t diffArea = FindRingArea(upperlimit)-FindRingArea(lowerlimit);
325 if(diffArea>0) weight = 1./diffArea;
326 }
327 photsw->Fill(angle,weight);
328 fPhotWei[i]=weight;
329 }//photon candidates loop
330
331 for (Int_t i=1; i<=nBin;i++){
332 Int_t bin1= i-nCorrBand;
333 Int_t bin2= i+nCorrBand;
334 if(bin1<1) bin1=1;
335 if(bin2>nBin)bin2=nBin;
336 Double_t sumPhots=phots->Integral(bin1,bin2);
337 if(sumPhots<3) continue; // if less then 3 photons don't trust to this ring
338 Double_t sumPhotsw=photsw->Integral(bin1,bin2);
339 resultw->Fill((Double_t)((i+0.5)*fDTheta),sumPhotsw);
340 }
341// evaluate the "BEST" theta ckov as the maximum value of histogramm
342 Double_t *pVec = resultw->GetArray();
343 Int_t locMax = TMath::LocMax(nBin,pVec);
344 phots->Delete();photsw->Delete();resultw->Delete(); // Reset and delete objects
345
346 return (Double_t)(locMax*fDTheta+0.5*fDTheta); //final most probable track theta ckov
347}//HoughResponse()
348//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
349Double_t AliHMPIDRecon::Sigma2(Double_t ckovTh, Double_t ckovPh)const
350{
351// Analithical calculation of total error (as a sum of localization, geometrical and chromatic errors) on Cerenkov angle for a given Cerenkov photon
352// created by a given MIP. Fromulae according to CERN-EP-2000-058
353// Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
354// dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
355// MIP beta
356// Returns: absolute error on Cerenkov angle, [radians]
357
358 TVector3 v(-999,-999,-999);
abb5f786 359 Double_t trkBeta = 1./(TMath::Cos(ckovTh)*fRadNmean);
d3da6dc4 360
361 v.SetX(SigLoc (ckovTh,ckovPh,trkBeta));
362 v.SetY(SigGeom(ckovTh,ckovPh,trkBeta));
363 v.SetZ(SigCrom(ckovTh,ckovPh,trkBeta));
364
365 return v.Mag2();
366}
367//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
368Double_t AliHMPIDRecon::SigLoc(Double_t thetaC, Double_t phiC,Double_t betaM)const
369{
370// Analithical calculation of localization error (due to finite segmentation of PC) on Cerenkov angle for a given Cerenkov photon
371// created by a given MIP. Fromulae according to CERN-EP-2000-058
372// Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
373// dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
374// MIP beta
375// Returns: absolute error on Cerenkov angle, [radians]
376 Double_t phiDelta = phiC - fTrkDir.Phi();
377
378 Double_t alpha =TMath::Cos(fTrkDir.Theta())-TMath::Tan(thetaC)*TMath::Cos(phiDelta)*TMath::Sin(fTrkDir.Theta());
abb5f786 379 Double_t k = 1.-fRadNmean*fRadNmean+alpha*alpha/(betaM*betaM);
d3da6dc4 380 if (k<0) return 1e10;
381
382 Double_t mu =TMath::Sin(fTrkDir.Theta())*TMath::Sin(fTrkDir.Phi())+TMath::Tan(thetaC)*(TMath::Cos(fTrkDir.Theta())*TMath::Cos(phiDelta)*TMath::Sin(fTrkDir.Phi())+TMath::Sin(phiDelta)*TMath::Cos(fTrkDir.Phi()));
383 Double_t e =TMath::Sin(fTrkDir.Theta())*TMath::Cos(fTrkDir.Phi())+TMath::Tan(thetaC)*(TMath::Cos(fTrkDir.Theta())*TMath::Cos(phiDelta)*TMath::Cos(fTrkDir.Phi())-TMath::Sin(phiDelta)*TMath::Sin(fTrkDir.Phi()));
384
385 Double_t kk = betaM*TMath::Sqrt(k)/(8*alpha);
386 Double_t dtdxc = kk*(k*(TMath::Cos(phiDelta)*TMath::Cos(fTrkDir.Phi())-TMath::Cos(fTrkDir.Theta())*TMath::Sin(phiDelta)*TMath::Sin(fTrkDir.Phi()))-(alpha*mu/(betaM*betaM))*TMath::Sin(fTrkDir.Theta())*TMath::Sin(phiDelta));
387 Double_t dtdyc = kk*(k*(TMath::Cos(phiDelta)*TMath::Sin(fTrkDir.Phi())+TMath::Cos(fTrkDir.Theta())*TMath::Sin(phiDelta)*TMath::Cos(fTrkDir.Phi()))+(alpha* e/(betaM*betaM))*TMath::Sin(fTrkDir.Theta())*TMath::Sin(phiDelta));
388
389 return TMath::Sqrt(0.2*0.2*dtdxc*dtdxc + 0.25*0.25*dtdyc*dtdyc);
390}
391//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
392Double_t AliHMPIDRecon::SigCrom(Double_t thetaC, Double_t phiC,Double_t betaM)const
393{
394// Analithical calculation of chromatic error (due to lack of knowledge of Cerenkov photon energy) on Cerenkov angle for a given Cerenkov photon
395// created by a given MIP. Fromulae according to CERN-EP-2000-058
396// Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
397// dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
398// MIP beta
399// Returns: absolute error on Cerenkov angle, [radians]
400 Double_t phiDelta = phiC - fTrkDir.Phi();
401 Double_t alpha =TMath::Cos(fTrkDir.Theta())-TMath::Tan(thetaC)*TMath::Cos(phiDelta)*TMath::Sin(fTrkDir.Theta());
402
abb5f786 403 Double_t dtdn = TMath::Cos(fTrkDir.Theta())*fRadNmean*betaM*betaM/(alpha*TMath::Tan(thetaC));
d3da6dc4 404
405 Double_t f = 0.00928*(7.75-5.635)/TMath::Sqrt(12.);
406
407 return f*dtdn;
408}//SigCrom()
409//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
410Double_t AliHMPIDRecon::SigGeom(Double_t thetaC, Double_t phiC,Double_t betaM)const
411{
412// Analithical calculation of geometric error (due to lack of knowledge of creation point in radiator) on Cerenkov angle for a given Cerenkov photon
413// created by a given MIP. Formulae according to CERN-EP-2000-058
414// Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
415// dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
416// MIP beta
417// Returns: absolute error on Cerenkov angle, [radians]
418
419 Double_t phiDelta = phiC - fTrkDir.Phi();
420 Double_t alpha =TMath::Cos(fTrkDir.Theta())-TMath::Tan(thetaC)*TMath::Cos(phiDelta)*TMath::Sin(fTrkDir.Theta());
421
abb5f786 422 Double_t k = 1.-fRadNmean*fRadNmean+alpha*alpha/(betaM*betaM);
d3da6dc4 423 if (k<0) return 1e10;
424
425 Double_t eTr = 0.5*1.5*betaM*TMath::Sqrt(k)/(8*alpha);
426 Double_t lambda = 1.-TMath::Sin(fTrkDir.Theta())*TMath::Sin(fTrkDir.Theta())*TMath::Sin(phiC)*TMath::Sin(phiC);
427
428 Double_t c = 1./(1.+ eTr*k/(alpha*alpha*TMath::Cos(thetaC)*TMath::Cos(thetaC)));
429 Double_t i = betaM*TMath::Tan(thetaC)*lambda*TMath::Power(k,1.5);
430 Double_t ii = 1.+eTr*betaM*i;
431
432 Double_t err = c * (i/(alpha*alpha*8) + ii*(1.-lambda) / ( alpha*alpha*8*betaM*(1.+eTr)) );
433 Double_t trErr = 1.5/(TMath::Sqrt(12.)*TMath::Cos(fTrkDir.Theta()));
434
435 return trErr*err;
436}//SigGeom()
437//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
43400d2d 438//
611e810d 439// From here HTA....
43400d2d 440//
441//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
611e810d 442Int_t AliHMPIDRecon::CkovHiddenTrk(AliESDtrack *pTrk,TClonesArray *pCluLst,Double_t nmean)
43400d2d 443{
611e810d 444// Pattern recognition method without any infos from tracking:HTA (Hidden Track Algorithm)...
43400d2d 445// The method finds in the chmber the cluster with the highest charge
446// compatibile with a MIP, then the strategy is applied
611e810d 447// Arguments: pTrk - pointer to ESD track
448// pCluLs - list of clusters for a given chamber
449// nmean - mean freon ref. index
450// Returns: - 0=ok,1=not fitted
451
452 AliHMPIDParam *pParam=AliHMPIDParam::Instance();
43400d2d 453
454 fRadNmean=nmean;
455
456 Float_t mipX=-1,mipY=-1;Int_t mipId=-1,mipQ=-1;
457 fPhotCnt=0;
458 Double_t qRef = 0;
459 fNClu = pCluLst->GetEntriesFast();
460 for (Int_t iClu=0;iClu<fNClu;iClu++){ //clusters loop
461 AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(iClu); //get pointer to current cluster
462 fXClu[iClu] = pClu->X();fYClu[iClu] = pClu->Y(); //store x,y for fitting procedure
463 if(pClu->Q()>qRef){ //searching the highest charge to select a MIP
464 qRef = pClu->Q();
465 mipId=iClu; mipX=pClu->X();mipY=pClu->Y();mipQ=(Int_t)pClu->Q();
466 }
467 }//clusters loop
43400d2d 468
611e810d 469 if(qRef>pParam->QCut()){ //charge compartible with MIP clusters
470 fIdxMip = mipId;
471 fMipX = mipX; fMipY=mipY; fMipQ = qRef;
472 if(!DoRecHiddenTrk()) return 1; //Do track and ring reconstruction,if problems returns 1
473 pTrk->SetHMPIDtrk(fRadX,fRadY,fThTrkFit,fPhTrkFit); //store track intersection info
474 pTrk->SetHMPIDmip(fMipX,fMipY,(Int_t)fMipQ,fNClu); //store mip info
475 pTrk->SetHMPIDcluIdx(pCluLst->GetUniqueID(),fIdxMip); //set cham number and index of cluster
476 pTrk->SetHMPIDsignal(fCkovFit); //find best Theta ckov for ring i.e. track
477 }
478 return 0;
43400d2d 479}//CkovHiddenTrk()
480//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
611e810d 481Bool_t AliHMPIDRecon::DoRecHiddenTrk()
43400d2d 482{
483// Pattern recognition method without any infos from tracking...
611e810d 484// First a preclustering filter to avoid part of the noise
43400d2d 485// Then only ellipsed-rings are fitted (no possibility,
611e810d 486// for the moment, to reconstruct very inclined tracks)
487// Finally a fitting with (th,ph) free, starting by very close values
43400d2d 488// previously evaluated.
489// Arguments: none
490// Returns: none
491 Double_t phiRec;
492 CluPreFilter();
611e810d 493 if(!FitEllipse(phiRec)) {return kFALSE;}
43400d2d 494 return FitFree(phiRec);
495}
496//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
497void AliHMPIDRecon::CluPreFilter()
498{
499// Filter of bkg clusters
500// based on elliptical-shapes...
501//
502 ;
503}
504//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
505Bool_t AliHMPIDRecon::FitEllipse(Double_t &phiRec)
506{
507//Fit a set of clusters with an analitical conical section function:
508 //
509 // Ax^2 + B*y^2 + 2Hxy + 2Gx + 2Fy + 1 = 0 ---> conical section
510 //
511 // H*H - A*B > 0 hyperbola
512 // < 0 ellipse
513 // = 0 parabola
514 //
515 // tan 2alfa = 2H/(A-B) alfa=angle of rotation
516 //
517 // coordinate of the centre of the conical section:
518 // x = x' + a
519 // y = y' + b
520 //
521 // HF - BG
522 // a = ---------
523 // AB - H^2
524 //
525 // HG - AF
526 // b = --------
527 // AB - H^2
528
529 Double_t cA,cB,cF,cG,cH;
611e810d 530 Double_t aArg=-1; Int_t iErrFlg; //tmp vars for TMinuit
43400d2d 531
611e810d 532 if(!gMinuit) gMinuit = new TMinuit(5); //init MINUIT with this number of parameters (5 params)
43400d2d 533 gMinuit->mncler(); // reset Minuit list of paramters
534 gMinuit->SetObjectFit((TObject*)this); gMinuit->SetFCN(AliHMPIDRecon::FunMinEl); //set fit function
535 gMinuit->mnexcm("SET PRI",&aArg,1,iErrFlg); //suspend all printout from TMinuit
536 gMinuit->mnexcm("SET NOW",&aArg,0,iErrFlg); //suspend all warning printout from TMinuit
537
538 Double_t d1,d2,d3;
539 TString sName;
540
611e810d 541 gMinuit->mnparm(0," A ",1,0.01,0,0,iErrFlg);
542 gMinuit->mnparm(1," B ",1,0.01,0,0,iErrFlg);
543 gMinuit->mnparm(2," H ",1,0.01,0,0,iErrFlg);
544 gMinuit->mnparm(3," G ",1,0.01,0,0,iErrFlg);
545 gMinuit->mnparm(4," F ",1,0.01,0,0,iErrFlg);
43400d2d 546
547 gMinuit->mnexcm("SIMPLEX" ,&aArg,0,iErrFlg);
548 gMinuit->mnexcm("MIGRAD" ,&aArg,0,iErrFlg);
549 gMinuit->mnpout(0,sName,cA,d1,d2,d3,iErrFlg);
550 gMinuit->mnpout(1,sName,cB,d1,d2,d3,iErrFlg);
551 gMinuit->mnpout(2,sName,cH,d1,d2,d3,iErrFlg);
552 gMinuit->mnpout(3,sName,cG,d1,d2,d3,iErrFlg);
553 gMinuit->mnpout(4,sName,cF,d1,d2,d3,iErrFlg);
554 delete gMinuit;
555
556 Double_t i2 = cA*cB-cH*cH; //quartic invariant : i2 > 0 ellipse, i2 < 0 hyperbola
557 Double_t aX = (cH*cF-cB*cG)/i2; //x centre of the canonical section
558 Double_t bY = (cH*cG-cA*cF)/i2; //y centre of the canonical section
559 Double_t alfa1 = TMath::ATan(2*cH/(cA-cB)); //alpha = angle of rotation of the conical section
560 if(alfa1<0) alfa1+=TMath::Pi();
561 alfa1*=0.5;
562 Double_t alfa2 = alfa1+TMath::Pi();
563 Double_t phiref = TMath::ATan2(bY-fMipY,aX-fMipX); //evaluate in a unique way the angle of rotation comapring it
564 if(phiref<0) phiref+=TMath::TwoPi(); //with the vector that poinst to the centre from the mip
565 if(i2<0) phiref+=TMath::Pi();
566 if(phiref>TMath::TwoPi()) phiref-=TMath::TwoPi();
567
568// Printf(" alfa1 %f",alfa1*TMath::RadToDeg());
569// Printf(" alfa2 %f",alfa2*TMath::RadToDeg());
570// Printf(" firef %f",phiref*TMath::RadToDeg());
571 if(TMath::Abs(alfa1-phiref)<TMath::Abs(alfa2-phiref)) phiRec = alfa1; else phiRec = alfa2;
572
573// cout << " phi reconstructed " << phiRec*TMath::RadToDeg() << endl;
574 return (i2>0);
575//
576}
577//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
611e810d 578Bool_t AliHMPIDRecon::FitFree(Double_t phiRec)
43400d2d 579{
580// Fit performed by minimizing RMS/sqrt(n) of the
581// photons reconstructed. First phi is fixed and theta
582// is fouond, then (th,ph) of the track
583// as free parameters
584// Arguments: PhiRec phi of the track
585// Returns: none
611e810d 586 Double_t aArg=-1; Int_t iErrFlg; //tmp vars for TMinuit
587 if(!gMinuit) gMinuit = new TMinuit(2); //init MINUIT with this number of parameters (5 params)
43400d2d 588 gMinuit->mncler(); // reset Minuit list of paramters
589 gMinuit->SetObjectFit((TObject*)this); gMinuit->SetFCN(AliHMPIDRecon::FunMinPhot); //set fit function
590 gMinuit->mnexcm("SET PRI",&aArg,1,iErrFlg); //suspend all printout from TMinuit
591 gMinuit->mnexcm("SET NOW",&aArg,0,iErrFlg); //suspend all warning printout from TMinuit
592
593 Double_t d1,d2,d3;
594 TString sName;
595 Double_t th,ph;
596
597 gMinuit->mnexcm("SET PRI",&aArg,1,iErrFlg); //suspend all printout from TMinuit
598 gMinuit->mnexcm("SET NOW",&aArg,0,iErrFlg);
599
611e810d 600 gMinuit->mnparm(0," theta ", 0.01,0.01,0,TMath::PiOver2(),iErrFlg);
601 gMinuit->mnparm(1," phi ",phiRec,0.01,0,TMath::TwoPi() ,iErrFlg);
43400d2d 602
603 gMinuit->FixParameter(1);
604 gMinuit->mnexcm("SIMPLEX" ,&aArg,0,iErrFlg);
605 gMinuit->mnexcm("MIGRAD" ,&aArg,0,iErrFlg);
606 gMinuit->Release(1);
607 gMinuit->mnexcm("MIGRAD" ,&aArg,0,iErrFlg);
608
609 gMinuit->mnpout(0,sName,th,d1,d2,d3,iErrFlg);
610 gMinuit->mnpout(1,sName,ph,d1,d2,d3,iErrFlg);
611e810d 611
612 Double_t outPar[2] = {th,ph}; Double_t g; Double_t f;Int_t flag = 3;
613 gMinuit->Eval(2, &g, f, outPar,flag);
614
615 SetTrkFit(th,ph);
43400d2d 616
611e810d 617 return kTRUE;
43400d2d 618}
619//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
620Double_t AliHMPIDRecon::FunConSect(Double_t *c,Double_t x,Double_t y)
621{
622 return c[0]*x*x+c[1]*y*y+2*c[2]*x*y+2*c[3]*x+2*c[4]*y+1;
623}
624//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
625void AliHMPIDRecon::FunMinEl(Int_t &/* */,Double_t* /* */,Double_t &f,Double_t *par,Int_t /* */)
626{
627 AliHMPIDRecon *pRec=(AliHMPIDRecon*)gMinuit->GetObjectFit();
628 Double_t minFun = 0;
629 Int_t np = pRec->NClu();
630 for(Int_t i=0;i<np;i++) {
631 if(i==pRec->IdxMip()) continue;
632 Double_t el = pRec->FunConSect(par,pRec->XClu(i),pRec->YClu(i));
633 minFun +=el*el;
634 }
635 f = minFun;
636}
637//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
611e810d 638void AliHMPIDRecon::FunMinPhot(Int_t &/* */,Double_t* /* */,Double_t &f,Double_t *par,Int_t iflag)
43400d2d 639{
640 AliHMPIDRecon *pRec=(AliHMPIDRecon*)gMinuit->GetObjectFit();
611e810d 641 Double_t sizeCh = 0.5*fgkRadThick+fgkWinThick+fgkGapThick;
43400d2d 642 Double_t thTrk = par[0];
643 Double_t phTrk = par[1];
644 Double_t xrad = pRec->MipX() - sizeCh*TMath::Tan(thTrk)*TMath::Cos(phTrk);
645 Double_t yrad = pRec->MipY() - sizeCh*TMath::Tan(thTrk)*TMath::Sin(phTrk);
611e810d 646 pRec->SetRadXY(xrad,yrad);
43400d2d 647 pRec->SetTrack(xrad,yrad,thTrk,phTrk);
648
649 Double_t meanCkov=0;
650 Double_t meanCkov2=0;
651 Double_t thetaCer,phiCer;
652 for(Int_t i=0;i<pRec->NClu();i++) {
653 pRec->FindPhotCkov(pRec->XClu(i),pRec->YClu(i),thetaCer,phiCer);
654
655 meanCkov += thetaCer;
656 meanCkov2 += thetaCer*thetaCer;
657 }
658 meanCkov/=pRec->NClu();
659 Double_t rms = TMath::Sqrt(meanCkov2/pRec->NClu() - meanCkov*meanCkov);
660 f = rms/TMath::Sqrt(pRec->NClu());
611e810d 661 Printf(" mean %f rms/sqrt(n) %f",meanCkov,f);
662 if(iflag==3) pRec->SetCkovFit(meanCkov);
663
43400d2d 664}//FunMinPhot()
611e810d 665//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
666//
667// ended Hidden track algorithm....
668//
669//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++