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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
24#include "AliHMPIDRecon.h" //class header
25#include "AliHMPIDCluster.h" //CkovAngle()
26#include <TRotation.h> //TracePhot()
27#include <TH1D.h> //HoughResponse()
28#include <TClonesArray.h> //CkovAngle()
29#include <AliESDtrack.h> //CkovAngle()
30#include <AliESDfriendTrack.h> //CkovAngle()
31
32//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
33AliHMPIDRecon::AliHMPIDRecon():
34 TNamed("RichRec","RichPat"),
35 fPhotCnt(-1),
36 fPhotFlag(0x0),
37 fPhotClusIndex(0x0),
38 fPhotCkov(0x0),
39 fPhotPhi(0x0),
40 fPhotWei(0x0),
41 fCkovSigma2(0),
42 fIsWEIGHT(kFALSE),
43 fDTheta(0.001),
44 fWindowWidth(0.045),
45 fRingArea(0),
46 fRingAcc(0),
47 fTrkDir(0,0,1), // Just for test
48 fTrkPos(30,40), // Just for test
49 fMipPos(0,0),
50 fPc(0,0),
51 fParam(AliHMPIDParam::Instance())
52{
53//..
54//init of data members
55//..
56
57 fParam->SetRefIdx(fParam->MeanIdxRad()); // initialization of ref index to a default one
58}
59//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
60void AliHMPIDRecon::InitVars(Int_t n)
61{
62//..
63//Init some variables
64//..
65 if(n<=0) return;
66 fPhotFlag = new Int_t[n];
67 fPhotClusIndex = new Int_t[n];
68 fPhotCkov = new Double_t[n];
69 fPhotPhi = new Double_t[n];
70 fPhotWei = new Double_t[n];
71//
72}
73//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
74void AliHMPIDRecon::DeleteVars()const
75{
76//..
77//Delete variables
78//..
79 delete [] fPhotFlag;
80 delete [] fPhotClusIndex;
81 delete [] fPhotCkov;
82 delete [] fPhotPhi;
83 delete [] fPhotWei;
84}
85//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
86void AliHMPIDRecon::CkovAngle(AliESDtrack *pTrk,TClonesArray *pCluLst,Int_t index,Double_t nmean,Float_t xRa,Float_t yRa)
87{
88// Pattern recognition method based on Hough transform
89// Arguments: pTrk - track for which Ckov angle is to be found
90// pCluLst - list of clusters for this chamber
91// Returns: - track ckov angle, [rad],
92
93 const Int_t nMinPhotAcc = 3; // Minimum number of photons required to perform the pattern recognition
94
95 Int_t nClusTot = pCluLst->GetEntries();
96 if(nClusTot>fParam->MultCut()) fIsWEIGHT = kTRUE; // offset to take into account bkg in reconstruction
97 else fIsWEIGHT = kFALSE;
98
99 InitVars(nClusTot);
100
101 Float_t xPc,yPc,th,ph;
102 pTrk->GetHMPIDtrk(xPc,yPc,th,ph); //initialize this track: th and ph angles at middle of RAD
103 SetTrack(xRa,yRa,th,ph);
104
105 fParam->SetRefIdx(nmean);
106
107 Float_t mipX=-1,mipY=-1;
108 Int_t chId=-1,mipQ=-1,sizeClu = -1;
109
110 fPhotCnt=0;
111
112 Int_t nPads = 0;
113
114 for (Int_t iClu=0; iClu<pCluLst->GetEntriesFast();iClu++){//clusters loop
115 AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(iClu); //get pointer to current cluster
116 nPads+=pClu->Size();
117 if(iClu == index) { // this is the MIP! not a photon candidate: just store mip info
118 mipX = pClu->X();
119 mipY = pClu->Y();
120 mipQ=(Int_t)pClu->Q();
121 sizeClu=pClu->Size();
122 continue;
123 }
124 chId=pClu->Ch();
125 if(pClu->Q()>2*fParam->QCut()) continue;
126 Double_t thetaCer,phiCer;
127 if(FindPhotCkov(pClu->X(),pClu->Y(),thetaCer,phiCer)){ //find ckov angle for this photon candidate
128 fPhotCkov[fPhotCnt]=thetaCer; //actual theta Cerenkov (in TRS)
129 fPhotPhi [fPhotCnt]=phiCer;
130 fPhotClusIndex[fPhotCnt]=iClu; //actual phi Cerenkov (in TRS): -pi to come back to "unusual" ref system (X,Y,-Z)
131 fPhotCnt++; //increment counter of photon candidates
132 }
133 }//clusters loop
134
135 pTrk->SetHMPIDmip(mipX,mipY,mipQ,fPhotCnt); //store mip info in any case
136 pTrk->SetHMPIDcluIdx(chId,index+1000*sizeClu); //set index of cluster
137
138 if(fPhotCnt<=nMinPhotAcc) { //no reconstruction with <=3 photon candidates
139 pTrk->SetHMPIDsignal(kNoPhotAccept); //set the appropriate flag
140 return;
141 }
142
143 fMipPos.Set(mipX,mipY);
144
145//PATTERN RECOGNITION STARTED:
146
147 Int_t iNrec=FlagPhot(HoughResponse(),pCluLst,pTrk); //flag photons according to individual theta ckov with respect to most probable
148
149 pTrk->SetHMPIDmip(mipX,mipY,mipQ,iNrec); //store mip info
150
151 if(iNrec<1){
152 pTrk->SetHMPIDsignal(kNoPhotAccept); //no photon candidates are accepted
153 return;
154 }
155
156 Int_t occupancy = (Int_t)(1000*(nPads/(6.*80.*48.)));
157
158 Double_t thetaC = FindRingCkov(pCluLst->GetEntries()); //find the best reconstructed theta Cherenkov
159// FindRingGeom(thetaC,2);
160 pTrk->SetHMPIDsignal(thetaC+occupancy); //store theta Cherenkov
161 pTrk->SetHMPIDchi2(fCkovSigma2); //store errors squared
162
163 DeleteVars();
164}//CkovAngle()
165//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
166Bool_t AliHMPIDRecon::FindPhotCkov(Double_t cluX,Double_t cluY,Double_t &thetaCer,Double_t &phiCer)
167{
168// Finds Cerenkov angle for this photon candidate
169// Arguments: cluX,cluY - position of cadidate's cluster
170// Returns: Cerenkov angle
171
172 TVector3 dirCkov;
173
174 Double_t zRad= -0.5*fParam->RadThick()-0.5*fParam->WinThick(); //z position of middle of RAD
175 TVector3 rad(fTrkPos.X(),fTrkPos.Y(),zRad); //impact point at middle of RAD
176 TVector3 pc(cluX,cluY,0.5*fParam->WinThick()+fParam->GapIdx()); //mip at PC
177 Double_t cluR = TMath::Sqrt((cluX-fTrkPos.X())*(cluX-fTrkPos.X())+
178 (cluY-fTrkPos.Y())*(cluY-fTrkPos.Y()));//ref. distance impact RAD-CLUSTER
179 Double_t phi=(pc-rad).Phi(); //phi of photon
180
181 Double_t ckov1=0;
182 Double_t ckov2=0.75+fTrkDir.Theta(); //start to find theta cerenkov in DRS
183 const Double_t kTol=0.01;
184 Int_t iIterCnt = 0;
185 while(1){
186 if(iIterCnt>=50) return kFALSE;
187 Double_t ckov=0.5*(ckov1+ckov2);
188 dirCkov.SetMagThetaPhi(1,ckov,phi);
189 TVector2 posC=TraceForward(dirCkov); //trace photon with actual angles
190 Double_t dist=cluR-(posC-fTrkPos).Mod(); //get distance between trial point and cluster position
191 if(posC.X()==-999) dist = - 999; //total reflection problem
192 iIterCnt++; //counter step
193 if (dist> kTol) ckov1=ckov; //cluster @ larger ckov
194 else if(dist<-kTol) ckov2=ckov; //cluster @ smaller ckov
195 else{ //precision achived: ckov in DRS found
196 dirCkov.SetMagThetaPhi(1,ckov,phi); //
197 Lors2Trs(dirCkov,thetaCer,phiCer); //find ckov (in TRS:the effective Cherenkov angle!)
198 return kTRUE;
199 }
200 }
201}//FindPhotTheta()
202//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
203TVector2 AliHMPIDRecon::TraceForward(TVector3 dirCkov)const
204{
205 //Trace forward a photon from (x,y) up to PC
206 // Arguments: dirCkov photon vector in LORS
207 // Returns: pos of traced photon at PC
208
209 TVector2 pos(-999,-999);
210 Double_t thetaCer = dirCkov.Theta();
211 if(thetaCer > TMath::ASin(1./fParam->GetRefIdx())) return pos; //total refraction on WIN-GAP boundary
212 Double_t zRad= -0.5*fParam->RadThick()-0.5*fParam->WinThick(); //z position of middle of RAD
213 TVector3 posCkov(fTrkPos.X(),fTrkPos.Y(),zRad); //RAD: photon position is track position @ middle of RAD
214 Propagate(dirCkov,posCkov, -0.5*fParam->WinThick()); //go to RAD-WIN boundary
215 Refract (dirCkov, fParam->GetRefIdx(),fParam->WinIdx()); //RAD-WIN refraction
216 Propagate(dirCkov,posCkov, 0.5*fParam->WinThick()); //go to WIN-GAP boundary
217 Refract (dirCkov, fParam->WinIdx(),fParam->GapIdx()); //WIN-GAP refraction
218 Propagate(dirCkov,posCkov,0.5*fParam->WinThick()+fParam->GapThick()); //go to PC
219 pos.Set(posCkov.X(),posCkov.Y());
220 return pos;
221}//TraceForward()
222//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
223void AliHMPIDRecon::Lors2Trs(TVector3 dirCkov,Double_t &thetaCer,Double_t &phiCer)const
224{
225 //Theta Cerenkov reconstruction
226 // Arguments: dirCkov photon vector in LORS
227 // Returns: thetaCer of photon in TRS
228 // phiCer of photon in TRS
229// TVector3 dirTrk;
230// dirTrk.SetMagThetaPhi(1,fTrkDir.Theta(),fTrkDir.Phi());
231// Double_t thetaCer = TMath::ACos(dirCkov*dirTrk);
232 TRotation mtheta; mtheta.RotateY(-fTrkDir.Theta());
233 TRotation mphi; mphi.RotateZ(-fTrkDir.Phi());
234 TRotation mrot=mtheta*mphi;
235 TVector3 dirCkovTRS;
236 dirCkovTRS=mrot*dirCkov;
237 phiCer = dirCkovTRS.Phi(); //actual value of the phi of the photon
238 thetaCer= dirCkovTRS.Theta(); //actual value of thetaCerenkov of the photon
239}
240//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
241void AliHMPIDRecon::Trs2Lors(TVector3 dirCkov,Double_t &thetaCer,Double_t &phiCer)const
242{
243 //Theta Cerenkov reconstruction
244 // Arguments: dirCkov photon vector in TRS
245 // Returns: thetaCer of photon in LORS
246 // phiCer of photon in LORS
247 TRotation mtheta; mtheta.RotateY(fTrkDir.Theta());
248 TRotation mphi; mphi.RotateZ(fTrkDir.Phi());
249 TRotation mrot=mphi*mtheta;
250 TVector3 dirCkovLORS;
251 dirCkovLORS=mrot*dirCkov;
252 phiCer = dirCkovLORS.Phi(); //actual value of the phi of the photon
253 thetaCer= dirCkovLORS.Theta(); //actual value of thetaCerenkov of the photon
254}
255//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
256void AliHMPIDRecon::FindRingGeom(Double_t ckovAng,Int_t level)
257{
258// Find area covered in the PC acceptance
259// Arguments: ckovAng - cerenkov angle
260// level - precision in finding area and portion of ring accepted (multiple of 50)
261// Returns: area of the ring in cm^2 for given theta ckov
262
263 Int_t kN=50*level;
264 Int_t nPoints = 0;
265 Double_t area=0;
266
267 Bool_t first=kFALSE;
268 TVector2 pos1;
269
270 for(Int_t i=0;i<kN;i++){
271 if(!first) {
272 pos1=TracePhot(ckovAng,Double_t(TMath::TwoPi()*(i+1)/kN)); //find a good trace for the first photon
273 if(pos1.X()==-999) continue; //no area: open ring
274 if(!fParam->IsInside(pos1.X(),pos1.Y(),0)) {
275 pos1 = IntWithEdge(fMipPos,pos1); // find the very first intersection...
276 } else {
277 if(!AliHMPIDParam::IsInDead(pos1.X(),pos1.Y())) nPoints++; //photon is accepted if not in dead zone
278 }
279 first=kTRUE;
280 continue;
281 }
282 TVector2 pos2=TracePhot(ckovAng,Double_t(TMath::TwoPi()*(i+1)/kN)); //trace the next photon
283 if(pos2.X()==-999) continue; //no area: open ring
284 if(!fParam->IsInside(pos2.X(),pos2.Y(),0)) {
285 pos2 = IntWithEdge(fMipPos,pos2);
286 } else {
287 if(!AliHMPIDParam::IsInDead(pos2.X(),pos2.Y())) nPoints++; //photon is accepted if not in dead zone
288 }
289 area+=TMath::Abs((pos1-fMipPos).X()*(pos2-fMipPos).Y()-(pos1-fMipPos).Y()*(pos2-fMipPos).X()); //add area of the triangle...
290 pos1 = pos2;
291 }
292//--- find area and length of the ring;
293 fRingAcc = (Double_t)nPoints/(Double_t)kN;
294 area*=0.5;
295 fRingArea = area;
296}//FindRingGeom()
297//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
298TVector2 AliHMPIDRecon::IntWithEdge(TVector2 p1,TVector2 p2)const
299{
300// It finds the intersection of the line for 2 points traced as photons
301// and the edge of a given PC
302// Arguments: 2 points obtained tracing the photons
303// Returns: intersection point with detector (PC) edges
304
305 Double_t xmin = (p1.X()<p2.X())? p1.X():p2.X();
306 Double_t xmax = (p1.X()<p2.X())? p2.X():p1.X();
307 Double_t ymin = (p1.Y()<p2.Y())? p1.Y():p2.Y();
308 Double_t ymax = (p1.Y()<p2.Y())? p2.Y():p1.Y();
309
310 Double_t m = TMath::Tan((p2-p1).Phi());
311 TVector2 pint;
312 //intersection with low X
313 pint.Set((Double_t)(p1.X() + (0-p1.Y())/m),0.);
314 if(pint.X()>=0 && pint.X()<=fParam->SizeAllX() &&
315 pint.X()>=xmin && pint.X()<=xmax &&
316 pint.Y()>=ymin && pint.Y()<=ymax) return pint;
317 //intersection with high X
318 pint.Set((Double_t)(p1.X() + (fParam->SizeAllY()-p1.Y())/m),(Double_t)(fParam->SizeAllY()));
319 if(pint.X()>=0 && pint.X()<=fParam->SizeAllX() &&
320 pint.X()>=xmin && pint.X()<=xmax &&
321 pint.Y()>=ymin && pint.Y()<=ymax) return pint;
322 //intersection with left Y
323 pint.Set(0.,(Double_t)(p1.Y() + m*(0-p1.X())));
324 if(pint.Y()>=0 && pint.Y()<=fParam->SizeAllY() &&
325 pint.Y()>=ymin && pint.Y()<=ymax &&
326 pint.X()>=xmin && pint.X()<=xmax) return pint;
327 //intersection with righ Y
328 pint.Set((Double_t)(fParam->SizeAllX()),(Double_t)(p1.Y() + m*(fParam->SizeAllX()-p1.X())));
329 if(pint.Y()>=0 && pint.Y()<=fParam->SizeAllY() &&
330 pint.Y()>=ymin && pint.Y()<=ymax &&
331 pint.X()>=xmin && pint.X()<=xmax) return pint;
332 return p1;
333}//IntWithEdge()
334//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
335Double_t AliHMPIDRecon::FindRingCkov(Int_t)
336{
337// 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
338// collecting errors for all single Ckov candidates thetas. (Assuming they are independent)
339// Arguments: iNclus- total number of clusters in chamber for background estimation
340// Return: best estimation of track Theta ckov
341
342 Double_t wei = 0.;
343 Double_t weightThetaCerenkov = 0.;
344
345 Double_t ckovMin=9999.,ckovMax=0.;
346 Double_t sigma2 = 0; //to collect error squared for this ring
347
348 for(Int_t i=0;i<fPhotCnt;i++){//candidates loop
349 if(fPhotFlag[i] == 2){
350 if(fPhotCkov[i]<ckovMin) ckovMin=fPhotCkov[i]; //find max and min Theta ckov from all candidates within probable window
351 if(fPhotCkov[i]>ckovMax) ckovMax=fPhotCkov[i];
352 weightThetaCerenkov += fPhotCkov[i]*fPhotWei[i];
353 wei += fPhotWei[i]; //collect weight as sum of all candidate weghts
354
355 sigma2 += 1./fParam->Sigma2(fTrkDir.Theta(),fTrkDir.Phi(),fPhotCkov[i],fPhotPhi[i]);
356 }
357 }//candidates loop
358
359 if(sigma2>0) fCkovSigma2=1./sigma2;
360 else fCkovSigma2=1e10;
361
362 if(wei != 0.) weightThetaCerenkov /= wei; else weightThetaCerenkov = 0.;
363 return weightThetaCerenkov;
364}//FindCkovRing()
365//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
366Int_t AliHMPIDRecon::FlagPhot(Double_t ckov,TClonesArray *pCluLst, AliESDtrack *pTrk)
367{
368// Flag photon candidates if their individual ckov angle is inside the window around ckov angle returned by HoughResponse()
369// Arguments: ckov- value of most probable ckov angle for track as returned by HoughResponse()
370// Returns: number of photon candidates happened to be inside the window
371
372// Photon Flag: Flag = 0 initial set;
373// Flag = 1 good candidate (charge compatible with photon);
374// Flag = 2 photon used for the ring;
375
376 Int_t steps = (Int_t)((ckov )/ fDTheta); //how many times we need to have fDTheta to fill the distance between 0 and thetaCkovHough
377
378 Double_t tmin = (Double_t)(steps - 1)*fDTheta;
379 Double_t tmax = (Double_t)(steps)*fDTheta;
380 Double_t tavg = 0.5*(tmin+tmax);
381
382 tmin = tavg - 0.5*fWindowWidth; tmax = tavg + 0.5*fWindowWidth;
383
384 Int_t iInsideCnt = 0; //count photons which Theta ckov inside the window
385 for(Int_t i=0;i<fPhotCnt;i++){//photon candidates loop
386 fPhotFlag[i] = 0;
387 if(fPhotCkov[i] >= tmin && fPhotCkov[i] <= tmax) {
388 fPhotFlag[i]=2;
389 AddObjectToFriends(pCluLst,i,pTrk);
390 iInsideCnt++;
391 }
392 }
393
394 return iInsideCnt;
395
396}//FlagPhot()
397//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
398void AliHMPIDRecon::AddObjectToFriends(TClonesArray *pCluLst, Int_t photonIndex, AliESDtrack *pTrk)
399{
400// Add AliHMPIDcluster object to ESD friends
401
402 AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(fPhotClusIndex[photonIndex]);
403 AliHMPIDCluster *pClus = new AliHMPIDCluster(*pClu);
404 pClus->SetChi2(fPhotCkov[photonIndex]);
405 pTrk->AddCalibObject(pClus);
406}
407//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
408TVector2 AliHMPIDRecon::TracePhot(Double_t ckovThe,Double_t ckovPhi)const
409{
410// Trace a single Ckov photon from emission point somewhere in radiator up to photocathode taking into account ref indexes of materials it travereses
411// Arguments: ckovThe,ckovPhi- photon ckov angles in TRS, [rad]
412// Returns: distance between photon point on PC and track projection
413
414 Double_t theta,phi;
415 TVector3 dirTRS,dirLORS;
416 dirTRS.SetMagThetaPhi(1,ckovThe,ckovPhi); //photon in TRS
417 Trs2Lors(dirTRS,theta,phi);
418 dirLORS.SetMagThetaPhi(1,theta,phi); //photon in LORS
419 return TraceForward(dirLORS); //now foward tracing
420}//TracePhot()
421//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
422void AliHMPIDRecon::Propagate(const TVector3 dir,TVector3 &pos,Double_t z)const
423{
424// Finds an intersection point between a line and XY plane shifted along Z.
425// Arguments: dir,pos - vector along the line and any point of the line
426// z - z coordinate of plain
427// Returns: none
428// On exit: pos is the position if this intesection if any
429 static TVector3 nrm(0,0,1);
430 TVector3 pnt(0,0,z);
431
432 TVector3 diff=pnt-pos;
433 Double_t sint=(nrm*diff)/(nrm*dir);
434 pos+=sint*dir;
435}//Propagate()
436//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
437void AliHMPIDRecon::Refract(TVector3 &dir,Double_t n1,Double_t n2)const
438{
439// Refract direction vector according to Snell law
440// Arguments:
441// n1 - ref idx of first substance
442// n2 - ref idx of second substance
443// Returns: none
444// On exit: dir is new direction
445 Double_t sinref=(n1/n2)*TMath::Sin(dir.Theta());
446 if(TMath::Abs(sinref)>1.) dir.SetXYZ(-999,-999,-999);
447 else dir.SetTheta(TMath::ASin(sinref));
448}//Refract()
449//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
450Double_t AliHMPIDRecon::HoughResponse()
451{
452//
453// fIdxMip = mipId;
454
455//
456 Double_t kThetaMax=0.75;
457 Int_t nChannels = (Int_t)(kThetaMax/fDTheta+0.5);
458 TH1D *phots = new TH1D("Rphot" ,"phots" ,nChannels,0,kThetaMax);
459 TH1D *photsw = new TH1D("RphotWeighted" ,"photsw" ,nChannels,0,kThetaMax);
460 TH1D *resultw = new TH1D("resultw","resultw" ,nChannels,0,kThetaMax);
461 Int_t nBin = (Int_t)(kThetaMax/fDTheta);
462 Int_t nCorrBand = (Int_t)(fWindowWidth/(2*fDTheta));
463
464 for (Int_t i=0; i< fPhotCnt; i++){//photon cadidates loop
465 Double_t angle = fPhotCkov[i]; if(angle<0||angle>kThetaMax) continue;
466 phots->Fill(angle);
467 Int_t bin = (Int_t)(0.5+angle/(fDTheta));
468 Double_t weight=1.;
469 if(fIsWEIGHT){
470 Double_t lowerlimit = ((Double_t)bin)*fDTheta - 0.5*fDTheta; Double_t upperlimit = ((Double_t)bin)*fDTheta + 0.5*fDTheta;
471 FindRingGeom(lowerlimit);
472 Double_t areaLow = GetRingArea();
473 FindRingGeom(upperlimit);
474 Double_t areaHigh = GetRingArea();
475 Double_t diffArea = areaHigh - areaLow;
476 if(diffArea>0) weight = 1./diffArea;
477 }
478 photsw->Fill(angle,weight);
479 fPhotWei[i]=weight;
480 }//photon candidates loop
481
482 for (Int_t i=1; i<=nBin;i++){
483 Int_t bin1= i-nCorrBand;
484 Int_t bin2= i+nCorrBand;
485 if(bin1<1) bin1=1;
486 if(bin2>nBin)bin2=nBin;
487 Double_t sumPhots=phots->Integral(bin1,bin2);
488 if(sumPhots<3) continue; // if less then 3 photons don't trust to this ring
489 Double_t sumPhotsw=photsw->Integral(bin1,bin2);
490 if((Double_t)((i+0.5)*fDTheta)>0.7) continue;
491 resultw->Fill((Double_t)((i+0.5)*fDTheta),sumPhotsw);
492 }
493// evaluate the "BEST" theta ckov as the maximum value of histogramm
494 Double_t *pVec = resultw->GetArray();
495 Int_t locMax = TMath::LocMax(nBin,pVec);
496 delete phots;delete photsw;delete resultw; // Reset and delete objects
497
498 return (Double_t)(locMax*fDTheta+0.5*fDTheta); //final most probable track theta ckov
499}//HoughResponse()
500//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
501 Double_t AliHMPIDRecon::FindRingExt(Double_t ckov,Int_t ch,Double_t xPc,Double_t yPc,Double_t thRa,Double_t phRa)
502{
503// To find the acceptance of the ring even from external inputs.
504//
505//
506 Double_t xRa = xPc - (fParam->RadThick()+fParam->WinThick()+fParam->GapThick())*TMath::Cos(phRa)*TMath::Tan(thRa); //just linear extrapolation back to RAD
507 Double_t yRa = yPc - (fParam->RadThick()+fParam->WinThick()+fParam->GapThick())*TMath::Sin(phRa)*TMath::Tan(thRa);
508
509 Int_t nStep = 500;
510 Int_t nPhi = 0;
511
512 Int_t ipc,ipadx,ipady;
513
514 if(ckov>0){
515 SetTrack(xRa,yRa,thRa,phRa);
516 for(Int_t j=0;j<nStep;j++){
517 TVector2 pos; pos=TracePhot(ckov,j*TMath::TwoPi()/(Double_t)(nStep-1));
518 if(fParam->IsInDead(pos.X(),pos.Y())) continue;
519 fParam->Lors2Pad(pos.X(),pos.Y(),ipc,ipadx,ipady);
520 ipadx+=(ipc%2)*fParam->kPadPcX;
521 ipady+=(ipc/2)*fParam->kPadPcY;
522 if(ipadx<0 || ipady>160 || ipady<0 || ipady>144 || ch<0 || ch>6) continue;
523 if(fParam->IsDeadPad(ipadx,ipady,ch)) continue;
524 nPhi++;
525 }//point loop
526 return ((Double_t)nPhi/(Double_t)nStep);
527 }//if
528 return -1;
529}