Fixes, and extra debug
[u/mrichter/AliRoot.git] / FMD / AliFMDMultPoisson.cxx
CommitLineData
56b1929b 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/* $Id$ */
17
18//____________________________________________________________________
19//
7684b53c 20// Reconstruct charged particle multiplicity in the FMD
21//
22// [See also the AliFMDReconstructor class]
56b1929b 23//
7684b53c 24// This class reconstructs the muliplicity in regions based on the
25// ratio of empty to full strips.
26//
56b1929b 27#include "AliFMD.h" // ALIFMD_H
1a1fdef7 28#include "AliFMDGeometry.h" // ALIFMDGEOMETRY_H
29#include "AliFMDDetector.h" // ALIFMDDETECTOR_H
30#include "AliFMDRing.h" // ALIFMDRING_H
56b1929b 31#include "AliFMDMultPoisson.h" // ALIFMDMULTPOISSON_H
32#include "AliFMDMultRegion.h" // ALIFMDMULTREGION_H
33#include "AliFMDDigit.h" // ALIFMDDIGIT_H
34#include "AliLog.h" // ALILOG_H
35#include <TClonesArray.h> // ROOT_TClonesArray
36#include <TTree.h> // ROOT_TTree
37
38//____________________________________________________________________
925e6570 39ClassImp(AliFMDMultPoisson)
1a1fdef7 40#if 0
41 ; // This is here to keep Emacs for indenting the next line
42#endif
56b1929b 43
44//____________________________________________________________________
45AliFMDMultPoisson::AliFMDMultPoisson()
46 : AliFMDMultAlgorithm("Poisson", "Poisson"),
47 fDeltaEta(0),
48 fDeltaPhi(0),
49 fThreshold(0)
50{
51 SetDeltaEta();
52 SetDeltaPhi();
53 SetThreshold();
54 fMult = new TClonesArray("AliFMDMultRegion", 1000);
55}
56
57//____________________________________________________________________
58void
59AliFMDMultPoisson::PreEvent(TTree* tree, Float_t ipZ)
60{
61 // Reset internal data
62 AliFMDMultAlgorithm::PreEvent(tree, ipZ);
63 fCurrentVertexZ = ipZ;
69b696b9 64 fEmpty.Reset(kFALSE);
56b1929b 65
66 // Make a branch in the reconstruction tree.
67 const Int_t kBufferSize = 16000;
68 fTreeR->Branch("FMDPoisson", &fMult, kBufferSize);
69
70}
71
72//____________________________________________________________________
73void
74AliFMDMultPoisson::ProcessDigit(AliFMDDigit* digit,
75 Float_t /* eta */,
76 Float_t /* phi */,
77 UShort_t count)
78{
79 // Process one digit.
80 //
81 // Parameters:
82 //
83 // digit Digit to process
84 // ipZ Z--coordinate of the primary interaction
85 // vertex of this event
86 //
87 if (!digit) return;
88 if (count < fThreshold) fEmpty(digit->Detector() - 1,
89 digit->Ring(),
90 digit->Sector(),
91 digit->Strip()) = kTRUE;
92}
93
94//____________________________________________________________________
95void
96AliFMDMultPoisson::PostEvent()
97{
98 // Fill the branch
99 // Based on the information in the cache, do the reconstruction.
100
101 // Loop over the detectors
102 for (Int_t i = 1; i <= 3; i++) {
1a1fdef7 103 AliFMDGeometry* fmd = AliFMDGeometry::Instance();
104 AliFMDDetector* sub = fmd->GetDetector(i);
56b1929b 105 if (!sub) continue;
106
107 // Loop over the rings in the detector
108 for (Int_t j = 0; j < 2; j++) {
1a1fdef7 109 AliFMDRing* r = sub->GetRing((j == 0 ? 'I' : 'O'));
110 Float_t rZ = sub->GetRingZ((j == 0 ? 'I' : 'O'));
56b1929b 111 if (!r) continue;
112
113 // Calculate low/high theta and eta
114 // FIXME: Is this right?
115 Float_t realZ = fCurrentVertexZ + rZ;
116 Float_t thetaOut = TMath::ATan2(r->GetHighR(), realZ);
117 Float_t thetaIn = TMath::ATan2(r->GetLowR(), realZ);
118 Float_t etaOut = - TMath::Log(TMath::Tan(thetaOut / 2));
119 Float_t etaIn = - TMath::Log(TMath::Tan(thetaIn / 2));
120 if (TMath::Abs(etaOut) > TMath::Abs(etaIn)) {
121 Float_t tmp = etaIn;
122 etaIn = etaOut;
123 etaOut = tmp;
124 }
125
126 //-------------------------------------------------------------
127 //
128 // Here starts poisson method
129 //
130 // Calculate eta step per strip, number of eta steps, number of
131 // phi steps, and check the sign of the eta increment
132 Float_t stripEta = (Float_t(r->GetNStrips()) / (etaIn - etaOut));
133 Int_t nEta = Int_t(TMath::Abs(etaIn - etaOut) / fDeltaEta);
134 Int_t nPhi = Int_t(360. / fDeltaPhi);
135 Float_t sign = TMath::Sign(Float_t(1.), etaIn);
136
137 AliDebug(10, Form("FMD%d%c Eta range: %f, %f %d Phi steps",
138 sub->GetId(), r->GetId(), etaOut, etaIn, nPhi));
139
140 // Loop over relevant phi values
141 for (Int_t p = 0; p < nPhi; p++) {
142 Float_t minPhi = p * fDeltaPhi;
143 Float_t maxPhi = minPhi + fDeltaPhi;
144 UShort_t minSector = UShort_t(minPhi / 360) * r->GetNSectors();
145 UShort_t maxSector = UShort_t(maxPhi / 360) * r->GetNSectors();
146
c263f0ab 147 // AliDebug(10, Form(" Now in phi range %f, %f (sectors %d,%d)",
148 // minPhi, maxPhi, minSector, maxSector));
56b1929b 149 // Loop over relevant eta values
150 for (Int_t e = nEta; e >= 0; --e) {
151 Float_t maxEta = etaIn - sign * e * fDeltaEta;
152 Float_t minEta = maxEta - sign * fDeltaEta;
153 if (sign > 0) minEta = TMath::Max(minEta, etaOut);
154 else minEta = TMath::Min(minEta, etaOut);
155 Float_t theta1 = 2 * TMath::ATan(TMath::Exp(-minEta));
156 Float_t theta2 = 2 * TMath::ATan(TMath::Exp(-maxEta));
157 Float_t minR = TMath::Abs(realZ * TMath::Tan(theta2));
158 Float_t maxR = TMath::Abs(realZ * TMath::Tan(theta1));
a3537838 159 // Calculate the weighted mean eta of the region
160 Float_t minW2 = TMath::Power(minR * 2 * TMath::Pi() *
161 ((maxPhi - minPhi)/360),2);
162 Float_t maxW2 = TMath::Power(minR * 2 * TMath::Pi() *
163 ((maxPhi - minPhi)/360), 2);
164 Float_t meanEta = ((minEta / minW2 + maxEta / maxW2) /
165 (1 / (minW2 + maxW2)));
c263f0ab 166 //UShort_t minStrip = UShort_t((etaIn - maxEta) * stripEta + 0.5);
167 // UShort_t maxStrip = UShort_t((etaIn - minEta) * stripEta + 0.5);
168
a3537838 169 UShort_t minStrip = UShort_t(r->GetNStrips() -
170 (etaIn - minEta) * stripEta + 0.5);
171 UShort_t maxStrip = UShort_t(r->GetNStrips() -
172 (etaIn - maxEta) * stripEta + 0.5);
56b1929b 173
174 AliDebug(10, Form(" Now in eta range %f, %f (strips %d, %d)\n"
c263f0ab 175 " [radii %f, %f, thetas %f, %f, sign %d]",
176 minEta, maxEta, minStrip, maxStrip,
56b1929b 177 minR, maxR, theta1, theta2, sign));
c263f0ab 178
56b1929b 179 // Count number of empty strips
180 Int_t emptyStrips = 0;
181 for (Int_t sector = minSector; sector < maxSector; sector++)
182 for (Int_t strip = minStrip; strip < maxStrip; strip++)
183 if (fEmpty(sub->GetId() - 1, r->GetId(), sector, strip))
184 emptyStrips++;
185
186 // The total number of strips
187 Float_t nTotal = (maxSector - minSector) * (maxStrip - minStrip);
56b1929b 188 // Log ratio of empty to total number of strips
56b1929b 189
190 Double_t lambda = (emptyStrips > 0 ?
191 - TMath::Log(Double_t(emptyStrips) / nTotal) :
192 1);
193
194 // The reconstructed number of particles is then given by
195 Int_t reconstructed = Int_t(lambda * nTotal + 0.5);
c263f0ab 196 AliDebug(10, Form("Lambda= %d / %f = %f particles %d",
197 emptyStrips, nTotal,
198 Float_t(emptyStrips) / nTotal , reconstructed));
56b1929b 199
200 // Add a AliFMDMultRegion to the reconstruction tree.
7684b53c 201 AliFMDMultRegion* m = new((*fMult)[fNMult])
56b1929b 202 AliFMDMultRegion(sub->GetId(), r->GetId(),
203 minSector, maxSector, minStrip, maxStrip,
a3537838 204 minEta, maxEta, meanEta, minPhi, maxPhi,
56b1929b 205 reconstructed, AliFMDMultRegion::kPoission);
7684b53c 206 (void)m;
56b1929b 207 fNMult++;
208 } // phi
209 } // eta
210 } // ring
211 } // detector
212}
213
214
215//____________________________________________________________________
216//
217// EOF
218//