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10d100d4 | 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 | // Implementation of the TOF PID class // | |
19 | // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch // | |
20 | // // | |
21 | //-----------------------------------------------------------------// | |
22 | ||
23 | #include "TMath.h" | |
24 | #include "AliLog.h" | |
25 | ||
26 | #include "AliTOFPIDResponse.h" | |
27 | ||
28 | ClassImp(AliTOFPIDResponse) | |
29 | ||
30 | //_________________________________________________________________________ | |
31 | AliTOFPIDResponse::AliTOFPIDResponse(): | |
32 | fSigma(0), | |
33 | fPmax(0), // zero at 0.5 GeV/c for pp | |
34 | fTime0(0) | |
35 | { | |
679de35e | 36 | fPar[0] = 0.008; |
37 | fPar[1] = 0.008; | |
38 | fPar[2] = 0.002; | |
39 | fPar[3] = 40.0; | |
95ad1018 | 40 | |
6c68754e | 41 | // Reset T0 info |
42 | ResetT0info(); | |
43 | SetMomBoundary(); | |
10d100d4 | 44 | } |
45 | //_________________________________________________________________________ | |
46 | AliTOFPIDResponse::AliTOFPIDResponse(Double_t *param): | |
47 | fSigma(param[0]), | |
48 | fPmax(0), // zero at 0.5 GeV/c for pp | |
49 | fTime0(0) | |
50 | { | |
51 | // | |
52 | // The main constructor | |
53 | // | |
54 | // | |
55 | ||
56 | //fPmax=TMath::Exp(-0.5*3*3)/fSigma; // ~3 sigma at 0.5 GeV/c for PbPb | |
6c68754e | 57 | |
679de35e | 58 | fPar[0] = 0.008; |
59 | fPar[1] = 0.008; | |
60 | fPar[2] = 0.002; | |
61 | fPar[3] = 40.0; | |
95ad1018 | 62 | |
6c68754e | 63 | // Reset T0 info |
64 | ResetT0info(); | |
65 | SetMomBoundary(); | |
10d100d4 | 66 | } |
67 | //_________________________________________________________________________ | |
68 | Double_t | |
69 | AliTOFPIDResponse::GetMismatchProbability(Double_t p, Double_t mass) const { | |
70 | // | |
71 | // Returns the probability of mismatching | |
72 | // assuming 1/(p*beta)^2 scaling | |
73 | // | |
74 | const Double_t km=0.5; // "reference" momentum (GeV/c) | |
75 | ||
76 | Double_t ref2=km*km*km*km/(km*km + mass*mass);// "reference" (p*beta)^2 | |
77 | Double_t p2beta2=p*p*p*p/(p*p + mass*mass); | |
78 | ||
79 | return fPmax*ref2/p2beta2; | |
80 | } | |
81 | //_________________________________________________________________________ | |
82 | Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, Float_t mass) const { | |
83 | // | |
84 | // Return the expected sigma of the PID signal for the specified | |
67376d1d | 85 | // particle mass/Z. |
10d100d4 | 86 | // If the operation is not possible, return a negative value. |
87 | // | |
88 | ||
95ad1018 | 89 | Double_t dpp=fPar[0] + fPar[1]*mom + fPar[2]*mass/mom; //mean relative pt resolution; |
10d100d4 | 90 | |
91 | ||
92 | Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass)); | |
6c68754e | 93 | |
94 | Int_t index = GetMomBin(mom); | |
95 | ||
96 | Double_t t0res = fT0resolution[index]; | |
97 | ||
95ad1018 | 98 | return TMath::Sqrt(sigma*sigma + fPar[3]*fPar[3]/mom/mom + fSigma*fSigma + t0res*t0res); |
10d100d4 | 99 | |
10d100d4 | 100 | } |
6c68754e | 101 | //_________________________________________________________________________ |
67376d1d | 102 | Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, AliPID::EParticleType type) const { |
103 | // | |
104 | // Return the expected sigma of the PID signal for the specified | |
105 | // particle type. | |
106 | // If the operation is not possible, return a negative value. | |
107 | // | |
108 | ||
109 | Double_t mass = AliPID::ParticleMassZ(type); | |
110 | Double_t dpp=fPar[0] + fPar[1]*mom + fPar[2]*mass/mom; //mean relative pt resolution; | |
111 | ||
112 | ||
113 | Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass)); | |
114 | ||
115 | Int_t index = GetMomBin(mom); | |
116 | ||
117 | Double_t t0res = fT0resolution[index]; | |
118 | ||
119 | return TMath::Sqrt(sigma*sigma + fPar[3]*fPar[3]/mom/mom + fSigma*fSigma + t0res*t0res); | |
120 | ||
121 | } | |
122 | //_________________________________________________________________________ | |
123 | Double_t AliTOFPIDResponse::GetExpectedSignal(const AliVTrack* track,AliPID::EParticleType type) const { | |
124 | // | |
125 | // Return the expected signal of the PID signal for the particle type | |
126 | // If the operation is not possible, return a negative value. | |
127 | // | |
128 | Double_t expt[5]; | |
129 | track->GetIntegratedTimes(expt); | |
130 | if (type<=AliPID::kProton) return expt[type]; | |
131 | else { | |
132 | Double_t p = track->P(); | |
133 | Double_t massZ = AliPID::ParticleMassZ(type); | |
134 | return expt[0]/p*massZ*TMath::Sqrt(1.+p*p/massZ/massZ); | |
135 | } | |
136 | } | |
137 | //_________________________________________________________________________ | |
6c68754e | 138 | Int_t AliTOFPIDResponse::GetMomBin(Float_t p) const{ |
f858b00e | 139 | // |
140 | // Returns the momentum bin index | |
141 | // | |
142 | ||
6c68754e | 143 | Int_t i=0; |
144 | while(p > fPCutMin[i] && i < fNmomBins) i++; | |
145 | if(i > 0) i--; | |
10d100d4 | 146 | |
6c68754e | 147 | return i; |
148 | } | |
149 | //_________________________________________________________________________ | |
150 | void AliTOFPIDResponse::SetMomBoundary(){ | |
f858b00e | 151 | // |
152 | // Set boundaries for momentum bins | |
153 | // | |
154 | ||
6c68754e | 155 | fPCutMin[0] = 0.3; |
156 | fPCutMin[1] = 0.5; | |
157 | fPCutMin[2] = 0.6; | |
158 | fPCutMin[3] = 0.7; | |
159 | fPCutMin[4] = 0.8; | |
160 | fPCutMin[5] = 0.9; | |
161 | fPCutMin[6] = 1; | |
162 | fPCutMin[7] = 1.2; | |
163 | fPCutMin[8] = 1.5; | |
164 | fPCutMin[9] = 2; | |
165 | fPCutMin[10] = 3; | |
166 | } | |
f858b00e | 167 | //_________________________________________________________________________ |
7170298c | 168 | Float_t AliTOFPIDResponse::GetStartTime(Float_t mom) const { |
f858b00e | 169 | // |
170 | // Returns event_time value as estimated by TOF combinatorial algorithm | |
171 | // | |
172 | ||
173 | Int_t ibin = GetMomBin(mom); | |
174 | return GetT0bin(ibin); | |
175 | ||
176 | } | |
177 | //_________________________________________________________________________ | |
7170298c | 178 | Float_t AliTOFPIDResponse::GetStartTimeRes(Float_t mom) const { |
f858b00e | 179 | // |
180 | // Returns event_time resolution as estimated by TOF combinatorial algorithm | |
181 | // | |
182 | ||
183 | Int_t ibin = GetMomBin(mom); | |
184 | return GetT0binRes(ibin); | |
185 | ||
186 | } | |
d4d15b21 | 187 | //_________________________________________________________________________ |
188 | Int_t AliTOFPIDResponse::GetStartTimeMask(Float_t mom) const { | |
189 | // | |
190 | // Returns event_time mask | |
191 | // | |
192 | ||
193 | Int_t ibin = GetMomBin(mom); | |
194 | return GetT0binMask(ibin); | |
195 | ||
196 | } |