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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 | { | |
6c68754e | 36 | // Reset T0 info |
37 | ResetT0info(); | |
38 | SetMomBoundary(); | |
10d100d4 | 39 | } |
40 | //_________________________________________________________________________ | |
41 | AliTOFPIDResponse::AliTOFPIDResponse(Double_t *param): | |
42 | fSigma(param[0]), | |
43 | fPmax(0), // zero at 0.5 GeV/c for pp | |
44 | fTime0(0) | |
45 | { | |
46 | // | |
47 | // The main constructor | |
48 | // | |
49 | // | |
50 | ||
51 | //fPmax=TMath::Exp(-0.5*3*3)/fSigma; // ~3 sigma at 0.5 GeV/c for PbPb | |
6c68754e | 52 | |
53 | // Reset T0 info | |
54 | ResetT0info(); | |
55 | SetMomBoundary(); | |
10d100d4 | 56 | } |
57 | //_________________________________________________________________________ | |
58 | Double_t | |
59 | AliTOFPIDResponse::GetMismatchProbability(Double_t p, Double_t mass) const { | |
60 | // | |
61 | // Returns the probability of mismatching | |
62 | // assuming 1/(p*beta)^2 scaling | |
63 | // | |
64 | const Double_t km=0.5; // "reference" momentum (GeV/c) | |
65 | ||
66 | Double_t ref2=km*km*km*km/(km*km + mass*mass);// "reference" (p*beta)^2 | |
67 | Double_t p2beta2=p*p*p*p/(p*p + mass*mass); | |
68 | ||
69 | return fPmax*ref2/p2beta2; | |
70 | } | |
71 | //_________________________________________________________________________ | |
72 | Double_t AliTOFPIDResponse::GetExpectedSigma(Float_t mom, Float_t time, Float_t mass) const { | |
73 | // | |
74 | // Return the expected sigma of the PID signal for the specified | |
75 | // particle type. | |
76 | // If the operation is not possible, return a negative value. | |
77 | // | |
78 | ||
6c68754e | 79 | Double_t dpp=0.018*mass/mom; //mean relative pt resolution; |
10d100d4 | 80 | |
81 | ||
82 | Double_t sigma = dpp*time/(1.+ mom*mom/(mass*mass)); | |
6c68754e | 83 | |
84 | Int_t index = GetMomBin(mom); | |
85 | ||
86 | Double_t t0res = fT0resolution[index]; | |
87 | ||
88 | return TMath::Sqrt(sigma*sigma + 50.0*50.0/mom/mom + fSigma*fSigma + t0res*t0res); | |
10d100d4 | 89 | |
10d100d4 | 90 | } |
6c68754e | 91 | //_________________________________________________________________________ |
92 | Int_t AliTOFPIDResponse::GetMomBin(Float_t p) const{ | |
f858b00e | 93 | // |
94 | // Returns the momentum bin index | |
95 | // | |
96 | ||
6c68754e | 97 | Int_t i=0; |
98 | while(p > fPCutMin[i] && i < fNmomBins) i++; | |
99 | if(i > 0) i--; | |
10d100d4 | 100 | |
6c68754e | 101 | return i; |
102 | } | |
103 | //_________________________________________________________________________ | |
104 | void AliTOFPIDResponse::SetMomBoundary(){ | |
f858b00e | 105 | // |
106 | // Set boundaries for momentum bins | |
107 | // | |
108 | ||
6c68754e | 109 | fPCutMin[0] = 0.3; |
110 | fPCutMin[1] = 0.5; | |
111 | fPCutMin[2] = 0.6; | |
112 | fPCutMin[3] = 0.7; | |
113 | fPCutMin[4] = 0.8; | |
114 | fPCutMin[5] = 0.9; | |
115 | fPCutMin[6] = 1; | |
116 | fPCutMin[7] = 1.2; | |
117 | fPCutMin[8] = 1.5; | |
118 | fPCutMin[9] = 2; | |
119 | fPCutMin[10] = 3; | |
120 | } | |
f858b00e | 121 | //_________________________________________________________________________ |
7170298c | 122 | Float_t AliTOFPIDResponse::GetStartTime(Float_t mom) const { |
f858b00e | 123 | // |
124 | // Returns event_time value as estimated by TOF combinatorial algorithm | |
125 | // | |
126 | ||
127 | Int_t ibin = GetMomBin(mom); | |
128 | return GetT0bin(ibin); | |
129 | ||
130 | } | |
131 | //_________________________________________________________________________ | |
7170298c | 132 | Float_t AliTOFPIDResponse::GetStartTimeRes(Float_t mom) const { |
f858b00e | 133 | // |
134 | // Returns event_time resolution as estimated by TOF combinatorial algorithm | |
135 | // | |
136 | ||
137 | Int_t ibin = GetMomBin(mom); | |
138 | return GetT0binRes(ibin); | |
139 | ||
140 | } |