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7cc34f08 | 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 | // ESD track and V0 resolution parameterization | |
19 | // | |
20 | // | |
21 | // Origin: Marian Ivanov marian.ivanov@cern.ch | |
22 | //------------------------------------------------------------------------- | |
23 | ||
24 | /* | |
25 | The track parameter resolution is determined by the intrinsic detector | |
26 | resolution and by the multiple scattering and fluctuation of the energy | |
27 | loss in the material. | |
28 | ||
29 | The contribution from the intrinsic detector resolution is independent of | |
30 | the particle momenta and the mass of particle. In the limit limit of infinite | |
31 | momenta - zero curvature, the intrinsic detector resolution can be obtained. | |
32 | ||
33 | Multiple effect scaling: | |
34 | ||
35 | SCATERING ANGLE - fi, theta | |
36 | sigma A += sqrt(14.1*14.1/(beta2*p2*1e6)*TMath::Abs(xOverX0)); | |
37 | sigma A ~ 1/p | |
38 | sigma sfi += sigma A * sqrt((1-sfi^2) * (1+ tth^2)) | |
39 | sigma tth += sigma A * (1+tth^2) | |
40 | ||
41 | MOMENTUM Pt: | |
42 | sigma 1/pt = sigma A * 1/pt * tth | |
43 | sigma 1/pt ~ (1/pt)^2 | |
44 | ||
45 | POSITION y, z: | |
46 | sigma y +~ sigma A * eff length (between update measurements) ~ 1/pt | |
47 | sigma z +~ sigma A * eff length (between update measurements) ~ 1/pt | |
48 | Example usage: | |
49 | ||
50 | ||
51 | */ | |
52 | ||
53 | ||
54 | #include "TVectorD.h" | |
55 | #include "TMath.h" | |
56 | #include "TObjArray.h" | |
57 | #include "AliESDresolParams.h" | |
58 | ||
59 | ||
60 | ClassImp(AliESDresolParams) | |
61 | ||
62 | ||
63 | AliESDresolParams* AliESDresolParams::fgInstance = 0x0; //! Instance of this class (singleton implementation) | |
64 | ||
65 | ||
66 | AliESDresolParams::AliESDresolParams() : | |
67 | TObject(), | |
68 | fResolDCAyy(0), // resolution Y parameterization | |
69 | fResolDCAzz(0), // resolution Z parameterization | |
70 | fResolDCAphi(0), // resolution phi parameterization - pt-theta | |
71 | fResolDCAth(0), // resolution theta parameterization -pt-theta | |
72 | fResolDCA1pt(0), // resolution 1/pt parameterization - pt-theta | |
73 | // | |
74 | fResolCyy(0), // DCA resolution Y parameterization - r-pt | |
75 | fResolCzz(0), // DCA resolution Z parameterization - r-pt | |
76 | fResolCphi(0), // DCA resolution phi parameterization - r-pt | |
77 | fResolCth(0), // DCA resolution theta parameterization - r-pt | |
78 | fResolC1pt(0) // DCA resolution 1/pt parameterization - r-pt | |
79 | { | |
80 | // | |
81 | // Default constructor | |
82 | // | |
83 | } | |
84 | ||
85 | Double_t AliESDresolParams::GetResolPrimFast(Int_t param, Float_t onept, Float_t tanth) const { | |
86 | // | |
87 | // Resolution at primary vertex | |
88 | // simple Resolution parameterization | |
89 | // polynom of second order in 2D | |
90 | // | |
91 | if (!fResolDCAyy) return 0; | |
92 | TVectorD * pvec = fResolDCAyy; | |
93 | if (param==1) pvec = fResolDCAzz; | |
94 | if (param==2) pvec = fResolDCAphi; | |
95 | if (param==3) pvec = fResolDCAth; | |
96 | if (param==4) pvec = fResolDCA1pt; | |
97 | TVectorD &vec = *pvec; | |
98 | // | |
99 | Float_t val = vec[0]; | |
100 | val+= vec[1]*TMath::Abs(onept); | |
101 | val+= vec[2]*TMath::Abs(onept*onept); | |
102 | val+= vec[3]*TMath::Abs(tanth); | |
103 | val+= vec[4]*TMath::Abs(tanth*tanth); | |
104 | val+= vec[5]*TMath::Abs(onept*tanth); | |
105 | Float_t shift1pt=0; | |
106 | if (param==0 || param==1) shift1pt=0.2; | |
107 | if (param==2 || param==3) shift1pt=0.1; | |
108 | if (param==4) shift1pt=1.; | |
109 | val*= (onept+shift1pt); | |
110 | if (param==4) val*=(onept+shift1pt); | |
111 | return val; | |
112 | } | |
113 | ||
114 | Double_t AliESDresolParams::GetResolRFast(Int_t param, Float_t onept, Float_t radius) const { | |
115 | // | |
116 | // simple DCA resolution parameterization | |
117 | // polynom of second order in 2D | |
118 | // | |
119 | if (!fResolCyy) return 0; | |
120 | TVectorD * pvec = fResolCyy; | |
121 | if (param==1) pvec = fResolCzz; | |
122 | if (param==2) pvec = fResolCphi; | |
123 | if (param==3) pvec = fResolCth; | |
124 | if (param==4) pvec = fResolC1pt; | |
125 | TVectorD &vec = *pvec; | |
126 | // | |
127 | Float_t val = vec[0]; | |
128 | val+= vec[1]*TMath::Abs(onept); | |
129 | val+= vec[2]*TMath::Abs(radius); | |
130 | val+= vec[3]*TMath::Abs(onept*onept); | |
131 | val+= vec[4]*TMath::Abs(radius*radius); | |
132 | val+= vec[5]*TMath::Abs(radius*onept); | |
133 | val+= vec[6]*TMath::Abs(radius*radius*onept); | |
134 | val*=val; | |
135 | return val; | |
136 | } | |
137 | ||
138 | void AliESDresolParams::SetResolPrimFast(TObjArray* array){ | |
139 | // | |
140 | // Set parameters - resolution at prim vertex | |
141 | // | |
142 | if (!array) return; | |
143 | if (array->At(0)) | |
144 | fResolDCAyy = new TVectorD(*((TVectorD*)array->At(0))); | |
145 | if (array->At(1)) | |
146 | fResolDCAzz = new TVectorD(*((TVectorD*)array->At(1))); | |
147 | if (array->At(2)) | |
148 | fResolDCAphi = new TVectorD(*((TVectorD*)array->At(2))); | |
149 | if (array->At(3)) | |
150 | fResolDCAth = new TVectorD(*((TVectorD*)array->At(3))); | |
151 | if (array->At(4)) | |
152 | fResolDCA1pt = new TVectorD(*((TVectorD*)array->At(4))); | |
153 | } | |
154 | ||
155 | void AliESDresolParams::SetResolRFast(TObjArray* array){ | |
156 | // | |
157 | // Set parameters - resolution at prim vertex | |
158 | // | |
159 | if (!array) return; | |
160 | if (array->At(0)) | |
161 | fResolCyy = new TVectorD(*((TVectorD*)array->At(0))); | |
162 | if (array->At(1)) | |
163 | fResolCzz = new TVectorD(*((TVectorD*)array->At(1))); | |
164 | if (array->At(2)) | |
165 | fResolCphi = new TVectorD(*((TVectorD*)array->At(2))); | |
166 | if (array->At(3)) | |
167 | fResolCth = new TVectorD(*((TVectorD*)array->At(3))); | |
168 | if (array->At(4)) | |
169 | fResolC1pt = new TVectorD(*((TVectorD*)array->At(4))); | |
170 | } | |
171 | ||
172 | ||
173 | ||
174 |