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0116859c | 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 | // AliTPCExBTwist class // | |
19 | // The class calculates the space point distortions due to a mismatch // | |
20 | // of the E and B field axis (original code from STAR) // | |
21 | // The class allows "effective Omega Tau" corrections. // | |
22 | // // | |
23 | // date: 27/04/2010 // | |
24 | // Authors: Jim Thomas, Magnus Mager, Stefan Rossegger // | |
25 | // // | |
26 | // Example usage: // | |
27 | // AliTPCExBTwist twist; // | |
28 | // twist.SetOmegaTauT1T2(0.32,1.,1.); // values ideally from OCDB // | |
29 | // twist.SetXTwist(0.001); // set twist in X direction (in rad) // | |
30 | // // plot dRPhi distortions ... // | |
31 | // twist.CreateHistoDRPhiinZR(1.,100,100)->Draw("surf2"); // | |
32 | //////////////////////////////////////////////////////////////////////////// | |
534fd34a | 33 | #include "AliMagF.h" |
34 | #include "TGeoGlobalMagField.h" | |
35 | #include "AliTPCcalibDB.h" | |
36 | #include "AliTPCParam.h" | |
37 | #include "AliLog.h" | |
0116859c | 38 | |
39 | #include "AliTPCExBTwist.h" | |
40 | ||
41 | AliTPCExBTwist::AliTPCExBTwist() | |
42 | : AliTPCCorrection("exb_twist","ExB twist"), | |
43 | fC1(0.),fC2(0.), | |
44 | fXTwist(0.),fYTwist(0.) | |
45 | { | |
46 | // | |
47 | // default constructor | |
48 | // | |
49 | } | |
50 | ||
51 | AliTPCExBTwist::~AliTPCExBTwist() { | |
52 | // | |
53 | // default destructor | |
54 | // | |
55 | } | |
56 | ||
534fd34a | 57 | |
58 | ||
e527a1b9 | 59 | void AliTPCExBTwist::Init() { |
60 | // | |
534fd34a | 61 | // Initialization funtion |
e527a1b9 | 62 | // |
63 | ||
534fd34a | 64 | AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField(); |
65 | if (!magF) AliError("Magneticd field - not initialized"); | |
66 | Double_t bzField = magF->SolenoidField()/10.; //field in T | |
67 | AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters(); | |
68 | if (!param) AliError("Parameters - not initialized"); | |
69 | Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally) | |
e527a1b9 | 70 | Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully) |
71 | Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ; | |
e527a1b9 | 72 | // Correction Terms for effective omegaTau; obtained by a laser calibration run |
534fd34a | 73 | SetOmegaTauT1T2(wt,fT1,fT2); |
e527a1b9 | 74 | |
e527a1b9 | 75 | |
e527a1b9 | 76 | } |
77 | ||
78 | void AliTPCExBTwist::Update(const TTimeStamp &/*timeStamp*/) { | |
79 | // | |
80 | // Update function | |
81 | // | |
534fd34a | 82 | AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField(); |
83 | if (!magF) AliError("Magneticd field - not initialized"); | |
84 | Double_t bzField = magF->SolenoidField()/10.; //field in T | |
85 | AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters(); | |
86 | if (!param) AliError("Parameters - not initialized"); | |
87 | Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally) | |
e527a1b9 | 88 | Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully) |
89 | Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ; | |
e527a1b9 | 90 | // Correction Terms for effective omegaTau; obtained by a laser calibration run |
534fd34a | 91 | SetOmegaTauT1T2(wt,fT1,fT2); |
92 | ||
e527a1b9 | 93 | |
e527a1b9 | 94 | } |
95 | ||
96 | ||
97 | ||
0116859c | 98 | void AliTPCExBTwist::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) { |
99 | // | |
100 | // Calculates the correction of a mismatch between the E and B field axis | |
101 | // | |
102 | ||
103 | const Float_t zstart=x[2]; | |
b1f0a2a5 | 104 | const Float_t zend =(roc%36<18?fgkTPCZ0:-fgkTPCZ0); |
0116859c | 105 | const Float_t zdrift=zstart-zend; |
106 | ||
107 | dx[0]=(fC2*fXTwist-fC1*fYTwist)*zdrift; | |
108 | dx[1]=(fC1*fXTwist+fC2*fYTwist)*zdrift; | |
109 | dx[2]=0.; | |
110 | } | |
111 | ||
b1f0a2a5 | 112 | void AliTPCExBTwist::Print(const Option_t* option) const { |
0116859c | 113 | // |
114 | // Print function to check the settings (e.g. the twist in the X direction) | |
115 | // option=="a" prints the C0 and C1 coefficents for calibration purposes | |
116 | // | |
117 | ||
118 | TString opt = option; opt.ToLower(); | |
119 | printf("%s\n",GetTitle()); | |
120 | ||
121 | printf(" - Twist settings: X-Twist: %1.5f rad, Y-Twist: %1.5f rad \n",fXTwist,fYTwist); | |
122 | if (opt.Contains("a")) { // Print all details | |
534fd34a | 123 | printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2); |
0116859c | 124 | printf(" - C1: %1.4f, C2: %1.4f \n",fC1,fC2); |
125 | } | |
126 | ||
127 | ||
128 | } |