1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
16 ////////////////////////////////////////////////////////////////////////////
17 // AliTPCExBTwist class //
18 ////////////////////////////////////////////////////////////////////////////
22 #include "TGeoGlobalMagField.h"
23 #include "AliTPCcalibDB.h"
24 #include "AliTPCParam.h"
27 #include "AliTPCExBTwist.h"
29 AliTPCExBTwist::AliTPCExBTwist()
30 : AliTPCCorrection("exb_twist","ExB twist"),
32 fXTwist(0.),fYTwist(0.)
35 // default constructor
39 AliTPCExBTwist::~AliTPCExBTwist() {
47 void AliTPCExBTwist::Init() {
49 // Initialization funtion
52 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
53 if (!magF) AliError("Magneticd field - not initialized");
54 Double_t bzField = magF->SolenoidField()/10.; //field in T
55 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
56 if (!param) AliError("Parameters - not initialized");
57 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
58 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
59 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
60 // Correction Terms for effective omegaTau; obtained by a laser calibration run
61 SetOmegaTauT1T2(wt,fT1,fT2);
66 void AliTPCExBTwist::Update(const TTimeStamp &/*timeStamp*/) {
70 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
71 if (!magF) AliError("Magneticd field - not initialized");
72 Double_t bzField = magF->SolenoidField()/10.; //field in T
73 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
74 if (!param) AliError("Parameters - not initialized");
75 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
76 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
77 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
78 // Correction Terms for effective omegaTau; obtained by a laser calibration run
79 SetOmegaTauT1T2(wt,fT1,fT2);
86 void AliTPCExBTwist::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
88 // Calculates the correction of a mismatch between the E and B field axis
91 const Float_t zstart=x[2];
92 const Float_t zend =(roc%36<18?fgkTPCZ0:-fgkTPCZ0);
93 const Float_t zdrift=zstart-zend;
95 dx[0]=(fC2*fXTwist-fC1*fYTwist)*zdrift;
96 dx[1]=(fC1*fXTwist+fC2*fYTwist)*zdrift;
100 void AliTPCExBTwist::Print(const Option_t* option) const {
102 // Print function to check the settings (e.g. the twist in the X direction)
103 // option=="a" prints the C0 and C1 coefficents for calibration purposes
106 TString opt = option; opt.ToLower();
107 printf("%s\n",GetTitle());
109 printf(" - Twist settings: X-Twist: %1.5f rad, Y-Twist: %1.5f rad \n",fXTwist,fYTwist);
110 if (opt.Contains("a")) { // Print all details
111 printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);
112 printf(" - C1: %1.4f, C2: %1.4f \n",fC1,fC2);