+/**************************************************************************
+ * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
+ * *
+ * Author: The ALICE Off-line Project. *
+ * Contributors are mentioned in the code where appropriate. *
+ * *
+ * Permission to use, copy, modify and distribute this software and its *
+ * documentation strictly for non-commercial purposes is hereby granted *
+ * without fee, provided that the above copyright notice appears in all *
+ * copies and that both the copyright notice and this permission notice *
+ * appear in the supporting documentation. The authors make no claims *
+ * about the suitability of this software for any purpose. It is *
+ * provided "as is" without express or implied warranty. *
+ **************************************************************************/
+
+////
+// This implementation AliTPCExB is using an "exact" calculation of the ExB
+// effect. That is, it uses the drift ODE to calculate the distortion
+// without any further assumption.
+// Due to the numerical integration of the ODE, there are some numerical
+// uncertencies involed.
+////
+
#include "TMath.h"
#include "TTreeStream.h"
+#include "AliMagF.h"
#include "AliTPCExBExact.h"
ClassImp(AliTPCExBExact)
const Double_t AliTPCExBExact::fgkEM=1.602176487e-19/9.10938215e-31;
-const Double_t AliTPCExBExact::fgkDriftField=40.e3;
+const Double_t AliTPCExBExact::fgkDriftField=-40.e3;
AliTPCExBExact::AliTPCExBExact()
: fDriftVelocity(0),
- fkMap(0),fkField(0),fkN(0),
+ //fkMap(0),
+ fkField(0),fkN(0),
fkNX(0),fkNY(0),fkNZ(0),
fkXMin(-250.),fkXMax(250.),fkYMin(-250.),fkYMax(250.),
fkZMin(-250.),fkZMax(250.),
Double_t driftVelocity,
Int_t nx,Int_t ny,Int_t nz,Int_t n)
: fDriftVelocity(driftVelocity),
- fkMap(0),fkField(bField),fkN(n),
+ //fkMap(0),
+ fkField(bField),fkN(n),
fkNX(nx),fkNY(ny),fkNZ(nz),
fkXMin(-250.),fkXMax(250.),fkYMin(-250.),fkYMax(250.),
fkZMin(-250.),fkZMax(250.),
CreateLookupTable();
}
+/*
AliTPCExBExact::AliTPCExBExact(const AliFieldMap *bFieldMap,
Double_t driftVelocity,Int_t n)
: fDriftVelocity(driftVelocity),
CreateLookupTable();
}
+*/
AliTPCExBExact::~AliTPCExBExact() {
//
// corrected[2]=position[2];
}
+/*
void AliTPCExBExact::TestThisBeautifulObject(const AliFieldMap *bFieldMap,
const char* fileName) {
+ //
+ // Have a look at the common part "TestThisBeautifulObjectGeneric".
+ //
fkMap=bFieldMap;
fkField=0;
TestThisBeautifulObjectGeneric(fileName);
}
+*/
void AliTPCExBExact::TestThisBeautifulObject(const AliMagF *bField,
const char* fileName) {
+ //
+ // Have a look at the common part "TestThisBeautifulObjectGeneric".
+ //
fkField=bField;
- fkMap=0;
+ //fkMap=0;
TestThisBeautifulObjectGeneric(fileName);
}
void AliTPCExBExact::TestThisBeautifulObjectGeneric(const char* fileName) {
//
- // well, as the name sais...
+ // Well, as the name sais... it tests the object.
//
TTreeSRedirector ts(fileName);
Double_t x[3];
Double_t dnlx=x[0]-dnl[0];
Double_t dnly=x[1]-dnl[1];
Double_t dnlz=x[2]-dnl[2];
+ Double_t b[3];
+ GetB(b,x);
ts<<"positions"
+ <<"bx="<<b[0]
+ <<"by="<<b[1]
+ <<"bz="<<b[2]
<<"x0="<<x[0]
<<"x1="<<x[1]
<<"x2="<<x[2]
}
}
-void AliTPCExBExact::GetE(Double_t *E,const Double_t *x) const {
+void AliTPCExBExact::GetE(Double_t *e,const Double_t *x) const {
//
// Helper function returning the E field in SI units (V/m).
//
- E[0]=0.;
- E[1]=0.;
- E[2]=(x[2]<0.?-1.:1.)*fgkDriftField; // in V/m
+ e[0]=0.;
+ e[1]=0.;
+ e[2]=(x[2]<0.?-1.:1.)*fgkDriftField; // in V/m
}
-void AliTPCExBExact::GetB(Double_t *B,const Double_t *x) const {
+void AliTPCExBExact::GetB(Double_t *b,const Double_t *x) const {
//
// Helper function returning the B field in SI units (T).
//
- Float_t xm[3];
+ Double_t xm[3];
// the beautiful m to cm (and the ugly "const_cast") and Double_t
// to Float_t read the NRs introduction!:
for (int i=0;i<3;++i) xm[i]=x[i]*100.;
- Float_t Bf[3];
- if (fkMap!=0)
- fkMap->Field(xm,Bf);
- else
- fkField->Field(xm,Bf);
- for (int i=0;i<3;++i) B[i]=Bf[i]/10.;
+ Double_t bf[3];
+ //if (fkMap!=0)
+ // fkMap->Field(xm,bf);
+ //else
+ ((AliMagF*)fkField)->Field(xm,bf);
+ for (int i=0;i<3;++i) b[i]=bf[i]/10.;
}
void AliTPCExBExact::Motion(const Double_t *x,Double_t,
//
// The differential equation of motion of the electrons.
//
- const Double_t tau=fDriftVelocity/fgkDriftField/fgkEM;
- const Double_t tau2=tau*tau;
- Double_t E[3];
- Double_t B[3];
- GetE(E,x);
- GetB(B,x);
- Double_t wx=fgkEM*B[0];
- Double_t wy=fgkEM*B[1];
- Double_t wz=fgkEM*B[2];
- Double_t ex=fgkEM*E[0];
- Double_t ey=fgkEM*E[1];
- Double_t ez=fgkEM*E[2];
+ Double_t tau=fDriftVelocity/fgkDriftField/fgkEM;
+ Double_t tau2=tau*tau;
+ Double_t e[3];
+ Double_t b[3];
+ GetE(e,x);
+ GetB(b,x);
+ Double_t wx=fgkEM*b[0];
+ Double_t wy=fgkEM*b[1];
+ Double_t wz=fgkEM*b[2];
+ Double_t ex=fgkEM*e[0];
+ Double_t ey=fgkEM*e[1];
+ Double_t ez=fgkEM*e[2];
Double_t w2=(wx*wx+wy*wy+wz*wz);
dxdt[0]=(1.+wx*wx*tau2)*ex+(wz*tau+wx*wy*tau2)*ey+(-wy*tau+wx*wz*tau2)*ez;
dxdt[1]=(-wz*tau+wx*wy*tau2)*ex+(1.+wy*wy*tau2)*ey+(wx*tau+wy*wz*tau2)*ez;
// Helper function that calculates one distortion by integration
// (only used to fill the lookup table).
//
- const Double_t h=0.01*250./fDriftVelocity/fkN;
+ Double_t h=0.01*250./fDriftVelocity/fkN;
Double_t t=0.;
Double_t xt[3];
Double_t xo[3];
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff