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G4DELPHIMagField.cc
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27 // $Id: G4DELPHIMagField.cc 96751 2016-05-04 09:39:38Z gcosmo $
28 // -------------------------------------------------------------------
29 
30 #include "G4DELPHIMagField.hh"
31 #include "globals.hh"
32 #include "G4SystemOfUnits.hh"
33 
35 {
36 }
37 
39 {
40  return new G4DELPHIMagField;
41 }
43 
45 {
46 }
47 
49 
50 
52  G4double B[3] ) const
53 {
54  G4int i, n = 8 ;
55  G4double a = 0.001 ; // mm -> m
56  G4double x = a*yTrack[0], y = a*yTrack[1], z = a*yTrack[2] ;
57  G4double x2 = x*x, y2 = y*y, z2 = z*z, r2 = x2 + y2 ;
58  G4double r4 = r2*r2, z4 = z2*z2, r6 = r4*r2, z6 = z4*z2 ;
59  G4double r8 = r4*r4, z8 = z4*z4, r10 = r8*r2, z10 = z8*z2 ;
60  G4double rz = z*std::sqrt(r2), r = std::sqrt(r2+a*a) ;
61  G4double Br ;
62  G4double P[8], Q[8] ;
63  static G4ThreadLocal G4double c[8] = {
64  -9.26e-5, -3.51e-5, 2.94e-6, -1.10e-6,
65  6.25e-8, -1.77e-8, -6.88e-10, -7.52e-11
66  } ;
67  P[0] = 2*rz ;
68  P[1] = 4*rz*(r2 - 4.0*z2/3.0) ;
69  P[2] = 6*rz*(r4 - 4*r2*z2 + 1.6*z4) ;
70  P[3] = 8*rz*(r6 - 8*r4*z2 + 9.6*r2*z4 - 64.0*z6/35.0) ;
71  P[4] = 10*rz*(r8 - 40.0*r6*z2/3.0 + 32*r4*z4
72  - 128.0*r2*z6/7.0 + 128.0*z8/63.0);
73  P[5] = 0 ;
74  P[6] = 0 ;
75  P[7] = 0 ;
76 
77  Q[0] = r2 - 2*z2 ;
78  Q[1] = r4 - 8*r2*z2 + 8.0*z4/3.0 ;
79  Q[2] = r6 - 18*r4*z2 + 24*r2*z4 - 3.2*z6 ;
80  Q[3] = r8 - 32*r6*z2 + 96*r4*z4 - 51.2*r2*z6 +128.0*z8/35.0 ;
81  Q[4] = r10 - 50*r8*z2 + 800.0*r6*z4/3.0 - 320*r4*z6
82  + 640.0*r2*z8/7.0 - 256.0*z10/63.0 ;
83  Q[5] = 0 ;
84  Q[6] = 0 ;
85  Q[7] = 0 ;
86 
87  Br = 0 ;
88  B[2] = 1.2*tesla ; // the principal Bz value of DELPHI detector
89  for(i=0;i<n;i++)
90  {
91  Br += c[i]*P[i] ;
92  B[2] += c[i]*Q[i] ;
93  }
94  B[0] = Br*x/r ;
95  B[1] = Br*y/r ;
96  return ;
97 }
98 
99 // -----------------------------------------------------------------
Float_t x
Definition: compare.C:6
void GetFieldValue(const G4double yTrack[], G4double B[]) const
std::vector< ExP01TrackerHit * > a
Definition: ExP01Classes.hh:33
Float_t y
Definition: compare.C:6
Double_t z
#define G4ThreadLocal
Definition: tls.hh:69
Float_t y2[n_points_geant4]
Definition: compare.C:26
double G4double
Definition: G4Types.hh:76
G4Field * Clone() const
static double P[]
int G4int
Definition: G4Types.hh:78
Char_t n[5]
static double Q[]
Float_t x2[n_points_geant4]
Definition: compare.C:26
double B(double temperature)
static constexpr double tesla
Definition: G4SIunits.hh:268