Geant4  10.01.p02
G4AngularDistributionNP.cc
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27 #include "G4PhysicalConstants.hh"
28 #include "G4SystemOfUnits.hh"
29 #include "Randomize.hh"
30 #include "G4ios.hh"
31 
32 // Initialization of static data arrays:
34 #include "Randomize.hh"
35 
36 
38 {
39  G4int verboseLevel=1;
40 
41  G4double ek= ((S - sqr(m_1) -sqr(m_2) )/(2*m_1) - m_1 )/GeV ; // kinetic energy in GeV
42 
43  // Find energy bin
44 
45  G4int je1 = 0;
46  G4int je2 = NENERGY - 1;
47  do {
48  G4int midBin = (je1 + je2)/2;
49  if (ek < elab[midBin])
50  je2 = midBin;
51  else
52  je1 = midBin;
53  } while (je2 - je1 > 1);
54  // G4int j;
55  //std::abs(ek-elab[je1]) < std::abs(ek-elab[je2]) ? j = je1 : j = je2;
56  G4double delab = elab[je2] - elab[je1];
57 
58  // Sample the angle
59 
60  G4float sample = G4UniformRand();
61  G4int ke1 = 0;
62  G4int ke2 = NANGLE - 1;
63  G4double dsig = sig[je2][0] - sig[je1][0];
64  G4double rc = dsig/delab;
65  G4double b = sig[je1][0] - rc*elab[je1];
66  G4double sigint1 = rc*ek + b;
67  G4double sigint2 = 0.;
68 
69  if (verboseLevel > 1) G4cout << "sample=" << sample << G4endl
70  << ek << " " << ke1 << " " << ke2 << " "
71  << sigint1 << " " << sigint2 << G4endl;
72 
73  do {
74  G4int midBin = (ke1 + ke2)/2;
75  dsig = sig[je2][midBin] - sig[je1][midBin];
76  rc = dsig/delab;
77  b = sig[je1][midBin] - rc*elab[je1];
78  G4double sigint = rc*ek + b;
79  if (sample < sigint) {
80  ke2 = midBin;
81  sigint2 = sigint;
82  }
83  else {
84  ke1 = midBin;
85  sigint1 = sigint;
86  }
87  if (verboseLevel > 1)G4cout << ke1 << " " << ke2 << " "
88  << sigint1 << " " << sigint2 << G4endl;
89  } while (ke2 - ke1 > 1);
90 
91  // sigint1 and sigint2 should be recoverable from above loop
92 
93  // G4double dsig = sig[je2][ke1] - sig[je1][ke1];
94  // G4double rc = dsig/delab;
95  // G4double b = sig[je1][ke1] - rc*elab[je1];
96  // G4double sigint1 = rc*ek + b;
97 
98  // G4double dsig = sig[je2][ke2] - sig[je1][ke2];
99  // G4double rc = dsig/delab;
100  // G4double b = sig[je1][ke2] - rc*elab[je1];
101  // G4double sigint2 = rc*ek + b;
102 
103  dsig = sigint2 - sigint1;
104  rc = 1./dsig;
105  b = ke1 - rc*sigint1;
106  G4double kint = rc*sample + b;
107  G4double theta = (0.5 + kint)*pi/180.;
108 
109  // G4int k;
110  //std::abs(sample-sig[j][ke1]) < std::abs(sample-sig[j][ke2]) ? k = ke1 : k = ke2;
111  // G4double theta = (0.5 + k)*pi/180.;
112 
113  if (verboseLevel > 1) {
114  G4cout << " energy bin " << je1 << " energy=" << elab[je1] << G4endl;
115  G4cout << " angle bin " << kint << " angle=" << theta/degree << G4endl;
116  }
117  G4double costh= std::cos(theta);
118  return costh;
119 }
120 
122 {
123  return twopi * G4UniformRand();
124 }
const G4double pi
float G4float
Definition: G4Types.hh:77
int G4int
Definition: G4Types.hh:78
#define G4UniformRand()
Definition: Randomize.hh:93
G4GLOB_DLL std::ostream G4cout
static const double GeV
Definition: G4SIunits.hh:196
virtual G4double CosTheta(G4double s, G4double m1, G4double m2) const
static const G4float elab[NENERGY]
virtual G4double Phi() const
static const double degree
Definition: G4SIunits.hh:125
#define G4endl
Definition: G4ios.hh:61
T sqr(const T &x)
Definition: templates.hh:145
double G4double
Definition: G4Types.hh:76
static const G4float sig[NENERGY][NANGLE]