Geant4  10.03.p03
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
G4Absorber.cc
Go to the documentation of this file.
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 #include "G4Absorber.hh"
27 #include "G4KineticTrack.hh"
28 #include "G4PionPlus.hh"
29 #include "G4PionMinus.hh"
30 #include "G4PionZero.hh"
31 #include "G4Proton.hh"
32 #include "G4Neutron.hh"
33 
34 #include "G4PhysicalConstants.hh"
35 #include "G4SystemOfUnits.hh"
36 #include "G4LorentzRotation.hh"
37 
39 {
40  theCutOnP = cutOnP;
41  theAbsorbers = new G4KineticTrackVector;
42  theProducts = new G4KineticTrackVector;
43 }
44 
45 
47 {
48  delete theAbsorbers;
49  delete theProducts;
50 }
51 
52 
54 {
55  // FixMe: actually only for pions
56 // if(kt.Get4Momentum().vect().mag() < theCutOnP)
57 // Cut on kinetic Energy...
58  if (kt.Get4Momentum().e() - kt.GetActualMass() < theCutOnP)
59  {
60  if(kt.GetDefinition() == G4PionPlus::PionPlus() ||
63  {
64  return true;
65  }
66  }
67  return false;
68 }
69 
70 
71 
73 {
74  if(!FindAbsorbers(kt, tgt))
75  return false;
76  return FindProducts(kt);
77 }
78 
79 
82 {
83 // Find a closest ( in space) pair of Nucleons capable to absorb pi+/pi-
84 // pi+ can be absorbed on np or nn resulting in pp or np
85 // pi- can be absorbed on np or pp resulting in nn or np
86 
87 // @GF: FindAbsorbers is unused, logic is seriously wrong
88 
89  G4KineticTrack * kt1 = NULL;
90  G4KineticTrack * kt2 = NULL;
91  G4double dist1 = DBL_MAX; // dist to closest nucleon
92  G4double dist2 = DBL_MAX; // dist to next close
93  G4double charge1 = 0;
94 // G4double charge2 = 0; // charge2 is only assigned to, never used
95  G4double charge0 = kt.GetDefinition()->GetPDGCharge();
97 
98  std::vector<G4KineticTrack *>::iterator iter;
99  for(iter = tgt.begin(); iter != tgt.end(); ++iter)
100  {
101  G4KineticTrack * curr = *iter;
102  G4double dist = (pos-curr->GetPosition()).mag();
103  if(dist >= dist2)
104  continue;
105  if(dist < dist1)
106  {
107  if(dist1 == DBL_MAX) // accept 1st as a candidate,
108  {
109  kt1 = curr;
110  charge1 = kt1->GetDefinition()->GetPDGCharge();
111  dist1 = dist;
112  continue;
113  }
114  if(dist2 == DBL_MAX) // accept the candidate and shift kt1 to kt2
115  { // @GF: should'nt we check if compatible?
116  kt2 = kt1;
117 // charge2 = charge1;
118  dist2 = dist1;
119  kt1 = curr;
120  charge1 = kt1->GetDefinition()->GetPDGCharge();
121  dist1 = dist;
122  continue;
123  }
124 // test the compatibility with charge conservation for new config
125  G4double charge = curr->GetDefinition()->GetPDGCharge();
126  if((charge0+charge1+charge < 0.) || //test config (curr,kt1)
127  (charge0+charge1+charge) > 2*eplus)
128  { // incompatible: change kt1 with curr.
129  kt1 = curr;
130  charge1 = charge;
131  dist1 = dist;
132  }
133  else
134  { // compatible: change kt1 with curr and kt2 with kt1
135  kt2 = kt1;
136 // charge2 = charge1;
137  dist2 = dist1;
138  kt1 = curr;
139  charge1 = charge;
140  dist1 = dist;
141  }
142  continue;
143  }
144 // here if dist1 < dist < dist2
145  if(dist2 == DBL_MAX) // accept the candidate
146  {
147  kt2 = curr;
148 // charge2 = kt2->GetDefinition()->GetPDGCharge();
149  dist2 = dist;
150  continue;
151  }
152 // test the compatibility with charge conservation
153  G4double charge = curr->GetDefinition()->GetPDGCharge();
154  if((charge0+charge1+charge < 0.) ||
155  (charge0+charge1+charge) > 2*eplus)
156  continue; // incomatible: do nothing
157 // compatible: change kt2 with curr
158  kt2 = curr;
159 // charge2 = charge;
160  dist2 = dist;
161  }
162 
163  theAbsorbers->clear(); // do not delete tracks in theAbsorbers vector!
164  if((kt1 == NULL) || (kt2 == NULL))
165  return false;
166 
167  theAbsorbers->push_back(kt1);
168  theAbsorbers->push_back(kt2);
169  return true;
170 }
171 
172 
173 
175 {
176 // Choose the products type
177  const G4ParticleDefinition * prod1;
178  const G4ParticleDefinition * prod2;
179  G4KineticTrack * abs1 = (*theAbsorbers)[0];
180  G4KineticTrack * abs2 = (*theAbsorbers)[1];
181 
182  G4double charge = kt.GetDefinition()->GetPDGCharge();
183  if(charge == eplus)
184  { // a neutron become proton
185  prod1 = G4Proton::Proton();
186  if(abs1->GetDefinition() == G4Neutron::Neutron())
187  prod2 = abs2->GetDefinition();
188  else
189  prod2 = G4Proton::Proton();
190  }
191  else if(charge == -eplus)
192  { // a proton become neutron
193  prod1 = G4Neutron::Neutron();
194  if(abs1->GetDefinition() == G4Proton::Proton())
195  prod2 = abs2->GetDefinition();
196  else
197  prod2 = G4Neutron::Neutron();
198  }
199  else // charge = 0: leave particle types unchenged
200  {
201  prod1 = abs1->GetDefinition();
202  prod2 = abs2->GetDefinition();
203  }
204 
205 // Translate to the CMS frame
206  G4LorentzVector momLab = kt.Get4Momentum()+abs1->Get4Momentum()+
207  abs2->Get4Momentum();
208  G4LorentzRotation toCMSFrame((-1)*momLab.boostVector());
209  G4LorentzRotation toLabFrame(momLab.boostVector());
210  G4LorentzVector momCMS = toCMSFrame*momLab;
211 
212 // Evaluate the final momentum of products
213  G4double ms1 = prod1->GetPDGMass();
214  G4double ms2 = prod2->GetPDGMass();
215  G4double e0 = momCMS.e();
216  G4double squareP = (e0*e0*e0*e0-2*e0*e0*(ms1*ms1+ms2*ms2)+
217  (ms2*ms2-ms1*ms1)*(ms2*ms2-ms1*ms1))/(4*e0*e0);
218 // if(squareP < 0) // should never happen
219 // squareP = 0;
220  G4ThreeVector mom1CMS = GetRandomDirection();
221  mom1CMS = std::sqrt(squareP)*mom1CMS;
222  G4LorentzVector final4Mom1CMS(mom1CMS, std::sqrt(squareP+ms1*ms1));
223  G4LorentzVector final4Mom2CMS((-1)*mom1CMS, std::sqrt(squareP+ms2*ms2));
224 
225 // Go back to the lab frame
226  G4LorentzVector mom1 = toLabFrame*final4Mom1CMS;
227  G4LorentzVector mom2 = toLabFrame*final4Mom2CMS;
228 
229 // ------ debug
230 /*
231  G4LorentzVector temp = mom1+mom2;
232 
233  cout << (1/MeV)*momLab.x() << " " << (1/MeV)*momLab.y() << " "
234  << (1/MeV)*momLab.z() << " " << (1/MeV)*momLab.t() << " "
235  << (1/MeV)*momLab.vect().mag() << " " << (1/MeV)*momLab.mag() << " "
236  << (1/MeV)*temp.x() << " " << (1/MeV)*temp.y() << " "
237  << (1/MeV)*temp.z() << " " << (1/MeV)*temp.t() << " "
238  << (1/MeV)*temp.vect().mag() << " " << (1/MeV)*temp.mag() << " "
239  << (1/MeV)*std::sqrt(squareP) << endl;
240 
241 */
242 // ------ end debug
243 
244 // Build two new kinetic tracks and add to products
245  G4KineticTrack * kt1 = new G4KineticTrack(prod1, 0., abs1->GetPosition(),
246  mom1);
247  G4KineticTrack * kt2 = new G4KineticTrack(prod2, 0., abs2->GetPosition(),
248  mom2);
249 // ------ debug
250 /*
251  G4LorentzVector initialMom1 = abs1->Get4Momentum();
252  G4LorentzVector initialMom2 = abs2->Get4Momentum();
253  G4LorentzVector pion4MomCMS = toCMSFrame*kt.Get4Momentum();
254  cout << (1/MeV)*initialMom1.x() << " " << (1/MeV)*initialMom1.y() << " "
255  << (1/MeV)*initialMom1.z() << " " << (1/MeV)*initialMom1.e() << " "
256  << (1/MeV)*initialMom1.vect().mag() << " "
257  << (1/MeV)*initialMom2.x() << " " << (1/MeV)*initialMom2.y() << " "
258  << (1/MeV)*initialMom2.z() << " " << (1/MeV)*initialMom2.e() << " "
259  << (1/MeV)*initialMom2.vect().mag() << " "
260  << (1/MeV)*mom1.x() << " " << (1/MeV)*mom1.y() << " "
261  << (1/MeV)*mom1.z() << " " << (1/MeV)*mom1.e() << " "
262  << (1/MeV)*mom1.vect().mag() << " "
263  << (1/MeV)*mom2.x() << " " << (1/MeV)*mom2.y() << " "
264  << (1/MeV)*mom2.z() << " " << (1/MeV)*mom2.e() << " "
265  << (1/MeV)*mom2.vect().mag() << " "
266  << (1/MeV)*pion4MomCMS.x() << " " << (1/MeV)*pion4MomCMS.y() << " "
267  << (1/MeV)*pion4MomCMS.z() << " " << (1/MeV)*pion4MomCMS.e() << " "
268  << (1/MeV)*pion4MomCMS.vect().mag() << " "
269  << (1/MeV)*final4Mom1CMS.x() << " " << (1/MeV)*final4Mom1CMS.y() << " "
270  << (1/MeV)*final4Mom1CMS.z() << " " << (1/MeV)*final4Mom1CMS.e() << " "
271  << (1/MeV)*final4Mom1CMS.vect().mag() << " "
272  << (1/MeV)*final4Mom2CMS.x() << " " << (1/MeV)*final4Mom2CMS.y() << " "
273  << (1/MeV)*final4Mom2CMS.z() << " " << (1/MeV)*final4Mom2CMS.e() << " "
274  << (1/MeV)*final4Mom2CMS.vect().mag() << endl;
275 */
276 // ------ end debug
277 
278  theProducts->clear();
279  theProducts->push_back(kt1);
280  theProducts->push_back(kt2);
281  return true;
282 }
283 
284 
285 
286 G4ThreeVector G4Absorber::GetRandomDirection()
287 {
288  G4double theta = 2.0*G4UniformRand()-1.0;
289  theta = std::acos(theta);
290  G4double phi = G4UniformRand()*2*pi;
291  G4ThreeVector direction(std::sin(theta)*std::cos(phi), std::sin(theta)*std::sin(phi), std::cos(theta));
292  return direction;
293 }
294 
295 
296 
297 
298 
299 
300 
Hep3Vector boostVector() const
const G4ThreeVector & GetPosition() const
G4bool Absorb(G4KineticTrack &kt, G4KineticTrackVector &tgt)
Definition: G4Absorber.cc:72
G4double GetActualMass() const
#define G4UniformRand()
Definition: Randomize.hh:97
G4bool FindAbsorbers(G4KineticTrack &kt, G4KineticTrackVector &tgt)
Definition: G4Absorber.cc:80
bool G4bool
Definition: G4Types.hh:79
static constexpr double eplus
Definition: G4SIunits.hh:199
static G4Proton * Proton()
Definition: G4Proton.cc:93
static G4PionPlus * PionPlus()
Definition: G4PionPlus.cc:98
static G4Neutron * Neutron()
Definition: G4Neutron.cc:104
G4Absorber(G4double cutOnP)
Definition: G4Absorber.cc:38
static G4PionZero * PionZero()
Definition: G4PionZero.cc:108
G4bool WillBeAbsorbed(const G4KineticTrack &kt)
Definition: G4Absorber.cc:53
G4double GetPDGMass() const
G4bool FindProducts(G4KineticTrack &kt)
Definition: G4Absorber.cc:174
static G4PionMinus * PionMinus()
Definition: G4PionMinus.cc:98
static constexpr double pi
Definition: G4SIunits.hh:75
double G4double
Definition: G4Types.hh:76
G4double GetPDGCharge() const
const G4LorentzVector & Get4Momentum() const
#define DBL_MAX
Definition: templates.hh:83
const G4ParticleDefinition * GetDefinition() const
static const G4double pos