Geant4  10.00.p03
G4PreCompoundEmission.cc
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26 // $Id: G4PreCompoundEmission.cc 74903 2013-10-23 16:47:40Z gcosmo $
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28 // -------------------------------------------------------------------
29 //
30 // GEANT4 Class file
31 //
32 //
33 // File name: G4PreCompoundEmission
34 //
35 // Author: V.Lara
36 //
37 // Modified:
38 // 15.01.2010 J.M.Quesada added protection against unphysical values of parameter an
39 // 19.01.2010 V.Ivanchenko simplified computation of parameter an, sample cosTheta
40 // instead of theta; protect all calls to sqrt
41 // 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
42 // use int Z and A and cleanup
43 //
44 
45 #include "G4PreCompoundEmission.hh"
46 #include "G4PhysicalConstants.hh"
47 #include "G4SystemOfUnits.hh"
48 #include "G4Pow.hh"
49 #include "G4Exp.hh"
50 #include "G4Log.hh"
51 #include "Randomize.hh"
54 #include "G4HETCEmissionFactory.hh"
55 #include "G4HadronicException.hh"
56 
58 {
65  fFermiEnergy = param.GetFermiEnergy();
66 }
67 
69 {
70  delete theFragmentsFactory;
71  delete theFragmentsVector;
72 }
73 
75 {
78  if (theFragmentsVector) {
80  } else {
83  }
84 }
85 
87 {
90  if (theFragmentsVector) {
92  } else {
95  }
96 }
97 
100 {
101  // Choose a Fragment for emission
102  G4VPreCompoundFragment * thePreFragment =
104  if (thePreFragment == 0)
105  {
106  G4cout << "G4PreCompoundEmission::PerformEmission : "
107  << "I couldn't choose a fragment\n"
108  << "while trying to de-excite\n"
109  << aFragment << G4endl;
110  throw G4HadronicException(__FILE__, __LINE__, "");
111  }
112 
113  //G4cout << "Chosen fragment: " << G4endl;
114  //G4cout << *thePreFragment << G4endl;
115 
116  // Kinetic Energy of emitted fragment
117  G4double kinEnergyOfEmittedFragment =
118  thePreFragment->GetKineticEnergy(aFragment);
119  // if(kinEnergyOfEmittedFragment < MeV) {
120  // G4cout << "Chosen fragment: " << G4endl;
121  // G4cout << *thePreFragment << G4endl;
122  // G4cout << "Ekin= " << kinEnergyOfEmittedFragment << G4endl;
123  // }
124  if(kinEnergyOfEmittedFragment < 0.0) { kinEnergyOfEmittedFragment = 0.0; }
125 
126  // Calculate the fragment momentum (three vector)
127  AngularDistribution(thePreFragment,aFragment,kinEnergyOfEmittedFragment);
128 
129  // Mass of emittef fragment
130  G4double EmittedMass = thePreFragment->GetNuclearMass();
131  // Now we can calculate the four momentum
132  // both options are valid and give the same result but 2nd one is faster
133  G4LorentzVector Emitted4Momentum(theFinalMomentum,
134  EmittedMass + kinEnergyOfEmittedFragment);
135 
136  // Perform Lorentz boost
137  G4LorentzVector Rest4Momentum = aFragment.GetMomentum();
138  Emitted4Momentum.boost(Rest4Momentum.boostVector());
139 
140  // Set emitted fragment momentum
141  thePreFragment->SetMomentum(Emitted4Momentum);
142 
143  // NOW THE RESIDUAL NUCLEUS
144  // ------------------------
145 
146  Rest4Momentum -= Emitted4Momentum;
147 
148  // Update nucleus parameters:
149  // --------------------------
150 
151  // Z and A
152  aFragment.SetZandA_asInt(thePreFragment->GetRestZ(),
153  thePreFragment->GetRestA());
154 
155  // Number of excitons
156  aFragment.SetNumberOfParticles(aFragment.GetNumberOfParticles()-
157  thePreFragment->GetA());
158  // Number of charges
159  aFragment.SetNumberOfCharged(aFragment.GetNumberOfCharged()-
160  thePreFragment->GetZ());
161 
162  // Update nucleus momentum
163  // A check on consistence of Z, A, and mass will be performed
164  aFragment.SetMomentum(Rest4Momentum);
165 
166  // Create a G4ReactionProduct
167  G4ReactionProduct * MyRP = thePreFragment->GetReactionProduct();
168 
169  // if(kinEnergyOfEmittedFragment < MeV) {
170  // G4cout << "G4PreCompoundEmission::Fragment emitted" << G4endl;
171  // G4cout << thePreFragment << G4endl;
172  // }
173  return MyRP;
174 }
175 
177  G4VPreCompoundFragment* thePreFragment,
178  const G4Fragment& aFragment,
179  G4double ekin)
180 {
181  G4int p = aFragment.GetNumberOfParticles();
182  G4int h = aFragment.GetNumberOfHoles();
183  G4double U = aFragment.GetExcitationEnergy();
184 
185  // Emission particle separation energy
186  G4double Bemission = thePreFragment->GetBindingEnergy();
187 
188  //
189  // G4EvaporationLevelDensityParameter theLDP;
190  // G4double gg = (6.0/pi2)*aFragment.GetA()*
191 
192  G4double gg = (6.0/pi2)*aFragment.GetA_asInt()*fLevelDensity;
193 
194  // Average exciton energy relative to bottom of nuclear well
195  G4double Eav = 2*p*(p+1)/((p+h)*gg);
196 
197  // Excitation energy relative to the Fermi Level
198  G4double Uf = std::max(U - (p - h)*fFermiEnergy , 0.0);
199  // G4double Uf = U - KineticEnergyOfEmittedFragment - Bemission;
200 
201  G4double w_num = rho(p+1, h, gg, Uf, fFermiEnergy);
202  G4double w_den = rho(p, h, gg, Uf, fFermiEnergy);
203  if (w_num > 0.0 && w_den > 0.0)
204  {
205  Eav *= (w_num/w_den);
206  Eav += - Uf/(p+h) + fFermiEnergy;
207  }
208  else
209  {
210  Eav = fFermiEnergy;
211  }
212 
213  // VI + JMQ 19/01/2010 update computation of the parameter an
214  //
215  G4double an = 0.0;
216  G4double Eeff = ekin + Bemission + fFermiEnergy;
217  if(ekin > DBL_MIN && Eeff > DBL_MIN) {
218 
219  G4double zeta = std::max(1.0,9.3/std::sqrt(ekin/MeV));
220 
221  // This should be the projectile energy. If I would know which is
222  // the projectile (proton, neutron) I could remove the binding energy.
223  // But, what happens if INC precedes precompound? This approximation
224  // seems to work well enough
225  G4double ProjEnergy = aFragment.GetExcitationEnergy();
226 
227  an = 3*std::sqrt((ProjEnergy+fFermiEnergy)*Eeff)/(zeta*Eav);
228 
229  G4int ne = aFragment.GetNumberOfExcitons() - 1;
230  if ( ne > 1 ) { an /= (G4double)ne; }
231 
232  // protection of exponent
233  if ( an > 10. ) { an = 10.; }
234  }
235 
236  // sample cosine of theta and not theta as in old versions
237  G4double random = G4UniformRand();
238  G4double cost;
239 
240  if(an < 0.1) { cost = 1. - 2*random; }
241  else {
242  G4double exp2an = G4Exp(-2*an);
243  cost = 1. + G4Log(1-random*(1-exp2an))/an;
244  if(cost > 1.) { cost = 1.; }
245  else if(cost < -1.) {cost = -1.; }
246  }
247 
248  G4double phi = CLHEP::twopi*G4UniformRand();
249 
250  // Calculate the momentum magnitude of emitted fragment
251  G4double pmag =
252  std::sqrt(ekin*(ekin + 2.0*thePreFragment->GetNuclearMass()));
253 
254  G4double sint = std::sqrt((1.0-cost)*(1.0+cost));
255 
256  theFinalMomentum.set(pmag*std::cos(phi)*sint,pmag*std::sin(phi)*sint,
257  pmag*cost);
258 
259  // theta is the angle wrt the incident direction
260  G4ThreeVector theIncidentDirection = aFragment.GetMomentum().vect().unit();
261  theFinalMomentum.rotateUz(theIncidentDirection);
262 }
263 
265  G4double E, G4double Ef) const
266 {
267  // 25.02.2010 V.Ivanchenko added more protections
268  G4double Aph = (p*p + h*h + p - 3.0*h)/(4.0*gg);
269  // G4double alpha = (p*p + h*h)/(2.0*gg);
270 
271  if ( E - Aph < 0.0) { return 0.0; }
272 
273  G4double logConst = (p+h)*G4Log(gg)
274  - g4pow->logfactorial(p+h-1) - g4pow->logfactorial(p)
275  - g4pow->logfactorial(h);
276 
277  // initialise values using j=0
278 
279  G4double t1=1;
280  G4double t2=1;
281  G4double logt3 = (p+h-1) * G4Log(E-Aph) + logConst;
282  const G4double logmax = 200.;
283  if(logt3 > logmax) { logt3 = logmax; }
284  G4double tot = G4Exp( logt3 );
285 
286  // and now sum rest of terms
287  // 25.02.2010 V.Ivanchenko change while to for loop and cleanup
288  G4double Eeff = E - Aph;
289  for(G4int j=1; j<=h; ++j)
290  {
291  Eeff -= Ef;
292  if(Eeff < 0.0) { break; }
293  t1 *= -1.;
294  t2 *= (G4double)(h+1-j)/(G4double)j;
295  logt3 = (p+h-1) * G4Log( Eeff) + logConst;
296  if(logt3 > logmax) { logt3 = logmax; }
297  tot += t1*t2*G4Exp(logt3);
298  }
299 
300  return tot;
301 }
static G4Pow * GetInstance()
Definition: G4Pow.cc:53
G4ReactionProduct * GetReactionProduct() const
static const double MeV
Definition: G4SIunits.hh:193
CLHEP::Hep3Vector G4ThreeVector
std::vector< G4VPreCompoundFragment * > * GetFragmentVector()
void AngularDistribution(G4VPreCompoundFragment *theFragment, const G4Fragment &aFragment, G4double KineticEnergy)
G4int GetA() const
G4int GetNumberOfParticles() const
Definition: G4Fragment.hh:325
G4double rho(G4int p, G4int h, G4double gg, G4double E, G4double Ef) const
int G4int
Definition: G4Types.hh:78
G4double GetBindingEnergy() const
G4int GetNumberOfHoles() const
Definition: G4Fragment.hh:345
void SetMomentum(const G4LorentzVector &value)
#define G4UniformRand()
Definition: Randomize.hh:87
G4GLOB_DLL std::ostream G4cout
G4int GetA_asInt() const
Definition: G4Fragment.hh:238
const G4LorentzVector & GetMomentum() const
Definition: G4Fragment.hh:271
void SetMomentum(const G4LorentzVector &value)
Definition: G4Fragment.hh:276
G4int GetRestZ() const
G4PreCompoundFragmentVector * theFragmentsVector
void SetNumberOfParticles(G4int value)
Definition: G4Fragment.hh:364
G4VPreCompoundEmissionFactory * theFragmentsFactory
G4double G4Log(G4double x)
Definition: G4Log.hh:230
G4double G4Exp(G4double initial_x)
Exponential Function double precision.
Definition: G4Exp.hh:183
G4VPreCompoundFragment * ChooseFragment()
G4double GetNuclearMass() const
G4ReactionProduct * PerformEmission(G4Fragment &aFragment)
G4int GetNumberOfExcitons() const
Definition: G4Fragment.hh:320
T max(const T t1, const T t2)
brief Return the largest of the two arguments
G4double logfactorial(G4int Z) const
Definition: G4Pow.hh:273
void SetZandA_asInt(G4int Znew, G4int Anew)
Definition: G4Fragment.hh:248
#define DBL_MIN
Definition: templates.hh:75
G4int GetRestA() const
#define G4endl
Definition: G4ios.hh:61
G4int GetZ() const
void SetNumberOfCharged(G4int value)
Definition: G4Fragment.hh:369
double G4double
Definition: G4Types.hh:76
virtual G4double GetKineticEnergy(const G4Fragment &aFragment)=0
G4int GetNumberOfCharged() const
Definition: G4Fragment.hh:330
G4double GetExcitationEnergy() const
Definition: G4Fragment.hh:255
CLHEP::HepLorentzVector G4LorentzVector