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G4EvaporationProbability.cc
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25 //
26 //J.M. Quesada (August2008). Based on:
27 //
28 // Hadronic Process: Nuclear De-excitations
29 // by V. Lara (Oct 1998)
30 //
31 // Modif (03 September 2008) by J. M. Quesada for external choice of inverse
32 // cross section option
33 // JMQ (06 September 2008) Also external choices have been added for
34 // superimposed Coulomb barrier (if useSICB is set true, by default is false)
35 //
36 // JMQ (14 february 2009) bug fixed in emission width: hbarc instead of
37 // hbar_Planck in the denominator
38 //
40 #include "G4NuclearLevelData.hh"
41 #include "G4VCoulombBarrier.hh"
42 #include "G4PhysicalConstants.hh"
43 #include "G4SystemOfUnits.hh"
44 #include "G4PairingCorrection.hh"
45 #include "G4NucleiProperties.hh"
46 #include "G4KalbachCrossSection.hh"
48 #include "Randomize.hh"
49 #include "G4Exp.hh"
50 
51 using namespace std;
52 
54  G4double aGamma,
56  : theA(anA),
57  theZ(aZ),
58  Gamma(aGamma)
59 {
60  resZ = resA = fragA = fragZ = 0;
61  resA13 = muu = resMass = Mass = U = delta0 = delta1 = a0 = probmax = 0.0;
62  partMass = G4NucleiProperties::GetNuclearMass(theA, theZ);
63  pcoeff = Gamma*partMass*CLHEP::millibarn
65 
66  if(0 == theZ) { index = 0; }
67  else if(1 == theZ) { index = theA; }
68  else { index = theA + 1; }
69  fLevelData = G4NuclearLevelData::GetInstance();
70 }
71 
73 {}
74 
75 // obsolete method
77  const G4Fragment&, G4double)
78 {
79  return 0.0;
80 }
81 
83  const G4Fragment & fragment, G4double minEnergy, G4double maxEnergy,
84  G4double CoulombBarrier)
85 {
86  fragA = fragment.GetA_asInt();
87  fragZ = fragment.GetZ_asInt();
88  resA = fragA - theA;
89  resZ = fragZ - theZ;
90 
91  G4double fragMass = fragment.GetGroundStateMass();
92  U = fragment.GetExcitationEnergy();
93  Mass = fragMass + U;
94  delta0 = std::max(0.0, fPairCorr->GetPairingCorrection(fragA,fragZ));
95  delta1 = std::max(0.0, fPairCorr->GetPairingCorrection(resA,resZ));
96  resMass = G4NucleiProperties::GetNuclearMass(resA, resZ);
97  resA13 = fG4pow->Z13(resA);
98  a0 = LevelDensity*fragA;
99  /*
100  G4cout << "G4EvaporationProbability: resZ= " << resZ << " resA= " << resA
101  << " fragZ= " << fragZ << " fragA= " << fragA << " U= "
102  << U << " d0= " << delta0 << G4endl;
103  */
104  if(U < delta0 || maxEnergy <= minEnergy) { return 0.0; }
105 
106  G4double Width = 0.0;
107  if (OPTxs==0) {
108 
109  G4double SystemEntropy = 2.0*std::sqrt(a0*(U-delta0));
110 
111  static const G4double RN2 =
113 
114  G4double Alpha = CalcAlphaParam(fragment);
115  G4double Beta = CalcBetaParam(fragment);
116 
117  // to be checked where to use a0, where - a1
118  G4double a1 = LevelDensity*resA;
119  G4double GlobalFactor = Gamma*Alpha*partMass*RN2*resA13*resA13/(a1*a1);
120 
121  G4double maxea = maxEnergy*a1;
122  G4double Term1 = Beta*a1 - 1.5 + maxea;
123  G4double Term2 = (2.0*Beta*a1-3.0)*std::sqrt(maxea) + 2*maxea;
124 
125  static const G4double explim = 350.;
126  G4double ExpTerm1 = (SystemEntropy <= explim) ? G4Exp(-SystemEntropy) : 0.0;
127 
128  G4double ExpTerm2 = 2.*std::sqrt(maxea) - SystemEntropy;
129  ExpTerm2 = std::min(ExpTerm2, explim);
130  ExpTerm2 = G4Exp(ExpTerm2);
131 
132  Width = GlobalFactor*(Term1*ExpTerm1 + Term2*ExpTerm2);
133 
134  } else {
135 
136  // compute power once
137  if(OPTxs <= 2) {
139  } else {
141  }
142  // if Coulomb barrier cutoff is superimposed for all cross sections
143  // then the limit is the Coulomb Barrier
144  Width = IntegrateEmissionProbability(minEnergy, maxEnergy,
145  CoulombBarrier);
146  }
147  return Width;
148 }
149 
150 G4double G4EvaporationProbability::IntegrateEmissionProbability(
151  G4double low, G4double up, G4double cb)
152 {
153  static const G4double den = 2.0/CLHEP::MeV;
154  G4double del = (up - low);
155  G4int nbins = std::max(3,(G4int)(del*den));
156  del /= (G4double)nbins;
157  G4double e = low;
159  probmax = y0;
160  //G4cout << " 0. e= " << low << " y= " << y0 << G4endl;
161 
162  G4double sum(0.0), ds(0.0), y;
163  for (G4int i=0; i<nbins; ++i) {
164  e += del;
166  probmax = std::max(probmax, y);
167  ds = y0 + y;
168  sum += ds;
169  if(ds < sum*0.01) { break; }
170  //G4cout << " " << i << ". e= " << e << " y= " << y << " sum= " << sum << G4endl;
171  y0 = y;
172  }
173  sum *= del*0.5;
174  //G4cout << "Evap prob: " << sum << " probmax= " << probmax << G4endl;
175  return sum;
176 }
177 
179  G4double cb)
180 {
181  //G4cout << "### G4EvaporationProbability::ProbabilityDistributionFunction"
182  // << G4endl;
183 
184  G4double E0 = U - delta0;
185  //G4double E1 = Mass - partMass - resMass - delta1 - K;
186  G4double E1 = sqrt((Mass - partMass)*(Mass - partMass) - 2*Mass*K)
187  - resMass - delta1;
188  /*
189  G4cout << "PDF: FragZ= " << fragZ << " FragA= " << fragA
190  << " Z= " << theZ << " A= " << theA
191  << " K= " << K << " E0= " << E0 << " E1= " << E1 << G4endl;
192  */
193  if(E1 < 0.0) { return 0.0; }
194 
195  G4double a1 = LevelDensity*resA;
196 
197  //JMQ 14/02/09 BUG fixed: hbarc should be in the denominator instead
198  // of hbar_Planck; without 1/hbar_Panck remains as a width
199 
200  G4double Prob = pcoeff*G4Exp(2.0*(std::sqrt(a1*E1) - std::sqrt(a0*E0)))
201  *K*CrossSection(K, cb);
202 
203  return Prob;
204 }
205 
206 G4double
207 G4EvaporationProbability::CrossSection(G4double K, G4double cb)
208 {
209  G4double res;
210  if(OPTxs <= 2) {
211  res = G4ChatterjeeCrossSection::ComputeCrossSection(K, cb, resA13, muu,
212  index, theZ, resA);
213  } else {
214  res = G4KalbachCrossSection::ComputeCrossSection(K, cb, resA13, muu,
215  index, theZ, theA, resA);
216  }
217  //G4cout << " K= " << K << " res= " << res << " muu= " << muu << G4endl;
218  return res;
219 }
220 
221 G4double
223  G4double maxKinEnergy,
224  G4double cb)
225 {
226  /*
227  G4cout << "### Sample probability Emin= " << minKinEnergy
228  << " Emax= " << maxKinEnergy << " CoulombBarrier= "
229  << cb << " Z= " << theZ << " A= " << theA << G4endl;
230  */
231  G4double T = 0.0;
232  CLHEP::HepRandomEngine* rndm = G4Random::getTheEngine();
233  static const G4int nmax = 100;
234  if (OPTxs==0) {
235  // JMQ:
236  // It uses Dostrovsky's approximation for the inverse reaction cross
237  // in the probability for fragment emission
238  // MaximalKineticEnergy energy in the original version (V.Lara) was
239  // calculated at the Coulomb barrier.
240 
241  G4double Rb = 4.0*a0*maxKinEnergy;
242  G4double RbSqrt = std::sqrt(Rb);
243  G4double PEX1 = 0.0;
244  if (RbSqrt < 160.0) { PEX1 = G4Exp(-RbSqrt); }
245  G4double Rk = 0.0;
246  G4double FRk = 0.0;
247  G4int nn = 0;
248  do {
249  G4double RandNumber = rndm->flat();
250  Rk = 1.0 + (1./RbSqrt)*G4Log(RandNumber + (1.0-RandNumber)*PEX1);
251  G4double Q1 = 1.0;
252  G4double Q2 = 1.0;
253  if (theZ == 0) { // for emitted neutron
254  G4double Beta = (2.12/(resA13*resA13) - 0.05)*MeV/(0.76 + 2.2/resA13);
255  Q1 = 1.0 + Beta/maxKinEnergy;
256  Q2 = Q1*std::sqrt(Q1);
257  }
258 
259  static const G4double ssqr3 = 1.5*std::sqrt(3.0);
260  FRk = ssqr3 * Rk * (Q1 - Rk*Rk)/Q2;
261  if(nn > nmax) { break; }
262  ++nn;
263  // Loop checking, 05-Aug-2015, Vladimir Ivanchenko
264  } while (FRk < rndm->flat());
265 
266  T = maxKinEnergy * (1.0-Rk*Rk) + minKinEnergy;
267 
268  } else {
269 
270  G4double delta = maxKinEnergy - minKinEnergy;
271  probmax *= 1.25;
272  for(G4int i=0; i<nmax; ++i) {
273  T = minKinEnergy + delta*rndm->flat();
275  /*
276  if(probmax < prob) {
277  G4cout << "### G4EvaporationProbability::SampleKineticEnergy: "
278  << " prob= " << prob << " > probmax= " << probmax
279  << " T= " << T << " Emin= " << minKinEnergy
280  << " Emax= " << maxKinEnergy << " Z= " << theZ
281  << " A= " << theA << " FragZ= " << fragZ
282  << " FragA= " << fragA << " i= " << i << G4endl;
283  }
284  */
285  if(probmax*rndm->flat() <= prob) { break; }
286  }
287  }
288  //G4cout << "-- new Z= " << theZ << " A= " << theA << " ekin= " << T << G4endl;
289  return T;
290  //return fLevelData->FindLevel(resZ, resA, resMass, Mass, partMass, T);
291 }
static G4double GetNuclearMass(const G4double A, const G4double Z)
static constexpr double millibarn
Definition: SystemOfUnits.h:86
static constexpr double hbarc
G4double ProbabilityDistributionFunction(G4double K, G4double CoulombBarrier=0.0)
static G4double ComputePowerParameter(G4int resA, G4int idx)
static G4double ComputePowerParameter(G4int resA, G4int idx)
virtual double flat()=0
int G4int
Definition: G4Types.hh:78
static G4double ComputeCrossSection(G4double K, G4double cb, G4double resA13, G4double amu1, G4int idx, G4int Z, G4int resA)
static constexpr double twopi
Definition: G4SIunits.hh:76
G4double SampleKineticEnergy(G4double minKineticEnergy, G4double maxKineticEnergy, G4double CoulombBarrier=0.0)
G4double Z13(G4int Z) const
Definition: G4Pow.hh:127
G4int GetA_asInt() const
Definition: G4Fragment.hh:266
G4double TotalProbability(const G4Fragment &fragment, G4double minKineticEnergy, G4double maxKineticEnergy, G4double CoulombBarrier=0.0)
static G4double ComputeCrossSection(G4double K, G4double cb, G4double resA13, G4double amu1, G4int idx, G4int Z, G4int A, G4int resA)
static constexpr double MeV
virtual G4double CalcBetaParam(const G4Fragment &fragment)=0
G4double GetPairingCorrection(G4int A, G4int Z) const
G4double EmissionProbability(const G4Fragment &fragment, G4double maxKineticEnergy)
G4EvaporationProbability(G4int anA, G4int aZ, G4double aGamma, G4VCoulombBarrier *)
const G4int nmax
G4double GetGroundStateMass() const
Definition: G4Fragment.hh:288
virtual G4double CalcAlphaParam(const G4Fragment &fragment)=0
double flat()
Definition: G4AblaRandom.cc:47
G4double G4Log(G4double x)
Definition: G4Log.hh:230
G4double G4Exp(G4double initial_x)
Exponential Function double precision.
Definition: G4Exp.hh:183
T max(const T t1, const T t2)
brief Return the largest of the two arguments
T min(const T t1, const T t2)
brief Return the smallest of the two arguments
G4int GetZ_asInt() const
Definition: G4Fragment.hh:271
static constexpr double MeV
Definition: G4SIunits.hh:214
G4PairingCorrection * fPairCorr
double G4double
Definition: G4Types.hh:76
static constexpr double fermi
Definition: G4SIunits.hh:103
static G4NuclearLevelData * GetInstance()
static constexpr double pi
Definition: SystemOfUnits.h:54
G4double GetExcitationEnergy() const
Definition: G4Fragment.hh:283