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25 //
26 // Hadronic Process: Nuclear De-excitations
27 // by V. Lara (Oct 1998)
28 //
29 // Modifications:
30 // 28.10.2010 V.Ivanchenko defined members in constructor and cleaned up
31
32 #include "G4VEmissionProbability.hh"
33 #include "G4NuclearLevelData.hh"
34 #include "G4LevelManager.hh"
35 #include "G4DeexPrecoParameters.hh"
36 #include "Randomize.hh"
37 #include "G4Pow.hh"
38 #include "G4Log.hh"
39 #include "G4Exp.hh"
40
41 G4VEmissionProbability::G4VEmissionProbability(G4int Z, G4int A)
42 : pVerbose(1), theZ(Z), theA(A), elimit(CLHEP::MeV)
43 {
44 pNuclearLevelData = G4NuclearLevelData::GetInstance();
45 pG4pow = G4Pow::GetInstance();
46 if(A > 0) { pEvapMass = G4NucleiProperties::GetNuclearMass(theA, theZ); }
47 G4DeexPrecoParameters* param = pNuclearLevelData->GetParameters();
48 OPTxs = param->GetDeexModelType();
49 }
50
51 void G4VEmissionProbability::Initialise()
52 {
53 G4DeexPrecoParameters* param = pNuclearLevelData->GetParameters();
54 pVerbose = param->GetVerbose();
55 fFD = param->GetDiscreteExcitationFlag();
56 pTolerance = param->GetMinExcitation();
57 pWidth = param->GetNuclearLevelWidth();
58 }
59
60 void G4VEmissionProbability::ResetIntegrator(size_t, G4double de, G4double eps)
61 {
62 if(de > 0.0) { elimit = de; }
63 if(eps > 0.0) { accuracy = eps; }
64 }
65
66 G4double G4VEmissionProbability::EmissionProbability(const G4Fragment&, G4double)
67 {
68 return 0.0;
69 }
70
71 G4double G4VEmissionProbability::ComputeProbability(G4double, G4double)
72 {
73 return 0.0;
74 }
75
76 G4double G4VEmissionProbability::IntegrateProbability(G4double elow,
77 G4double ehigh,
78 G4double cb)
79 {
80 pProbability = 0.0;
81 if(elow >= ehigh) { return pProbability; }
82
83 emin = elow;
84 emax = ehigh;
85 eCoulomb = cb;
86
87 const G4double edeltamin = 0.1*CLHEP::MeV;
88 const G4double edeltamax = 2*CLHEP::MeV;
89 G4double edelta = std::min(std::min(elimit, edeltamax), edeltamin);
90 G4double xbin = (emax - emin)/edelta + 1.0;
91 G4int ibin = std::max((G4int)xbin, 4);
92
93 // providing smart binning
94 G4int nbin = ibin*5;
95 edelta = (emax - emin)/ibin;
96
97 G4double x(emin), y(0.0);
98 G4double edelmicro = edelta*0.02;
99 probmax = ComputeProbability(x + edelmicro, eCoulomb);
100 G4double problast = probmax;
101 if(pVerbose > 1) {
102 G4cout << "### G4VEmissionProbability::IntegrateProbability: "
103 << "probmax=" << probmax << " Emin=" << emin
104 << " Emax=" << emax << " QB=" << cb << " nbin=" << nbin
105 << G4endl;
106 }
107 fE1 = fE2 = fP2 = 0.0;
108 G4double emax0 = emax - edelmicro;
109 G4bool endpoint = false;
110 for(G4int i=0; i<nbin; ++i) {
111 x += edelta;
112 if(x >= emax0) {
113 x = emax0;
114 endpoint = true;
115 }
116 y = ComputeProbability(x, eCoulomb);
117 if(pVerbose > 2) {
118 G4cout << " " << i << ". E= " << x << " prob= " << y
119 << " Edel= " << edelta << G4endl;
120 }
121 if(y >= probmax) {
122 probmax = y;
123 } else if(0.0 == fE1 && 2*y < probmax) {
124 fE1 = x;
125 }
126
127 G4double del = (y + problast)*edelta*0.5;
128 pProbability += del;
129 // end of the loop
130 if(del < accuracy*pProbability || endpoint) { break; }
131 problast = y;
132
133 // smart step definition
134 if(del != pProbability && del > 0.8*pProbability &&
135 0.7*edelta > edeltamin) {
136 edelta *= 0.7;
137 } else if(del < 0.1*pProbability && 1.5*edelta < edeltamax) {
138 edelta *= 1.5;
139 }
140 }
141 if(fE1 > emin && fE1 < emax) {
142 fE2 = std::max(0.5*(fE1 + emax), emax - edelta);
143 fP2 = 2*ComputeProbability(fE2, eCoulomb);
144 }
145
146 if(pVerbose > 1) {
147 G4cout << " Probability= " << pProbability << " probmax= "
148 << probmax << " emin=" << emin << " emax=" << emax
149 << " E1=" << fE1 << " E2=" << fE2 << G4endl;
150 }
151 return pProbability;
152 }
153
154 G4double G4VEmissionProbability::SampleEnergy()
155 {
156 static const G4double fact = 1.05;
157 static const G4double alim = 0.05;
158 static const G4double blim = 20.;
159 probmax *= fact;
160
161 // two regions with flat and exponential majorant
162 G4double del = emax - emin;
163 G4double p1 = 1.0;
164 G4double p2 = 0.0;
165 G4double a0 = 0.0;
166 G4double a1 = 1.0;
167 G4double x;
168 if(fE1 > 0.0 && fP2 > 0.0 && fP2 < 0.5*probmax) {
169 a0 = G4Log(probmax/fP2)/(fE2 - fE1);
170 del= fE1 - emin;
171 p1 = del;
172 x = a0*(emax - fE1);
173 if(x < blim) {
174 a1 = (x > alim) ? 1.0 - G4Exp(-x) : x*(1.0 - 0.5*x);
175 }
176 p2 = a1/a0;
177 p1 /= (p1 + p2);
178 p2 = 1.0 - p1;
179 }
180
181 if(pVerbose > 1) {
182 G4cout << "### G4VEmissionProbability::SampleEnergy: "
183 << " Emin= " << emin << " Emax= " << emax
184 << "/n E1=" << fE1 << " p1=" << p1
185 << " probmax=" << probmax << " P2=" << fP2 << G4endl;
186 }
187
188 CLHEP::HepRandomEngine* rndm = G4Random::getTheEngine();
189 const G4int nmax = 1000;
190 G4double ekin, gg, gmax;
191 G4int n = 0;
192 do {
193 ++n;
194 G4double q = rndm->flat();
195 if (p2 == 0.0) {
196 gmax = probmax;
197 ekin = del*q + emin;
198 } else if (q <= p1) {
199 gmax = probmax;
200 ekin = del*q/p1 + emin;
201 } else {
202 ekin = fE1 - G4Log(1.0 - (q - p1)*a1/p2)/a0;
203 x = a0*(ekin - fE1);
204 gmax = fP2;
205 if(x < blim) {
206 gmax = probmax*((x > alim) ? G4Exp(-x) : 1.0 - x*(1.0 - 0.5*x));
207 }
208 }
209 gg = ComputeProbability(ekin, eCoulomb);
210 if(pVerbose > 2) {
211 G4cout << " " << n
212 << ". prob= " << gg << " probmax= " << probmax
213 << " Ekin= " << ekin << G4endl;
214 }
215 if((gg > gmax || n > nmax) && pVerbose > 1) {
216 G4cout << "### G4VEmissionProbability::SampleEnergy for Z= " << theZ
217 << " A= " << theA << " Eex(MeV)=" << fExc << " p1=" << p1
218 << "\n Warning n= " << n
219 << " prob/gmax=" << gg/gmax
220 << " prob=" << gg << " gmax=" << gmax << " probmax=" << probmax
221 << "\n Ekin= " << ekin << " Emin= " << emin
222 << " Emax= " << emax << G4endl;
223 }
224 } while(gmax*rndm->flat() > gg && n < nmax);
225 G4double enew = FindRecoilExcitation(ekin);
226 if(pVerbose > 1) {
227 G4cout << "### SampleEnergy: Efinal= "
228 << enew << " E=" << ekin << " Eexc=" << fExcRes << G4endl;
229 }
230 return enew;
231 }
232
233 G4double G4VEmissionProbability::FindRecoilExcitation(const G4double e)
234 {
235 G4double mass = pEvapMass + fExc;
236
237 G4double m02 = pMass*pMass;
238 G4double m12 = mass*mass;
239 G4double m22 = pResMass*pResMass;
240 G4double mres = std::sqrt(m02 + m12 - 2.*pMass*(mass + e));
241
242 fExcRes = mres - pResMass;
243
244 if(pVerbose > 1) {
245 G4cout << "### FindRecoilExcitation for resZ= "
246 << resZ << " resA= " << resA
247 << " evaporated Z= " << theZ << " A= " << theA
248 << " Ekin= " << e << " Eexc= " << fExcRes << G4endl;
249 }
250
251 // residual nucleus is in the ground state
252 if(fExcRes < pTolerance) {
253 fExcRes = 0.0;
254 return std::max(0.5*(m02 + m12 - m22)/pMass - mass, 0.0);
255 }
256 if(!fFD) { return e; }
257
258 // select final state excitation
259 auto lManager = pNuclearLevelData->GetLevelManager(resZ, resA);
260 if(nullptr == lManager) { return e; }
261
262 // levels are not known
263 if(fExcRes > lManager->MaxLevelEnergy() + pTolerance) { return e; }
264
265 // find level
266 std::size_t idx = lManager->NearestLevelIndex(fExcRes);
267 auto level = lManager->GetLevel(idx);
268
269 // unstable level
270 if (level->GetTimeGamma() == 0.0) { return e; }
271
272 // is possible to use level energy?
273 G4double elevel = lManager->LevelEnergy(idx);
274 if (std::abs(elevel - fExcRes) > pWidth || pMass < mass + pResMass + elevel) {
275 return e;
276 }
277
278 // long-lived level
279 G4double massR = pResMass + elevel;
280 G4double mr2 = massR*massR;
281 fExcRes = elevel;
282 return std::max(0.5*(m02 + m12 - mr2)/pMass - mass, 0.0);
283 }
284