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>> 27 // $Id: G4SingleDiffractiveExcitation.cc 106980 2017-10-31 09:02:49Z gcosmo $
27 // ------------------------------------------- 28 // ------------------------------------------------------------
28 // GEANT 4 class implemetation file 29 // GEANT 4 class implemetation file
29 // 30 //
30 // ---------------- G4SingleDiffractiveEx 31 // ---------------- G4SingleDiffractiveExcitation --------------
31 // by Gunter Folger, October 1998. 32 // by Gunter Folger, October 1998.
32 // diffractive Excitation used by strings 33 // diffractive Excitation used by strings models
33 // Take a projectile and a target 34 // Take a projectile and a target
34 // excite the projectile and target 35 // excite the projectile and target
35 // ------------------------------------------- 36 // ------------------------------------------------------------
36 37
37 #include "G4SingleDiffractiveExcitation.hh" 38 #include "G4SingleDiffractiveExcitation.hh"
38 #include "globals.hh" 39 #include "globals.hh"
39 #include "G4PhysicalConstants.hh" 40 #include "G4PhysicalConstants.hh"
40 #include "G4SystemOfUnits.hh" 41 #include "G4SystemOfUnits.hh"
41 #include "Randomize.hh" 42 #include "Randomize.hh"
42 #include "G4LorentzRotation.hh" 43 #include "G4LorentzRotation.hh"
43 #include "G4ThreeVector.hh" 44 #include "G4ThreeVector.hh"
44 #include "G4ParticleDefinition.hh" 45 #include "G4ParticleDefinition.hh"
45 #include "G4VSplitableHadron.hh" 46 #include "G4VSplitableHadron.hh"
46 #include "G4ExcitedString.hh" 47 #include "G4ExcitedString.hh"
47 48
48 #include "G4Log.hh" 49 #include "G4Log.hh"
49 #include "G4Pow.hh" <<
50 50
51 //#define debugSingleDiffraction <<
52 51
53 G4SingleDiffractiveExcitation::G4SingleDiffrac << 52 G4SingleDiffractiveExcitation::G4SingleDiffractiveExcitation(G4double sigmaPt, G4double minextraMass,G4double x0mass)
>> 53 : widthOfPtSquare(-2*sqr(sigmaPt)) , minExtraMass(minextraMass), minmass(x0mass)
>> 54 {}
54 55
55 G4SingleDiffractiveExcitation::~G4SingleDiffra << 56 G4SingleDiffractiveExcitation::~G4SingleDiffractiveExcitation()
>> 57 {}
56 58
57 G4bool G4SingleDiffractiveExcitation:: 59 G4bool G4SingleDiffractiveExcitation::
58 ExciteParticipants( G4VSplitableHadron *projec << 60 ExciteParticipants(G4VSplitableHadron *projectile, G4VSplitableHadron *target) const
59 G4bool ProjectileDiffracti <<
60 { 61 {
61 #ifdef debugSingleDiffraction <<
62 G4cout<<G4endl<<"G4SingleDiffractiveExcita <<
63 #endif <<
64 <<
65 G4LorentzVector Pprojectile=projectile->Get4 62 G4LorentzVector Pprojectile=projectile->Get4Momentum();
66 G4double Mprojectile = projectile->GetDef << 63 G4double Mprojectile2=sqr(projectile->GetDefinition()->GetPDGMass() + minExtraMass);
67 G4double Mprojectile2=sqr(projectile->GetDef <<
68 64
69 G4LorentzVector Ptarget=target->Get4Momentum 65 G4LorentzVector Ptarget=target->Get4Momentum();
70 G4double Mtarget = target->GetDefinition( << 66 G4double Mtarget2=sqr(target->GetDefinition()->GetPDGMass() + minExtraMass);
71 G4double Mtarget2=sqr(target->GetDefinition( << 67 //G4cout << "E proj, target :" << Pprojectile.e() << ", " << Ptarget.e() << G4endl;
>> 68
>> 69 G4bool KeepProjectile= G4UniformRand() > 0.5;
72 70
73 #ifdef debugSingleDiffraction << 71 // reset the min.mass of the non diffractive particle to its value, ( minus a bit for rounding...)
74 G4cout<<"Proj Targ "<<projectile->GetDefin << 72 if ( KeepProjectile )
75 G4cout<<"Pr Tr 4-Mom "<<Pprojectile<<" "<< << 73 {
76 <<" "<<Ptarget <<" "<< << 74 //cout << " Projectile fix" << G4endl;
77 #endif << 75 Mprojectile2 = sqr(projectile->GetDefinition()->GetPDGMass() * (1-perCent) );
78 << 76 } else {
79 G4LorentzVector Psum=Pprojectile+Ptarget; << 77 //cout << " Target fix" << G4endl;
80 G4double SqrtS=Psum.mag(); << 78 Mtarget2=sqr(target->GetDefinition()->GetPDGMass() * (1-perCent) );
81 G4double S =Psum.mag2(); <<
82 <<
83 #ifdef debugSingleDiffraction <<
84 G4cout<<"SqrtS-Mprojectile-Mtarget "<<Sqrt <<
85 <<" "<<SqrtS-Mprojectile-Mtarget<<G4 <<
86 #endif <<
87 if (SqrtS-Mprojectile-Mtarget <= 250.0*MeV) <<
88 #ifdef debugSingleDiffraction <<
89 G4cerr<<"Projectile: "<<projectile->GetDef <<
90 <<Pprojectile<<" "<<Pprojectile.mag( <<
91 G4cerr<<"Target: "<<target->GetDefinit <<
92 <<Ptarget<<" "<<Ptarget.mag()<<G4end <<
93 G4cerr<<"sqrt(S) = "<<SqrtS<<" Mp + Mt = " <<
94 #endif <<
95 return true; <<
96 } 79 }
97 80
>> 81 // Transform momenta to cms and then rotate parallel to z axis;
>> 82
>> 83 G4LorentzVector Psum;
>> 84 Psum=Pprojectile+Ptarget;
>> 85
98 G4LorentzRotation toCms(-1*Psum.boostVector( 86 G4LorentzRotation toCms(-1*Psum.boostVector());
99 87
100 G4LorentzVector Ptmp=toCms*Pprojectile; 88 G4LorentzVector Ptmp=toCms*Pprojectile;
101 89
102 if ( Ptmp.pz() <= 0. ) 90 if ( Ptmp.pz() <= 0. )
103 { 91 {
104 // "String" moving backwards in CMS, abor 92 // "String" moving backwards in CMS, abort collision !!
105 // G4cout << " abort Collision!! " << 93 //G4cout << " abort Collision!! " << G4endl;
106 return false; 94 return false;
107 } 95 }
108 96
109 toCms.rotateZ(-1*Ptmp.phi()); 97 toCms.rotateZ(-1*Ptmp.phi());
110 toCms.rotateY(-1*Ptmp.theta()); 98 toCms.rotateY(-1*Ptmp.theta());
111 99
>> 100 //G4cout << "Pprojectile be4 boost " << Pprojectile << G4endl;
>> 101 //G4cout << "Ptarget be4 boost : " << Ptarget << G4endl;
>> 102
112 G4LorentzRotation toLab(toCms.inverse()); 103 G4LorentzRotation toLab(toCms.inverse());
113 104
114 Pprojectile.transform(toCms); 105 Pprojectile.transform(toCms);
115 Ptarget.transform(toCms); 106 Ptarget.transform(toCms);
116 #ifdef debugSingleDiffraction <<
117 G4cout << "Pprojectile in CMS " << Pproje <<
118 G4cout << "Ptarget in CMS " << Ptarge <<
119 #endif <<
120 G4double maxPtSquare=sqr(Ptarget.pz()); <<
121 <<
122 G4double ProjectileMinDiffrMass(0.), TargetM <<
123 G4double AveragePt2(0.); <<
124 G4int absPDGcode=std::abs(projectile->GetDef <<
125 <<
126 if ( ProjectileDiffraction ) { <<
127 if ( absPDGcode > 1000 ) <<
128 { <<
129 if ( absPDGcode > 4000 && absPDGcode < 6 <<
130 { <<
131 ProjectileMinDiffrMass = projectile->G <<
132 AveragePt2 = 0.3; <<
133 } <<
134 else <<
135 { <<
136 ProjectileMinDiffrMass = 1.16; <<
137 AveragePt2 = 0.3; <<
138 } <<
139 } <<
140 else if( absPDGcode == 211 || absPDGcode = <<
141 { <<
142 ProjectileMinDiffrMass = 1.0; <<
143 AveragePt2 = 0.3; <<
144 } <<
145 else if( absPDGcode == 321 || absPDGcode = <<
146 { <<
147 ProjectileMinDiffrMass = 1.1; <<
148 AveragePt2 = 0.3; <<
149 } <<
150 else if( absPDGcode == 22) <<
151 { <<
152 ProjectileMinDiffrMass = 0.25; <<
153 AveragePt2 = 0.36; <<
154 } <<
155 else if( absPDGcode > 400 && absPDGcode < <<
156 { <<
157 ProjectileMinDiffrMass = projectile->Get <<
158 AveragePt2 = 0.3; <<
159 } <<
160 else <<
161 { <<
162 ProjectileMinDiffrMass = 1.1; <<
163 AveragePt2 = 0.3; <<
164 }; <<
165 <<
166 ProjectileMinDiffrMass = ProjectileMinDiff <<
167 Mprojectile2=sqr(ProjectileMinDiffrMass); <<
168 } <<
169 else <<
170 { <<
171 TargetMinDiffrMass = 1.16*GeV; <<
172 Mtarget2 = sqr( TargetMinDiffrMass) ; <<
173 AveragePt2 = 0.3; <<
174 } // end of if ( ProjectileDiffraction ) <<
175 <<
176 AveragePt2 = AveragePt2 * GeV*GeV; <<
177 <<
178 G4double Pt2, PZcms, PZcms2; <<
179 G4double ProjMassT2, ProjMassT; <<
180 G4double TargMassT2, TargMassT; <<
181 G4double PMinusMin, PMinusMax; <<
182 G4double TPlusMin, TPlusMax; <<
183 G4double PMinusNew, PPlusNew, TPlusNew, TMin <<
184 107
185 G4LorentzVector Qmomentum; 108 G4LorentzVector Qmomentum;
186 G4double Qminus, Qplus; <<
187 <<
188 G4int whilecount=0; 109 G4int whilecount=0;
189 do { 110 do {
190 whilecount++; << 111 // Generate pt
>> 112
>> 113 G4double maxPtSquare=sqr(Ptarget.pz());
>> 114 if (whilecount++ >= 500 && (whilecount%100)==0)
>> 115 //G4cout << "G4SingleDiffractiveExcitation::ExciteParticipants possibly looping"
>> 116 // << ", loop count/ maxPtSquare : "
>> 117 // << whilecount << " / " << maxPtSquare << G4endl;
191 118
192 if (whilecount > 1000 ) 119 if (whilecount > 1000 )
193 { 120 {
194 Qmomentum=G4LorentzVector(0.,0.,0.,0.); 121 Qmomentum=G4LorentzVector(0.,0.,0.,0.);
>> 122 //G4cout << "G4SingleDiffractiveExcitation::ExciteParticipants: Aborting loop!" << G4endl;
195 return false; // Ignore this intera 123 return false; // Ignore this interaction
196 } 124 }
197 << 125 Qmomentum=G4LorentzVector(GaussianPt(widthOfPtSquare,maxPtSquare),0);
198 // Generate pt <<
199 Qmomentum=G4LorentzVector(GaussianPt(Avera <<
200 <<
201 Pt2 = G4ThreeVector( Qmomentum.vect() ).ma <<
202 <<
203 ProjMassT2 = Mprojectile2 + Pt2; <<
204 ProjMassT = std::sqrt( ProjMassT2 ); <<
205 TargMassT2 = Mtarget2 + Pt2; <<
206 TargMassT = std::sqrt( TargMassT2 ); <<
207 <<
208 #ifdef debugSingleDiffraction <<
209 G4cout<<whilecount<<" "<<Pt2<<" "<<ProjM <<
210 #endif <<
211 if ( SqrtS < ProjMassT + TargMassT ) conti <<
212 <<
213 PZcms2 = ( S*S + ProjMassT2*ProjMassT2 + T <<
214 - 2.0*S*ProjMassT2 - 2.0*S*TargM <<
215 <<
216 if ( PZcms2 < 0 ) continue; <<
217 <<
218 PZcms = std::sqrt( PZcms2 ); <<
219 <<
220 if ( ProjectileDiffraction ) <<
221 { // The projectile will fragment, t <<
222 PMinusMin = std::sqrt( ProjMassT2 + PZcm <<
223 PMinusMax = SqrtS - TargMassT; <<
224 <<
225 PMinusNew = ChooseX( PMinusMin, PMinusMa <<
226 TMinusNew = SqrtS - PMinusNew; <<
227 126
228 Qminus = Ptarget.minus() - TMinusNew; << 127 // Momentum transfer
229 TPlusNew = TargMassT2 / TMinusNew; << 128 G4double Xmin = minmass / ( Pprojectile.e() + Ptarget.e() );
230 Qplus = Ptarget.plus() - TPlusNew; << 129 G4double Xmax=1.;
>> 130 G4double Xplus =ChooseX(Xmin,Xmax);
>> 131 G4double Xminus=ChooseX(Xmin,Xmax);
>> 132
>> 133 G4double pt2=G4ThreeVector(Qmomentum.vect()).mag2();
>> 134 G4double Qplus =-1 * pt2 / Xminus/Ptarget.minus();
>> 135 G4double Qminus= pt2 / Xplus /Pprojectile.plus();
>> 136
>> 137 if ( KeepProjectile )
>> 138 {
>> 139 Qminus = (sqr(projectile->GetDefinition()->GetPDGMass()) + pt2 )
>> 140 / (Pprojectile.plus() + Qplus ) - Pprojectile.minus();
>> 141 } else {
>> 142 Qplus = Ptarget.plus() - (sqr(target->GetDefinition()->GetPDGMass()) + pt2 )
>> 143 / (Ptarget.minus() - Qminus );
>> 144 }
>> 145
>> 146 Qmomentum.setPz( (Qplus-Qminus)/2 );
>> 147 Qmomentum.setE( (Qplus+Qminus)/2 );
>> 148
>> 149 //G4cout << "Qplus / Qminus " << Qplus << " / " << Qminus<<G4endl;
>> 150 //G4cout << "pt2 " << pt2 << G4endl;
>> 151 //G4cout << "Qmomentum " << Qmomentum << G4endl;
>> 152 //G4cout << " Masses (P/T) : " << (Pprojectile+Qmomentum).mag() <<
>> 153 // " / " << (Ptarget-Qmomentum).mag() << G4endl;
>> 154
>> 155 } while ( (Ptarget-Qmomentum).mag2() <= Mtarget2 /* Loop checking, 26.10.2015, A.Ribon */
>> 156 || (Pprojectile+Qmomentum).mag2() <= Mprojectile2
>> 157 || (Ptarget-Qmomentum).e() < 0.
>> 158 || (Pprojectile+Qmomentum).e() < 0. );
231 159
232 } else { // The target will fragment, the << 160 //G4double Ecms=Pprojectile.e() + Ptarget.e();
233 TPlusMin = std::sqrt( TargMassT2 + PZcms <<
234 TPlusMax = SqrtS - ProjMassT; <<
235 <<
236 TPlusNew = ChooseX( TPlusMin, TPlusMax ) <<
237 PPlusNew = SqrtS - TPlusNew; <<
238 <<
239 Qplus = PPlusNew - Pprojectile.plus(); <<
240 PMinusNew = ProjMassT2 / PPlusNew; <<
241 Qminus = PMinusNew - Pprojectile.minus() <<
242 } <<
243 <<
244 Qmomentum.setPz( (Qplus - Qminus)/2 ); <<
245 Qmomentum.setE( (Qplus + Qminus)/2 ); <<
246 <<
247 #ifdef debugSingleDiffraction <<
248 G4cout<<ProjectileDiffraction<<" "<<( Pp <<
249 G4cout<<!ProjectileDiffraction<<" "<<( P <<
250 #endif <<
251 <<
252 } while ( ( ProjectileDiffraction&&( Pprojec <<
253 (!ProjectileDiffraction&&( Ptarget <<
254 // Repeat the sampling because there was n <<
255 161
256 Pprojectile += Qmomentum; 162 Pprojectile += Qmomentum;
257 <<
258 Ptarget -= Qmomentum; 163 Ptarget -= Qmomentum;
259 164
>> 165 //G4cout << "Pprojectile.e() : " << Pprojectile.e() << G4endl;
>> 166 //G4cout << "Ptarget.e() : " << Ptarget.e() << G4endl;
>> 167 //G4cout << "end event_______________________________________________"<<G4endl;
>> 168 //G4cout << "Pprojectile with Q : " << Pprojectile << G4endl;
>> 169 //G4cout << "Ptarget with Q : " << Ptarget << G4endl;
>> 170 //G4cout << "Projectile back: " << toLab * Pprojectile << G4endl;
>> 171 //G4cout << "Target back: " << toLab * Ptarget << G4endl;
>> 172
260 // Transform back and update SplitableHadron 173 // Transform back and update SplitableHadron Participant.
261 Pprojectile.transform(toLab); 174 Pprojectile.transform(toLab);
262 Ptarget.transform(toLab); 175 Ptarget.transform(toLab);
263 176
264 #ifdef debugSingleDiffraction << 177 //G4cout << "G4SingleDiffractiveExcitation- Target mass " << Ptarget.mag() << G4endl;
265 G4cout << "Pprojectile in Lab. " << Pproj << 178 //G4cout << "G4SingleDiffractiveExcitation- Projectile mass " << Pprojectile.mag() << G4endl;
266 G4cout << "Ptarget in Lab. " << Ptarg <<
267 G4cout << "G4SingleDiffractiveExcitation- <<
268 G4cout << "G4SingleDiffractiveExcitation- <<
269 #endif <<
270 179
271 target->Set4Momentum(Ptarget); 180 target->Set4Momentum(Ptarget);
272 projectile->Set4Momentum(Pprojectile); 181 projectile->Set4Momentum(Pprojectile);
273 182
274 return true; 183 return true;
275 } 184 }
276 185
>> 186
277 // --------- private methods ----------------- 187 // --------- private methods ----------------------
278 188
279 G4double G4SingleDiffractiveExcitation::Choose 189 G4double G4SingleDiffractiveExcitation::ChooseX(G4double Xmin, G4double Xmax) const
280 { 190 {
281 // choose an x between Xmin and Xmax with P( 191 // choose an x between Xmin and Xmax with P(x) ~ 1/x
>> 192 // to be improved...
>> 193
282 G4double range=Xmax-Xmin; 194 G4double range=Xmax-Xmin;
283 195
284 if ( Xmin <= 0. || range <=0. ) 196 if ( Xmin <= 0. || range <=0. )
285 { 197 {
286 G4cout << " Xmin, range : " << Xmin << " , 198 G4cout << " Xmin, range : " << Xmin << " , " << range << G4endl;
287 throw G4HadronicException(__FILE__, __LINE 199 throw G4HadronicException(__FILE__, __LINE__, "G4SingleDiffractiveExcitation::ChooseX : Invalid arguments ");
288 } 200 }
289 201
290 G4double x = Xmin*G4Pow::GetInstance()->powA << 202 G4double x;
291 // G4double x = 1.0/sqr(1.0/std::sqrt(Xmin) << 203 do {
>> 204 x=Xmin + G4UniformRand() * range;
>> 205 } while ( Xmin/x < G4UniformRand() ); /* Loop checking, 26.10.2015, A.Ribon */
>> 206
>> 207 //cout << "DiffractiveX "<<x<<G4endl;
292 return x; 208 return x;
293 } 209 }
294 210
295 <<
296 G4ThreeVector G4SingleDiffractiveExcitation::G 211 G4ThreeVector G4SingleDiffractiveExcitation::GaussianPt(G4double widthSquare, G4double maxPtSquare) const
297 { // @@ this method is used in FTF << 212 {
>> 213 // @@ this method is used in FTFModel as well. Should go somewhere common!
298 214
299 G4double pt2; 215 G4double pt2;
300 216
301 const G4int maxNumberOfLoops = 1000; 217 const G4int maxNumberOfLoops = 1000;
302 G4int loopCounter = 0; << 218 G4int loopCounter = -1;
303 do { 219 do {
304 pt2=-widthSquare * G4Log( G4UniformRand() << 220 pt2=widthSquare * G4Log( G4UniformRand() );
305 } while ( ( pt2 > maxPtSquare) && ++loopCoun << 221 } while ( ( pt2 > maxPtSquare) && ++loopCounter < maxNumberOfLoops ); /* Loop checking, 26.10.2015, A.Ribon */
306 if ( loopCounter >= maxNumberOfLoops ) { << 222 if ( loopCounter >= maxNumberOfLoops ) pt2 = 0.0;
307 pt2 = 0.99*maxPtSquare; // Just an accept <<
308 } <<
309 223
310 pt2=std::sqrt(pt2); 224 pt2=std::sqrt(pt2);
311 225
312 G4double phi=G4UniformRand() * twopi; 226 G4double phi=G4UniformRand() * twopi;
313 227
314 return G4ThreeVector (pt2*std::cos(phi), pt2 228 return G4ThreeVector (pt2*std::cos(phi), pt2*std::sin(phi), 0.);
315 } 229 }
316 230
317 231