Geant4 9.6.0
Toolkit for the simulation of the passage of particles through matter
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Public Member Functions | List of all members
G4ScreeningMottCrossSection Class Reference

#include <G4ScreeningMottCrossSection.hh>

Public Member Functions

 G4ScreeningMottCrossSection ()
 
virtual ~G4ScreeningMottCrossSection ()
 
void Initialise (const G4ParticleDefinition *, G4double cosThetaLim)
 
G4double GetScreeningAngle ()
 
void SetScreeningCoefficient ()
 
void SetupParticle (const G4ParticleDefinition *)
 
void SetupKinematic (G4double kinEnergy, G4double Z)
 
G4double NuclearCrossSection ()
 
G4ThreeVector GetNewDirection ()
 
G4double GetMom2CM () const
 
G4double GetMom2Lab () const
 
G4double GetTrec () const
 
G4double GetScreeningCoefficient () const
 
G4double GetTotalCross () const
 
G4double McFcorrection (G4double)
 
G4double RatioMottRutherford (G4double)
 
G4double FormFactor2ExpHof (G4double)
 
G4double GetScatteringAngle ()
 
G4double AngleDistribution (G4double)
 

Detailed Description

Definition at line 86 of file G4ScreeningMottCrossSection.hh.

Constructor & Destructor Documentation

◆ G4ScreeningMottCrossSection()

G4ScreeningMottCrossSection::G4ScreeningMottCrossSection ( )

Definition at line 83 of file G4ScreeningMottCrossSection.cc.

83 :
84 cosThetaMin(1.0),
85 cosThetaMax(-1.0),
86 alpha(fine_structure_const),
87 htc2(hbarc_squared),
88 e2(electron_mass_c2*classic_electr_radius)
89{
90
91 TotalCross=0;
92
93 fNistManager = G4NistManager::Instance();
94 particle=0;
95
96 spin = mass = mu_rel=0;
97 tkinLab = momLab2 = invbetaLab2=0;
98 tkin = mom2 = invbeta2=beta=gamma=0;
99
100 Trec=targetZ = targetMass = As =0;
101 etag = ecut = 0.0;
102
103 targetA = 0;
104
105 cosTetMinNuc=0;
106 cosTetMaxNuc=0;
107
108 for(G4int i=0 ; i<5; i++){
109 for(G4int j=0; j< 6; j++){
110 coeffb[i][j]=0;
111 }
112 }
113
114
115
116
117}
G4int
int G4int
Definition: G4Types.hh:66
G4NistManager::Instance
static G4NistManager * Instance()
Definition: G4NistManager.cc:68

◆ ~G4ScreeningMottCrossSection()

G4ScreeningMottCrossSection::~G4ScreeningMottCrossSection ( )
virtual

Definition at line 120 of file G4ScreeningMottCrossSection.cc.

121{}

Member Function Documentation

◆ AngleDistribution()

G4double G4ScreeningMottCrossSection::AngleDistribution ( G4double  anglein)

Definition at line 393 of file G4ScreeningMottCrossSection.cc.

393 {
394
395
396 G4double total=TotalCross ;
397 G4double fatt= e2*targetZ/(mu_rel*gamma*beta*beta);
398 G4double fatt2=fatt*fatt;
399 total/=fatt2;
400
401 G4double R=0;
402 if (coeffb[0][0]!=0){
403 // cout<<" Mott....targetZ "<< targetZ<<endl;
404 R=RatioMottRutherford(anglein);
405 }
406
407 else if (coeffb[0][0]==0){
408 // cout<<" McF.... targetZ "<< targetZ<<endl;
409 R=McFcorrection(anglein);
410 }
411
412
413 G4double y=2.*pi*sin(anglein)*R*FormFactor2ExpHof(anglein)/
414 ((2*As+2.*pow(sin(anglein/2.),2.))*(2.*As+2.*pow(sin(anglein/2.),2.) ));
415
416return y/total;
417
418}
G4double
double G4double
Definition: G4Types.hh:64
G4INCL::Math::pi
const G4double pi
Definition: G4INCLGlobals.hh:70

Referenced by GetScatteringAngle().

◆ FormFactor2ExpHof()

G4double G4ScreeningMottCrossSection::FormFactor2ExpHof ( G4double  angle)

Definition at line 237 of file G4ScreeningMottCrossSection.cc.

237 {
238
239
240 G4double M=targetMass;
241 G4double E=tkinLab;
242 G4double Etot=E+mass;
243 G4double Tmax=2.*M*E*(E+2.*mass)/(mass*mass+M*M+2.*M*Etot);
244 G4double T=Tmax*pow(sin(angle/2.),2.);
245 G4double q2=T*(T+2.*M);
246 q2/=htc2;//1/cm2
247 G4double RN=1.27e-13*pow(targetA,0.27)*cm;
248 G4double xN= (RN*RN*q2);
249 G4double den=(1.+xN/12.);
250 G4double FN=1./(den*den);
251 G4double form2=(FN*FN);
252
253
254 return form2;
255
256//cout<<"..................... form2 "<< form2<<endl;
257}

Referenced by AngleDistribution(), and NuclearCrossSection().

◆ GetMom2CM()

G4double G4ScreeningMottCrossSection::GetMom2CM ( ) const
inline

Definition at line 195 of file G4ScreeningMottCrossSection.hh.

196{
197 return mom2;
198}

◆ GetMom2Lab()

G4double G4ScreeningMottCrossSection::GetMom2Lab ( ) const
inline

Definition at line 202 of file G4ScreeningMottCrossSection.hh.

203{
204 return momLab2;
205}

Referenced by G4eSingleCoulombScatteringModel::SampleSecondaries().

◆ GetNewDirection()

G4ThreeVector G4ScreeningMottCrossSection::GetNewDirection ( )

Definition at line 496 of file G4ScreeningMottCrossSection.cc.

496 {
497
498G4ThreeVector dir(0.0,0.0,1.0);
499
500
501 G4double z1=GetScatteringAngle();
502
503 G4double cost = cos(z1);
504 G4double sint = sin(z1);
505 G4double phi = twopi* G4UniformRand();
506 G4double dirx = sint*cos(phi);
507 G4double diry = sint*sin(phi);
508 G4double dirz = cost;
509
510
511 //.......set Trc
512 G4double etot=tkinLab+mass;
513 G4double mass2=targetMass;
514 Trec=(1.0 - cost)* mass2*(etot*etot - mass*mass )/
515 (mass*mass + mass2*mass2+ 2.*mass2*etot);
516
517
518
519 dir.set(dirx,diry,dirz);
520
521
522
523
524return dir;
525
526}
G4UniformRand
#define G4UniformRand()
Definition: Randomize.hh:53

Referenced by G4eSingleCoulombScatteringModel::SampleSecondaries().

◆ GetScatteringAngle()

G4double G4ScreeningMottCrossSection::GetScatteringAngle ( )

Definition at line 422 of file G4ScreeningMottCrossSection.cc.

423{
424
425
426//cout<<" G4ScreeningMottCrossSection::SampleCosineTheta ............."<<endl;
427
428 if(cosTetMaxNuc >= cosTetMinNuc) return 0.0;
429
430 G4double anglemin=std::acos(cosTetMinNuc);
431 G4double anglemax= std::acos(cosTetMaxNuc);
432
433 const G4double limit = 1.e-9;
434 if(anglemin < limit) {
435 anglemin = GetScreeningAngle()/10.;
436 if(anglemin < limit) { anglemin = limit; }
437 }
438
439// cout<<"................ tkinLab "<< G4BestUnit(tkinLab,"Energy") << " anglemin= "<<anglemin<<endl;
440 //cout<<"anglemax= "<<anglemax<<endl;
441 G4double r =G4UniformRand();
442
443 G4double loganglemin=log10(anglemin);
444 G4double loganglemax=log10(anglemax);
445 G4double logdangle=0.01;
446
447 G4int bins=(G4int)((loganglemax-loganglemin)/logdangle);
448
449 std::vector<G4double> angle;
450 std::vector<G4double> tet;
451 std::vector<G4double> dangle;
452
453 for(G4int i=0; i<=bins; i++ ){
454 tet.push_back(0);
455 dangle.push_back(0);
456 angle.push_back(pow(10.,loganglemin+logdangle*i));
457 }
458
459
460 G4int dim = tet.size();
461 G4double scattangle=0;
462 G4double y=0;
463 G4double dy=0;
464 G4double area=0;
465
466 for(G4int i=0; i<dim;i++){
467
468 if(i!=dim-1){
469 dangle[i]=(angle[i+1]-angle[i]);
470 tet[i]=(angle[i+1]+angle[i])/2.;
471 }else if(i==dim-1){
472 break;
473 }
474
475 y+=AngleDistribution(tet[i])*dangle[i];
476 dy= y-area ;
477 area=y;
478
479 if(r >=y-dy && r<=y+dy ){
480 scattangle= angle[i] +G4UniformRand()*dangle[i];
481 //cout<<"y "<<y <<" r "<< r << " y/r "<<y/r << endl;
482 break;
483
484 }
485
486 }
487
488
489 return scattangle;
490
491
492}

Referenced by GetNewDirection().

◆ GetScreeningAngle()

G4double G4ScreeningMottCrossSection::GetScreeningAngle ( )

Definition at line 157 of file G4ScreeningMottCrossSection.cc.

157 {
158
159 SetScreeningCoefficient();
160
161 //cout<<" As "<<As<<endl;
162 if(As < 0.0) { As = 0.0; }
163 else if(As > 1.0) { As = 1.0; }
164
165 G4double screenangle=2.*asin(sqrt(As));
166
167 // cout<<" screenangle "<< screenangle <<endl;
168
169 if(screenangle>=pi) screenangle=pi;
170
171
172return screenangle;
173
174}

Referenced by GetScatteringAngle(), NuclearCrossSection(), and SetupKinematic().

◆ GetScreeningCoefficient()

G4double G4ScreeningMottCrossSection::GetScreeningCoefficient ( ) const
inline

Definition at line 217 of file G4ScreeningMottCrossSection.hh.

218{
219 return As;
220}

◆ GetTotalCross()

G4double G4ScreeningMottCrossSection::GetTotalCross ( ) const
inline

Definition at line 225 of file G4ScreeningMottCrossSection.hh.

226{
227 return TotalCross;
228}

Referenced by G4eSingleCoulombScatteringModel::SampleSecondaries().

◆ GetTrec()

G4double G4ScreeningMottCrossSection::GetTrec ( ) const
inline

Definition at line 210 of file G4ScreeningMottCrossSection.hh.

211{
212 return Trec;
213}

Referenced by G4eSingleCoulombScatteringModel::SampleSecondaries().

◆ Initialise()

void G4ScreeningMottCrossSection::Initialise ( const G4ParticleDefinition *  p,
G4double  cosThetaLim 
)

Definition at line 124 of file G4ScreeningMottCrossSection.cc.

126{
127
128 SetupParticle(p);
129 tkin = targetZ = mom2 = DBL_MIN;
130 ecut = etag = DBL_MAX;
131 particle = p;
132 cosThetaMin = CosThetaLim;
133
134}
G4ScreeningMottCrossSection::SetupParticle
void SetupParticle(const G4ParticleDefinition *)
Definition: G4ScreeningMottCrossSection.hh:184
DBL_MIN
#define DBL_MIN
Definition: templates.hh:75
DBL_MAX
#define DBL_MAX
Definition: templates.hh:83

Referenced by G4eSingleCoulombScatteringModel::Initialise().

◆ McFcorrection()

G4double G4ScreeningMottCrossSection::McFcorrection ( G4double  angle)

Definition at line 261 of file G4ScreeningMottCrossSection.cc.

261 {
262
263
264 G4double beta2=1./invbeta2;
265 G4double sintmezzi=std::sin(angle/2.);
266 G4double sin2tmezzi = sintmezzi*sintmezzi;
267 G4double R=1.-beta2*sin2tmezzi + targetZ*alpha*beta*pi*sintmezzi*(1.-sintmezzi);
268
269
270return R;
271}

Referenced by AngleDistribution(), and NuclearCrossSection().

◆ NuclearCrossSection()

G4double G4ScreeningMottCrossSection::NuclearCrossSection ( )

Definition at line 303 of file G4ScreeningMottCrossSection.cc.

304{
305 if(cosTetMaxNuc >= cosTetMinNuc) return 0.0;
306
307 TotalCross=0;
308
309 G4double anglemin =std::acos(cosTetMinNuc);
310 G4double anglemax =std::acos(cosTetMaxNuc);
311
312 const G4double limit = 1.e-9;
313 if(anglemin < limit) {
314 anglemin = GetScreeningAngle()/10.;
315 if(anglemin < limit) { anglemin = limit; }
316 }
317
318 //cout<<" anglemin "<< anglemin <<endl;
319
320 G4double loganglemin=log10(anglemin);
321 G4double loganglemax=log10(anglemax);
322 G4double logdangle=0.01;
323
324 G4int bins=(G4int)((loganglemax-loganglemin)/logdangle);
325
326
327 vector<G4double> angle;
328 vector<G4double> tet;
329 vector<G4double> dangle;
330 vector<G4double> cross;
331
332 for(G4int i=0; i<=bins; i++ ){
333 tet.push_back(0);
334 dangle.push_back(0);
335 angle.push_back(pow(10.,loganglemin+logdangle*i));
336 cross.push_back(0);
337 }
338
339
340 G4int dim = tet.size();
341 //cout<<"dim--- "<<dim<<endl;
342
343
344 for(G4int i=0; i<dim;i++){
345
346 if(i!=dim-1){
347 dangle[i]=(angle[i+1]-angle[i]);
348 tet[i]=(angle[i+1]+angle[i])/2.;
349 }else if(i==dim-1){
350 break;
351 }
352
353
354 G4double R=0;
355 G4double F2=FormFactor2ExpHof(tet[i]);
356
357 if (coeffb[0][0]!=0){
358 //cout<<" Mott....targetZ "<< targetZ<<endl;
359 R=RatioMottRutherford(tet[i]);
360 }
361
362 else if (coeffb[0][0]==0){
363 // cout<<" McF.... targetZ "<< targetZ<<endl;
364 R=McFcorrection(tet[i]);
365 }
366
367
368//cout<<"----------------- R "<<R<<" F2 "<<F2<<endl;
369
370
371// cout<<"angle "<<tet[i] << " F2 "<<F2<<endl;
372
373 G4double e4=e2*e2;
374 G4double den=2.*As+2.*pow(sin(tet[i]/2.),2.);
375 G4double func=1./(den*den);
376
377 G4double fatt= targetZ/(mu_rel*gamma*beta*beta);
378 G4double sigma=e4*fatt*fatt*func;
379 cross[i]=F2*R*sigma;
380 G4double pi2sintet=2.*pi*sin(tet[i]);
381
382 TotalCross+=pi2sintet*cross[i]*dangle[i];
383 }//end integral
384
385
386//cout<< "ok ......... TotalCross "<<TotalCross<<endl;
387
388
389return TotalCross;
390
391}

Referenced by G4eSingleCoulombScatteringModel::ComputeCrossSectionPerAtom().

◆ RatioMottRutherford()

G4double G4ScreeningMottCrossSection::RatioMottRutherford ( G4double  angle)

Definition at line 273 of file G4ScreeningMottCrossSection.cc.

273 {
274
275
276 G4double R=0;
277 G4double fcost=std::sqrt((1. -cos(angle)));
278 G4double a[5];
279 G4double shift=0.7181228;
280 G4double beta0= beta -shift;
281
282 for(G4int j=0 ;j<=4;j++){
283 a[j]=0;
284 }
285
286 for(G4int j=0 ;j<=4;j++){
287 for(G4int k=0;k<=5;k++ ){
288 a[j]+=coeffb[j][k]*pow(beta0,k);
289 }
290 }
291
292 for(G4int j=0 ;j<=4 ;j++){
293 R+=a[j]* pow(fcost,j);
294 }
295
296
297
298return R;
299
300}

Referenced by AngleDistribution(), and NuclearCrossSection().

◆ SetScreeningCoefficient()

void G4ScreeningMottCrossSection::SetScreeningCoefficient ( )

Definition at line 136 of file G4ScreeningMottCrossSection.cc.

136 {
137
138 G4double alpha2=alpha*alpha;
139 //Bohr radius
140 G4double a0= Bohr_radius ;//0.529e-8*cm;
141 //Thomas-Fermi screening length
142 G4double aU=0.88534*a0/pow(targetZ,1./3.);
143 G4double twoR2=aU*aU;
144
145 G4double factor= 1.13 + 3.76*targetZ*targetZ*invbeta2*alpha2;
146 As=0.25*(htc2)/(twoR2*mom2)*factor;
147
148
149
150
151//cout<<"0k .........................As "<<As<<endl;
152
153}

Referenced by GetScreeningAngle().

◆ SetupKinematic()

void G4ScreeningMottCrossSection::SetupKinematic ( G4double  kinEnergy,
G4double  Z 
)

Definition at line 177 of file G4ScreeningMottCrossSection.cc.

178{
179
180 //...Target
181 G4int iz = G4int(Z);
182 G4double A = fNistManager->GetAtomicMassAmu(iz);
183 G4int ia = G4int(A);
184 G4double mass2 = G4NucleiProperties::GetNuclearMass(ia, iz);
185
186 targetZ = Z;
187 targetA = fNistManager->GetAtomicMassAmu(iz);
188 targetMass= mass2;
189
190 mottcoeff->SetMottCoeff(targetZ, coeffb);
191
192 //cout<<"......... targetA "<< targetA <<endl;
193 //cout<<"......... targetMass "<< targetMass/MeV <<endl;
194
195 // incident particle lab
196 tkinLab = ekin;
197 momLab2 = tkinLab*(tkinLab + 2.0*mass);
198 invbetaLab2 = 1.0 + mass*mass/momLab2;
199
200 G4double etot = tkinLab + mass;
201 G4double ptot = sqrt(momLab2);
202 G4double m12 = mass*mass;
203
204
205 // relativistic reduced mass from publucation
206 // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
207
208 //incident particle & target nucleus
209 G4double Ecm=sqrt(m12 + mass2*mass2 + 2.0*etot*mass2);
210 mu_rel=mass*mass2/Ecm;
211 G4double momCM= ptot*mass2/Ecm;
212 // relative system
213 mom2 = momCM*momCM;
214 invbeta2 = 1.0 + mu_rel*mu_rel/mom2;
215 tkin = momCM*sqrt(invbeta2) - mu_rel;//Ekin of mu_rel
216 G4double beta2=1./invbeta2;
217 beta=std::sqrt(beta2) ;
218 G4double gamma2= 1./(1.-beta2);
219 gamma=std::sqrt(gamma2);
220
221
222
223 //.........................................................
224
225
226 G4double screenangle=GetScreeningAngle()/10.;
227 //cout<<" screenangle [rad] "<<screenangle/rad <<endl;
228
229 cosTetMinNuc =min( cosThetaMin ,cos(screenangle));
230 cosTetMaxNuc =cosThetaMax;
231
232//cout<<"ok..............mu_rel "<<mu_rel<<endl;
233
234}
G4MottCoefficients::SetMottCoeff
void SetMottCoeff(G4double targetZ, G4double coeff[5][6])
Definition: G4MottCoefficients.cc:81
G4NistManager::GetAtomicMassAmu
G4double GetAtomicMassAmu(const G4String &symb) const
Definition: G4NistManager.hh:343
G4NucleiProperties::GetNuclearMass
static G4double GetNuclearMass(const G4double A, const G4double Z)
Definition: G4NucleiProperties.cc:53

Referenced by G4eSingleCoulombScatteringModel::ComputeCrossSectionPerAtom().

◆ SetupParticle()

void G4ScreeningMottCrossSection::SetupParticle ( const G4ParticleDefinition *  p)
inline

Definition at line 184 of file G4ScreeningMottCrossSection.hh.

185{
186 particle = p;
187 mass = particle->GetPDGMass();
188 spin = particle->GetPDGSpin();
189 if(0.0 != spin) { spin = 0.5; }
190 tkin = 0.0;
191}

Referenced by Initialise(), and G4eSingleCoulombScatteringModel::SetupParticle().

The documentation for this class was generated from the following files: