source: trunk/source/processes/electromagnetic/xrays/src/G4SynchrotronRadiation.cc@ 1347

Last change on this file since 1347 was 1340, checked in by garnier, 15 years ago

update ti head
File size: 15.3 KB
Line 
1//
2// ********************************************************************
3// * License and Disclaimer *
4// * *
5// * The Geant4 software is copyright of the Copyright Holders of *
6// * the Geant4 Collaboration. It is provided under the terms and *
7// * conditions of the Geant4 Software License, included in the file *
8// * LICENSE and available at http://cern.ch/geant4/license . These *
9// * include a list of copyright holders. *
10// * *
11// * Neither the authors of this software system, nor their employing *
12// * institutes,nor the agencies providing financial support for this *
13// * work make any representation or warranty, express or implied, *
14// * regarding this software system or assume any liability for its *
15// * use. Please see the license in the file LICENSE and URL above *
16// * for the full disclaimer and the limitation of liability. *
17// * *
18// * This code implementation is the result of the scientific and *
19// * technical work of the GEANT4 collaboration. *
20// * By using, copying, modifying or distributing the software (or *
21// * any work based on the software) you agree to acknowledge its *
22// * use in resulting scientific publications, and indicate your *
23// * acceptance of all terms of the Geant4 Software license. *
24// ********************************************************************
25//
26//
27// $Id: G4SynchrotronRadiation.cc,v 1.8 2010/10/14 18:38:21 vnivanch Exp $
28// GEANT4 tag $Name: xrays-V09-03-05 $
29//
30// --------------------------------------------------------------
31// GEANT 4 class implementation file
32// CERN Geneva Switzerland
33//
34// History: first implementation,
35// 21-5-98 V.Grichine
36// 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation
37// 04.03.05, V.Grichine: get local field interface
38// 18-05-06 H. Burkhardt: Energy spectrum from function rather than table
39//
40//
41//
42//
43///////////////////////////////////////////////////////////////////////////
44
45#include "G4SynchrotronRadiation.hh"
46#include "G4UnitsTable.hh"
47#include "G4EmProcessSubType.hh"
48
49///////////////////////////////////////////////////////////////////////
50//
51// Constructor
52//
53
54G4SynchrotronRadiation::G4SynchrotronRadiation(const G4String& processName,
55 G4ProcessType type):G4VDiscreteProcess (processName, type),
56 theGamma (G4Gamma::Gamma() ),
57 theElectron ( G4Electron::Electron() ),
58 thePositron ( G4Positron::Positron() )
59{
60 G4TransportationManager* transportMgr =
61 G4TransportationManager::GetTransportationManager();
62
63 fFieldPropagator = transportMgr->GetPropagatorInField();
64
65 fLambdaConst = std::sqrt(3.0)*electron_mass_c2/
66 (2.5*fine_structure_const*eplus*c_light) ;
67 fEnergyConst = 1.5*c_light*c_light*eplus*hbar_Planck/electron_mass_c2 ;
68
69 SetProcessSubType(fSynchrotronRadiation);
70 verboseLevel=1;
71}
72
73/////////////////////////////////////////////////////////////////////////
74//
75// Destructor
76//
77
78G4SynchrotronRadiation::~G4SynchrotronRadiation()
79{}
80
81/////////////////////////////// METHODS /////////////////////////////////
82//
83//
84// Production of synchrotron X-ray photon
85// GEANT4 internal units.
86//
87
88
89G4double
90G4SynchrotronRadiation::GetMeanFreePath( const G4Track& trackData,
91 G4double,
92 G4ForceCondition* condition)
93{
94 // gives the MeanFreePath in GEANT4 internal units
95 G4double MeanFreePath;
96
97 const G4DynamicParticle* aDynamicParticle = trackData.GetDynamicParticle();
98
99 *condition = NotForced ;
100
101 G4double gamma = aDynamicParticle->GetTotalEnergy()/
102 aDynamicParticle->GetMass();
103
104 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
105
106 if ( gamma < 1.0e3 ) MeanFreePath = DBL_MAX;
107 else
108 {
109
110 G4ThreeVector FieldValue;
111 const G4Field* pField = 0;
112
113 G4FieldManager* fieldMgr=0;
114 G4bool fieldExertsForce = false;
115
116 if( (particleCharge != 0.0) )
117 {
118 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
119
120 if ( fieldMgr != 0 )
121 {
122 // If the field manager has no field, there is no field !
123
124 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
125 }
126 }
127 if ( fieldExertsForce )
128 {
129 pField = fieldMgr->GetDetectorField() ;
130 G4ThreeVector globPosition = trackData.GetPosition();
131
132 G4double globPosVec[3], FieldValueVec[3];
133
134 globPosVec[0] = globPosition.x();
135 globPosVec[1] = globPosition.y();
136 globPosVec[2] = globPosition.z();
137
138 pField->GetFieldValue( globPosVec, FieldValueVec );
139
140 FieldValue = G4ThreeVector( FieldValueVec[0],
141 FieldValueVec[1],
142 FieldValueVec[2] );
143
144
145
146 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
147 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum) ;
148 G4double perpB = unitMcrossB.mag() ;
149
150 if( perpB > 0.0 ) MeanFreePath = fLambdaConst/perpB;
151 else MeanFreePath = DBL_MAX;
152
153 static G4bool FirstTime=true;
154 if(verboseLevel > 0 && FirstTime)
155 {
156 G4cout << "G4SynchrotronRadiation::GetMeanFreePath :" << '\n' << std::setprecision(4)
157 << " MeanFreePath = " << G4BestUnit(MeanFreePath, "Length")
158 << G4endl;
159 if(verboseLevel > 1)
160 {
161 G4ThreeVector pvec=aDynamicParticle->GetMomentum();
162 G4double Btot=FieldValue.getR();
163 G4double ptot=pvec.getR();
164 G4double rho= ptot / (MeV * c_light * Btot ); // full bending radius
165 G4double Theta=unitMomentum.theta(FieldValue); // angle between particle and field
166 G4cout
167 << " B = " << Btot/tesla << " Tesla"
168 << " perpB = " << perpB/tesla << " Tesla"
169 << " Theta = " << Theta << " std::sin(Theta)=" << std::sin(Theta) << '\n'
170 << " ptot = " << G4BestUnit(ptot,"Energy")
171 << " rho = " << G4BestUnit(rho,"Length")
172 << G4endl;
173 }
174 FirstTime=false;
175 }
176 }
177 else MeanFreePath = DBL_MAX;
178
179
180 }
181
182 return MeanFreePath;
183}
184
185////////////////////////////////////////////////////////////////////////////////
186//
187//
188
189G4VParticleChange*
190G4SynchrotronRadiation::PostStepDoIt(const G4Track& trackData,
191 const G4Step& stepData )
192
193{
194 aParticleChange.Initialize(trackData);
195
196 const G4DynamicParticle* aDynamicParticle=trackData.GetDynamicParticle();
197
198 G4double gamma = aDynamicParticle->GetTotalEnergy()/
199 (aDynamicParticle->GetMass() );
200
201 if(gamma <= 1.0e3 )
202 {
203 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
204 }
205 G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
206
207 G4ThreeVector FieldValue;
208 const G4Field* pField = 0 ;
209
210 G4FieldManager* fieldMgr=0;
211 G4bool fieldExertsForce = false;
212
213 if( (particleCharge != 0.0) )
214 {
215 fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
216 if ( fieldMgr != 0 )
217 {
218 // If the field manager has no field, there is no field !
219
220 fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
221 }
222 }
223 if ( fieldExertsForce )
224 {
225 pField = fieldMgr->GetDetectorField() ;
226 G4ThreeVector globPosition = trackData.GetPosition() ;
227 G4double globPosVec[3], FieldValueVec[3] ;
228 globPosVec[0] = globPosition.x() ;
229 globPosVec[1] = globPosition.y() ;
230 globPosVec[2] = globPosition.z() ;
231
232 pField->GetFieldValue( globPosVec, FieldValueVec ) ;
233 FieldValue = G4ThreeVector( FieldValueVec[0],
234 FieldValueVec[1],
235 FieldValueVec[2] );
236
237 G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
238 G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum);
239 G4double perpB = unitMcrossB.mag() ;
240 if(perpB > 0.0)
241 {
242 // M-C of synchrotron photon energy
243
244 G4double energyOfSR = GetRandomEnergySR(gamma,perpB);
245
246 // check against insufficient energy
247
248 if( energyOfSR <= 0.0 )
249 {
250 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
251 }
252 G4double kineticEnergy = aDynamicParticle->GetKineticEnergy();
253 G4ParticleMomentum
254 particleDirection = aDynamicParticle->GetMomentumDirection();
255
256 // M-C of its direction
257
258 G4double Teta = G4UniformRand()/gamma ; // Very roughly
259
260 G4double Phi = twopi * G4UniformRand() ;
261
262 G4double dirx = std::sin(Teta)*std::cos(Phi) ,
263 diry = std::sin(Teta)*std::sin(Phi) ,
264 dirz = std::cos(Teta) ;
265
266 G4ThreeVector gammaDirection ( dirx, diry, dirz);
267 gammaDirection.rotateUz(particleDirection);
268
269 // polarization of new gamma
270
271 // G4double sx = std::cos(Teta)*std::cos(Phi);
272 // G4double sy = std::cos(Teta)*std::sin(Phi);
273 // G4double sz = -std::sin(Teta);
274
275 G4ThreeVector gammaPolarization = FieldValue.cross(gammaDirection);
276 gammaPolarization = gammaPolarization.unit();
277
278 // (sx, sy, sz);
279 // gammaPolarization.rotateUz(particleDirection);
280
281 // create G4DynamicParticle object for the SR photon
282
283 G4DynamicParticle* aGamma= new G4DynamicParticle ( theGamma,
284 gammaDirection,
285 energyOfSR );
286 aGamma->SetPolarization( gammaPolarization.x(),
287 gammaPolarization.y(),
288 gammaPolarization.z() );
289
290
291 aParticleChange.SetNumberOfSecondaries(1);
292 aParticleChange.AddSecondary(aGamma);
293
294 // Update the incident particle
295
296 G4double newKinEnergy = kineticEnergy - energyOfSR ;
297 aParticleChange.ProposeLocalEnergyDeposit (0.);
298
299 if (newKinEnergy > 0.)
300 {
301 aParticleChange.ProposeMomentumDirection( particleDirection );
302 aParticleChange.ProposeEnergy( newKinEnergy );
303 }
304 else
305 {
306 aParticleChange.ProposeEnergy( 0. );
307 }
308 }
309 }
310 return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
311}
312
313
314/////////////////////////////////////////////////////////////////////////////////
315//
316//
317
318G4double G4SynchrotronRadiation::InvSynFracInt(G4double x)
319// direct generation
320{
321 // from 0 to 0.7
322 const G4double aa1=0 ,aa2=0.7;
323 const G4int ncheb1=27;
324 static const G4double cheb1[] =
325 { 1.22371665676046468821,0.108956475422163837267,0.0383328524358594396134,0.00759138369340257753721,
326 0.00205712048644963340914,0.000497810783280019308661,0.000130743691810302187818,0.0000338168760220395409734,
327 8.97049680900520817728e-6,2.38685472794452241466e-6,6.41923109149104165049e-7,1.73549898982749277843e-7,
328 4.72145949240790029153e-8,1.29039866111999149636e-8,3.5422080787089834182e-9,9.7594757336403784905e-10,
329 2.6979510184976065731e-10,7.480422622550977077e-11,2.079598176402699913e-11,5.79533622220841193e-12,
330 1.61856011449276096e-12,4.529450993473807e-13,1.2698603951096606e-13,3.566117394511206e-14,1.00301587494091e-14,
331 2.82515346447219e-15,7.9680747949792e-16};
332 // from 0.7 to 0.9132260271183847
333 const G4double aa3=0.9132260271183847;
334 const G4int ncheb2=27;
335 static const G4double cheb2[] =
336 { 1.1139496701107756,0.3523967429328067,0.0713849171926623,0.01475818043595387,0.003381255637322462,
337 0.0008228057599452224,0.00020785506681254216,0.00005390169253706556,0.000014250571923902464,3.823880733161044e-6,
338 1.0381966089136036e-6,2.8457557457837253e-7,7.86223332179956e-8,2.1866609342508474e-8,6.116186259857143e-9,
339 1.7191233618437565e-9,4.852755117740807e-10,1.3749966961763457e-10,3.908961987062447e-11,1.1146253766895824e-11,
340 3.1868887323415814e-12,9.134319791300977e-13,2.6211077371181566e-13,7.588643377757906e-14,2.1528376972619e-14,
341 6.030906040404772e-15,1.9549163926819867e-15};
342 // Chebyshev with exp/log scale
343 // a = -Log[1 - SynFracInt[1]]; b = -Log[1 - SynFracInt[7]];
344 const G4double aa4=2.4444485538746025480,aa5=9.3830728608909477079;
345 const G4int ncheb3=28;
346 static const G4double cheb3[] =
347 { 1.2292683840435586977,0.160353449247864455879,-0.0353559911947559448721,0.00776901561223573936985,
348 -0.00165886451971685133259,0.000335719118906954279467,-0.0000617184951079161143187,9.23534039743246708256e-6,
349 -6.06747198795168022842e-7,-3.07934045961999778094e-7,1.98818772614682367781e-7,-8.13909971567720135413e-8,
350 2.84298174969641838618e-8,-9.12829766621316063548e-9,2.77713868004820551077e-9,-8.13032767247834023165e-10,
351 2.31128525568385247392e-10,-6.41796873254200220876e-11,1.74815310473323361543e-11,-4.68653536933392363045e-12,
352 1.24016595805520752748e-12,-3.24839432979935522159e-13,8.44601465226513952994e-14,-2.18647276044246803998e-14,
353 5.65407548745690689978e-15,-1.46553625917463067508e-15,3.82059606377570462276e-16,-1.00457896653436912508e-16};
354 const G4double aa6=33.122936966163038145;
355 const G4int ncheb4=27;
356 static const G4double cheb4[] =
357 {1.69342658227676741765,0.0742766400841232319225,-0.019337880608635717358,0.00516065527473364110491,
358 -0.00139342012990307729473,0.000378549864052022522193,-0.000103167085583785340215,0.0000281543441271412178337,
359 -7.68409742018258198651e-6,2.09543221890204537392e-6,-5.70493140367526282946e-7,1.54961164548564906446e-7,
360 -4.19665599629607704794e-8,1.13239680054166507038e-8,-3.04223563379021441863e-9,8.13073745977562957997e-10,
361 -2.15969415476814981374e-10,5.69472105972525594811e-11,-1.48844799572430829499e-11,3.84901514438304484973e-12,
362 -9.82222575944247161834e-13,2.46468329208292208183e-13,-6.04953826265982691612e-14,1.44055805710671611984e-14,
363 -3.28200813577388740722e-15,6.96566359173765367675e-16,-1.294122794852896275e-16};
364
365 if(x<aa2) return x*x*x*Chebyshev(aa1,aa2,cheb1,ncheb1,x);
366 else if(x<aa3) return Chebyshev(aa2,aa3,cheb2,ncheb2,x);
367 else if(x<1-0.0000841363)
368 { G4double y=-std::log(1-x);
369 return y*Chebyshev(aa4,aa5,cheb3,ncheb3,y);
370 }
371 else
372 { G4double y=-std::log(1-x);
373 return y*Chebyshev(aa5,aa6,cheb4,ncheb4,y);
374 }
375}
376
377G4double G4SynchrotronRadiation::GetRandomEnergySR(G4double gamma, G4double perpB)
378{
379
380 G4double Ecr=fEnergyConst*gamma*gamma*perpB;
381
382 static G4bool FirstTime=true;
383 if(verboseLevel > 0 && FirstTime)
384 { G4double Emean=8./(15.*std::sqrt(3.))*Ecr; // mean photon energy
385 G4double E_rms=std::sqrt(211./675.)*Ecr; // rms of photon energy distribution
386 G4cout << "G4SynchrotronRadiation::GetRandomEnergySR :" << '\n' << std::setprecision(4)
387 << " Ecr = " << G4BestUnit(Ecr,"Energy") << '\n'
388 << " Emean = " << G4BestUnit(Emean,"Energy") << '\n'
389 << " E_rms = " << G4BestUnit(E_rms,"Energy") << G4endl;
390 FirstTime=false;
391 }
392
393 G4double energySR=Ecr*InvSynFracInt(G4UniformRand());
394 return energySR;
395}
396
397
398void G4SynchrotronRadiation::BuildPhysicsTable(const G4ParticleDefinition& part)
399{
400 if(0 < verboseLevel && &part==theElectron ) PrintInfoDefinition();
401}
402
403void G4SynchrotronRadiation::PrintInfoDefinition() // not yet called, usually called from BuildPhysicsTable
404{
405 G4String comments ="Incoherent Synchrotron Radiation\n";
406 G4cout << G4endl << GetProcessName() << ": " << comments
407 << " good description for long magnets at all energies" << G4endl;
408}
409
410///////////////////// end of G4SynchrotronRadiation.cc
Note: See TracBrowser for help on using the repository browser.