source: trunk/source/processes/hadronic/models/pre_equilibrium/exciton_model/src/G4PreCompoundAlpha.cc @ 1340

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26// $Id: G4PreCompoundAlpha.cc,v 1.7 2010/08/28 15:16:55 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-ref-09 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name:     G4PreCompoundAlpha
35//
36// Author:         V.Lara
37//
38// Modified: 
39// 21.08.2008 J. M. Quesada add choice of options 
40// 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
41//                         use int Z and A and cleanup
42//
43
44#include "G4PreCompoundAlpha.hh"
45#include "G4Alpha.hh"
46
47G4PreCompoundAlpha::G4PreCompoundAlpha()
48  : G4PreCompoundIon(G4Alpha::Alpha(), &theAlphaCoulombBarrier)
49{}
50
51G4PreCompoundAlpha::~G4PreCompoundAlpha()
52{}
53
54G4double G4PreCompoundAlpha::FactorialFactor(G4int N, G4int P)
55{
56  return G4double((N-4)*(P-3)*(N-3)*(P-2)*(N-2)*(P-1)*(N-1)*P)/12.0;
57}
58 
59G4double G4PreCompoundAlpha::CoalescenceFactor(G4int A)
60{
61  return 4096.0/G4double(A*A*A); 
62}   
63
64G4double G4PreCompoundAlpha::GetRj(G4int nParticles, G4int nCharged)
65{
66  G4double rj = 0.0;
67  if(nCharged >=2 && (nParticles-nCharged) >=2 ) {
68    G4double denominator = 
69      G4double(nParticles*(nParticles-1)*(nParticles-2)*(nParticles-3));
70    rj = 6.0*nCharged*(nCharged-1)*(nParticles-nCharged)*(nParticles-nCharged-1)
71      /denominator; 
72  }
73  return rj;
74}
75
76/////////////////////////////////////////////////////////////////////////////////
77//J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections
78//OPT=0 Dostrovski's parameterization
79//OPT=1,2 Chatterjee's paramaterization
80//OPT=3,4 Kalbach's parameterization
81//
82G4double G4PreCompoundAlpha::CrossSection(G4double K)
83{
84  ResidualA = GetRestA();
85  ResidualZ = GetRestZ(); 
86  theA = GetA();
87  theZ = GetZ();
88  ResidualAthrd = ResidualA13();
89  FragmentA = theA + ResidualA;
90  FragmentAthrd = g4pow->Z13(FragmentA);
91
92  if (OPTxs==0) { return GetOpt0( K); }
93  else if( OPTxs==1 || OPTxs==2) { return GetOpt12( K); }
94  else if (OPTxs==3 || OPTxs==4) { return GetOpt34( K); }
95  else{
96    std::ostringstream errOs;
97    errOs << "BAD Alpha CROSS SECTION OPTION !!"  <<G4endl;
98    throw G4HadronicException(__FILE__, __LINE__, errOs.str());
99    return 0.;
100  }
101}
102
103G4double G4PreCompoundAlpha::GetAlpha()
104{
105  G4double C = 0.0;
106  G4int aZ = theZ + ResidualZ;
107  if (aZ <= 30) 
108    {
109      C = 0.10;
110    } 
111  else if (aZ <= 50) 
112    {
113      C = 0.1 - (aZ-30)*0.001;
114    } 
115  else if (aZ < 70) 
116    {
117      C = 0.08 - (aZ-50)*0.001;
118    }
119  else 
120    {
121      C = 0.06;
122    }
123  return 1.0+C;
124}
125
126//
127//********************* OPT=1,2 : Chatterjee's cross section ********************
128//(fitting to cross section from Bechetti & Greenles OM potential)
129
130G4double G4PreCompoundAlpha::GetOpt12(G4double K)
131{
132  G4double Kc=K;
133
134  // JMQ xsec is set constant above limit of validity
135  if (K > 50*MeV) { Kc = 50*MeV; }
136
137  G4double landa ,mu ,nu ,p , Ec,q,r,ji,xs;
138
139  G4double     p0 = 10.95;
140  G4double     p1 = -85.2;
141  G4double     p2 = 1146.;
142  G4double     landa0 = 0.0643;
143  G4double     landa1 = -13.96;
144  G4double     mu0 = 781.2;
145  G4double     mu1 = 0.29;
146  G4double     nu0 = -304.7;
147  G4double     nu1 = -470.0;
148  G4double     nu2 = -8.580;   
149  G4double     delta=1.2;         
150
151  Ec = 1.44*theZ*ResidualZ/(1.5*ResidualAthrd+delta);
152  p = p0 + p1/Ec + p2/(Ec*Ec);
153  landa = landa0*ResidualA + landa1;
154  G4double resmu1 = g4pow->powZ(ResidualA,mu1); 
155  mu = mu0*resmu1;
156  nu = resmu1*(nu0 + nu1*Ec + nu2*(Ec*Ec));
157  q = landa - nu/(Ec*Ec) - 2*p*Ec;
158  r = mu + 2*nu/Ec + p*(Ec*Ec);
159
160  ji=std::max(Kc,Ec);
161  if(Kc < Ec) { xs = p*Kc*Kc + q*Kc + r;}
162  else {xs = p*(Kc - ji)*(Kc - ji) + landa*Kc + mu + nu*(2 - Kc/ji)/ji ;}
163 
164  if (xs <0.0) {xs=0.0;}
165             
166  return xs;
167}
168
169// *********** OPT=3,4 : Kalbach's cross sections (from PRECO code)*************
170G4double G4PreCompoundAlpha::GetOpt34(G4double K)
171// c     ** alpha from huizenga and igo
172{
173  G4double landa, mu, nu, p , signor(1.),sig;
174  G4double ec,ecsq,xnulam,etest(0.),a; 
175  G4double b,ecut,cut,ecut2,geom,elab;
176
177  G4double     flow = 1.e-18;
178  G4double     spill= 1.e+18;
179
180  G4double     p0 = 10.95;
181  G4double     p1 = -85.2;
182  G4double     p2 = 1146.;
183  G4double     landa0 = 0.0643;
184  G4double     landa1 = -13.96;
185  G4double     mu0 = 781.2;
186  G4double     mu1 = 0.29;
187  G4double     nu0 = -304.7;
188  G4double     nu1 = -470.0;
189  G4double     nu2 = -8.580;       
190 
191  G4double      ra=1.20;
192       
193  //JMQ 13/02/09 increase of reduced radius to lower the barrier
194  // ec = 1.44 * theZ * ResidualZ / (1.5*ResidualAthrd+ra);
195  ec = 1.44 * theZ * ResidualZ / (1.7*ResidualAthrd+ra);
196  ecsq = ec * ec;
197  p = p0 + p1/ec + p2/ecsq;
198  landa = landa0*ResidualA + landa1;
199  a = g4pow->powZ(ResidualA,mu1);
200  mu = mu0 * a;
201  nu = a* (nu0+nu1*ec+nu2*ecsq); 
202  xnulam = nu / landa;
203  if (xnulam > spill) { xnulam=0.; }
204  if (xnulam >= flow) { etest = 1.2 *std::sqrt(xnulam); }
205
206  a = -2.*p*ec + landa - nu/ecsq;
207  b = p*ecsq + mu + 2.*nu/ec;
208  ecut = 0.;
209  cut = a*a - 4.*p*b;
210  if (cut > 0.) { ecut = std::sqrt(cut); }
211  ecut = (ecut-a) / (p+p);
212  ecut2 = ecut;
213  //JMQ 290310 for avoiding unphysical increase below minimum (at ecut)
214  // ecut<0 means that there is no cut with energy axis, i.e. xs is set
215  // to 0 bellow minimum
216  //  if (cut < 0.) ecut2 = ecut - 2.;
217  if (cut < 0.) { ecut2 = ecut; }
218  elab = K * FragmentA / G4double(ResidualA);
219  sig = 0.;
220 
221  if (elab <= ec) { //start for E<Ec
222    if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; }
223  }           //end for E<Ec
224  else {           //start for E>Ec
225    sig = (landa*elab+mu+nu/elab) * signor;
226    geom = 0.;
227    if (xnulam < flow || elab < etest) { return sig; }
228    geom = std::sqrt(theA*K);
229    geom = 1.23*ResidualAthrd + ra + 4.573/geom;
230    geom = 31.416 * geom * geom;
231    sig = std::max(geom,sig);
232  }           //end for E>Ec
233  return sig;
234}
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