G4AlphaEvaporationProbability.cc

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00025 //
00026 // $Id$
00027 //
00028 // J.M. Quesada (August2008). Based on:
00029 //
00030 // Hadronic Process: Nuclear De-excitations
00031 // by V. Lara (Oct 1998)
00032 //
00033 // Modified:
00034 // 03-09-2008 J.M. Quesada for external choice of inverse cross section option
00035 // 17-11-2010 V.Ivanchenko integer Z and A
00036 
00037 #include "G4AlphaEvaporationProbability.hh"
00038 #include "G4SystemOfUnits.hh"
00039 
00040 G4AlphaEvaporationProbability::G4AlphaEvaporationProbability() :
00041     G4EvaporationProbability(4,2,1,&theCoulombBarrier) // A,Z,Gamma,&theCoumlombBarrier
00042 {
00043   ResidualA = ResidualZ = theA = theZ = FragmentA = 0;
00044   ResidualAthrd = FragmentAthrd = 0.0;
00045 }
00046 
00047 G4AlphaEvaporationProbability::~G4AlphaEvaporationProbability()
00048 {}
00049 
00050 G4double G4AlphaEvaporationProbability::CalcAlphaParam(const G4Fragment & fragment)  
00051   { return 1.0 + CCoeficient(fragment.GetZ_asInt()-GetZ());}
00052         
00053 G4double G4AlphaEvaporationProbability::CalcBetaParam(const G4Fragment &) 
00054   { return 0.0; }
00055 
00056 G4double G4AlphaEvaporationProbability::CCoeficient(G4int aZ) 
00057 {
00058   // Data comes from 
00059   // Dostrovsky, Fraenkel and Friedlander
00060   // Physical Review, vol 116, num. 3 1959
00061   // 
00062   // const G4int size = 5;
00063   // G4double Zlist[5] = { 10.0, 20.0, 30.0, 50.0, 70.0};
00064   //    G4double Calpha[5] = { 0.10, 0.10, 0.10, 0.08, 0.06};
00065   G4double C = 0.0;
00066         
00067   if (aZ <= 30) 
00068     {
00069       C = 0.10;
00070     }
00071   else if (aZ <= 50)
00072     {
00073       C = 0.1 - (aZ-30)*0.001;
00074     }
00075   else if (aZ < 70)
00076     {
00077       C = 0.08 - (aZ-50)*0.001;
00078     }
00079   else 
00080     {
00081       C = 0.06;
00082     }
00083   return C;
00084 }
00085 
00087 //J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections 
00088 //OPT=0 Dostrovski's parameterization
00089 //OPT=1,2 Chatterjee's paramaterization 
00090 //OPT=3,4 Kalbach's parameterization 
00091 // 
00092 G4double 
00093 G4AlphaEvaporationProbability::CrossSection(const G4Fragment & fragment, G4double K)
00094 {
00095   theA=GetA();
00096   theZ=GetZ();
00097   ResidualA=fragment.GetA_asInt()-theA;
00098   ResidualZ=fragment.GetZ_asInt()-theZ; 
00099   
00100   ResidualAthrd=fG4pow->Z13(ResidualA);
00101   FragmentA=fragment.GetA_asInt();
00102   FragmentAthrd=fG4pow->Z13(FragmentA);
00103   
00104   if (OPTxs==0) {std::ostringstream errOs;
00105     errOs << "We should'n be here (OPT =0) at evaporation cross section calculation (Alpha's)!!"  
00106           <<G4endl;
00107     throw G4HadronicException(__FILE__, __LINE__, errOs.str());
00108     return 0.;}
00109   
00110   if( OPTxs==1 || OPTxs==2) return G4AlphaEvaporationProbability::GetOpt12( K);
00111   else if (OPTxs==3 || OPTxs==4)  return G4AlphaEvaporationProbability::GetOpt34( K);
00112   else{
00113     std::ostringstream errOs;
00114     errOs << "BAD Alpha CROSS SECTION OPTION AT EVAPORATION!!"  <<G4endl;
00115     throw G4HadronicException(__FILE__, __LINE__, errOs.str());
00116     return 0.;
00117   }
00118 }
00119 
00120 //
00121 //********************* OPT=1,2 : Chatterjee's cross section ********************
00122 //(fitting to cross section from Bechetti & Greenles OM potential)
00123 
00124 G4double G4AlphaEvaporationProbability::GetOpt12(G4double K)
00125 {
00126   G4double Kc=K;
00127 
00128   // JMQ xsec is set constant above limit of validity
00129   if (K > 50*MeV) { Kc = 50*MeV; }
00130 
00131   G4double landa ,mu ,nu ,p , Ec,q,r,ji,xs;
00132 
00133   G4double     p0 = 10.95;
00134   G4double     p1 = -85.2;
00135   G4double     p2 = 1146.;
00136   G4double     landa0 = 0.0643;
00137   G4double     landa1 = -13.96;
00138   G4double     mum0 = 781.2;
00139   G4double     mu1 = 0.29;
00140   G4double     nu0 = -304.7;
00141   G4double     nu1 = -470.0;
00142   G4double     nu2 = -8.580;   
00143   G4double     delta=1.2;          
00144 
00145   Ec = 1.44*theZ*ResidualZ/(1.5*ResidualAthrd+delta);
00146   p = p0 + p1/Ec + p2/(Ec*Ec);
00147   landa = landa0*ResidualA + landa1;
00148   G4double resmu1 = fG4pow->powZ(ResidualA,mu1); 
00149   mu = mum0*resmu1;
00150   nu = resmu1*(nu0 + nu1*Ec + nu2*(Ec*Ec));
00151   q = landa - nu/(Ec*Ec) - 2*p*Ec;
00152   r = mu + 2*nu/Ec + p*(Ec*Ec);
00153 
00154   ji=std::max(Kc,Ec);
00155   if(Kc < Ec) { xs = p*Kc*Kc + q*Kc + r;}
00156   else {xs = p*(Kc - ji)*(Kc - ji) + landa*Kc + mu + nu*(2 - Kc/ji)/ji ;}
00157   
00158   if (xs <0.0) {xs=0.0;}
00159               
00160   return xs;
00161 }
00162 
00163 // *********** OPT=3,4 : Kalbach's cross sections (from PRECO code)*************
00164 G4double G4AlphaEvaporationProbability::GetOpt34(G4double K)
00165 // c     ** alpha from huizenga and igo
00166 {
00167   G4double landa, mu, nu, p , signor(1.),sig;
00168   G4double ec,ecsq,xnulam,etest(0.),a; 
00169   G4double b,ecut,cut,ecut2,geom,elab;
00170 
00171   G4double     flow = 1.e-18;
00172   G4double     spill= 1.e+18;
00173 
00174   G4double     p0 = 10.95;
00175   G4double     p1 = -85.2;
00176   G4double     p2 = 1146.;
00177   G4double     landa0 = 0.0643;
00178   G4double     landa1 = -13.96;
00179   G4double     mum0 = 781.2;
00180   G4double     mu1 = 0.29;
00181   G4double     nu0 = -304.7;
00182   G4double     nu1 = -470.0;
00183   G4double     nu2 = -8.580;        
00184   
00185   G4double      ra=1.20;
00186         
00187   //JMQ 13/02/09 increase of reduced radius to lower the barrier
00188   // ec = 1.44 * theZ * ResidualZ / (1.5*ResidualAthrd+ra);
00189   ec = 1.44 * theZ * ResidualZ / (1.7*ResidualAthrd+ra);
00190   ecsq = ec * ec;
00191   p = p0 + p1/ec + p2/ecsq;
00192   landa = landa0*ResidualA + landa1;
00193   a = fG4pow->powZ(ResidualA,mu1);
00194   mu = mum0 * a;
00195   nu = a* (nu0+nu1*ec+nu2*ecsq);  
00196   xnulam = nu / landa;
00197   if (xnulam > spill) { xnulam=0.; }
00198   if (xnulam >= flow) { etest = 1.2 *std::sqrt(xnulam); }
00199 
00200   a = -2.*p*ec + landa - nu/ecsq;
00201   b = p*ecsq + mu + 2.*nu/ec;
00202   ecut = 0.;
00203   cut = a*a - 4.*p*b;
00204   if (cut > 0.) { ecut = std::sqrt(cut); }
00205   ecut = (ecut-a) / (p+p);
00206   ecut2 = ecut;
00207   //JMQ 290310 for avoiding unphysical increase below minimum (at ecut)
00208   // ecut<0 means that there is no cut with energy axis, i.e. xs is set 
00209   // to 0 bellow minimum
00210   //  if (cut < 0.) ecut2 = ecut - 2.;
00211   if (cut < 0.) { ecut2 = ecut; }
00212   elab = K * FragmentA / G4double(ResidualA);
00213   sig = 0.;
00214   
00215   if (elab <= ec) { //start for E<Ec
00216     if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; }
00217   }           //end for E<Ec
00218   else {           //start for E>Ec
00219     sig = (landa*elab+mu+nu/elab) * signor;
00220     geom = 0.;
00221     if (xnulam < flow || elab < etest) { return sig; }
00222     geom = std::sqrt(theA*K);
00223     geom = 1.23*ResidualAthrd + ra + 4.573/geom;
00224     geom = 31.416 * geom * geom;
00225     sig = std::max(geom,sig);
00226   }           //end for E>Ec
00227   return sig;
00228 }
00229 

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