G4PreCompoundHe3.cc

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00025 //
00026 // $Id$
00027 //
00028 // -------------------------------------------------------------------
00029 //
00030 // GEANT4 Class file
00031 //
00032 //
00033 // File name:     G4PreCompoundHe3
00034 //
00035 // Author:         V.Lara
00036 //
00037 // Modified:  
00038 // 21.08.2008 J. M. Quesada add choice of options  
00039 // 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
00040 //                         use int Z and A and cleanup
00041 //
00042  
00043 #include "G4PreCompoundHe3.hh"
00044 #include "G4SystemOfUnits.hh"
00045 #include "G4He3.hh"
00046 
00047 G4PreCompoundHe3::G4PreCompoundHe3()
00048   : G4PreCompoundIon(G4He3::He3(), &theHe3CoulombBarrier)
00049 {
00050   ResidualA = GetRestA();
00051   ResidualZ = GetRestZ(); 
00052   theA = GetA();
00053   theZ = GetZ();
00054   ResidualAthrd = ResidualA13();
00055   FragmentAthrd = ResidualAthrd;
00056   FragmentA = theA + ResidualA;
00057 }
00058 
00059 G4PreCompoundHe3::~G4PreCompoundHe3()
00060 {}
00061 
00062 G4double G4PreCompoundHe3::FactorialFactor(G4int N, G4int P)
00063 {
00064   return G4double((N-3)*(P-2)*(N-2)*(P-1)*(N-1)*P)/6.0; 
00065 }
00066   
00067 G4double G4PreCompoundHe3::CoalescenceFactor(G4int A)
00068 {
00069   return 243.0/G4double(A*A);
00070 }    
00071 
00072 G4double G4PreCompoundHe3::GetRj(G4int nParticles, G4int nCharged)
00073 {
00074   G4double rj = 0.0;
00075   if(nCharged >=2 && (nParticles-nCharged) >= 1) {
00076     G4double denominator = G4double(nParticles*(nParticles-1)*(nParticles-2));
00077     rj = G4double(3*nCharged*(nCharged-1)*(nParticles-nCharged))/denominator;  
00078   }
00079   return rj;
00080 }
00081 
00083 //J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections 
00084 //OPT=0 Dostrovski's parameterization
00085 //OPT=1,2 Chatterjee's paramaterization 
00086 //OPT=3,4 Kalbach's parameterization 
00087 // 
00088 G4double G4PreCompoundHe3::CrossSection(G4double K)
00089 {
00090   ResidualA = GetRestA();
00091   ResidualZ = GetRestZ(); 
00092   theA = GetA();
00093   theZ = GetZ();
00094   ResidualAthrd = ResidualA13();
00095   FragmentA = theA + ResidualA;
00096   FragmentAthrd = g4pow->Z13(FragmentA);
00097 
00098   if (OPTxs==0) return GetOpt0( K);
00099   else if( OPTxs==1 || OPTxs==2) return GetOpt12( K);
00100   else if (OPTxs==3 || OPTxs==4)  return GetOpt34( K);
00101   else{
00102     std::ostringstream errOs;
00103     errOs << "BAD He3 CROSS SECTION OPTION !!"  <<G4endl;
00104     throw G4HadronicException(__FILE__, __LINE__, errOs.str());
00105     return 0.;
00106   }
00107 }
00108 
00109 G4double G4PreCompoundHe3::GetAlpha()
00110 {
00111   G4double C = 0.0;
00112   G4int aZ = theZ + ResidualZ;
00113   if (aZ <= 30) 
00114     {
00115       C = 0.10;
00116     }
00117   else if (aZ <= 50) 
00118     {
00119       C = 0.1 - (aZ - 30)*0.001;
00120     } 
00121   else if (aZ < 70) 
00122     {
00123       C = 0.08 - (aZ - 50)*0.001;
00124     }
00125   else 
00126     {
00127       C = 0.06;
00128     }
00129   return 1.0 + C*(4.0/3.0);
00130 }
00131 
00132 //********************* OPT=1,2 : Chatterjee's cross section *****************
00133 //(fitting to cross section from Bechetti & Greenles OM potential)
00134 
00135 G4double G4PreCompoundHe3::GetOpt12(const  G4double K)
00136 {
00137   G4double Kc = K;
00138 
00139   // JMQ xsec is set constat above limit of validity
00140   if (K > 50*MeV) { Kc = 50*MeV; }
00141 
00142   G4double landa ,mu ,nu ,p , Ec,q,r,ji,xs;
00143 
00144   G4double     p0 = -3.06;
00145   G4double     p1 = 278.5;
00146   G4double     p2 = -1389.;
00147   G4double     landa0 = -0.00535;
00148   G4double     landa1 = -11.16;
00149   G4double     mm0 = 555.5;
00150   G4double     mu1 = 0.40;
00151   G4double     nu0 = 687.4;
00152   G4double     nu1 = -476.3;
00153   G4double     nu2 = 0.509;    
00154   G4double     delta=1.2;              
00155 
00156   Ec = 1.44*theZ*ResidualZ/(1.5*ResidualAthrd+delta);
00157   p = p0 + p1/Ec + p2/(Ec*Ec);
00158   landa = landa0*ResidualA + landa1;
00159 
00160   G4double resmu1 = g4pow->powZ(ResidualA,mu1); 
00161   mu = mm0*resmu1;
00162   nu = resmu1*(nu0 + nu1*Ec + nu2*(Ec*Ec));
00163   q = landa - nu/(Ec*Ec) - 2*p*Ec;
00164   r = mu + 2*nu/Ec + p*(Ec*Ec);
00165   
00166   ji=std::max(Kc,Ec);
00167   if(Kc < Ec) { xs = p*Kc*Kc + q*Kc + r;}
00168   else {xs = p*(Kc - ji)*(Kc - ji) + landa*Kc + mu + nu*(2 - Kc/ji)/ji ;}
00169   
00170   if (xs <0.0) {xs=0.0;}
00171               
00172   return xs;
00173 
00174 }
00175 
00176 // *********** OPT=3,4 : Kalbach's cross sections (from PRECO code)*************
00177 G4double G4PreCompoundHe3::GetOpt34(const  G4double K)
00178 //c     ** 3he from o.m. of gibson et al
00179 {
00180   G4double landa, mu, nu, p , signor(1.),sig;
00181   G4double ec,ecsq,xnulam,etest(0.),a; 
00182   G4double b,ecut,cut,ecut2,geom,elab;
00183 
00184   G4double     flow = 1.e-18;
00185   G4double     spill= 1.e+18;
00186 
00187   G4double     p0 = -2.88;
00188   G4double     p1 = 205.6;
00189   G4double     p2 = -1487.;
00190   G4double     landa0 = 0.00459;
00191   G4double     landa1 = -8.93;
00192   G4double     mm0 = 611.2;
00193   G4double     mu1 = 0.35;
00194   G4double     nu0 = 473.8;
00195   G4double     nu1 = -468.2;
00196   G4double     nu2 = -2.225;      
00197   
00198   G4double      ra=0.80;
00199         
00200   //JMQ 13/02/09 increase of reduced radius to lower the barrier
00201   // ec = 1.44 * theZ * ResidualZ / (1.5*ResidualAthrd+ra);
00202   ec = 1.44 * theZ * ResidualZ / (1.7*ResidualAthrd+ra);
00203   ecsq = ec * ec;
00204   p = p0 + p1/ec + p2/ecsq;
00205   landa = landa0*ResidualA + landa1;
00206   a = g4pow->powZ(ResidualA,mu1);
00207   mu = mm0 * a;
00208   nu = a* (nu0+nu1*ec+nu2*ecsq);  
00209   xnulam = nu / landa;
00210   if (xnulam > spill) { xnulam=0.; }
00211   if (xnulam >= flow) { etest = 1.2 *std::sqrt(xnulam); }
00212   
00213   a = -2.*p*ec + landa - nu/ecsq;
00214   b = p*ecsq + mu + 2.*nu/ec;
00215   ecut = 0.;
00216   cut = a*a - 4.*p*b;
00217   if (cut > 0.) ecut = std::sqrt(cut);
00218   ecut = (ecut-a) / (p+p);
00219   ecut2 = ecut;
00220   //JMQ 290310 for avoiding unphysical increase below minimum (at ecut)
00221   // ecut<0 means that there is no cut with energy axis, i.e. xs is set
00222   // to 0 bellow minimum
00223   //  if (cut < 0.) ecut2 = ecut - 2.;
00224   if (cut < 0.) { ecut2 = ecut; }
00225   elab = K * FragmentA /G4double(ResidualA);
00226   sig = 0.;
00227   
00228   if (elab <= ec) { //start for E<Ec
00229     if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; }
00230   }           //end for E<Ec
00231   else {           //start for E>Ec
00232     sig = (landa*elab+mu+nu/elab) * signor;
00233     geom = 0.;
00234     if (xnulam < flow || elab < etest) { return sig; }
00235     geom = std::sqrt(theA*K);
00236     geom = 1.23*ResidualAthrd + ra + 4.573/geom;
00237     geom = 31.416 * geom * geom;
00238     sig = std::max(geom,sig);
00239   }           //end for E>Ec
00240   return sig;
00241   
00242 }

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