G4PreCompoundAlpha.cc

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00025 //
00026 // $Id$
00027 //
00028 // -------------------------------------------------------------------
00029 //
00030 // GEANT4 Class file
00031 //
00032 //
00033 // File name:     G4PreCompoundAlpha
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 "G4PreCompoundAlpha.hh"
00044 #include "G4SystemOfUnits.hh"
00045 #include "G4Alpha.hh"
00046 
00047 G4PreCompoundAlpha::G4PreCompoundAlpha()
00048   : G4PreCompoundIon(G4Alpha::Alpha(), &theAlphaCoulombBarrier)
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 G4PreCompoundAlpha::~G4PreCompoundAlpha()
00060 {}
00061 
00062 G4double G4PreCompoundAlpha::FactorialFactor(G4int N, G4int P)
00063 {
00064   return G4double((N-4)*(P-3)*(N-3)*(P-2)*(N-2)*(P-1)*(N-1)*P)/12.0;
00065 }
00066   
00067 G4double G4PreCompoundAlpha::CoalescenceFactor(G4int A)
00068 {
00069   return 4096.0/G4double(A*A*A);  
00070 }    
00071 
00072 G4double G4PreCompoundAlpha::GetRj(G4int nParticles, G4int nCharged)
00073 {
00074   G4double rj = 0.0;
00075   if(nCharged >=2 && (nParticles-nCharged) >=2 ) {
00076     G4double denominator = 
00077       G4double(nParticles*(nParticles-1)*(nParticles-2)*(nParticles-3));
00078     rj = 6.0*nCharged*(nCharged-1)*(nParticles-nCharged)*(nParticles-nCharged-1)
00079       /denominator;  
00080   }
00081   return rj;
00082 }
00083 
00085 //J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections 
00086 //OPT=0 Dostrovski's parameterization
00087 //OPT=1,2 Chatterjee's paramaterization 
00088 //OPT=3,4 Kalbach's parameterization 
00089 // 
00090 G4double G4PreCompoundAlpha::CrossSection(G4double K)
00091 {
00092   ResidualA = GetRestA();
00093   ResidualZ = GetRestZ(); 
00094   theA = GetA();
00095   theZ = GetZ();
00096   ResidualAthrd = ResidualA13();
00097   FragmentA = theA + ResidualA;
00098   FragmentAthrd = g4pow->Z13(FragmentA);
00099 
00100   if (OPTxs==0) { return GetOpt0( K); }
00101   else if( OPTxs==1 || OPTxs==2) { return GetOpt12( K); }
00102   else if (OPTxs==3 || OPTxs==4) { return GetOpt34( K); }
00103   else{
00104     std::ostringstream errOs;
00105     errOs << "BAD Alpha CROSS SECTION OPTION !!"  <<G4endl;
00106     throw G4HadronicException(__FILE__, __LINE__, errOs.str());
00107     return 0.;
00108   }
00109 }
00110 
00111 G4double G4PreCompoundAlpha::GetAlpha()
00112 {
00113   G4double C = 0.0;
00114   G4int aZ = theZ + ResidualZ;
00115   if (aZ <= 30) 
00116     {
00117       C = 0.10;
00118     } 
00119   else if (aZ <= 50) 
00120     {
00121       C = 0.1 - (aZ-30)*0.001;
00122     } 
00123   else if (aZ < 70) 
00124     {
00125       C = 0.08 - (aZ-50)*0.001;
00126     }
00127   else 
00128     {
00129       C = 0.06;
00130     }
00131   return 1.0+C;
00132 }
00133 
00134 //
00135 //********************* OPT=1,2 : Chatterjee's cross section ********************
00136 //(fitting to cross section from Bechetti & Greenles OM potential)
00137 
00138 G4double G4PreCompoundAlpha::GetOpt12(G4double K)
00139 {
00140   G4double Kc=K;
00141 
00142   // JMQ xsec is set constant above limit of validity
00143   if (K > 50*MeV) { Kc = 50*MeV; }
00144 
00145   G4double landa ,mu ,nu ,p , Ec,q,r,ji,xs;
00146 
00147   G4double     p0 = 10.95;
00148   G4double     p1 = -85.2;
00149   G4double     p2 = 1146.;
00150   G4double     landa0 = 0.0643;
00151   G4double     landa1 = -13.96;
00152   G4double     mm0 = 781.2;
00153   G4double     mu1 = 0.29;
00154   G4double     nu0 = -304.7;
00155   G4double     nu1 = -470.0;
00156   G4double     nu2 = -8.580;   
00157   G4double     delta=1.2;          
00158 
00159   Ec = 1.44*theZ*ResidualZ/(1.5*ResidualAthrd+delta);
00160   p = p0 + p1/Ec + p2/(Ec*Ec);
00161   landa = landa0*ResidualA + landa1;
00162   G4double resmu1 = g4pow->powZ(ResidualA,mu1); 
00163   mu = mm0*resmu1;
00164   nu = resmu1*(nu0 + nu1*Ec + nu2*(Ec*Ec));
00165   q = landa - nu/(Ec*Ec) - 2*p*Ec;
00166   r = mu + 2*nu/Ec + p*(Ec*Ec);
00167 
00168   ji=std::max(Kc,Ec);
00169   if(Kc < Ec) { xs = p*Kc*Kc + q*Kc + r;}
00170   else {xs = p*(Kc - ji)*(Kc - ji) + landa*Kc + mu + nu*(2 - Kc/ji)/ji ;}
00171   
00172   if (xs <0.0) {xs=0.0;}
00173               
00174   return xs;
00175 }
00176 
00177 // *********** OPT=3,4 : Kalbach's cross sections (from PRECO code)*************
00178 G4double G4PreCompoundAlpha::GetOpt34(G4double K)
00179 // c     ** alpha from huizenga and igo
00180 {
00181   G4double landa, mu, nu, p , signor(1.),sig;
00182   G4double ec,ecsq,xnulam,etest(0.),a; 
00183   G4double b,ecut,cut,ecut2,geom,elab;
00184 
00185   G4double     flow = 1.e-18;
00186   G4double     spill= 1.e+18;
00187 
00188   G4double     p0 = 10.95;
00189   G4double     p1 = -85.2;
00190   G4double     p2 = 1146.;
00191   G4double     landa0 = 0.0643;
00192   G4double     landa1 = -13.96;
00193   G4double     mm0 = 781.2;
00194   G4double     mu1 = 0.29;
00195   G4double     nu0 = -304.7;
00196   G4double     nu1 = -470.0;
00197   G4double     nu2 = -8.580;        
00198   
00199   G4double      ra=1.20;
00200         
00201   //JMQ 13/02/09 increase of reduced radius to lower the barrier
00202   // ec = 1.44 * theZ * ResidualZ / (1.5*ResidualAthrd+ra);
00203   ec = 1.44 * theZ * ResidualZ / (1.7*ResidualAthrd+ra);
00204   ecsq = ec * ec;
00205   p = p0 + p1/ec + p2/ecsq;
00206   landa = landa0*ResidualA + landa1;
00207   a = g4pow->powZ(ResidualA,mu1);
00208   mu = mm0 * a;
00209   nu = a* (nu0+nu1*ec+nu2*ecsq);  
00210   xnulam = nu / landa;
00211   if (xnulam > spill) { xnulam=0.; }
00212   if (xnulam >= flow) { etest = 1.2 *std::sqrt(xnulam); }
00213 
00214   a = -2.*p*ec + landa - nu/ecsq;
00215   b = p*ecsq + mu + 2.*nu/ec;
00216   ecut = 0.;
00217   cut = a*a - 4.*p*b;
00218   if (cut > 0.) { ecut = std::sqrt(cut); }
00219   ecut = (ecut-a) / (p+p);
00220   ecut2 = ecut;
00221   //JMQ 290310 for avoiding unphysical increase below minimum (at ecut)
00222   // ecut<0 means that there is no cut with energy axis, i.e. xs is set 
00223   // to 0 bellow minimum
00224   //  if (cut < 0.) ecut2 = ecut - 2.;
00225   if (cut < 0.) { ecut2 = ecut; }
00226   elab = K * FragmentA / G4double(ResidualA);
00227   sig = 0.;
00228   
00229   if (elab <= ec) { //start for E<Ec
00230     if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; }
00231   }           //end for E<Ec
00232   else {           //start for E>Ec
00233     sig = (landa*elab+mu+nu/elab) * signor;
00234     geom = 0.;
00235     if (xnulam < flow || elab < etest) { return sig; }
00236     geom = std::sqrt(theA*K);
00237     geom = 1.23*ResidualAthrd + ra + 4.573/geom;
00238     geom = 31.416 * geom * geom;
00239     sig = std::max(geom,sig);
00240   }           //end for E>Ec
00241   return sig;
00242 }

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