Geant4: G4AngularDistribution Class Reference

G4AngularDistribution::G4AngularDistribution ( G4bool symmetrize )

Definition at line 33 of file G4AngularDistribution.cc.

00034   : sym(symmetrize)
00035 {
00036   // The following are parameters of the model - not to be confused with the PDG values!
00037 
00038       mSigma = 0.55; 
00039       cmSigma = 1.20; 
00040       gSigma  = 9.4;
00041 
00042       mOmega = 0.783; 
00043       cmOmega = 0.808; 
00044       gOmega = 10.95;
00045 
00046       mPion = 0.138; 
00047       cmPion = 0.51; 
00048       gPion  = 7.27;
00049 
00050       mNucleon = 0.938;   
00051 
00052       // Definition of constants for pion-Term (no s-dependence)
00053 
00054       m42   = 4. * mNucleon * mNucleon;
00055       mPion2  = mPion * mPion;           
00056       cmPion2 = cmPion * cmPion;
00057       dPion1 = cmPion2-mPion2;
00058       dPion2 = dPion1 * dPion1;
00059       cm6gp = 1.5 * (cmPion2*cmPion2*cmPion2) * (gPion*gPion*gPion*gPion) * m42 * m42 / dPion2;
00060 
00061       cPion_3 = -(cm6gp/3.);
00062       cPion_2 = -(cm6gp * mPion2/dPion1);
00063       cPion_1 = -(cm6gp * mPion2 * (2. * cmPion2 + mPion2) / dPion2);
00064       cPion_m = -(cm6gp * cmPion2 * mPion2 / dPion2);
00065       cPion_L = -(cm6gp * 2. * cmPion2 * mPion2 * (cmPion2 + mPion2) / dPion2 / dPion1);
00066       cPion_0 = -(cPion_3 + cPion_2 + cPion_1 + cPion_m);
00067     
00068      // Definition of constants for sigma-Term (no s-dependence)
00069 
00070       G4double gSigmaSq = gSigma * gSigma; 
00071 
00072       mSigma2  = mSigma * mSigma;
00073       cmSigma2 = cmSigma * cmSigma;
00074       cmSigma4 = cmSigma2 * cmSigma2;
00075       cmSigma6 = cmSigma2 * cmSigma4;
00076       dSigma1 = m42 - cmSigma2;
00077       dSigma2 = m42 - mSigma2;
00078       dSigma3 = cmSigma2 - mSigma2;
00079 
00080       G4double dSigma1Sq = dSigma1 * dSigma1;
00081       G4double dSigma2Sq = dSigma2 * dSigma2;
00082       G4double dSigma3Sq = dSigma3 * dSigma3;
00083 
00084       cm2gs = 0.5 * cmSigma2 * gSigmaSq*gSigmaSq / dSigma3Sq;     
00085 
00086 
00087       cSigma_3 = -(cm2gs * dSigma1Sq / 3.);
00088       cSigma_2 = -(cm2gs * cmSigma2 * dSigma1 * dSigma2 / dSigma3);
00089       cSigma_1 = -(cm2gs * cmSigma4 * (2. * dSigma1 + dSigma2) * dSigma2 / dSigma3Sq);
00090       cSigma_m = -(cm2gs * cmSigma6 * dSigma2Sq / mSigma2 / dSigma3Sq);
00091       cSigma_L = -(cm2gs * cmSigma6 * dSigma2 * (dSigma1 + dSigma2) * 2. / (dSigma3 * dSigma3Sq));
00092       cSigma_0 = -(cSigma_3 + cSigma_2 + cSigma_1 + cSigma_m);
00093 
00094       // Definition of constants for omega-Term
00095 
00096       G4double gOmegaSq = gOmega * gOmega;
00097 
00098       mOmega2  = mOmega * mOmega;
00099       cmOmega2 = cmOmega * cmOmega;
00100       cmOmega4 = cmOmega2 * cmOmega2;
00101       cmOmega6 = cmOmega2 * cmOmega4;
00102       dOmega1 = m42 - cmOmega2;
00103       dOmega2 = m42 - mOmega2;
00104       dOmega3 = cmOmega2 - mOmega2;
00105       sOmega1 = cmOmega2 + mOmega2;
00106 
00107       G4double dOmega3Sq = dOmega3 * dOmega3;
00108 
00109       cm2go = 0.5 * cmOmega2 * gOmegaSq * gOmegaSq / dOmega3Sq;
00110 
00111       cOmega_3 =  cm2go / 3.;
00112       cOmega_2 = -(cm2go * cmOmega2 / dOmega3);
00113       cOmega_1 =  cm2go * cmOmega4 / dOmega3Sq;
00114       cOmega_m =  cm2go * cmOmega6 / (dOmega3Sq * mOmega2);
00115       cOmega_L = -(cm2go * cmOmega6 * 4. / (dOmega3 * dOmega3Sq));
00116 
00117       // Definition of constants for mix-Term
00118 
00119       G4double fac1Tmp = (gSigma * gOmega * cmSigma2 * cmOmega2);
00120       fac1 = -(fac1Tmp *  fac1Tmp * m42);  
00121       dMix1 = cmOmega2 - cmSigma2;
00122       dMix2 = cmOmega2 - mSigma2;
00123       dMix3 = cmSigma2 - mOmega2;
00124 
00125       G4double dMix1Sq = dMix1 * dMix1;
00126       G4double dMix2Sq = dMix2 * dMix2;
00127       G4double dMix3Sq = dMix3 * dMix3;
00128 
00129       cMix_o1 =    fac1 / (cmOmega2  * dMix1Sq * dMix2 * dOmega3);
00130       cMix_s1 =    fac1 / (cmSigma2  * dMix1Sq * dMix3 * dSigma3);
00131       cMix_Omega = fac1 / (dOmega3Sq * dMix3Sq * (mOmega2 - mSigma2));
00132       cMix_sm =    fac1 / (dSigma3Sq * dMix2Sq * (mSigma2 - mOmega2)); 
00133       fac2 = (-fac1) / (dMix1*dMix1Sq * dOmega3Sq * dMix2Sq);
00134       fac3 = (-fac1) / (dMix1*dMix1Sq * dSigma3Sq * dMix3Sq); 
00135       
00136       cMix_oLc = fac2 * (3. * cmOmega2*cmOmega4            - cmOmega4 * cmSigma2 
00137                        - 2. * cmOmega4 * mOmega2           - 2. * cmOmega4 * mSigma2 
00138                        + cmOmega2 * mOmega2 * mSigma2      + cmSigma2 * mOmega2 * mSigma2 
00139                        - 4. * cmOmega4 * m42               + 2. * cmOmega2 * cmSigma2 * m42 
00140                        + 3. * cmOmega2 * mOmega2 * m42     - cmSigma2 * mOmega2 * m42 
00141                        + 3. * cmOmega2 * mSigma2 * m42     - cmSigma2 * mSigma2 * m42 
00142                        - 2. * mOmega2 * mSigma2 * m42);
00143       
00144       cMix_oLs = fac2 * (8. * cmOmega4                     - 4. * cmOmega2 * cmSigma2 
00145                          - 6. * cmOmega2 * mOmega2         + 2. * cmSigma2 * mOmega2 
00146                          - 6. * cmOmega2 * mSigma2         + 2. * cmSigma2 * mSigma2 
00147                          + 4. * mOmega2 * mSigma2);
00148       
00149       cMix_sLc = fac3 * (cmOmega2 * cmSigma4               - 3. * cmSigma6    
00150                          + 2. * cmSigma4 * mOmega2         + 2. * cmSigma4 * mSigma2 
00151                          - cmOmega2 * mOmega2 * mSigma2    - cmSigma2 * mOmega2 * mSigma2 
00152                          - 2. * cmOmega2 * cmSigma2 * m42  + 4. * cmSigma4 * m42 
00153                          + cmOmega2 * mOmega2 * m42        - 3. * cmSigma2 * mOmega2 * m42 
00154                          + cmOmega2 * mSigma2 * m42        - 3. * cmSigma2 * mSigma2 * m42 
00155                          + 2. * mOmega2 * mSigma2 * m42);
00156 
00157       cMix_sLs = fac3 * (4. * cmOmega2 * cmSigma2          - 8. * cmSigma4
00158                        - 2. * cmOmega2 * mOmega2           + 6. * cmSigma2 * mOmega2 
00159                        - 2. * cmOmega2 * mSigma2           + 6. * cmSigma2 * mSigma2 
00160                        - 4. * mOmega2 * mSigma2);
00161 }

G4AngularDistribution::~G4AngularDistribution ( ) [virtual]

Definition at line 165 of file G4AngularDistribution.cc.

00166 { }

G4double G4AngularDistribution::CosTheta	(	G4double	s,
		G4double	m1,
		G4double	m2
	)			const `[virtual]`

Implements G4VAngularDistribution.

Definition at line 169 of file G4AngularDistribution.cc.

References DifferentialCrossSection(), and G4UniformRand.

00170 {
00171    G4double random = G4UniformRand();
00172    G4double dCosTheta = 2.;
00173    G4double cosTheta = -1.;
00174 
00175    // For jmax=12 the accuracy is better than 0.1 degree 
00176    G4int jMax = 12;
00177 
00178    for (G4int j = 1; j <= jMax; ++j)
00179    {
00180       // Accuracy is 2^-jmax 
00181       dCosTheta *= 0.5;
00182       G4double cosTh = cosTheta + dCosTheta;
00183       if(DifferentialCrossSection(S, m_1, m_2, cosTh) <= random) cosTheta = cosTh;
00184     }
00185 
00186    // Randomize in final interval in order to avoid discrete angles 
00187    cosTheta += G4UniformRand() * dCosTheta;
00188 
00189 
00190    if (cosTheta > 1. || cosTheta < -1.)
00191      throw G4HadronicException(__FILE__, __LINE__, "G4AngularDistribution::CosTheta - std::cos(theta) outside allowed range");
00192 
00193    return cosTheta;
00194 }

G4double G4AngularDistribution::Cross	(	G4double	tpPion,
		G4double	tpSigma,
		G4double	tpOmega,
		G4double	tmPion,
		G4double	tmSigma,
		G4double	tmOmega,
		G4double	bMix_o1,
		G4double	bMix_s1,
		G4double	bMix_Omega,
		G4double	bMix_sm,
		G4double	bMix_oL,
		G4double	bMix_sL,
		G4double	bOmega_0,
		G4double	bOmega_1,
		G4double	bOmega_2,
		G4double	bOmega_3,
		G4double	bOmega_m,
		G4double	bOmega_L
	)			const

Definition at line 294 of file G4AngularDistribution.cc.

Referenced by DifferentialCrossSection().

00312 {
00313   G4double cross = 0;
00314      //  Pion
00315     cross += ((cPion_3 * tpPion  + cPion_2)  * tpPion  + cPion_1)  * tpPion  + cPion_m/tmPion   + cPion_0  +  cPion_L * std::log(tpPion*tmPion);
00316 //    G4cout << "cross1 "<< cross<<G4endl;
00317     //  Sigma
00318     cross += ((cSigma_3 * tpSigma + cSigma_2) * tpSigma + cSigma_1) * tpSigma + cSigma_m/tmSigma + cSigma_0 + cSigma_L * std::log(tpSigma*tmSigma);
00319 //    G4cout << "cross2 "<< cross<<G4endl;
00320     // Omega
00321     cross += ((bOmega_3 * tpOmega + bOmega_2) * tpOmega + bOmega_1) * tpOmega + bOmega_m/tmOmega + bOmega_0 + bOmega_L * std::log(tpOmega*tmOmega)
00322     // Mix
00323     +  bMix_o1 * (tpOmega - 1.)
00324     +  bMix_s1 * (tpSigma - 1.)
00325     +  bMix_Omega * std::log(tmOmega)
00326     +  bMix_sm * std::log(tmSigma)
00327     +  bMix_oL * std::log(tpOmega)
00328     +  bMix_sL * std::log(tpSigma);
00329 /*      G4cout << "cross3 "<< cross<<" "
00330              <<bMix_o1<<" "
00331              <<bMix_s1<<" "
00332              <<bMix_Omega<<" "
00333              <<bMix_sm<<" "
00334              <<bMix_oL<<" "
00335              <<bMix_sL<<" "
00336              <<tpOmega<<" "
00337              <<tpSigma<<" "
00338              <<tmOmega<<" "
00339              <<tmSigma<<" "
00340              <<tpOmega<<" "
00341              <<tpSigma
00342              <<G4endl;
00343 */
00344   return cross;
00345 
00346 }

G4double G4AngularDistribution::DifferentialCrossSection	(	G4double	sIn,
		G4double	m1,
		G4double	m2,
		G4double	cosTheta
	)			const

Definition at line 197 of file G4AngularDistribution.cc.

References Cross(), and sqr().

Referenced by CosTheta().

00199 {
00200 // local calculus is in GeV, ie. normalize input
00201   sIn = sIn/sqr(GeV)+m42/2.;
00202   m_1  = m_1/GeV;
00203   m_2  = m_2/GeV;
00204 //  G4cout << "Here we go"<<sIn << " "<<m1 << " " << m2 <<" " m42<< G4endl;
00205 // scaling from masses other than p,p.
00206   G4double S = sIn - (m_1+m_2) * (m_1+m_2) + m42;
00207   G4double tMax = S - m42;
00208   G4double tp = 0.5 * (cosTheta + 1.) * tMax; 
00209   G4double twoS = 2. * S;
00210   
00211   // Define s-dependent stuff for omega-Term
00212   G4double brak1 = (twoS-m42) * (twoS-m42);
00213   G4double bOmega_3 = cOmega_3 * (-2. * cmOmega4 - 2. * cmOmega2 * twoS - brak1);
00214   G4double bOmega_2 = cOmega_2 * ( 2. * cmOmega2 * mOmega2 + sOmega1 * twoS + brak1);
00215   G4double bOmega_1 = cOmega_1 * (-4. * cmOmega2 * mOmega2 
00216                          - 2. * mOmega2*mOmega2 
00217                          - 2. * (cmOmega2 + 2 * mOmega2) * twoS 
00218                          - 3. * brak1);
00219   G4double bOmega_m = cOmega_m * (-2. * mOmega2*mOmega2 - 2. * mOmega2 * twoS - brak1);
00220   G4double bOmega_L = cOmega_L * (sOmega1 * mOmega2 + (cmOmega2 + 3. * mOmega2) * S + brak1);
00221   G4double bOmega_0 = -(bOmega_3 + bOmega_2 + bOmega_1 + bOmega_m);
00222   
00223   // Define s-dependent stuff for mix-Term            
00224   G4double bMix_o1 = cMix_o1 * (dOmega1 - twoS);
00225   G4double bMix_s1 = cMix_s1 * (dSigma1 - twoS);
00226   G4double bMix_Omega = cMix_Omega * (dOmega2 - twoS);
00227   G4double bMix_sm = cMix_sm * (dSigma2 - twoS);
00228   G4double bMix_oL = cMix_oLc + cMix_oLs * S;
00229   G4double bMix_sL = cMix_sLc + cMix_sLs * S;
00230   
00231   G4double t1_Pion = 1. / (1. + tMax / cmPion2);
00232   G4double t2_Pion = 1. + tMax / mPion2;
00233   G4double t1_Sigma = 1. / (1. + tMax / cmSigma2);
00234   G4double t2_Sigma = 1. + tMax / mSigma2;
00235   G4double t1_Omega = 1. / (1. + tMax / cmOmega2);
00236   G4double t2_Omega = 1. + tMax / mOmega2;
00237   
00238   G4double norm = Cross(t1_Pion, t1_Sigma, t1_Omega,
00239                         t2_Pion, t2_Sigma, t2_Omega,
00240                         bMix_o1, bMix_s1, bMix_Omega,
00241                         bMix_sm, bMix_oL, bMix_sL,
00242                         bOmega_0, bOmega_1, bOmega_2,
00243                         bOmega_3, bOmega_m, bOmega_L);
00244   
00245   t1_Pion = 1. / (1. + tp / cmPion2);
00246   t2_Pion = 1. + tp / mPion2;
00247   t1_Sigma = 1. / (1. + tp / cmSigma2);
00248   t2_Sigma = 1. + tp / mSigma2;
00249   t1_Omega = 1. / (1. + tp / cmOmega2);
00250   t2_Omega = 1. + tp / mOmega2;
00251   
00252   G4double dSigma;
00253   if (sym) 
00254     { 
00255       G4double to;
00256       norm = 2. * norm;
00257       to = tMax - tp;
00258       G4double t3_Pion = 1. / (1. + to / cmPion2);
00259       G4double t4_Pion = 1. + to / mPion2;
00260       G4double t3_Sigma = 1. / (1. + to / cmSigma2);
00261       G4double t4_Sigma = 1. + to / mSigma2;
00262       G4double t3_Omega = 1. / (1. + to / cmOmega2);
00263       G4double t4_Omega = 1. + to / mOmega2;
00264       
00265       dSigma = ( Cross(t1_Pion, t1_Sigma, t1_Omega,
00266                        t2_Pion,t2_Sigma, t2_Omega,
00267                        bMix_o1, bMix_s1, bMix_Omega,
00268                        bMix_sm, bMix_oL, bMix_sL,
00269                        bOmega_0, bOmega_1, bOmega_2,
00270                        bOmega_3, bOmega_m, bOmega_L) - 
00271                  Cross(t3_Pion,t3_Sigma, t3_Omega,
00272                        t4_Pion, t4_Sigma, t4_Omega,
00273                        bMix_o1, bMix_s1, bMix_Omega,
00274                        bMix_sm, bMix_oL, bMix_sL,
00275                        bOmega_0, bOmega_1, bOmega_2,
00276                        bOmega_3, bOmega_m, bOmega_L) ) 
00277         / norm + 0.5;
00278     }
00279   else
00280     {
00281       dSigma = Cross(t1_Pion, t1_Sigma, t1_Omega, 
00282                      t2_Pion, t2_Sigma, t2_Omega,
00283                      bMix_o1, bMix_s1, bMix_Omega,
00284                      bMix_sm, bMix_oL, bMix_sL,
00285                      bOmega_0, bOmega_1, bOmega_2,
00286                      bOmega_3, bOmega_m, bOmega_L) 
00287         / norm;
00288     }
00289   
00290   return dSigma;
00291 }


Public Member Functions
	G4AngularDistribution (G4bool symmetrize)
virtual	~G4AngularDistribution ()
virtual G4double	CosTheta (G4double s, G4double m1, G4double m2) const
G4double	DifferentialCrossSection (G4double sIn, G4double m1, G4double m2, G4double cosTheta) const
G4double	Cross (G4double tpPion, G4double tpSigma, G4double tpOmega, G4double tmPion, G4double tmSigma, G4double tmOmega, G4double bMix_o1, G4double bMix_s1, G4double bMix_Omega, G4double bMix_sm, G4double bMix_oL, G4double bMix_sL, G4double bOmega_0, G4double bOmega_1, G4double bOmega_2, G4double bOmega_3, G4double bOmega_m, G4double bOmega_L) const

G4AngularDistribution Class Reference

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation