158 lines
4.9 KiB
C
158 lines
4.9 KiB
C
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#ifndef ReactionParameters_H
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#define ReactionParameters_H
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#include "ClassDetGeo.h"
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class ReactionParas{
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public:
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ReactionParas();
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double Et; // total energy in CM frame
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double beta; // Lorentz beta from Lab to CM
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double gamma; // Lorentz gamma from Lab to CM
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double alpha; // E-Z slope / beta
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double G; //The G-coefficient....
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double massB; // heavy mass
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double q; // charge of light particle
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double mass; //light mass
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bool hasReactionPara;
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double detPrepDist;
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void LoadReactionParas(bool verbose = false);
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std::pair<double, double> CalExTheta(double e, double z)
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};
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ReactionParas::ReactionParas(){
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}
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//~========================================= reaction parameters
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inline void ReactionParas::LoadReactionParas(bool verbose = false){
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//check is the transfer.root is using the latest reactionConfig.txt
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//sicne reaction.dat is generated as a by-product of transfer.root
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//TFile * transfer = new TFile("transfer.root");
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//TString aaa1 = "";
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//TString aaa2 = "";
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//if( transfer->IsOpen() ){
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// TMacro * reactionConfig = (TMacro *) transfer->FindObjectAny("reactionConfig");
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// TMacro presentReactionConfig ("reactionConfig.txt");
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// aaa1 = ((TMD5*) reactionConfig->Checksum())->AsString();
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// aaa2 = ((TMD5*) presentReactionConfig.Checksum())->AsString();
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//}
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//printf("%s\n", aaa1.Data());
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//printf("%s\n", aaa2.Data());
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//if( aaa1 != aaa2 ) {
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// printf("########################## recalculate transfer.root \n");
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// system("../Cleopatra/Transfer");
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// printf("########################## transfer.root updated\n");
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//}
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std::string fileName;
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detPrepDist = Array::detPerpDist;
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printf(" loading reaction parameters");
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std::ifstream file;
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file.open(fileName.c_str());
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hasReactionPara = false;
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if( file.is_open() ){
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std::string x;
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int i = 0;
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while( file >> x ){
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if( x.substr(0,2) == "//" ) continue;
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if( i == 0 ) mass = atof(x.c_str());
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if( i == 1 ) q = atof(x.c_str());
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if( i == 2 ) beta = atof(x.c_str());
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if( i == 3 ) Et = atof(x.c_str());
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if( i == 4 ) massB = atof(x.c_str());
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i = i + 1;
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}
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printf("........ done.\n");
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hasReactionPara = true;
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alpha = 299.792458 * abs(detGeo.Bfield) * q / TMath::TwoPi()/1000.; //MeV/mm
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gamma = 1./TMath::Sqrt(1-beta * beta);
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G = alpha * gamma * beta * detPrepDist ;
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if( verbose ){
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printf("\tmass-b : %f MeV/c2 \n", mass);
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printf("\tcharge-b : %f \n", q);
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printf("\tE-total : %f MeV \n", Et);
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printf("\tmass-B : %f MeV/c2 \n", massB);
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printf("\tbeta : %f \n", beta);
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printf("\tB-field : %f T \n", detGeo.Bfield);
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printf("\tslope : %f MeV/mm \n", alpha * beta);
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printf("\tdet radius: %f mm \n", detPrepDist);
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printf("\tG-coeff : %f MeV \n", G);
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printf("=====================================================\n");
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}
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}else{
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printf("........ fail.\n");
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}
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file.close();
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}
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inline std::pair<double, double> ReactionParas::CalExTheta(double e, double z){
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ReactionParas * reactParas = nullptr;
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if( detGeo.array1.zMin <= z && z <= detGeo.array1.zMax ){
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reactParas = &reactParas1;
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if( !hasReactionPara) return {TMath::QuietNaN(), TMath::QuietNaN()};
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}
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if( detGeo.array2.zMin <= z && z <= detGeo.array2.zMax ){
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reactParas = &reactParas2;
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if( !hasReactionPara) return {TMath::QuietNaN(), TMath::QuietNaN()};
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}
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double Ex = TMath::QuietNaN();
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double thetaCM = TMath::QuietNaN();
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double y = e + mass; // to give the KE + mass of proton;
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double Z = alpha * gamma * beta * z;
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double H = TMath::Sqrt(TMath::Power(gamma * beta,2) * (y*y - mass * mass) ) ;
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if( TMath::Abs(Z) < H ) {
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///using Newton's method to solve 0 == H * sin(phi) - G * tan(phi) - Z = f(phi)
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double tolerrence = 0.001;
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double phi = 0; ///initial phi = 0 -> ensure the solution has f'(phi) > 0
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double nPhi = 0; /// new phi
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int iter = 0;
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do{
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phi = nPhi;
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nPhi = phi - (H * TMath::Sin(phi) - G * TMath::Tan(phi) - Z) / (H * TMath::Cos(phi) - G /TMath::Power( TMath::Cos(phi), 2));
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iter ++;
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if( iter > 10 || TMath::Abs(nPhi) > TMath::PiOver2()) break;
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}while( TMath::Abs(phi - nPhi ) > tolerrence);
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phi = nPhi;
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/// check f'(phi) > 0
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double Df = H * TMath::Cos(phi) - G / TMath::Power( TMath::Cos(phi),2);
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if( Df > 0 && TMath::Abs(phi) < TMath::PiOver2() ){
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double K = H * TMath::Sin(phi);
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double x = TMath::ACos( mass / ( y * gamma - K));
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double momt = mass * TMath::Tan(x); /// momentum of particel b or B in CM frame
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double EB = TMath::Sqrt(mass * mass + Et * Et - 2 * Et * TMath::Sqrt(momt*momt + mass * mass));
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Ex = EB - massB;
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double hahaha1 = gamma * TMath::Sqrt(mass * mass + momt * momt) - y;
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double hahaha2 = gamma * beta * momt;
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thetaCM = TMath::ACos(hahaha1/hahaha2) * TMath::RadToDeg();
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}
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}
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return std::make_pair(Ex, thetaCM);
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}
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#endif
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