git://git.uio.no / u / mrichter / AliRoot.git / blame
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1 | /////////////////////////////////////////////////////////////////////////// |
| 2 | // | |
| 3 | // Copyright 2010 | |
| 4 | // | |
| 5 | // This file is part of starlight. | |
| 6 | // | |
| 7 | // starlight is free software: you can redistribute it and/or modify | |
| 8 | // it under the terms of the GNU General Public License as published by | |
| 9 | // the Free Software Foundation, either version 3 of the License, or | |
| 10 | // (at your option) any later version. | |
| 11 | // | |
| 12 | // starlight is distributed in the hope that it will be useful, | |
| 13 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 14 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 15 | // GNU General Public License for more details. | |
| 16 | // | |
| 17 | // You should have received a copy of the GNU General Public License | |
| 18 | // along with starlight. If not, see <http://www.gnu.org/licenses/>. | |
| 19 | // | |
| 20 | /////////////////////////////////////////////////////////////////////////// | |
| 21 | // | |
| 22 | // File and Version Information: | |
| 23 | // $Rev:: $: revision of last commit | |
| 24 | // $Author:: $: author of last commit | |
| 25 | // $Date:: $: date of last commit | |
| 26 | // | |
| 27 | // Description: | |
| 28 | // | |
| 29 | // | |
| 30 | // | |
| 31 | /////////////////////////////////////////////////////////////////////////// | |
| 32 | ||
| 33 | ||
| 34 | #include <iostream> | |
| 35 | #include <fstream> | |
| 36 | #include <cmath> | |
| 37 | ||
| 38 | #include "starlightconstants.h" | |
| 39 | #include "narrowResonanceCrossSection.h" | |
| 40 | ||
| 41 | ||
| 42 | using namespace std; | |
| 43 | using namespace starlightConstants; | |
| 44 | ||
| 45 | ||
| 46 | //______________________________________________________________________________ | |
| 47 | narrowResonanceCrossSection::narrowResonanceCrossSection(const beamBeamSystem& bbsystem) | |
| 48 | :photonNucleusCrossSection(bbsystem) | |
| 49 | { | |
| 50 | _narrowYmax = inputParametersInstance.maxRapidity(); | |
| 51 | _narrowYmin = -1.0*_narrowYmax; | |
| 52 | _narrowNumY = inputParametersInstance.nmbRapidityBins(); | |
| 53 | _Ep = inputParametersInstance.protonEnergy(); | |
| 54 | } | |
| 55 | ||
| 56 | ||
| 57 | //______________________________________________________________________________ | |
| 58 | narrowResonanceCrossSection::~narrowResonanceCrossSection() | |
| 59 | { } | |
| 60 | ||
| 61 | ||
| 62 | //______________________________________________________________________________ | |
| 63 | void | |
| 64 | narrowResonanceCrossSection::crossSectionCalculation(const double) // _bwnormsave (unused) | |
| 65 | { | |
| 66 | // This subroutine calculates the vector meson cross section assuming | |
| 67 | // a narrow resonance. For reference, see STAR Note 386. | |
| 68 | ||
| 69 | // double Av,Wgp,cs,cvma; | |
| 70 | double W,dY; | |
| 71 | double y1,y2,y12,ega1,ega2,ega12; | |
| 72 | // double t,tmin,tmax; | |
| 73 | double csgA1,csgA2,csgA12,int_r,dR,rate; | |
| 74 | double tmp; | |
| 75 | // double ax,bx; | |
| 76 | double Eth; | |
| 77 | int J,NY; | |
| 78 | // int K,NGAUSS; | |
| 79 | ||
| 80 | NY = _narrowNumY; | |
| 81 | dY = (_narrowYmax-_narrowYmin)/double(NY); | |
| 82 | ||
| 83 | cout<<" Using Narrow Resonance ..."<<endl; | |
| 84 | ||
| 85 | W = getChannelMass(); | |
| 86 | Eth=0.5*(((W+protonMass)*(W+protonMass)- | |
| 87 | protonMass*protonMass)/(_Ep+sqrt(_Ep*_Ep-protonMass*protonMass))); | |
| 88 | ||
| 89 | cout<<" gamma+nucleon Threshold: "<<Eth<<endl; | |
| 90 | int_r=0.; | |
| 91 | ||
| 92 | tmp = 0.0; | |
| 93 | ||
| 94 | for(J=0;J<=(NY-1);J++){ | |
| 95 | ||
| 96 | y1 = _narrowYmin + double(J)*dY; | |
| 97 | y2 = _narrowYmin + double(J+1)*dY; | |
| 98 | y12 = 0.5*(y1+y2); | |
| 99 | ||
| 100 | ega1 = 0.5*W*exp(y1); | |
| 101 | ega2 = 0.5*W*exp(y2); | |
| 102 | ega12 = 0.5*W*exp(y12); | |
| 103 | ||
| 104 | if(ega1 < Eth) | |
| 105 | continue; | |
| 106 | if(ega2 > maxPhotonEnergy()) | |
| 107 | continue; | |
| 108 | ||
| 109 | csgA1=getcsgA(ega1,W); | |
| 110 | ||
| 111 | // Middle Point =====>>> | |
| 112 | csgA12=getcsgA(ega12,W); | |
| 113 | ||
| 114 | // Second Point =====>>> | |
| 115 | csgA2=getcsgA(ega2,W); | |
| 116 | ||
| 117 | // Sum the contribution for this W,Y. | |
| 118 | dR = ega1*photonFlux(ega1)*csgA1; | |
| 119 | dR = dR + 4.*ega12*photonFlux(ega12)*csgA12; | |
| 120 | dR = dR + ega2*photonFlux(ega2)*csgA2; | |
| 121 | tmp = tmp+2.*dR*(dY/6.); | |
| 122 | dR = dR*(dY/6.); | |
| 123 | ||
| 124 | // cout<<" y: "<<y12<<" egamma: "<<ega12<<" flux: "<<photonFlux(ega12)<<" sigma_gA: "<<10000000.*csgA12<<" dsig/dy (microb): "<<10000.*dR/dY<<endl; | |
| 125 | ||
| 126 | // The 2 accounts for the 2 beams | |
| 127 | if(getbbs().beam1().A()==getbbs().beam2().A()){ | |
| 128 | dR = 2.*dR; | |
| 129 | } | |
| 130 | int_r = int_r+dR; | |
| 131 | } | |
| 132 | rate=luminosity()*int_r; | |
| 133 | cout<<" Cross section (mb): " <<10.*int_r<<endl; | |
| 134 | } |