DV Plotting XSect

Creating a program called MollerDiffXSect.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
main()
{
float angle,dSigma_dOmega;
double alpha=7.2973525664e-3;
double E_CM=53e6;                                               //CM E for 11GeV incident electrons

                /* using equation from Landau-Lifshitz & Azfar */
                /* units in MeV */
                for(angle=90;angle<=180; angle=angle+.5)
//                for(angle=90;angle<=180; angle=angle+1)

                        {
                        dSigma_dOmega=(alpha*(3+cos(angle*3.14159265359/180)*cos(angle*3.14159265359/180)));
                        dSigma_dOmega=dSigma_dOmega*dSigma_dOmega;

                        dSigma_dOmega=dSigma_dOmega/(4*E_CM*E_CM*sin(angle*3.14159265359/180)*sin(angle*3.14159265359/180)
                                *sin(angle*3.14159265359/180)*sin(angle*3.14159265359/180));
                        dSigma_dOmega=dSigma_dOmega*1e18;
                        dSigma_dOmega=dSigma_dOmega*.3892e-3;   //barns
                        dSigma_dOmega=dSigma_dOmega/2;          //2 electrons for LH2
                        fprintf(stdout," %f\t%f\n", angle, dSigma_dOmega);
                        }

}

Creating a Makefile with contents:

CC = gcc
DiffXSect: MollerDiffXSect.o
        $(CC) $(CFLAGS) MollerDiffXSect.o  -lm -o DiffXSect
MollerDiffXSect.o: MollerDiffXSect.c
        $(CC)  $(CFLAGS) -c MollerDiffXSect.c

The program can be run with the commands:

make DiffXSect
./DiffXSect >DiffXSect.dat

This creates a data file with the scattering angle theta and the corresponding theoretical Moller differential cross-section for said angle. A c++ macro can be written to input this into root

void MollerDiffXSect2Root()
{
    struct evt_t
        {
                Int_t event;
                Float_t Angle, dSigma_dOmega;
        };
  ifstream in;
  in.open("DiffXSect.dat");
  evt_t evt;
  Int_t nlines=0;

  int count=0;
  TFile *f = new TFile("DiffXSect.root","RECREATE");

  TTree *tree = new TTree("DiffXSect","Moller Diff Xsect");

  TH1F *Th=new TH1F("Theory","Theoretical Differential Cross Section",360,90,180);

  tree->Branch("evt",&evt.event,"event/F:Angle/F:dSigma_dOmega");
  while(in.good())
        {
                evt.event=nlines;
                in >> evt.Angle >> evt.dSigma_dOmega;
                        if(nlines==count)
                        {
                                printf( " %d  %f %f\n",evt.event, evt.Angle, evt.dSigma_dOmega);
                                count=count+4;
                        }
                 nlines++;
                tree->Fill();
                Th->Fill(evt.Angle,evt.dSigma_dOmega);
}
 tree->Print();
 tree->Write();
 f->Write();
 in.close();
 delete tree;
 delete f;
}

A data file is created with the differential cross-section for the scattering angle theta, by increments of 1

90.000000      0.000008
 90.500000      0.000008
 91.000000      0.000008
 91.500000      0.000008
 92.000000      0.000008
 92.500000      0.000008
 93.000000      0.000008
 93.500000      0.000008
 94.000000      0.000008
 94.500000      0.000008
 95.000000      0.000008
 95.500000      0.000009
 96.000000      0.000009
 96.500000      0.000009
 97.000000      0.000009
 97.500000      0.000009
 98.000000      0.000009
 98.500000      0.000009
 99.000000      0.000009
 99.500000      0.000009
 100.000000     0.000009
 100.500000     0.000009
 101.000000     0.000009
 101.500000     0.000009
 102.000000     0.000009
 102.500000     0.000009
 103.000000     0.000010
 103.500000     0.000010
 104.000000     0.000010
 104.500000     0.000010
 105.000000     0.000010
 105.500000     0.000010
 106.000000     0.000010
 106.500000     0.000010
 107.000000     0.000010
 107.500000     0.000011
 108.000000     0.000011
 108.500000     0.000011
 109.000000     0.000011
 109.500000     0.000011
110.000000     0.000011
 110.500000     0.000012
 111.000000     0.000012
 111.500000     0.000012
 112.000000     0.000012
 112.500000     0.000013
 113.000000     0.000013
 113.500000     0.000013
 114.000000     0.000013
 114.500000     0.000014
 115.000000     0.000014
 115.500000     0.000014
 116.000000     0.000014
 116.500000     0.000015
 117.000000     0.000015
 117.500000     0.000015
 118.000000     0.000016
 118.500000     0.000016
 119.000000     0.000016
 119.500000     0.000017
 120.000000     0.000017
 120.500000     0.000018
 121.000000     0.000018
 121.500000     0.000019
 122.000000     0.000019
 122.500000     0.000020
 123.000000     0.000020
 123.500000     0.000021
 124.000000     0.000021
 124.500000     0.000022
 125.000000     0.000023
 125.500000     0.000023
 126.000000     0.000024
 126.500000     0.000025
 127.000000     0.000026
 127.500000     0.000026
 128.000000     0.000027
 128.500000     0.000028
129.000000     0.000029
 129.500000     0.000030
 130.000000     0.000031
 130.500000     0.000032
 131.000000     0.000033
 131.500000     0.000035
 132.000000     0.000036
 132.500000     0.000037
 133.000000     0.000039
 133.500000     0.000040
 134.000000     0.000042
 134.500000     0.000043
 135.000000     0.000045
 135.500000     0.000047
 136.000000     0.000049
 136.500000     0.000051
 137.000000     0.000053
 137.500000     0.000056
 138.000000     0.000058
 138.500000     0.000061
 139.000000     0.000063
 139.500000     0.000066
 140.000000     0.000070
 140.500000     0.000073
 141.000000     0.000076
 141.500000     0.000080
 142.000000     0.000084
 142.500000     0.000088
 143.000000     0.000093
 143.500000     0.000098
 144.000000     0.000103
 144.500000     0.000109
 145.000000     0.000115
 145.500000     0.000121
 146.000000     0.000128
 146.500000     0.000136
 147.000000     0.000144
 147.500000     0.000152
148.000000     0.000162
 148.500000     0.000172
 149.000000     0.000183
 149.500000     0.000195
 150.000000     0.000208
 150.500000     0.000221
 151.000000     0.000237
 151.500000     0.000253
 152.000000     0.000271
 152.500000     0.000291
 153.000000     0.000312
 153.500000     0.000336
 154.000000     0.000362
 154.500000     0.000391
 155.000000     0.000422
 155.500000     0.000457
 156.000000     0.000495
 156.500000     0.000538
 157.000000     0.000586
 157.500000     0.000639
 158.000000     0.000698
 158.500000     0.000764
 159.000000     0.000838
 159.500000     0.000922
 160.000000     0.001016
 160.500000     0.001123
 161.000000     0.001245
 161.500000     0.001383
 162.000000     0.001542
 162.500000     0.001724
 163.000000     0.001934
 163.500000     0.002177
 164.000000     0.002460
 164.500000     0.002791
 165.000000     0.003179
 165.500000     0.003638
 166.000000     0.004183
 166.500000     0.004834
167.000000     0.005618
 167.500000     0.006568
 168.000000     0.007727
 168.500000     0.009156
 169.000000     0.010931
 169.500000     0.013159
 170.000000     0.015986
 170.500000     0.019616
 171.000000     0.024340
 171.500000     0.030579
 172.000000     0.038953
 172.500000     0.050406
 173.000000     0.066401
 173.500000     0.089281
 174.000000     0.122933
 174.500000     0.174058
 175.000000     0.254769
 175.500000     0.388214
 176.000000     0.621708
 176.500000     1.060403
 177.000000     1.964202
 177.500000     4.072398
 178.000000     9.941240
 178.500000     31.416433
 179.000000     159.035599
 179.500000     2544.472656
 180.000000     inf