/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_7/src/GeneratorInterface/CosmicMuonGenerator/src/CMSCGENnorm.cc

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//
// CMSCGENnorm.cc       P. Biallass 2006  
//
// code based on l3cgen.f by T.Hebbeker
// implemented in CMSSW by P. Biallass 11.04.2006  
// see header for documentation
//


#include "GeneratorInterface/CosmicMuonGenerator/interface/CMSCGENnorm.h"


//count muons which are around 100GeV and theta<33 deg (~vertical), do this for EVERY generated cosmic 

int CMSCGENnorm::events_n100cos(double energy, double theta)
{
   if(energy > 99.5 && energy < 100.5){ 
    n100=n100+1;
    
    if(1.-cos(theta) < 1./(2.*Pi)) { //theta is in rad
      n100cos = n100cos + 1 ;
    }
  }
  return n100cos;
}


// determine normalization using known flux, do this in the end. Percentage of rejected events and surface needs to be corrected for later!
// Note that the number of actually DICED cosmics is needed for normalisation, and sufficient statistics to have muons at 100 GeV!

float CMSCGENnorm::norm(int n100cos)
{ 
  flux = 2.63e-3 ; // +- 0.06e-3 [1/m**2/sr/GeV/s]

  n = n100cos ; // [1/sr/GeV]
  
  //rate=N/runtime --> Nnorm ~ (1/runtime/m^2 at surface plane) as rate corresponds to known flux
  Nnorm = flux/n ;

  //err of Nnorm = Nnorm* 1/sqrt(n)
  
  return Nnorm; 
}