PREM.cxx

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//____________________________________________________________________________
/*
 Copyright (c) 2003-2025, The GENIE Collaboration
 For the full text of the license visit http://copyright.genie-mc.org
 
 Costas Andreopoulos <c.andreopoulos \at cern.ch>
 University of Liverpool
*/
//____________________________________________________________________________
 
#include <TMath.h>
 
#include "Framework/Conventions/Constants.h"
#include "Framework/Conventions/Units.h"
#include "Framework/Utils/PREM.h"
 
//___________________________________________________________________________
double genie::utils::prem::Density(double r)
{
// Return the Earth density according to the PREM model
// Inputs:  r,   Distance from the centre of the Earth (in std GENIE units)
// Outputs: rho, Earth density (in std GENIE  units)
//
 
  r = TMath::Max(0., r/units::km); // convert to km
 
  double rE  = constants::kREarth/units::km;
  double rho = 0.;
  double x   = r / rE;
 
  if (r <= 1221.5 )
  {
    rho = 13.0885 - 8.8381*x*x;
  }
  else if (r >  1221.5 && r <= 3480.0 )
  {
    rho = 12.5815 - 1.2638*x - 3.6426*x*x - 5.5281*x*x*x;
  }
  else if (r >  3480.0 && r <= 5701.0 )
  {
    rho = 7.9565  - 6.4761*x + 5.5283*x*x - 3.0807*x*x*x;
  }
  else if (r >  5701.0 && r <= 5771.0 )
  {
    rho = 5.3197  - 1.4836*x;
  }
  else if (r >  5771.0 && r <= 5971.0 )
  {
    rho = 11.2494 - 8.0298*x;
  }
  else if (r >  5971.0 && r <= 6151.0 )
  {
    rho = 7.1089  - 3.8045*x;
  }
  else if (r >  6151.0 && r <= 6346.6 )
  {
    rho = 2.691   + 0.6924*x;
  }
  else if (r >  6346.6 && r <= 6356.0 )
  {
    rho = 2.90;
  }
  else if (r >  6356.0 && r <= 6368.0 )
  {
    rho = 2.60;
  }
  else if (r >  6368.0 && r <= rE)
  {
    rho = 1.02;
  }
 
  rho = rho * units::g_cm3;
 
  return rho;
}
//___________________________________________________________________________