JPDFToolkit.hh

Go to the documentation of this file.

#ifndef __JPHYSICS__JPDFTOOLKIT__
#define __JPHYSICS__JPDFTOOLKIT__
 
#include <cmath>
 
#include "JPhysics/JConstants.hh"
#include "JPhysics/JPhysicsToolkit.hh"
#include "JPhysics/JEnergyRange.hh"
 
 
/**
 * \file
 * Auxiliary methods for PDF calculations.
 * \author mdejong, bjung
 */
 
namespace JPHYSICS {}
namespace JPP { using namespace JPHYSICS; }
 
namespace JPHYSICS {
 
  /**
   * Get minimal wavelength for PDF evaluations.
   *
   * \return            wavelength of light [nm]
   */
  inline double getMinimalWavelength()
  {
    return 300.0;
  }
 
 
  /**
   * Get maximal wavelength for PDF evaluations.
   *
   * \return            wavelength of light [nm]
   */
  inline double getMaximalWavelength()
  {
    return 700.0;
  }
  
 
  /**
   * Number of Cherenkov photons per unit track length and per unit wavelength.
   *
   * \param  lambda     wavelength of light [nm]
   * \param  n          index of refraction
   * \return            number of photons per unit track length and per unit wavelength [m^-1 nm^-1]
   */
  inline double cherenkov(const double lambda,
                          const double n)
  {
    const double x = n*lambda;
    
    return 1.0e9 * 2 * PI * ALPHA_ELECTRO_MAGNETIC * (n*n - 1.0) / (x*x);
  }
 
 
  /**
   * Rayleigh cross section.
   *
   * \param  n          index of refraction
   * \param  lambda     wavelength of light [nm]
   * \return            cross section       [cm^2]
   */
  inline const double getRayleighCrossSection(const double n,
                                              const double lambda)
  {
    static const double d = 0.36;                    // size of H2O molecule [nm]
    static const double U = PI*PI*PI*PI*PI*2.0/3.0;
    static const double V = d*d*d*d*d*d;
 
    const double W     = (n*n - 1.0) / (n*n + 2.0);
    const double sigma = 1.0e-14 * U*V*W*W / (lambda*lambda*lambda*lambda);   // [cm^2]
 
    return sigma;
  }
 
 
  /**
   * Rayleigh scattering length.
   *
   * \param  n          index of refraction
   * \param  lambda     wavelength of light [nm]
   * \return            scattering length   [m]
   */
  inline const double getRayleighScatteringLength(const double n,
                                                  const double lambda)
  {
    static const double amu = 18.01528; // H20 mass in Atomic mass units
 
    const double sigma = getRayleighCrossSection(n, lambda);
    const double ls    = 1.0e-2 / (DENSITY_SEA_WATER * AVOGADRO * sigma / amu);     // [m]
 
    return ls;
  }
}
 
#endif