d5/d9f/beam_8cpp_source.html

//

//    Copyright 2010

//

//    This file is part of starlight.

//

//    starlight is free software: you can redistribute it and/or modify

//    it under the terms of the GNU General Public License as published by

//    the Free Software Foundation, either version 3 of the License, or

//    (at your option) any later version.

//

//    starlight is distributed in the hope that it will be useful,

//    but WITHOUT ANY WARRANTY; without even the implied warranty of

//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

//    GNU General Public License for more details.

//

//    You should have received a copy of the GNU General Public License

//    along with starlight. If not, see <http://www.gnu.org/licenses/>.

//

//

// File and Version Information:

// $Rev:: 259                         $: revision of last commit

// $Author:: jseger                   $: author of last commit

// $Date:: 2016-04-19 01:58:25 +0100 #$: date of last commit

//

// Description:

//

//

//


#include <iostream>

#include <fstream>

#include <cmath>


#include "starlightconstants.h"

#include "reportingUtils.h"

#include "bessel.h"

#include "beam.h"


using namespace std;

using namespace starlightConstants;


//______________________________________________________________________________

beam::beam(const int              Z,

           const int              A,

     const int      productionMode,

     const double     beamLorentzGamma):

  nucleus(Z, A, productionMode), _beamLorentzGamma(beamLorentzGamma)

{ }


//______________________________________________________________________________

beam::~beam()

{ }


//______________________________________________________________________________

double beam::photonDensity(const double impactparameter,

                        const double photonEnergy) const

{

  // function for the calculation of the "photon density".

  // photonFlux = number of photons / (energy * area)

  // assume beta = 1 and gamma >> 1, i.e. neglect the (1 / gamma^2) * K_0(x) term


  const double X

    = (impactparameter * photonEnergy) / (_beamLorentzGamma * starlightConstants::hbarc);

  if (X <= 0)

    printWarn << "X = " << X << endl;

  const double factor1 = (double(Z() * Z()) * starlightConstants::alpha) / (starlightConstants::pi * starlightConstants::pi);

  const double factor2 = 1. / (photonEnergy * impactparameter * impactparameter);

  const double bessel  = bessel::dbesk1(X);

  const double factor3 = X * X * bessel * bessel;


  return factor1 * factor2 * factor3;

}