primaryVertexGen.h

Go to the documentation of this file.

/*
 * author: Prometeusz (Promme) jasinski
 *         jasinski@kph.uni-mainz.de Promme@web.de
 *
 * This file contains some methods simulating the Primary Vertex distribution
 * in the target cell as well as the incoming beam properties
 * You might use this script directly via executing in root
 *
 * root -l Beam_simulation.C+
 *
 * or use the methods here to adapt it in your event generator
 *
 * (2010.03.03)
 * - implementing 2008 h- beam simulation
 *
 * (2010.06.16)
 * - moved to rootpwa svn repository and changed to class structure
 *
 */

#ifndef TPRIMARYVERTEXGEN_HH
#define TPRIMARYVERTEXGEN_HH

#include <string>

class TH2;

namespace rpwa {

        class primaryVertexGen {

          private:

                // ********* some global constants and variables **********
                TFile* _histogramfile;
                //static const string histogramfilename("properties_2008/primary_vertex_properties.root");
                TH2* _hist_angles_vert_mean;
                TH2* _hist_angles_horiz_mean;
                TH2* _hist_angles_vert_sigma;
                TH2* _hist_angles_horiz_sigma;
                TH2* _hist_vertex_distr_xy;
                TH1* _hist_vertex_distr_z;

                //const double beam_part_mass(0.13957018); // [GeV] 2008's PDG pi-/+ value
                //const double beam_part_mass(0.493677); // [GeV] 2008's PDG K-/+ value
                //const double beam_energy_mean(191.29); // [GeV] fit on pi- pi+ pi- energy
                //const double beam_energy_sigma(1.94476); // [GeV] fit on pi- pi+ pi- energy
                double _beam_part_mass;
                double _beam_energy_mean;
                double _beam_energy_sigma;
                bool   _histograms_loaded;
                // in principle the fitted values are missing the momentum transfer to the
                // recoil particle that should be taken into account in the future

          public:

                // loads histograms containing the measure vertex information
                // initialization of default values
                // see also above the out commented constants
                // please TPrimaryVertexGen::Check() afterwards if loading went correctly
                primaryVertexGen(std::string histfilename       = "properties_2008/primary_vertex_properties.root",
                                 double beam_part_mass          = 0.13957018, // by default pion
                                 double mean_beam_energy        = 191.29,     // measured 2008
                                 double mean_beam_energy_spread = 1.94476);   // measured sigma 2008

                // free histograms
                ~primaryVertexGen();

                // check if histograms were loaded properly
                bool check();

                // ************* the prototypes ************

          private:

                // Loading of distribution histograms specified by histogram filename
                // if you wish a window showing the loaded histograms then plot = true
                // returns false if something goes wrong
                // Please do not use any other methods then
                bool loadHistograms(std::string filename = "properties_2008/primary_vertex_properties.root",
                                    bool plot = true);

          public:

                // Get one Vertex point
                // the position is distributed randomly based on hist_vertex_distr_xy
                // and hist_vertex_distr_z
                // you may change the cuts but it is not recommended since the cuts
                // are tuned for the valid ranges in the histograms
                // Call Load_histograms() before!
                TVector3& getVertex(const float cutR = 1.47,
                                     const float cutZ_low = -70.,
                                     const float cutZ_high = -30.);

                // Based on the position of the Vertex retrieve the beam
                // direction properties
                // given by distributions of
                // hist_angles_vert_mean
                // hist_angles_horiz_mean
                // hist_angles_vert_sigma
                // hist_angles_horiz_sigma
                // Call Load_histograms() before!
                // returns a vector with Mag() == 0 if vertex is out of
                // range of stored values
                TVector3& getBeamDir(const TVector3 vertex);

                // Simulate the beam particle based on fitted
                // values given by
                // beam_energy_mean
                // beam_energy_sigma
                // beam_part_mass
                // in principal one should also measure the energy(spread) depending on
                // X Y in the target since we know that there is a dependence
                // but this is neglected for now
                TLorentzVector& getBeamPart(const TVector3 beam_dir);

          private:

                /*
                 * big thanks to Sergei Gerassimov for this
                 * smooth palette settings
                 */
                void gesPalette(int i=0);

        };

}

#endif
/* @} **/