Reaction.hh

//
// This file is part of MARLEY (Model of Argon Reaction Low Energy Yields)
//
// MARLEY is free software: you can redistribute it and/or modify it under the
// terms of version 3 of the GNU General Public License as published by the
// Free Software Foundation.
//
// For the full text of the license please see COPYING or
// visit http://opensource.org/licenses/GPL-3.0
//
// Please respect the MCnet academic usage guidelines. See GUIDELINES
// or visit https://www.montecarlonet.org/GUIDELINES for details.
 
#pragma once
#include <memory>
#include <string>
#include <vector>
 
#include "marley/Event.hh"
#include "marley/MassTable.hh"
#include "marley/TargetAtom.hh"
 
namespace marley {
 
  class Generator;
  class StructureDatabase;
 
  class Reaction {
 
    public:
 
      virtual ~Reaction() = default;
 
      enum ProcessType {
        NeutrinoCC = 0,     
        AntiNeutrinoCC = 1, 
        NC = 2,             
        NuElectronElastic = 3 
      };
 
      virtual double total_xs(int pdg_a, double KEa) const = 0;
 
      virtual double diff_xs(int pdg_a, double KEa,
        double cos_theta_c_cm) const = 0;
 
      virtual marley::Event create_event(int pdg_a, double KEa,
        marley::Generator& gen) const = 0;
 
      inline const std::string& get_description() const { return description_; }
 
      inline ProcessType process_type() const { return process_type_; }
 
      static std::string proc_type_to_string(const ProcessType& pt);
 
      inline int pdg_a() const { return pdg_a_; }
 
      inline int pdg_b() const { return pdg_b_; }
 
      virtual double threshold_kinetic_energy() const = 0;
 
      virtual marley::TargetAtom atomic_target() const = 0;
 
      static std::vector< std::unique_ptr<Reaction> >
        load_from_file(const std::string& filename,
        marley::StructureDatabase& db);
 
      static int get_ejectile_pdg(int pdg_a, ProcessType proc_type);
 
    protected:
 
      int pdg_a_; 
      int pdg_b_; 
      int pdg_c_; 
      int pdg_d_; 
 
      double ma_; 
      double mb_; 
      double mc_; 
 
      // Mutable because, for the nuclear reaction case, we
      // may modify the final nuclear mass based on a sampled
      // excitation energy
      mutable double md_; 
 
      std::string description_;
 
      ProcessType process_type_;
 
      void two_two_scatter(double KEa, double& s, double& Ec_cm,
        double& pc_cm, double& Ed_cm) const;
 
      virtual marley::Event make_event_object(double KEa,
        double pc_cm, double cos_theta_c_cm, double phi_c_cm,
        double Ec_cm, double Ed_cm, double E_level, int twoJ,
        const marley::Parity& P) const;
 
      static const std::vector<int>& get_projectiles(ProcessType proc_type);
  };
 
}