marley::KleinNystrandNuclearFormFactor Class Reference

#include <NuclearFormFactor.hh>

Inheritance diagram for marley::KleinNystrandNuclearFormFactor:

Public Member Functions
	KleinNystrandNuclearFormFactor (int Z, int A, bool adapted=false, double r0=DUMMY_r0_VALUE)
virtual double	F (double kappa) const override final
double	r0 () const
Public Member Functions inherited from marley::NuclearFormFactor
	NuclearFormFactor (int Z, int A)
int	A () const
int	Z () const

Static Public Attributes
static constexpr double	DUMMY_r0_VALUE = std::numeric_limits< double >::lowest()

Static Protected Member Functions
static void	initialize_r0_table ()

Protected Attributes
double	a_ = 0.7
	Range (fm) of the assumed Yukawa potential.
bool	adapted_ = false
double	r0_ = DUMMY_r0_VALUE
	Value of the rms charge radius, used only for the adapted version.
double	R_
	Effective nuclear radius (fm)
Protected Attributes inherited from marley::NuclearFormFactor
int	A_
	Nucleon number.
int	Z_
	Proton number.

Static Protected Attributes
static const std::string	r0_data_file_name_ = "nuclear_charge_radii.js"
	Name of the data file containing the measured rms charge radii.
static std::unique_ptr< std::map< int, double > >	r0_table_
	Stores measured rms charge radii for many nucleii.

Additional Inherited Members
Static Public Member Functions inherited from marley::NuclearFormFactor
static std::shared_ptr< marley::NuclearFormFactor >	create (int Z, int A, const JSON &ff_config)

Detailed Description

Implements a nuclear form factor based on Phys. Rev. C 60, 014903 (1999) Parameter values for the default and COHERENT's "adapted" version are described in Universe 9, 207 (2023)

Definition at line 134 of file NuclearFormFactor.hh.

Constructor & Destructor Documentation

KleinNystrandNuclearFormFactor()

marley::KleinNystrandNuclearFormFactor::KleinNystrandNuclearFormFactor ( int Z, int A, bool adapted = false, double r0 = DUMMY_r0_VALUE )

inline

Definition at line 137 of file NuclearFormFactor.hh.

        : NuclearFormFactor( Z, A ), adapted_( adapted ), r0_( r0 )
      {
        // COHERENT-style "adapted" treatment uses the rms charge radius r0 to
        // calculate the effective nuclear radius. If the user did not supply
        // one, then look it up from the table of measurements.
        if ( adapted_ ) {
          if ( r0_ == DUMMY_r0_VALUE ) {
            // Ensure that the table has been loaded
            if ( !r0_table_ ) this->initialize_r0_table();
 
            int pdg = marley_utils::get_nucleus_pid( Z, A );
            auto iter = r0_table_->find( pdg );
            if ( iter != r0_table_->end() ) {
              r0_ = iter->second;
            }
            else {
              throw marley::Error( "Unable to find tabulated rms charge"
                " radius for nucleus with PDG code " + std::to_string( pdg )
                + ". Please specify a value in fm using the \"r0\" JSON key." );
            }
          }
 
          R_ = marley_utils::real_sqrt( 5.*r0_*r0_/3. - 10.*a_*a_ );
          return;
        }
 
        // Default treatment assigns the effective nuclear radius based solely
        // on the nucleon number
        R_ = 1.23 * std::pow( A_, marley_utils::ONE_THIRD ); // fm
      }

Member Function Documentation

F()

double marley::KleinNystrandNuclearFormFactor::F ( double kappa ) const

finaloverridevirtual

Evaluate the nuclear form factor at a given 3-momentum transfer

Parameters

kappa

Magnitude of the 3-momentum transfer (MeV)

Implements marley::NuclearFormFactor.

Definition at line 100 of file NuclearFormFactor.cc.

                                                                   {
  if ( kappa == 0. ) return 1.;
  double kappa_in_inverse_fm = kappa / marley_utils::hbar_c;
  double x = kappa_in_inverse_fm * R_;
  double j1 = ( std::sin( x ) / x - std::cos( x ) ) / x;
  double F = 3. * j1 / x * ( 1. / ( 1.
    + kappa_in_inverse_fm*kappa_in_inverse_fm*a_*a_ ) );
  return F;
}

References a_, F(), and R_.

Referenced by F().

initialize_r0_table()

void marley::KleinNystrandNuclearFormFactor::initialize_r0_table ( )

staticprotected

Definition at line 110 of file NuclearFormFactor.cc.

                                                               {
 
  // Instantiate the file manager and use it to find the data file containing
  // the rms charge radii for many nuclei
  const auto& fm = marley::FileManager::Instance();
  std::string full_r0_file_name = fm.find_file( r0_data_file_name_ );
 
  if ( full_r0_file_name.empty() ) {
    throw marley::Error( "Could not find the MARLEY nuclear rms charge radii"
      " data file " + r0_data_file_name_ + ". Please ensure that"
      " the folder containing it is on the MARLEY search path."
      " If needed, the folder can be appended to the MARLEY_SEARCH_PATH"
      " environment variable." );
  }
 
  MARLEY_LOG( INFO, "init.structure" ) << "Loading ground-state nuclear rms charge radii from "
    << full_r0_file_name;
 
  marley::JSON r0_json_obj = marley::JSON::load_file( full_r0_file_name );
  if ( !r0_json_obj.has_key("nuclear_charge_radii") ) {
    throw marley::Error( "Missing \"nuclear_charge_radii\" key in "
      + full_r0_file_name );
  }
  const marley::JSON& r0_json_array = r0_json_obj.at( "nuclear_charge_radii" );
  if ( !r0_json_array.is_array() ) {
    throw marley::Error( "Invalid \"nuclear_charge_radii\" array in "
      + full_r0_file_name );
  }
 
  r0_table_ = std::make_unique< std::map< int, double > >();
 
  bool ok; // Helper flag to use when reading the JSON array elements
  for ( const auto& r0_js : r0_json_array.array_range() ) {
    int Z = assign_from_json< int >( "Z", r0_js, ok );
    int A = assign_from_json< int >( "A", r0_js, ok );
    double R = assign_from_json< double >( "R", r0_js, ok );
 
    // TODO: load and use the uncertainty on the rms charge radius
    //double R_unc = assign_from_json< double >( "R_unc", r0_js, ok );
 
    // Add the completed entry to the table of nuclear radii
    int pdg = marley_utils::get_nucleus_pid( Z, A );
    r0_table_->operator[]( pdg ) = R;
 
    MARLEY_LOG( TRACE, "init.structure.masstable" ) << "Nucleus with PDG code "
      << pdg << " has rms charge radius " << R << " fm";
  }
 
}

r0()

double marley::KleinNystrandNuclearFormFactor::r0 ( ) const

inline

Returns the value of the rms charge radius used with the adapted version

Definition at line 176 of file NuclearFormFactor.hh.

                               {
        if ( !adapted_ ) MARLEY_LOG( WARN, "physics.formfactor" )
          << "Requested rms charge radius"
          << " when using default Klein-Nystrand nuclear form factor";
        return r0_;
      }

References adapted_, and r0_.

Member Data Documentation

a_

double marley::KleinNystrandNuclearFormFactor::a_ = 0.7

protected

Range (fm) of the assumed Yukawa potential.

Definition at line 202 of file NuclearFormFactor.hh.

Referenced by F().

adapted_

bool marley::KleinNystrandNuclearFormFactor::adapted_ = false

protected

Flag indicating whether we are using the COHERENT-style "adapted" version

Definition at line 209 of file NuclearFormFactor.hh.

Referenced by r0().

DUMMY_r0_VALUE

double marley::KleinNystrandNuclearFormFactor::DUMMY_r0_VALUE = std::numeric_limits< double >::lowest()

staticconstexpr

Dummy value used to signal the need to look up the rms charge radius from a table of measurements

Definition at line 185 of file NuclearFormFactor.hh.

r0_

double marley::KleinNystrandNuclearFormFactor::r0_ = DUMMY_r0_VALUE

protected

Value of the rms charge radius, used only for the adapted version.

Definition at line 212 of file NuclearFormFactor.hh.

Referenced by r0().

r0_data_file_name_

const std::string marley::KleinNystrandNuclearFormFactor::r0_data_file_name_ = "nuclear_charge_radii.js"

inlinestaticprotected

Name of the data file containing the measured rms charge radii.

Definition at line 198 of file NuclearFormFactor.hh.

r0_table_

std::unique_ptr< std::map< int, double > > marley::KleinNystrandNuclearFormFactor::r0_table_

inlinestaticprotected

Stores measured rms charge radii for many nucleii.

Keys are nuclear PDG codes, values are rms charge radii (fm)

Definition at line 194 of file NuclearFormFactor.hh.

R_

double marley::KleinNystrandNuclearFormFactor::R_

protected

Effective nuclear radius (fm)

Definition at line 205 of file NuclearFormFactor.hh.

Referenced by F().

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The documentation for this class was generated from the following files:

• /home/sjg/Desktop/marley/include/marley/NuclearFormFactor.hh
• /home/sjg/Desktop/marley/src/NuclearFormFactor.cc