GField Framework Documentation

Overview

The GField framework provides an extensible mechanism for managing magnetic fields in GEMC simulations. It allows users to define, instantiate, and manage various types of magnetic fields, including multipoles fields. The users definitions are external to the framework and are loaded dynamically at runtime through plugins. The framework consists of several core classes:

• GField: Abstract base class representing a magnetic field.
• GFieldDefinition: Utility struct for loading field configurations from goptions. New variable can be added using the add_map_parameter method.
• GMagneto: Manages collections of fields and their corresponding Geant4 field managers.

Field factories implemented within GEMC:

• GField_MultipolesFactory: Implements a specific type of magnetic field characterized by multipoles.

The framework supports dynamic loading of field definitions and seamless integration with Geant4 field management.

Field Parameters

• Fields are identified by unique string names.
• A volume can be associated to a magnetic field by using the field name.
• Integration steppers are selected based on their names; only supported steppers are allowed. The default is G4DormandPrince745.
• Rotation axes for fields are encoded as integers:
  • 0 for X-axis
  • 1 for Y-axis
  • 2 for Z-axis
• Field strengths and other parameters are specified in standard Geant4 units.

TODO

Implementing a Custom Field:

To be completed

API Documentation

Class GField

• Description: Abstract base class for magnetic fields.
• Relevant Methods:
  • virtual void GetFieldValue(const double x[3], double* bfield): Computes the magnetic field vector at a given position.
  • G4FieldManager* create_FieldManager(): Creates a Geant4 field manager for the field. The field manager is created automatically by gemc using G4Mag_UsualEqRhs and the basic field parameters:
  • integration_stepper: The integration stepper to use.
  • minimum_step: The minimum step for the G4ChordFinder.

Class GFieldDefinition

• Description: Utility struct for field definitions.
• Methods:
  • void init_parameters(string name, string stepper, double step, string type, int verbosity): Initializes field parameters.
  • void add_map_parameter(string key, string value): Adds a key-value pair to the field's configuration.
  • string gfieldPluginName(): Returns the name of the field plugin.

Class GMagneto

• Description: Manages multiple magnetic fields and their field managers.
• Methods:
  • bool isField(string name): Checks if a field exists.
  • GField* getField(string name): Retrieves a field by name.
  • G4FieldManager* getFieldMgr(string name): Retrieves a field manager by name.

Class GField_MultipolesFactory

• Description: Implements a multipole magnetic field.
• Methods:
  • void GetFieldValue(const G4double pos[4], G4double* bfield) const: Computes the multipole field vector at a given position.

Continuous Integration

The GFields framework is continuously integrated and tested to ensure stability and reliability across updates.

Author

© Maurizio Ungaro

e-mail: ungar.nosp@m.o@jl.nosp@m.ab.or.nosp@m.g