Detailed Description

A class to load magnetic field maps and evaluate the field on those maps including interpolation.

TRestAxionMagneticField is a class that allows to load externally defined magnetic fields, and create magnetic volume regions associated to those pre-generated definitions. Once the field maps have been loaded this class will be able to evaluate the field vector at any coordinate (x,y,z). If the coordinate (x,y,z) is ourside any defined region, the returned field will be (0,0,0).

TODO Description of magnetic field interpolation

RML definition

We can add any number of magnetic volumes inside the RML definition as shown in the following piece of code,

<TRestAxionMagneticField>
        <addMagneticVolume file="magnetic.file" position="(30,0,0)cm" />
        <addMagneticVolume file="magnetic.file" position="(-30,0,0)cm" />
<TRestAxionMagneticField/>

where we produce 2 magnetic regions, using the same magnetic map provided in file magnetic.file and shifted by x=-30cm and x=30cm. The following parameters might be defined at each addMagneticVolume entry.

file : This allows to specify the filename that contains the values of the magnetic field. Few files will be found under data/magneticField. They all contain 3 columns for the position in the volume and 3 columns to define the magnetic field vector. It is not the full path but only the name of the file. The default value is "none", that identifies when no input field map is given. If no magnetic field map is provided the field will be constant in the volume definition, and fixed by the field parameter.
position : By convention, the volume is build using the coordinates provided in the magnetic field file given. However, it is possible to translate the volume using the position field. The default value is (0,0,0).
field : A 3D vector given in magnetic field units. If no units are given the vector is assumed to be expressed in Teslas. This field will be added as an offset to the magnetic field map given. The default value is (0,0,0).
boundMax : A 3D vector, (xMax,yMax,zMax) that defines the bounding box size. The box size will be bounded by the vertex (xMin,yMin,zMin) and (xMax,yMax,zMax). This parameter is required if no field map file is given. If a field map file is provided, the bounding box will be extracted from the field map. In that case, this parameter will be only used for validation.
meshSize : A 3D vector that defines the size of the cell in a regular grid where the field is defined. This parameter is required if no field map file is given. If a field map file is provided, the 3-dimensional cell element dimensions will be extracted from the field map. In that case, this parameter will be only used for validation.
meshType : It defines the type of mesh boundary. The default value will be cylinder. It defines a cylinder with its axis sitting on z. The radius of the cylinder will be the first component of the meshSize 3D vector. The second component will be ignored, as it is defined inside TRestMesh. This will affect to the identification of field boundaries, and to the evaluation of the field, which will only happen when the evaluated coordinates are inside the bounding volume.

All parameters are optional, and if not provided they will take their default values.

Note: If no magnetic field map is provided, i.e. we just want to define a constant magnetic field vector, we still need to provide a boundary box size and mesh size through the boundMax and meshSize parameters. We still have the possibility to define a constant magnetic field vector for that volume using the field parameter. In that case the method TRestMagneticField::IsFieldConstant will return true.

The magnetic field file format.

There are two possible formats to provide a magnetic field map.

Plain-text format (.dat) : The data file should describe the points of a box delimited by the vertexes (-xMax, -yMax, -zMax) and (xMax,yMax,zMax). The field (Bx,By,Bz) must be given for all the points in a regular grid. The default units are T for the field and mm for distances. The size of the grid cells will be deduced from the data. Each row in the text file should provide 6-tabulated values x, y, z, Bx, By, Bz.
Binary format (.bin) : Similar to the plain-text format. It should contain all the elements of the grid, bounded by (-xMax,-yMax,-zMax) and (xMax,yMax,zMax). Each element is built using the 3-coordinates x, y, z and the 3-field Bx, By, Bz values expressed in 4-bytes size, Float_t.

A more detailed example

The following example shows different allowed volume definition entries.

<TRestAxionMagneticField name="bFieldBabyIAXO" title="First magnetic field definition"
verboseLevel="info" >
 
    <!-- A volume from a text file centered at (0,0,0) -->
    <addMagneticVolume fileName="Bykovskiy_201906.dat" position="(0,0,0)mm" />
 
    <!-- A volume from binary file, include Bx=1T offset, and boundMax validation -->
    <addMagneticVolume fileName="Bykovskiy_202004.bin" position="(800,800,800)mm"
                field="(1,0,0)" boundMax="(350,350,4000)" />
 
    <!-- A magnetic volume with a constant field definition (no field map) -->
    <addMagneticVolume field="(0,0,3)T" position="(-800,-800,-800)mm"
                        boundMax="(100,200,300)" meshSize="(10,20,30)" />
</TRestAxionMagneticField>

Using this class

Once we have created an instance of this class we will be able to access the magnetic field directly, at any point by using trilinear interpolation.

For example, the following code will retrieve the field at a position found at a distance z=-2m at the magnet axis,

TRestAxionMagneticField *mag = new TRestAxionMagneticField("fields.rml", "babyIAXO" );

mag->GetMagneticField( 0, 0, -2000 );

TRestAxionMagneticField::TRestAxionMagneticField

TRestAxionMagneticField()

Default constructor.

Definition: TRestAxionMagneticField.cxx:248

TRestAxionMagneticField::GetMagneticField

TVector3 GetMagneticField(Double_t x, Double_t y, Double_t z)

It returns the magnetic field vector at x,y,z.

Definition: TRestAxionMagneticField.cxx:1006

or in a similar way,

TRestAxionMagneticField *mag = new TRestAxionMagneticField("fields.rml", "babyIAXO" );

mag->GetMagneticField( TVector3(0, 0, -2000), true );

where the second argument, true will enable the warning message system.

The following code evaluates the transversal field component at 1m distance along the Z-axis, for a vector pointing in the direction (0,1,1).

TRestAxionMagneticField *mag = new TRestAxionMagneticField("fields.rml", "babyIAXO" );

mag->GetTransversalComponent( TVector3(0,0,1000), TVector3(0,1,1) );

TRestAxionMagneticField::GetTransversalComponent

Double_t GetTransversalComponent(TVector3 position, TVector3 direction)

It returns the intensity of the transversal magnetic field component for the defined propagation dire...

Definition: TRestAxionMagneticField.cxx:1236

There are also geometric functions that allow to identify the boundaries of the magnetic volume. A test particle will penetrate in the bounding box and identify the moment where the field changes to a value different from (0,0,0) in order("fields.rml", "babyIAXO_2024"); to identify the entrance and exit point.

The following code will return two TVector3 with the magnetic volume entrance and exit coordinates, for a test particle being placed at x=10cm, y=10cm and z=-4m, pointing towards the magnetic field with a slight direction deviation from the magnet axis.

TRestAxionMagneticField *mag = new TRestAxionMagneticField("fields.rml", "babyIAXO" );

mag->GetFieldBoundaries(TVector3(100,100, -4000) , TVector3(0.02, 0.03, 1))

TRestAxionMagneticField::GetFieldBoundaries

std::vector< TVector3 > GetFieldBoundaries(TVector3 pos, TVector3 dir, Double_t precision=0, Int_t id=0)

Finds the in/out particle trajectory boundaries for a particular magnetic region, similar to the meth...

Definition: TRestAxionMagneticField.cxx:1497

In the other hand, TRestAxionMagneticField::GetVolumeBoundaries will return the bounding box containing that magnetic field.

Remapping the field

It is possible to remap the magnetic field in order to increase the size of the grid cells in order to gain in performance. We may only increase the size of the cells by a multiple of the original mesh size.

Given the original mesh granularity by 10mmx10mmx50mm, we might increase the granularity of the first volume, index 0 to 50mmx50mmx200mm as follows:

TRestAxionMagneticField *mag = new TRestAxionMagneticField("fields.rml", "babyIAXO" );
mag->PrintMetadata();
mag->ReMap( 0, TVector3(50, 50, 200) );
mag->PrintMetadata();

Visualizing the magnetic field

You may visualize the magnetic field profile along tracks towards a vanishing point by using the TRestAxionMagneticField::DrawTracks method, using:

TRestAxionMagneticField *field = new TRestAxionMagneticField( "fields.rml", "babyIAXO" );

field->DrawTracks( TVector3(0,0,8000), 100 );

TRestAxionMagneticField::DrawTracks

TCanvas * DrawTracks(TVector3 vanishingPoint, Int_t divisions, Int_t volId=0)

A method that creates a canvas where tracks traversing the magnetic volume are drawm together with th...

Definition: TRestAxionMagneticField.cxx:650

That will produce the following plot:

TODO Review and validate DrawHistogram drawing method and describe its use here.

RESTsoft - Software for Rare Event Searches with TPCs

History of developments:

2019-June: First concept and implementation of TRestAxionMagneticField class. Eve Pachoud

2020-April: Reviewing and validating TRestAxionMagneticField class. Javier Galan and Krešimir Jakovčić

Author: Eve Pachoud; Javier Galan javie.nosp@m.r.ga.nosp@m.lan@u.nosp@m.niza.nosp@m.r.es; Krešimir Jakovčić kjako.nosp@m.v@ir.nosp@m.b.hr

Definition at line 50 of file TRestAxionMagneticField.h.

#include <TRestAxionMagneticField.h>

Inheritance diagram for TRestAxionMagneticField:

Public Member Functions
Bool_t	CheckOverlaps ()
	It will return true if the magnetic the regions overlap.

TCanvas *	DrawComponents (Int_t volId=0)
	A method that creates a canvas where tracks traversing the magnetic volume are drawm together with their corresponding field intensity profile along the Z-axis.

TCanvas *	DrawHistogram (TString projection, TString Bcomp, Int_t volIndex=-1, Double_t step=-1, TString style="COLZ0", Double_t depth=-100010.0)
	A method that creates a canvas where magnetic field map is drawn. More...

TCanvas *	DrawTracks (TVector3 vanishingPoint, Int_t divisions, Int_t volId=0)
	A method that creates a canvas where tracks traversing the magnetic volume are drawm together with their corresponding field intensity profile along the Z-axis.

std::vector< Double_t >	GetComponentAlongPath (Int_t axis, TVector3 from, TVector3 to, Double_t dl=1., Int_t Nmax=0)
	It returns a vector describing the magnetic field profile component requested using the `axis` argument which may take values 0,1,2 for X,Y,Z components. The field profile will be constructed in the track defined between `from` and `to` positions given by argument. More...

TVector3	GetFieldAverageTransverseVector (TVector3 from, TVector3 to, Double_t dl=10., Int_t Nmax=0)
	It returns the transverse component of the average magnetic field vector calculated along the line that connects the 3-d coordinates `from` and `to` with respect to that line. More...

std::vector< TVector3 >	GetFieldBoundaries (TVector3 pos, TVector3 dir, Double_t precision=0, Int_t id=0)
	Finds the in/out particle trajectory boundaries for a particular magnetic region, similar to the method TRestAxionMagneticField::GetVolumeBoudaries, but requiring that the in/out points are the first/last points where the transversal field intensity is not zero. More...

TVector3	GetMagneticField (Double_t x, Double_t y, Double_t z)
	It returns the magnetic field vector at x,y,z.

TVector3	GetMagneticField (TVector3 pos, Bool_t showWarning=true)
	It returns the magnetic field vector at TVector3(pos) using trilinear interpolation that is implemented following instructions given at https://en.wikipedia.org/wiki/Trilinear_interpolation. More...

unsigned int	GetNumberOfVolumes ()
	The number of magnetic volumes loaded into the object.

Double_t	GetPhotonAbsorptionLength (Double_t x, Double_t y, Double_t z, Double_t en)

Double_t	GetPhotonAbsorptionLength (Int_t id, Double_t en)

Double_t	GetPhotonAbsorptionLength (TVector3 pos, Double_t en)

Double_t	GetPhotonMass (Double_t x, Double_t y, Double_t z, Double_t en)

Double_t	GetPhotonMass (Int_t id, Double_t en)

Double_t	GetPhotonMass (TVector3 pos, Double_t en)

TVector3	GetTrackDirection () const

Double_t	GetTrackLength () const

TVector3	GetTrackStart () const

Double_t	GetTransversalComponent (TVector3 position, TVector3 direction)
	It returns the intensity of the transversal magnetic field component for the defined propagation `direction` and `position` given by argument.

std::vector< Double_t >	GetTransversalComponentAlongPath (TVector3 from, TVector3 to, Double_t dl=1., Int_t Nmax=0)
	It returns a vector describing the transversal magnetic field component between `from` and `to` positions given by argument. More...

Double_t	GetTransversalComponentInParametricTrack (Double_t x)
	It will return the transversal magnetic field component evaluated at a parametric distance `x` (given by argument) for the track defined inside the class. The track will be defined by the data members fStartTrack and fEndTrack which should be initialized by external means by invoking the method SetTrack( position, direction );. More...

Double_t	GetTransversalFieldAverage (TVector3 from, TVector3 to, Double_t dl=1., Int_t Nmax=0)
	It returns the average of the transversal magnetic field intensity between the 3-d coordinates `from` and `to`. More...

std::vector< TVector3 >	GetVolumeBoundaries (TVector3 pos, TVector3 dir, Int_t id=0)
	Finds the in/out particle trajectory boundaries for a particular magnetic region bounding box. More...

TVector3	GetVolumeCenter (Int_t id)
	it returns the volume position (or center) for the given volume `id`.

Int_t	GetVolumeIndex (TVector3 pos)
	It returns the corresponding volume index at the given position. If not found it will return -1.

TVector3	GetVolumePosition (Int_t id)
	it returns the volume position (or center) for the given volume `id`.

Bool_t	IsFieldConstant (Int_t id)
	It returns true if no magnetic field map was loaded for that volume.

Bool_t	IsInside (TVector3 pos)
	It returns true if the given position is found inside a magnetic volume. False otherwise.

void	LoadMagneticVolumes ()
	It will load the magnetic field data from the data filenames specified at the RML definition. More...

void	PrintMetadata ()
	Prints on screen the information about the metadata members of TRestAxionMagneticField.

void	ReMap (const size_t &n, const TVector3 &newMapSize)
	It allows to remap the magnetic field to a larger mesh size. The new mesh size granularity must be provided by argument, and each dimension must be a factor of the present mesh size.

void	SetTrack (const TVector3 &position, const TVector3 &direction)
	It initializes the field track boundaries data members of this class using a track position and direction so that these values can be used later on in parameterization.

	TRestAxionMagneticField ()
	Default constructor.

	TRestAxionMagneticField (const char *cfgFileName, std::string name="")
	Constructor loading data from a config file. More...

	~TRestAxionMagneticField ()
	Default destructor.

Public Member Functions inherited from TRestMetadata
void	AddLog (std::string log="", bool print=true)
	Add logs to messageBuffer.

void	DoNotStore ()
	If this method is called the metadata information will not be stored in disk.

TVector2	Get2DVectorParameterWithUnits (std::string parName, TVector2 defaultValue=TVector2(-1, -1))

TVector3	Get3DVectorParameterWithUnits (std::string parName, TVector3 defaultValue=TVector3(-1, -1, -1))

TString	GetCommit ()
	Returns the REST commit value stored in fCommit.

std::string	GetConfigBuffer ()
	Returns the config section of this class.

std::string	GetDataMemberValue (std::string memberName)
	Get the value of data member as string. More...

std::vector< std::string >	GetDataMemberValues (std::string memberName, Int_t precision=0)
	Get the value of datamember as a vector of strings. More...

TString	GetDataPath ()
	Returns a std::string with the path used for data storage.

Double_t	GetDblParameterWithUnits (std::string parName, Double_t defaultValue=PARAMETER_NOT_FOUND_DBL)
	Gets the value of the parameter name parName, after applying unit conversion. More...

Bool_t	GetError () const
	It returns true if an error was identified by a derived metadata class.

TString	GetErrorMessage ()
	Returns a std::string containing the error message.

TString	GetLibraryVersion ()
	Returns the REST libraty version stored in fLibraryVersion.

TString	GetMainDataPath ()
	Gets a std::string with the path used for data storage.

Int_t	GetNumberOfErrors () const

Int_t	GetNumberOfWarnings () const

std::string	GetParameter (std::string parName, TString defaultValue=PARAMETER_NOT_FOUND_STR)
	Returns corresponding REST Metadata parameter from multiple sources. More...

std::string	GetSectionName ()
	Returns the section name of this class, defined at the beginning of fSectionName.

TRestStringOutput::REST_Verbose_Level	GetVerboseLevel ()
	returns the verboselevel in type of REST_Verbose_Level enumerator

TString	GetVerboseLevelString ()
	returns the verbose level in type of TString More...

TString	GetVersion ()
	Returns the REST version stored in fVersion.

Int_t	GetVersionCode ()

UInt_t	GetVersionMajor () const

UInt_t	GetVersionMinor () const

UInt_t	GetVersionPatch () const

Bool_t	GetWarning () const
	It returns true if an error was identified by a derived metadata class.

TString	GetWarningMessage ()
	Returns a std::string containing the warning message.

TRestMetadata *	InstantiateChildMetadata (int index, std::string pattern="")
	This method will retrieve a new TRestMetadata instance of a child element of the present TRestMetadata instance based on the `index` given by argument, which defines the element order to be retrieved, 0 for first element found, 1 for the second element found, etc. More...

TRestMetadata *	InstantiateChildMetadata (std::string pattern="", std::string name="")
	This method will retrieve a new TRestMetadata instance of a child element of the present TRestMetadata instance based on the `name` given by argument. More...

Bool_t	isCleanState () const

Bool_t	isOfficialRelease () const

Int_t	LoadConfigFromBuffer ()
	Initialize data from a string element buffer. More...

Int_t	LoadConfigFromElement (TiXmlElement eSectional, TiXmlElement eGlobal, std::map< std::string, std::string > envs={})
	Main starter method. More...

Int_t	LoadConfigFromFile (const std::string &configFilename, const std::string &sectionName="")
	Give the file name, find out the corresponding section. Then call the main starter.

virtual void	Merge (const TRestMetadata &)

TRestMetadata &	operator= (const TRestMetadata &)

void	Print ()
	Implementing TObject::Print() method.

void	PrintConfigBuffer ()
	Print the config xml section stored in the class. More...

void	PrintMessageBuffer ()
	Print the buffered message.

void	PrintTimeStamp (Double_t timeStamp)
	Print the current time on local machine. More...

void	SetConfigFile (std::string configFilename)
	set config file path from external

void	SetError (std::string message="", bool print=true, int maxPrint=5)
	A metadata class may use this method to signal that something went wrong.

void	SetHostmgr (TRestManager *m)
	Set the host manager for this class.

void	SetSectionName (std::string sName)
	set the section name, clear the section content

void	SetVerboseLevel (TRestStringOutput::REST_Verbose_Level v)
	sets the verbose level

void	SetWarning (std::string message="", bool print=true, int maxPrint=5)
	A metadata class may use this method to signal that something went wrong.

void	Store ()
	If this method is called the metadata information will be stored in disk.

	TRestMetadata (const TRestMetadata &)

virtual void	UpdateMetadataMembers ()
	Method to allow implementation of specific metadata members updates at inherited classes.

virtual Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0)
	overwriting the write() method with fStore considered

void	WriteConfigBuffer (std::string fName)
	Writes the config buffer to a file in append mode.

	~TRestMetadata ()
	TRestMetadata default destructor.

Private Member Functions
Bool_t	FieldLoaded ()
	This private method returns true if the magnetic field volumes loaded are the same as the volumes defined.

MagneticFieldVolume *	GetMagneticVolume (Int_t id)
	It returns a pointer to the corresponding magnetic volume id.

TVector3	GetMagneticVolumeNode (size_t id, TVector3 pos)
	It returns the corresponding mesh node in the magnetic volume. More...

void	InitFromConfigFile ()
	Initialization of TRestAxionMagnetic field members through a RML file.

void	Initialize ()
	Initialization of TRestAxionMagneticField members.

void	LoadMagneticFieldData (MagneticFieldVolume &mVol, std::vector< std::vector< Float_t >> data)
	A method to help loading magnetic field data, as x,y,z,Bx,By,Bz into a magnetic volume definition using its corresponding mesh. More...

Private Attributes
std::vector< TVector3 >	fBoundMax
	A vector to store the maximum bounding box values.

TCanvas *	fCanvas
	A canvas to insert the histogram drawing.

std::vector< TVector3 >	fConstantField
	A constant field component that will be added to the field map.

std::vector< std::string >	fFileNames
	The name of the filenames containing the field data.

TH2D *	fHisto
	A helper histogram to plot the field.

std::vector< MagneticFieldVolume >	fMagneticFieldVolumes
	A magnetic field volume structure to store field data and mesh.

std::vector< TVector3 >	fMeshSize

std::vector< TString >	fMeshType
	The type of the mesh used (default is cylindrical)

std::vector< TVector3 >	fPositions
	The absolute position of each of the magnetic volumes defined in this class.

TVector3	fReMap = TVector3(0, 0, 0)
	A vector that defines the new mesh cell volume. It will re-scale the original fMeshSize.

TVector3	fTrackDirection = TVector3(0, 0, 0)
	The track direction used to parameterize the field along a track.

Double_t	fTrackLength = 0
	The total length of the track which defines the limit for field parameterization.

TVector3	fTrackStart = TVector3(0, 0, 0)
	The start track position used to parameterize the field along a track.

Additional Inherited Members
Protected Member Functions inherited from TRestMetadata
std::string	ElementToString (TiXmlElement *ele)
	Convert an TiXmlElement object to string. More...

TVector2	Get2DVectorParameterWithUnits (std::string parName, TiXmlElement *e, TVector2 defaultValue=TVector2(-1, -1))

TVector3	Get3DVectorParameterWithUnits (std::string parName, TiXmlElement *e, TVector3 defaultValue=TVector3(-1, -1, -1))

Double_t	GetDblParameterWithUnits (std::string parName, TiXmlElement *e, Double_t defaultVal=PARAMETER_NOT_FOUND_DBL)

TiXmlElement *	GetElement (std::string eleDeclare, TiXmlElement *e=nullptr)
	Get an xml element from a given parent element, according to its declaration.

TiXmlElement *	GetElementFromFile (std::string configFilename, std::string NameOrDecalre="")
	Open an xml encoded file and find its element. More...

TiXmlElement *	GetElementWithName (std::string eleDeclare, std::string eleName)
	Get an xml element from the default location, according to its declaration and its field "name".

TiXmlElement *	GetElementWithName (std::string eleDeclare, std::string eleName, TiXmlElement *e)
	Get an xml element from a given parent element, according to its declaration and its field "name".

std::string	GetFieldValue (std::string fieldName, std::string definition, size_t fromPosition=0)
	Gets field value in an xml element string by parsing it as TiXmlElement.

std::string	GetFieldValue (std::string parName, TiXmlElement *e)
	Returns the field value of an xml element which has the specified name. More...

std::string	GetKEYDefinition (std::string keyName)
	Gets the first key definition for keyName found inside buffer starting at fromPosition. More...

std::string	GetKEYDefinition (std::string keyName, size_t &Position)

std::string	GetKEYDefinition (std::string keyName, size_t &Position, std::string buffer)

std::string	GetKEYDefinition (std::string keyName, std::string buffer)

std::string	GetKEYStructure (std::string keyName)
	Gets the first key structure for keyName found inside buffer after fromPosition. More...

std::string	GetKEYStructure (std::string keyName, size_t &Position)

std::string	GetKEYStructure (std::string keyName, size_t &Position, std::string buffer)

std::string	GetKEYStructure (std::string keyName, size_t &Position, TiXmlElement *ele)

std::string	GetKEYStructure (std::string keyName, std::string buffer)

TiXmlElement *	GetNextElement (TiXmlElement *e)
	Get the next sibling xml element of this element, with same eleDeclare.

std::string	GetParameter (std::string parName, size_t &pos, std::string inputString)
	Returns the value for the parameter name parName found in inputString. More...

std::string	GetParameter (std::string parName, TiXmlElement *e, TString defaultValue=PARAMETER_NOT_FOUND_STR)
	Returns the value for the parameter named parName in the given section. More...

std::pair< std::string, std::string >	GetParameterAndUnits (std::string parname, TiXmlElement *e=nullptr)
	Returns the unit string of the given parameter of the given xml section. More...

std::map< std::string, std::string >	GetParametersList ()
	It retrieves a map of all parameter:value found in the metadata class.

TString	GetSearchPath ()

virtual void	InitFromRootFile ()
	Method called after the object is retrieved from root file.

virtual Int_t	LoadSectionMetadata ()
	This method does some preparation of xml section. More...

void	ReadAllParameters ()
	Reflection methods, Set value of a datamember in class according to TRestMetadata::fElement. More...

void	ReadParametersList (std::map< std::string, std::string > &list)
	It reads a parameter list and associates it to its corresponding metadata member. par0 --> fPar0.

std::string	ReplaceConstants (const std::string buffer)
	Identifies "constants" in the input buffer, and replace them with corresponding value. More...

std::string	ReplaceVariables (const std::string buffer)
	Identifies environmental variable replacing marks in the input buffer, and replace them with corresponding value. More...

void	ReSetVersion ()
	Resets the version of TRestRun to REST_RELEASE. Only TRestRun is allowed to update version.

std::string	SearchFile (std::string filename)
	Search files in current directory and directories specified in "searchPath" section. More...

void	SetLibraryVersion (TString version)
	Set the library version of this metadata class.

TiXmlElement *	StringToElement (std::string definition)
	Parsing a string into TiXmlElement object. More...

	TRestMetadata ()
	TRestMetadata default constructor.

	TRestMetadata (const char *configFilename)
	constructor

void	UnSetVersion ()
	Resets the version of TRestRun to -1, in case the file is old REST file. Only TRestRun is allowed to update version.

Protected Attributes inherited from TRestMetadata
std::string	configBuffer
	The buffer where the corresponding metadata section is stored. Filled only during Write()

std::string	fConfigFileName
	Full name of the rml file. More...

std::map< std::string, std::string >	fConstants
	Saving a list of rml constants. name-value std::pair. Constants are temporary for this class only.

TiXmlElement *	fElement
	Saving the sectional element together with global element.

TiXmlElement *	fElementGlobal
	Saving the global element, to be passed to the resident class, if necessary.

Bool_t	fError = false
	It can be used as a way to identify that something went wrong using SetError method.

TString	fErrorMessage = ""
	A std::string to store an optional error message through method SetError.

TRestManager *	fHostmgr
	All metadata classes can be initialized and managed by TRestManager.

Int_t	fNErrors = 0
	It counts the number of errors notified.

Int_t	fNWarnings = 0
	It counts the number of warnings notified.

std::string	fSectionName
	Section name given in the constructor of the derived metadata class.

Bool_t	fStore
	This variable is used to determine if the metadata structure should be stored in the ROOT file.

std::map< std::string, std::string >	fVariables
	Saving a list of rml variables. name-value std::pair.

TRestStringOutput::REST_Verbose_Level	fVerboseLevel
	Verbose level used to print debug info.

Bool_t	fWarning = false
	It can be used as a way to identify that something went wrong using SetWarning method.

TString	fWarningMessage = ""
	It can be used as a way to identify that something went wrong using SetWarning method.

std::string	messageBuffer
	The buffer to store the output message through TRestStringOutput in this class.

endl_t	RESTendl
	Termination flag object for TRestStringOutput.

Constructor & Destructor Documentation

◆ TRestAxionMagneticField()

TRestAxionMagneticField::TRestAxionMagneticField	(	const char *	cfgFileName,
		std::string	name = `""`
	)

Constructor loading data from a config file.

If no configuration path is defined using TRestMetadata::SetConfigFilePath the path to the config file must be specified using full path, absolute or relative.

The default behaviour is that the config file must be specified with full path, absolute or relative.

Parameters

cfgFileName	A const char* giving the path to an RML file.
name	The name of the specific metadata. It will be used to find the corresponding TRestAxionMagneticField section inside the RML.

Definition at line 264 of file TRestAxionMagneticField.cxx.

Member Function Documentation

◆ DrawHistogram()

TCanvas * TRestAxionMagneticField::DrawHistogram	(	TString	projection,
		TString	Bcomp,
		Int_t	volIndex = `-1`,
		Double_t	step = `-1`,
		TString	style = `"COLZ0"`,
		Double_t	depth = `-100010.0`
	)

A method that creates a canvas where magnetic field map is drawn.

This method is used to create various 2D visualisations of the Bx, By and Bz magnetic field components for a given magnetic field region.

The following input parameters can be specified :

projection : it specifies the plane in the magnetic field region from which the plotted values of the magnetic field component were taken. The allowed values are: "XY", "XZ" and "YZ" for X-Y, X-Z and Y-Z plane, respectively.
Bcomp : it specifies which component of the magnetic field is plotted. The allowed values are: "X", "Y" and "Z" for Bx, By and Bz components, respectively.
volIndex : it specifies the index of the magnetic field region/volume for which the plot is shown.
step : it specifies the step/bin size for the 2D histogram that is shown. If this parameter is not specified, or if it has value < = 0, the values are taken from the corresponding mesh size values stored in data member fMeshSize.
style : it specifies the plotting style for the histogram. It can correspond to any draw option for 2D histograms in ROOT. The list of options can be found at: https://root.cern.ch/root/htmldoc/guides/users-guide/Histograms.html#drawing-histograms The default value is "COLZ0" which draws a box for each cell in the histogram with a color scale varying with values. The other useful option is "SURF3Z" which draws a surface plot with a coloured contour view on the top.
depth : it specifies the position of the plane in the magnetic field region from which the plotted values of the magnetic field component were taken. If this parameter is not specified, the histogram is plotted for the plane that goes through the middle of the region.

The following example will plot the values of the Bx component of the magnetic field taken in the X-Y plane positioned at z=5000mm in the magnetic field region with index 0. The step/bin size is 50mm, and the plotting style is "SURF3Z".

field->DrawHistogram("XY","X",0,50.0,"SURF3Z",5000.0)

where field is a pointer to the TRestAxionMagneticField object that describes the magnetic field.

Definition at line 337 of file TRestAxionMagneticField.cxx.

◆ GetComponentAlongPath()

std::vector< Double_t > TRestAxionMagneticField::GetComponentAlongPath	(	Int_t	axis,
		TVector3	from,
		TVector3	to,
		Double_t	dl = `1.`,
		Int_t	Nmax = `0`
	)

It returns a vector describing the magnetic field profile component requested using the axis argument which may take values 0,1,2 for X,Y,Z components. The field profile will be constructed in the track defined between from and to positions given by argument.

The differential element dl is by default 1mm, but it can be modified through the third argument of this function.

The maximum number of divisions (unlimited by default) of the output vector can be fixed by the forth argument. In that case, the differential element dl length might be increased to fullfil such condition.

Definition at line 1288 of file TRestAxionMagneticField.cxx.

◆ GetFieldAverageTransverseVector()

TVector3 TRestAxionMagneticField::GetFieldAverageTransverseVector	(	TVector3	from,
		TVector3	to,
		Double_t	dl = `10.`,
		Int_t	Nmax = `0`
	)

It returns the transverse component of the average magnetic field vector calculated along the line that connects the 3-d coordinates from and to with respect to that line.

The differential element dl defines the step, and it is by default 10mm, but it can be modified through the third argument of this function.

The maximum number of divisions (unlimited by default) can be fixed by the forth argument. In that case, the differential element dl length might be increased to fullfil such condition.

Definition at line 1385 of file TRestAxionMagneticField.cxx.

◆ GetFieldBoundaries()

std::vector< TVector3 > TRestAxionMagneticField::GetFieldBoundaries	(	TVector3	pos,
		TVector3	dir,
		Double_t	precision = `0`,
		Int_t	id = `0`
	)

Finds the in/out particle trajectory boundaries for a particular magnetic region, similar to the method TRestAxionMagneticField::GetVolumeBoudaries, but requiring that the in/out points are the first/last points where the transversal field intensity is not zero.

If no precision is given, the mesh size of the corresponding volume will be used as reference. The precision will be meshSize/2.

If no intersection is found the returned std::vector will be empty.

Definition at line 1497 of file TRestAxionMagneticField.cxx.

◆ GetMagneticField()

TVector3 TRestAxionMagneticField::GetMagneticField	(	TVector3	pos,
		Bool_t	showWarning = `true`
	)

It returns the magnetic field vector at TVector3(pos) using trilinear interpolation that is implemented following instructions given at https://en.wikipedia.org/wiki/Trilinear_interpolation.

The warning in case the evaluated point is found outside any volume might be disabled using the showWarning argument.

Definition at line 1018 of file TRestAxionMagneticField.cxx.

◆ GetMagneticVolumeNode()

TVector3 TRestAxionMagneticField::GetMagneticVolumeNode	(	size_t	id,
		TVector3	pos
	)

private

It returns the corresponding mesh node in the magnetic volume.

The corresponging node to x,y,z is the bottom, down, left node in the cell volume defined by 8-nodes.

This method will be made private, no reason to use it outside this class.

Definition at line 1433 of file TRestAxionMagneticField.cxx.

◆ GetTransversalComponentAlongPath()

std::vector< Double_t > TRestAxionMagneticField::GetTransversalComponentAlongPath	(	TVector3	from,
		TVector3	to,
		Double_t	dl = `1.`,
		Int_t	Nmax = `0`
	)

It returns a vector describing the transversal magnetic field component between from and to positions given by argument.

The differential element dl is by default 1mm, but it can be modified through the third argument of this function.

The maximum number of divisions (unlimited by default) of the output vector can be fixed by the forth argument. In that case, the differential element dl length might be increased to fullfil such condition.

Definition at line 1251 of file TRestAxionMagneticField.cxx.

◆ GetTransversalComponentInParametricTrack()

Double_t TRestAxionMagneticField::GetTransversalComponentInParametricTrack ( Double_t x )

It will return the transversal magnetic field component evaluated at a parametric distance x (given by argument) for the track defined inside the class. The track will be defined by the data members fStartTrack and fEndTrack which should be initialized by external means by invoking the method SetTrack( position, direction );.

This method will be used by the integration method

Definition at line 1346 of file TRestAxionMagneticField.cxx.

◆ GetTransversalFieldAverage()

Double_t TRestAxionMagneticField::GetTransversalFieldAverage	(	TVector3	from,
		TVector3	to,
		Double_t	dl = `1.`,
		Int_t	Nmax = `0`
	)

It returns the average of the transversal magnetic field intensity between the 3-d coordinates from and to.

The differential element dl defines the integration step, and it is by default 1mm, but it can be modified through the third argument of this function.

The maximum number of divisions of the output vector can be fixed by the forth argument. In that case, the differential element dl length might be increased to fullfil such condition.

Definition at line 1362 of file TRestAxionMagneticField.cxx.

◆ GetVolumeBoundaries()

std::vector< TVector3 > TRestAxionMagneticField::GetVolumeBoundaries	(	TVector3	pos,
		TVector3	dir,
		Int_t	id = `0`
	)

Finds the in/out particle trajectory boundaries for a particular magnetic region bounding box.

This method checks if the trajectory defined by the position pos and direction dir passes through the magnetic field region/volume id given. If two such points (entry point and exit point) are found, their coordinates are returned. In the example shown in Fig. 1 from TRestAxionFieldPropagationProcess these points are: IN 1 and OUT 1 for the region #1 and IN2 and OUT 2 for the region #2.

If no intersection is found, or the particle is not moving towards the volume, the returned std::vector will be empty.

Definition at line 1477 of file TRestAxionMagneticField.cxx.

◆ LoadMagneticFieldData()

void TRestAxionMagneticField::LoadMagneticFieldData	(	MagneticFieldVolume &	mVol,
		std::vector< std::vector< Float_t >>	data
	)

private

A method to help loading magnetic field data, as x,y,z,Bx,By,Bz into a magnetic volume definition using its corresponding mesh.

This method will be made private since it will only be used internally.

Definition at line 780 of file TRestAxionMagneticField.cxx.

◆ LoadMagneticVolumes()

void TRestAxionMagneticField::LoadMagneticVolumes ( )

It will load the magnetic field data from the data filenames specified at the RML definition.

This method will be made private since it will only be used internally.

Definition at line 834 of file TRestAxionMagneticField.cxx.

Field Documentation

◆ fMeshSize

std::vector<TVector3> TRestAxionMagneticField::fMeshSize

private

The size of a grid element from the mesh in mm. Initially, it must be the same as the binary input data

Definition at line 63 of file TRestAxionMagneticField.h.

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

Detailed Description

RML definition

The magnetic field file format.

A more detailed example

Using this class

Remapping the field

Visualizing the magnetic field

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ TRestAxionMagneticField()

Member Function Documentation

◆ DrawHistogram()

◆ GetComponentAlongPath()

◆ GetFieldAverageTransverseVector()

◆ GetFieldBoundaries()

◆ GetMagneticField()

◆ GetMagneticVolumeNode()

◆ GetTransversalComponentAlongPath()

◆ GetTransversalComponentInParametricTrack()

◆ GetTransversalFieldAverage()

◆ GetVolumeBoundaries()

◆ LoadMagneticFieldData()

◆ LoadMagneticVolumes()

Field Documentation

◆ fMeshSize