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McStas: Pol_simpleBfield

[ Identification | Description | Input parameters | Links ]

The Pol_simpleBfield Component

Magnetic field component.

Identification

  • Site:
  • Author: Erik B Knudsen, Peter Christiansen and Peter Willendrup
  • Origin: RISOE
  • Date: July 2011

Description

Region with a definable magnetic field.

The component is nestable. This means that it requires a

// START MAGNETIC FIELD
COMPONENT msf =
Pol_simpleBfield(xwidth=0.08, yheight=0.08, zdepth=0.2, Bx=0, By=-0.678332e-4, Bz=0)
AT (0, 0, 0) RELATIVE armMSF

// HERE CAN BE OTHER COMPONENTS INSIDE THE MAGNETIC FIELD

// STOP MAGNETIC FIELD
COMPONENT msf_stop = Pol_simpleBfield_stop(magnet_comp_stop=msf)
AT (0, 0, 0) RELATIVE armMSF

In between the two component instances the propagation routine
PROP_DT also handles spin propagation.
The current algorithm used for spin propagation is:
SimpleNumMagnetPrecession
in pol-lib.

Example: Pol_simpleBfield(xwidth=0.1, yheight=0.1, zdepth=0.2, Bx=0, By=1, Bz=0)
Pol_simpleBfield(xwidth=0.1, yheight=0.1, zdepth=0.2,
filename="bfield.dat", fieldFunction=table_magnetic_field)

The magetic field may be given as any definable c-function with a specific footprint:
int func(double x, double y, double z, double t, double *bx, double *by, double *bz, void *data)
where the magnetic field at coordinates (x,y,z, t) is returned in the variables
pointed to by bx,by, and bz. Additional parameters to be handed to the function
should be handed to the function using the pointer data.

Functions supplied by the system are:
1. const_magnetic_field: Constant field (Bx,By,Bz) within the region
2. rot_magnetic_field: Field is initially (0,By,0) but after a length of zdepth
has rotated to (By,0,0)
3. majorana_magnetic_field: Field is initially (Bx,By,0) liearly transforms to
(-Bx,By,0) after zdepth where By<

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
fieldFunctionpointerFunction describing the magnetic field.const_magnetic_field
xwidthmWidth of opening.
yheightmHeight of opening.
zdepthmLength of field.
BxTParameter used for x composant of field.
ByTParameter used for y composant of field.
BzTParameter used for z composant of field.
filenamefile where the magnetic field is tabulated."bfield.dat"
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43


Last Modified: Wednesday, 03-Jan-2024 19:59:11 CET
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