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/***************************************************************************
* McStas instrument definition URL=http://www.mcstas.org
*
* Instrument: Test_Magnetic_Userdefined
*
* %Identification
* Written by: Peter Christiansen and Peter Willendrup
* Date: August 2006
* Origin: RISOE
* %INSTRUMENT_SITE: Tests_polarization
*
* This instrument demonstrates how to use the Pol_Bfield
* component with a user-specified fieldFunction.
*
* %Description
* This instrument demonstrates how to use the component
* Pol_Bfield with a user-specified fieldFunction.
*
* The fieldFunction is specified in the DECLARE section and defined active
* using the fieldFunction parameter of the component. The example fieldFunction
* is timedependent (velocity-dependent), setting a B-field that will rotatate
* the neutron spins by PI.
*
* %Example: Test_Magnetic_Userdefined Detector: pollambdaMonitor2x_I=0.181511
*
* %Parameters
*
* %Link
*
* %End
****************************************************************************/
/* Change name of instrument and input parameters with default values */
DEFINE INSTRUMENT Test_Magnetic_Userdefined()
/* The DECLARE section allows us to declare variables or small */
/* functions in C syntax. These may be used in the whole instrument. */
DECLARE
%{
double omegaL = -2 * PI * 29.16e6;
double MagnetLength = 0.2;
double SrcMagnetDist = 1;
double user_parameters[3];
int magnetic_field_t(double x, double y, double z, double t,
double *bx, double *by, double *bz, void *data_Ptr) {
double *d=data_Ptr;
// Example of time-dependent field. Note parameters t0 and rho defined
// just above, initialized below
*by = (PI * (d[2] + d[1]/2))/(d[0]*d[1]*t);
*bx = 0;
*bz = 0;
return 1;
}
%}
/* The INITIALIZE section is executed when the simulation starts */
/* (C code). You may use them as component parameter values. */
INITIALIZE
%{
user_parameters[0]=omegaL;
user_parameters[1]=MagnetLength;
user_parameters[2]=SrcMagnetDist;
%}
/* Here comes the TRACE section, where the actual */
/* instrument is defined as a sequence of components. */
TRACE
/* The Arm() class component defines reference points and orientations */
/* in 3D space. Every component instance must have a unique name. Here, */
/* Origin is used. This Arm() component is set to define the origin of */
/* our global coordinate system (AT (0,0,0) ABSOLUTE). It may be used */
/* for further RELATIVE reference, Other useful keywords are : ROTATED */
/* EXTEND GROUP PREVIOUS. Also think about adding a neutron source ! */
/* Progress_bar is an Arm displaying simulation progress. */
COMPONENT Origin = Progress_bar()
AT (0,0,0) ABSOLUTE
COMPONENT source =
Source_simple(radius = 0.01, dist = 1.0, focus_xw = 0.1, focus_yh = 0.1, lambda0 = 5,
dlambda = 4.9, flux = 1)
AT (0, 0, 0) RELATIVE Origin
COMPONENT polSetter =
Set_pol(px=1)
AT (0, 0, 0.5) RELATIVE Origin
COMPONENT pollambdaMonitor1x =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=1, my=0, mz=0, filename="pollambdaMon1x.data")
AT (0, 0, 0.7) RELATIVE Origin
COMPONENT pollambdaMonitor1y =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=0, my=1, mz=0, filename="pollambdaMon1y.data")
AT (0, 0, 0.75) RELATIVE Origin
COMPONENT pollambdaMonitor1z =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=0, my=0, mz=1, filename="pollambdaMon1z.data")
AT (0, 0, 0.8) RELATIVE Origin
COMPONENT armMSF = Arm()
AT (0,0,1) RELATIVE Origin
// The By field is set to rotate the spin 180 degrees for neutrons of wavelenth
// 5 AA
COMPONENT msf =
Pol_Bfield(xwidth=0.08, yheight=0.08, Bx=0, By=-0.678332e-4, Bz=0,
fieldFunction=magnetic_field_t, field_prms=user_parameters)
AT (0, 0, 0) RELATIVE armMSF
COMPONENT msf_stop =
Pol_Bfield_stop()
AT(0,0,MagnetLength) RELATIVE armMSF
COMPONENT pollambdaMonitor2x =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=1, my=0, mz=0, filename="pollambdaMon2x.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
COMPONENT pollambdaMonitor2y =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=0, my=1, mz=0, filename="pollambdaMon2y.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
COMPONENT pollambdaMonitor2z =
PolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0, npol=21,
mx=0, my=0, mz=1, filename="pollambdaMon2z.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
COMPONENT mpollambdaMonitor2x =
MeanPolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0,
mx=1, my=0, mz=0, filename="mpollambdaMon2x.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
COMPONENT mpollambdaMonitor2y =
MeanPolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0,
mx=0, my=1, mz=0, filename="mpollambdaMon2y.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
COMPONENT mpollambdaMonitor2z =
MeanPolLambda_monitor(xwidth=0.1, yheight=0.1,
nL=100, Lmin = 0.0, Lmax = 10.0,
mx=0, my=0, mz=1, filename="mpollambdaMon2z.data")
AT (0, 0, 0.1) RELATIVE PREVIOUS
/* This section is executed when the simulation ends (C code). Other */
/* optional sections are : SAVE */
FINALLY
%{
%}
/* The END token marks the instrument definition end */
END
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