/*******************************************************************************
* Instrument: <SESANS_Delft>
*
* %I
* Written by: Wim Bouwman (w.g.bouwman@tudelft.nl), Peter Willendrup and Erik Knudsen
* Date: December 2019
* Origin: Delft University of Technology
* %INSTRUMENT_SITE: Reactor_Institute_Delft
* Idealised SESANS instrument using magnetised foil flippers with realistic sample
*
* %D
* <instrument description>
* A full description of the instrument can be found in J. Appl. Cryst. (2021) V. 54 https://doi.org/10.1107/S1600576720015496
* The instrument has the bare essentials to simulate the Larmor precession of the neutron spins in the foil flippers and the 
* geometry and wavelength distribution of the SESANS in Delft as described in
* Rev. Sci. Instrum. 76, 033901 (2005) https://doi.org/10.1063/1.1858579
* An essential component is the realistic SANS sample, describing both the scattered and transmitted neutron, including multiple scattering.
* In one scattering simulation both the up- and down intensities are simulated.
* For a full SESANS scan the applied magnetic field By has to be scanned.
* In principle the sample can be removed to study the empty beam instrument, which with this idealised setup have perfect polarisation.
* It is possible to monitor the evolution of the polarisation with several polarisation monitors that have beeen commented in this version.
* The foil-angle, thickness and wavelength yield now matched parameters to have the SESANS working. 
* These parameter and the sphere radius match now with the magnetic fields below to get a good measurement range.
*
* Example: SESANS_Delft -n 1000000 -N 31 L0=2.165 DL=0.02 By=0,0.0468
*
* %P
* <parameter1>: [<unit>] <parameter1 description>
* L0: [AA]		nominal wavelength
* DL: [AA]		wavelength band width
* By: [T]		Applied magnetic field in foil flippers
*
* %L
* <reference/HTML link>
* <a href="https://doi.org/10.1107/S1600576720015496">https://doi.org/10.1107/S1600576720015496</a>
* %E
*******************************************************************************/
DEFINE INSTRUMENT SESANS_Delft(L0=2.165, DL=0.02, By=4.68e-3)

DECLARE
%{
%}

INITIALIZE
%{
%}

TRACE

COMPONENT origin = Progress_bar()
AT (0, 0, 0) RELATIVE ABSOLUTE

// insert components here (e.g. Insert -> Source -> ...)
COMPONENT src = Source_simple(
    yheight=0.01, 
    xwidth=0.01, 
    dist=2.25, 
    focus_xw=0.01, 
    focus_yh=0.01, 
    lambda0=L0, 
    dlambda=DL,
    gauss=1)
AT (0, 0, 0) RELATIVE PREVIOUS


COMPONENT set_pol = Set_pol(
    px=1)
AT (0, 0, 0.1) RELATIVE PREVIOUS

COMPONENT px1 = PolLambda_monitor(
    restore_neutron=1, Lmin=L0-DL, Lmax=L0+DL, nL=501,
    mx=1,filename="pxAfterAnalyser")
AT (0, 0, 0.01) RELATIVE PREVIOUS

/*
COMPONENT py1 = PolLambda_monitor(
    restore_neutron=1, Lmin=L0-DL, Lmax=L0+DL, nL=501,
    my=1,filename="py1")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT f1 = Foil_flipper_magnet(
    xwidth=0.1, 
    yheight=0.1, 
    zdepth=0.3, 
    phi=0.095993, 
    foilthick=3.0, 
    Bx=0, 
    By=By, 
    Bz=0, 
    foil_in=1, verbose=0)
AT (0, 0, 0.5) RELATIVE src

COMPONENT px2 = COPY(px1)(filename="pxAfterFirstFoil")
AT (0, 0, 0.16) RELATIVE PREVIOUS

/*
COMPONENT py2 = COPY(py1)(filename="py2")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT f2 = COPY(f1)(By=By)
AT(0,0,2.0) RELATIVE src

COMPONENT px3 = COPY(px1)(filename="pxAfterSecondFoil")
AT (0, 0, 0.16) RELATIVE PREVIOUS

/*
COMPONENT py3 = COPY(py1)(filename="py3")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT sans_spheres = SANS_spheres2(xwidth=0.02, 
    yheight=0.02, 
	zthick=0.001, 
	dsdw_inc=0.0, 
	sc_aim=0.8, 
	sans_aim=0.95, 
	R=10000, 
	phi=0.015, 
	singlesp=0,
	Qmind = 0.00003,
	Qmaxd = 0.001)
  WHEN (1==1) AT (0, 0, 2.25) RELATIVE src

/*
COMPONENT px4 = COPY(px1)(filename="px4")
AT (0, 0, 0.01) RELATIVE PREVIOUS

COMPONENT py4 = COPY(py1)(filename="py4")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT f3 = COPY(f1)(By=-By)
AT(0,0,2.5) RELATIVE src

/*
COMPONENT px5 = COPY(px1)(filename="px5")
AT (0, 0, 0.16) RELATIVE PREVIOUS

COMPONENT py5 = COPY(py1)(filename="py5")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT f4 = COPY(f1)(By=-By)
AT(0,0,4.0) RELATIVE src

COMPONENT px6 = COPY(px1)(filename="px6")
AT (0, 0, 0.16) RELATIVE PREVIOUS

/*
COMPONENT py6 = COPY(py1)(filename="py6")
AT (0, 0, 0.01) RELATIVE PREVIOUS
*/

COMPONENT ana = PolAnalyser_ideal(mx=1)
AT(0,0,4.4) RELATIVE src

COMPONENT det = PSD_monitor(xwidth=0.011, yheight=0.011, filename="det",ny=101, nx=101)
AT(0,0,4.5) RELATIVE src

COMPONENT trick = Arm()
AT(0,0,4.4) RELATIVE src
EXTEND
%{
   RESTORE_NEUTRON(INDEX_CURRENT_COMP-2,x,y,z,vx,vy,vz,t,sx,sy,sz,p);
%}

COMPONENT ana2 = PolAnalyser_ideal(mx=-1)
AT(0,0,4.4) RELATIVE src

COMPONENT det2 = PSD_monitor(xwidth=0.011, yheight=0.011, filename="det2",ny=101, nx=101)
AT(0,0,4.5) RELATIVE src

FINALLY
%{
%}

END
