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From: Dominik K. <dom...@gm...> - 2020-12-10 23:38:04
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Dear Ruggero,
I think you seemed to look more or less in the right places. I see three
problems in the the dummy script you sent:
1) I am not sure which version or xrayutilities you are using but
reasonable up to date versions the material definition would need to be
sam = xu.materials.material.Crystal('sample1', xu.materials.SGLattice(1,
*abcabg))
2) Since you say you are describing a four circle machine you should likely
use FourC
hxrd = xu.FourC(sam.Q(-2, 0, 0), sam.Q(0, 0, -4), en=energy)
you then will need to specify chi and phi in your call to Ang2HKL
3) Ang2HKL takes an optional parameter dettype [1]. This should in your
case likely be set to 'area'
h,k,l = hxrd.Ang2HKL(omega, chi, phi, towtheta, U=ubmat, dettype='area')
h,k,l should then be matrices of the shape (Nch1, Nch2) for every angular
position you specify. If you specify arrays of angles h,k,l will be three
dimensional arrays with according dimensions.
I hope this helps.
kind regards
Dominik
[1]
https://xrayutilities.sourceforge.io/xrayutilities.html?highlight=ang2hkl#xrayutilities.experiment.Experiment.Ang2HKL
On Thu, Dec 10, 2020 at 6:38 PM ruggero frison <rug...@uz...>
wrote:
>
> Hello,
>
> I would need some help, I am trying to index a frame of an Area detector
into hkl coordinateds following the example provided in Appendix B of the
reference paper and in some scripts provided in the example folder of the
distribution.
>
> I have some frames of an area detector with a 4-circles Eulerian cradle.
>
> I paste below a dummy script, which
> I prepared a script building on the examples but it does not give
results, I do not understand why.
> I guess because I do not understand the underlying action of
xrayutilities.
>
> I understand that Ang2HKL would create the arrays of hkl vlaues using the
experimental angles.
> Thus I could feed it with the scan parameters I retrieve from the scan
files and the UB matrix determined during the sample alignment.
>
> Would that work or I am getting wrong?
>
> I paste below a dummy script to avoid useless details.
>
> Thanks
>
> Best regards
>
> Ruggero
>
>
> ##__set the material
> abcabg = [a,b,c,alpha, beta, gamma]
> sam = xru.materials.material.Crystal(’sample1', abcabg)
>
> ##__the UB matrix is retrieved during the experiment
> ubmat = np.array([[1.364,-0.131,0.270],[-0.044, 1.639, 0.083],[-0.950,
-0.264, 0.384]])
>
>
> ##__load the frame and associated parameter file to get scan parameters,
> omega, twotheta, chi, phi, energy, detector_distance = ...
>
> ##__fix detector spec
>
> #__define experiment geometry
> hxrd = xru.HXRD(sam.Q(-2, 0, 0), sam.Q(0, 0, -4), en=energy)
>
> ##__assign orientation matrix
> hxrd.Ang2Q.init_area('z+','x+', cch1=cpix, cch2=cpiy, Nch1=npix,
Nch2=npiy,
> pwidth1=xpix, pwidth2=ypix, distance=sam_det)
>
> ## conversion to h,k,l
> h,k,l = hxrd.Ang2HKL(omega, towtheta, U=ubmat)
>
>
>
> ==================================================================
> Ruggero Frison
> University of Zurich, Physik Institut
>
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> Office: Y36-H-76
> Phone: +41 44 635 5780
> ==================================================================
>
>
>
>
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