[NeXus-tech] Revised PX application definition

[Tobias.Richter at diamond.ac.uk]

For synchrotron person the polarisation comes from "the source" i.e. the undulator. NXsource unfortunately describes the accelerator as electron source.
I think if we use NXbeam we should describe the beam incident on the sample. The you can use the same group to describe the photon energy.
We'll discuss this and the rest here in the next days.

Tobias

On 6 Dec 2013 08:13, Mark Koennecke <Mark.Koennecke at psi.ch> wrote:
Hi,

find below my version of the PX application definition revised according to
our last Telco.

I took a possibly dubious decision here as I attached the polarisation
parameters to
the source. My interpretation of wikipedia is that this is where the
polarisation comes
from. Please correct me if this wrong.

diffrn_id:NXentry
    definition:NX_CHAR
    diffrn_id:NX_CHAR
    diffrn_scan_id:NX_CHAR
    measurement_details:NX_CHAR
    diffrn_crystal_id:NXsample
       diffrn_crystal_id:NX_CHAR
    instrument:NXinstrument
       source:NXsource
          name:NX_CHAR
          type:NX_CHAR
          current:NX_NUMBER
          probe:NX_CHAR
          polarisation_source_ratio:NX_NUMBER
          polarisation_source_norm:NX_NUMBER
       monochromator:NXmonochromator
          type:NX_CHAR
          radiation_id:NX_CHAR
          wavelength[] NX_NUMBER
          wavelength_weight[]:NX_NUMBER
       collimator:NXcollimator
          beam_divergence[]:NX_NUMBER
          collimation:NX_CHAR
       detector:NXdetector
          type:NX_CHAR
          frame_start_number:NX_NUMBER
          frame_end_number:NX_NUMBER
          description:NX_CHAR
          data[NP,XDIM,YDIM]
          x[XDIM]:NX_AXIS
          y[YDIM]:NX_AXIS
          azimuthal_angle:NX_AXIS
          distance:NX_AXIS
          height:NX_AXIS
          meridional_angle:NX_AXIS
          rotation_angle:NX_AXIS
          x_translation:NX_AXIS
          depends_on:NX_CHAR
          count_time[NP]:N_NUMBER
       goniometer:NXgoniometer
          chi[NP]:NX_AXIS
          phi[NP]:NX_AXIS
          rotation_angle[NP]:NX_AXIS
          depends_on:NX_CHAR
   data:NXdata
          link to instrument/detector/data
          link to instrument/goniomter/rotation_angle
          etc.


I took some liberties:
- I added some fields to NeXus base classes
- I use NX_AXIS which have not yet aggreed upon. Which means that the
thing is
   a NeXus axis with the attributes: transfromation_type, vector,
offset,depends_on etc.
- I put the polarisation into NXsource. Because wikipedia told me that
without further
   action the polrisation is a property of the source. Please tell me if
I am wrong.

It is to be understood that the axes in NXgoniometer and NXdetector may
vary. But that the
transformation necessary can always be constructed by following the
depends_on chain.

In NXdata should be links to all the fields varied during the scan.
Indicated by the etc.

Regards,


            Mark

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