NeXus standard

[Eric Boucher]

I am currently working on a tool to store our scan data into NeXus files.
We have a 1D scan modules that can be programmed to move positionners and
read detectors.
By linking scan modules together we can acquire multidimensional datasets.

A 1D scan will look like:

pos1: ++++++++++++++++++     (axis=1)

det1: ++++++++++++++++++     (signal=1)

Easy to store into NeXus.


A 2D scan will look like:

pos1_1: +++		 (axis=1 for det1_1 or axis=2 for det2_1)

det1_1: +++		 (signal=1)

pos2_1: ++++++++++ (axis=1)
        ++++++++++
        ++++++++++

det2_1: ++++++++++ (signal=1)
        ++++++++++
        ++++++++++

Their are some problems to store this kind of data into NeXus.
1) the pos1_1 is the X axis for det1_1 but the Y axis for det2_1 so I need
to duplicate the data to give each copy a different axis attribute.

That would be nice if plotable data sets could name their axis instead.
We could achieve that by assigning axis attributes to a plottable data set .
Example for a N dimensions data set:
axis1: (TAG REF) (TAG REF)		  would list all possible X axis
axis2: (TAG REF) (TAG REF) (TAG REF)  would list all possible Y axis
....
axisN: (TAG REF) (TAG REF) (TAG REF)  would list all possible N'th axis


2) The pos2_1 is the X axis for det2_1 but it is not a 1D array.

One way of resolving this problem would be by giving such data sets
(potential axis) another attribute to tell the NeXus tool how to use it as
an axis:
For example an attribute called 'projection' that would tell the NeXus tool
how to project the N dimensional data onto a 1D array. ie: pick one line,
average, standard deviation, etc...


Do you think it would be possible to add those features to the NeXus
standard ?


Regards,

Eric.