[NeXus-committee] Proposal for NXcrystal and NXmonochromator

[Pete Jemian]

Eugen:

You propose to:
* rename "usage" field to "type"
* add "channel_cut" as another possible value

As I said before, "channel_cut" is not an alternative to "Bragg" or 
"Laue" in its description of crystal orientation.  Most channel cut 
crystals use Bragg orientation.  I suggest a new field could be added to 
describe "channel_cut".  Another similar term could be 
"pseudo_channel_cut" which describes the crystal arrangement of most 
synchrotron X-ray monochromators.

Like many things in NeXus, the field name "usage" does not seem to fit 
so well, as you point out.

Rather than disrupt the historical use of the "usage" field in NeXus 
data files and however many data files have been written with this 
field, would it be acceptable to improve the documentation for the 
"usage" field?

Pete

On 3/8/2015 10:56 AM, Eugen Wintersberger wrote:
> Hi folks
>    as a result of the recent discussion I would like to propose the
> following changes to NXcrystal:
>
> remove the "usage" field from NXcrystal
>
> It makes no sense there as the way the crystal is used in a particular
> application is entirely unimportant for the particular crystal itself.
>
>
> Furthermore I would like to suggest the following change to
> NXmonochromator
>
> add a "type" field to NXmonochromator
>
> This field should basically hold the values of "usage" from the current
> NXcrystal class. I would also suggest to have an additional possible
> value "channel_cut" available for this field.
>
> Best regards
> Eugen
>
>
>
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>

-- 
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Pete R. Jemian, Ph.D.                <jemian at anl.gov>
Beam line Controls and Data Acquisition, Group Leader
Advanced Photon Source,   Argonne National Laboratory
Argonne, IL  60439                   630 - 252 - 3189
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