[pdDMG] DDLm pdCIF Issue 1: could detector and 2 theta offset be looped together in pd_calib?

[James Hester]

(Another missed message from Brian below)

The situation with Brian's single Huber seems to be described well with a
'correction against 2 theta' table using _pd_calib_offset_* (
http://comcifs.github.io/cif_pow.dic.html#PD_CALIB_OFFSET).  But you have
reminded me that our PD neutron detector here consists of 128 tubes, all of
which have their own 2 theta offset correction.  This is all absorbed
during the data reduction but would be nice to capture nevertheless in the
output pdCIF file.

What I suggest we then do is add a pd_calib_offset.detector_id dataname for
the situations in which there is a separate offset per detector. This
dataname would take a default value in the case of a single detector and so
could be left out of the _pd_calib_offset loop in that case.

James.


On 3 November 2016 at 16:15, Toby, Brian H. <toby at anl.gov> wrote:

> one more, from yesterday
>
> Begin forwarded message:
>
> *From: *Brian Toby <toby at anl.gov>
> *Subject: **Re: [pdDMG] DDLm pdCIF Issue 1: could detector and 2 theta
> offset be looped together in pd_calib?*
> *Date: *November 1, 2016 at 10:52:20 AM CDT
> *To: *Distribution list of the IUCr COMCIFS Powder Diffraction Dictionary
> Maintenance Group <pddmg at iucr.org>
>
> I put this aside for more thought originally, but I am not sure if that
> moment will arrive, so let me provide a few (perhaps random) comments.
>
> One concern here is that it is common with strip and area detectors that
> one often collects data at different two-theta settings due to gaps in the
> arrays. I will skip the self-citation, but I have worked on a detector
> where the CCD readout is synchronized to the two-theta sweep. One would
> probably not try to handle raw data from that in pdCIF, but I could
> certainly imagine having Mythen data collected at several different 2theta
> settings. I guess a separate block for each could be a solution, if we so
> choose.
>
> I think that I also considered the case where the 2-theta offset could
> vary with 2theta. At 11-BM we do apply corrections as a function of 2-theta
> since we can see that the Huber deviates from ideal.
>
> Brian
>
>
> On Oct 31, 2016, at 10:28 PM, James Hester <jamesrhester at gmail.com> wrote:
>
> There having been no response to this, I will assume that there is limited
> to no demand for a multi-detector+multi-offset capability and leave the
> current powCIF draft as is.
>
> James.
>
> On 24 October 2016 at 11:23, James Hester <jamesrhester at gmail.com> wrote:
>
>> In DDL1, items in the pd_calib category can vary by detector ("loops may
>> be used for calibration information that differs by detector channel").
>> Similarly, 2theta offset values can be looped where the offset varies by
>> point.  While this is fine, it is not clear if we wish the pd dictionary to
>> cover a situation where both detector and 2 theta offset vary, that is, for
>> each detector in a multi-detector setup the 2 theta offset can take
>> multiple values for different points collected by that detector.  Has
>> anyone encountered such a situation?
>>
>> If the situation is rare, but conceivable, we can create a separate
>> 'extension dictionary' which covers this case, but mainstream software is
>> protected from misinterpreting loops (this is a new feature).
>>
>> James.
>>
>> --
>> T +61 (02) 9717 9907
>> F +61 (02) 9717 3145
>> M +61 (04) 0249 4148
>>
>
>
>
> --
> T +61 (02) 9717 9907
> F +61 (02) 9717 3145
> M +61 (04) 0249 4148
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>
> ********************************************************************
> Brian H. Toby, Ph.D.                            office: 630-252-5488
> Advanced Photon Source Chief Computational Scientist
> Senior Physicist/Computational X-ray Science Group Leader
> 9700 S. Cass Ave, Bldg. 401/B4192                 cell: 630-327-8426
> Argonne National Laboratory
> Argonne, IL 60439-4856         e-mail: brian dot toby at anl dot gov
> ********************************************************************
> "We will restore science to its rightful place, and wield technology's
> wonders... We will harness the sun and the winds and the soil to fuel our
> cars and run our factories...  All this we can do. All this we will do."
>
>
> ********************************************************************
> Brian H. Toby, Ph.D.                            office: 630-252-5488
> Advanced Photon Source Chief Computational Scientist
> Senior Physicist/Computational X-ray Science Group Leader
> 9700 S. Cass Ave, Bldg. 401/B4192                 cell: 630-327-8426
> Argonne National Laboratory
> Argonne, IL 60439-4856         e-mail: brian dot toby at anl dot gov
> ********************************************************************
> "We will restore science to its rightful place, and wield technology's
> wonders... We will harness the sun and the winds and the soil to fuel our
> cars and run our factories...  All this we can do. All this we will do."
>
>


-- 
T +61 (02) 9717 9907
F +61 (02) 9717 3145
M +61 (04) 0249 4148
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