Discussion List Archives

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Imgcif-l] ... also

Hi Jon,

I can see that describing the beam profile in the complete way you
describe is correct - however for MX (where I'm sat!) we explicitly
assume that the beam has no structure :o) - it's wrong, I know, but for
the moment I'm happy with characterising the size of the beam.

However, your point you mention below about the focussing is a good one
- as things stand we have assumed a divergent beam with a point source,
and with a couple of mirrors you could break this assumption pretty
easily. Could we fix this by also including the focus of the beam? For a
bending magnet with no optics I guess that this would be the "source" -
the magnet itself. When there's some optics to be had a virtual source
may exist which corresponds to where the beam size would virtually be 0
tracking back the beam divergence. In some cases the focus could be at
the sample, it could be at the detector, in which case the beam focus
point could be at 0.0 or -200 (or whatever). The beam size could then be
approximated as a cone, perhaps slitted, starting at this focal point
with an angular width equal to the divergence.

Correspondingly I would propose:

_diffrn_radiation.beam_focus_z

As a CIF token, with a value of 0.0 indicating that the focus is at the
sample.

Does this answer the question proposed?

Thanks & best wishes,

Graeme

 

-----Original Message-----
From: imgcif-l-bounces@iucr.org [mailto:imgcif-l-bounces@iucr.org] On
Behalf Of Jon Wright
Sent: 17 February 2010 09:12
To: The Crystallographic Binary File and its imgCIF application to image
data
Subject: Re: [Imgcif-l] ... also

Dear Readers,

If you want to have enough information to generate reflection profiles
in a general case I think you need a lot more than you are proposing. 
Recording a 2D image (or some 1D scans) of the beam profile in different
positions along the beamline can give a very detailed characterisation,
but would not be suitable for everyone. With topography experiments, the
reflection profile is an image of the crystal shape, and should be
corrected both for the incident beam profile and detector response. It
starts to become like a tomography experiment, where the beam profiles
are separate images.

For slit size + divergence being enough: how do you compute the profiles
when focussing the beam on the detector versus sample?

Best wishes

Jon



Graeme.Winter@Diamond.ac.uk wrote:
> Hi James, Herbert,
> 
> What you say I think is correct but not complete. For instance, if the

> fundamental beam size is ~ 120 x 80 microns (as it is on our phase 1 
> stations here) then slits at 200 x 200 won't mean anything, but slits 
> at 80 x 80 will... Describing all of this information would help to 
> give hints about the expected beam profile - a 40 x 40 "beam" above 
> will likely be pretty uniform.
> 
> Based on this I would propose:
> 
> _diffrn_radiation.beam_size_x
> _diffrn_radiation.beam_size_y
> 
> To refer to the "fundamental" beam - that which you would receive with

> no additional collimation - as a FWHM I assume. Then:
> 
> _diffrn_radiation.collimation_x
> _diffrn_radiation.collimation_y
> 
> To refer to the recorded spacing of the slits. I could see in terms of

> actually recording this information that this would be doable - the 
> former would be a property of the beamline, the latter a data 
> collection choice.
> 
> Best wishes,
> 
> Graeme
> 
> -----Original Message-----
> From: imgcif-l-bounces@iucr.org [mailto:imgcif-l-bounces@iucr.org] On 
> Behalf Of James Hester
> Sent: 16 February 2010 23:14
> To: The Crystallographic Binary File and its imgCIF application to 
> image data
> Subject: Re: [Imgcif-l] ... also
> 
> I agree with Herbert's suggestion, although I would name the tags
> 
> _diffrn_radiation.beam_size_x
> _diffrn_radiation.beam_size_y
> 
> simply because that makes more immediate sense to me. 'Spread' reminds

> me of 'wavelength spread', 'angular spread', 'vegemite' etc. But that 
> might just be me.
> 
> I would advocate against the use of a slit width unless enough 
> information is provided to interpret its meaning i.e. location of the 
> slit relative to source/monochromator/sample/other slits.
> 
> NB The powder CIF dictionary defines beam size tags for the size of 
> the beam at the sample (DDL1, however).
> 
> James.
> 
> On Wed, Feb 17, 2010 at 12:05 AM, Herbert J. Bernstein < 
> yaya@bernstein-plus-sons.com> wrote:
> 
>> Another nice question.  We have the angular crossfire in
>>
>> _diffrn_radiation.div_x_source
>> _diffrn_radiation.div_y_source
>> _diffrn_radiation.div_x_y_source
>>
>> Should this new tag be viewed as a characteristic of the beam, say
>>
>> _diffrn_radiation.spread_x_source
>> _diffrn_radiation.spread_y_source
>> _diffrn_radiation.spread_x_y_source
>>
>> or, as Graeme suggests, the width of slits collimating the beam or as

>> ???
>>
>> Suggestions, please.
>>
>> =====================================================
>>  Herbert J. Bernstein, Professor of Computer Science
>>    Dowling College, Kramer Science Center, KSC 121
>>         Idle Hour Blvd, Oakdale, NY, 11769
>>
>>                  +1-631-244-3035
>>                  yaya@dowling.edu
>> =====================================================
>>
>> On Tue, 16 Feb 2010, Graeme.Winter@Diamond.ac.uk wrote:
>>
>>> Hello again,
>>>
>>> Is there a way to specify the size of the beam - or at least, the 
>>> gap between the slits? This obviously relates to the question
> before.
>>> Looking in the dictionary from version 1.5.4 - 2007-07-28 I could 
>>> not find these (this was the latest dictionary I could find in the 
>>> cbflib
>>> distribution)
>>>
>>> Thanks again,
>>>
>>> Graeme
>>>
>>> Graeme Winter
>>> Software and MX Support Scientist
>>> Diamond Light Source
>>>
>>> +44 1235 778091 (work)
>>> +44 7786 662784 (work mobile)
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> This e-mail and any attachments may contain confidential, copyright 
>>> and
>> or privileged material, and are for the use of the intended addressee
> only.
>> If you are not the intended addressee or an authorised recipient of 
>> the addressee please notify us of receipt by returning the e-mail and

>> do not use, copy, retain, distribute or disclose the information in 
>> or
> 
>> attached to the e-mail.
>>> Any opinions expressed within this e-mail are those of the 
>>> individual and
>> not necessarily of Diamond Light Source Ltd.
>>> Diamond Light Source Ltd. cannot guarantee that this e-mail or any
>> attachments are free from viruses and we cannot accept liability for 
>> any damage which you may sustain as a result of software viruses 
>> which
> 
>> may be transmitted in or with the message.
>>> Diamond Light Source Limited (company no. 4375679). Registered in 
>>> England
>> and Wales with its registered office at Diamond House, Harwell 
>> Science
> 
>> and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> imgcif-l mailing list
>>> imgcif-l@iucr.org
>>> http://scripts.iucr.org/mailman/listinfo/imgcif-l
>>>
>> _______________________________________________
>> imgcif-l mailing list
>> imgcif-l@iucr.org
>> http://scripts.iucr.org/mailman/listinfo/imgcif-l
>>
> 
> 
> 
> --
> T +61 (02) 9717 9907
> F +61 (02) 9717 3145
> M +61 (04) 0249 4148
> _______________________________________________
> imgcif-l mailing list
> imgcif-l@iucr.org
> http://scripts.iucr.org/mailman/listinfo/imgcif-l
> 

_______________________________________________
imgcif-l mailing list
imgcif-l@iucr.org
http://scripts.iucr.org/mailman/listinfo/imgcif-l

-- 
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. 
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
 



_______________________________________________
imgcif-l mailing list
imgcif-l@iucr.org
http://scripts.iucr.org/mailman/listinfo/imgcif-l

Reply to: [list | sender only]
International Union of Crystallography

Scientific Union Member of the International Science Council (admitted 1947). Member of CODATA, the ISC Committee on Data. Partner with UNESCO, the United Nations Educational, Scientific and Cultural Organization in the International Year of Crystallography 2014.

International Science Council Scientific Freedom Policy

The IUCr observes the basic policy of non-discrimination and affirms the right and freedom of scientists to associate in international scientific activity without regard to such factors as ethnic origin, religion, citizenship, language, political stance, gender, sex or age, in accordance with the Statutes of the International Council for Science.