Hi Tony!
I knew I had seen something before.
Ta
Mathew
On 30 Jul 2015 10:00 pm, "iangie" <ian...@126.com> wrote:
> Dear Friends,
>
> Below macro was already developed in 10th TOPAS user meeting @ Adelaide:
>
> TOPAS syntax code for the modified intensity correction and flat specimen
> asymmetry peak shape convolution
>
> ‘Variable_Divergence_Shape_Correction: v = footprint (EDFL); keh = knife
> edge height
>
> macro Variable_Divergence_Shape_with_knife_edge(v, keh)
> {one_on_x_conv = If(Th < 2*ArcTan(2keh/v), -v^2 Sin(2 Th) Rad/(4 Rs^2), -2
> keh^2 (Cos(Th))^3/Sin(Th) Rad/Rs^2);}
>
> ‘Variable_Divergence_Intensity_Correction: v = footprint (EDFL); keh =
> knife edge height
>
> macro Variable_Divergence_Intensity_with_knife_edge(v, keh)
>
> {scale_pks = If(Th < 2*ArcTan(2keh/v), Sin(Th), 2 keh/v Cos(Th));}
>
> If you use fix divergence slit:
>
> ‘Fix_Divergence_Shape_Correction: divang = divergence angle (EDFA); keh =
> knife edge height
>
> macro Fix_Divergence_Shape_with_knife_edge(v, keh)
> {prm v = R divang Deg /Sin(Th);
> one_on_x_conv = If( Rs Sin(divang/2 Deg) / Sin(Th - divang/2 Deg) Tan( (Th
> - divang/2 Deg) > keh, -(Pi/360)/Tan(Th) divang^2, -2 keh^2
> (Cos(Th))^3/Sin(Th) Rad/Rs^2);}
>
> ‘Fix_Divergence_Intensity_Correction: v = footprint; keh = knife edge
> height
>
> macro Fix_Divergence_Intensity_with_knife_edge(v, keh)
>
> {scale_pks = If(Rs Sin(divang/2 Deg) / Sin(Th - divang/2 Deg) Tan( (Th -
> divang/2 Deg) > keh, 1, 2 keh/v Cos(Th));}
>
>
> or something similar...
>
>
> Cheers!
>
>
> --
> Yours Sincerely,
> Dr. Xiaodong(Tony) Wang
> XRD Application Scientist
> Bruker Singapore Pte. Ltd.
>
> At 2015-07-30 21:29:40, "Matthew Rowles" <rowle...@gmail.com> wrote:
>
> Hi Robert
>
> Exactly! If installed properly, it doesn't affect anything except the
> background. I had a nice spreadsheet setup to give me knife heights vs
> divergence vs maximum 2T value to make sure that I don't run into forbidden
> teritory.
>
> I dispute your assertion that a knife wouldn't be necessary if the optics
> worked properly. As far as I know, the only way to get rid of air scatter
> would be to evacuate the beam path.
>
> I'm currently doing some experiments with an old knife setup on a D8, and
> I'm getting some funny bumps at low angle, but in my experience with a
> newer know setup, that is due to a divergence that is too big. I'll see if
> I can put something together.
>
> Matthew
> On 30 Jul 2015 2:04 pm, "Dr. Robert Möckel" <r.moec...@hzdr.de> wrote:
>
>> Hi Matthew,
>>
>> what you mentioned earlier is not completely correct:
>>
>> An anti-air scatter (or beam knife) does not only reduce background
>> (mainly at low angles), but also cuts intensity at higher 2theta values, if
>> not installed correctly. It does not result in a sample displacement error,
>> it just cuts intensity as it cuts off the beam like you mentioned.
>> This is also an relatively easy issue to modell, I even managed to put it
>> into an excel-file to calculate the max. 2theta angle that can be measured
>> at a certain knife height and detector length. BGMN "handles" this properly
>> as well. Nowadays, there are even knifes available that move vertically,
>> depending on the actual 2theta value.
>>
>> In general, a beam knife would not be necessary if the optics worked
>> properly, i.e. the optical path is not disturbed or diffracted or
>> fluorescence would not be generated somewhere in the beam path. Basing on
>> our experience, the main source of these unwanted X-rays are within or
>> close to the tube itself, making it hard to suppress it effectively.
>> All these things result in some strange background phenomena at low
>> angles (bumps/edges...). We discussed these issues with Reinhard Kleeberg
>> and others for a while. It seems to be a serious problem in modern devices,
>> as we experienced this on our own PANalytical and other (Bruker) devices
>> from colleagues.
>>
>> Regards,
>>
>> Robert
>>
>>
>>
>> , 30 Jul 2015 11:53:15 +0800 schrieb Matthew Rowles <rowle...@gmail.com>:
>>
>>> Hi Jilin
>>>
>>> You could probably add a note to your input file.
>>>
>>> Not everything you use in your hardware can be either properly modelled,
>>> or
>>> influence the pattern significantly. Do you need to model the
>>> anti-scatter
>>> slits? They help reduce background.
>>>
>>> One thing that could happen is that if the knife is set up incorrectly,
>>> it
>>> will cut off the beam, shifting the centroid of diffraction. That may
>>> mimic
>>> a sample displacement type error.
>>>
>>> Re your comment about double-digit results. Are you talking about the
>>> quant
>>> results given in the GUI? The actual answer is going to be a lot less
>>> precise than that.
>>>
>>>
>>> Matthew
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On 30 July 2015 at 09:19, ji zhang <jilin_zhang_hous...@yahoo.ca> wrote:
>>>
>>>
>>>>
>>>> Matthew
>>>>
>>>> I was thinking shouldn't we be able to input some parameters to reflect
>>>> this hardware configuration in the program?
>>>>
>>>> I forgot that I had asked the same question in2007 in this list. Nobody
>>>> seemed to care enough except Dr Bergmann. Then I went to do log
>>>> analysis,
>>>> and this thing is completely forgotten.
>>>>
>>>> Currently we have topaz where I can't find a way to circumvent this yet
>>>> or
>>>> to handle this as I called it. I am thinking we may need a copy of bgmn.
>>>> Certainly both give double digit results (albeit not the same) and both
>>>> look accurate.
>>>>
>>>>
>>>>
>>>> Sent from Yahoo Mail for iPhone <https://yho.com/footer0>
>>>>
>>>> On Jul 29, 2015, 5:56:41 PM, Matthew Rowles wrote:
>>>>
>>>> Hi
>>>>
>>>> What do you mean by "handle it"?
>>>>
>>>> If the knife edge is correctly set up, the only thing that should change
>>>> is the background.
>>>>
>>>> Matthew Rowles
>>>> On 30 Jul 2015 3:04 am, "ji zhang" <jilin_zhang_hous...@yahoo.ca>
>>>> wrote:
>>>>
>>>>
>>>>> About ten years ago, I was working on a D4 with lynx eye, had to put an
>>>>> air scatter blocker 1 or 2 mm above the powder sample. In the
>>>>> beginning, I
>>>>> had to put simple geometry into the bgmn configuration sav-file until
>>>>> Dr
>>>>> Bergmann put a parameter airscatter=#.
>>>>>
>>>>> Now I came back to the business with a D8 with lynx eye; is there
>>>>> anybody
>>>>> here willing to share the experience of handling it in TOPAZ?
>>>>>
>>>>> thanks
>>>>>
>>>>> Jilin zhang
>>>>>
>>>>> Sent from Yahoo Mail for iPhone <https://yho.com/footer0>
>>>>>
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>>>>> body
>>>>> text
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>>>>>
>>>>>
>>>>>
>>>>>
>> ---
>> Dr. rer. nat. Robert Möckel
>> Diplom-Mineraloge
>> Helmholtz-Institut Freiberg für Ressourcentechnologie
>> Tel.: +49 (0) 3731 39 2079
>> Helmholtz-Zentrum Dresden-Rossendorf
>> Halsbrücker Str. 34 | 09599 Freiberg
>> http://www.hzdr.de/hif | r.moec...@hzdr.de
>> Vorstand: Prof. Dr. Dr. h. c. Roland Sauerbrey | Prof. Dr. Dr. h. c.
>> Peter Joehnk | VR 1693 beim Amtsgericht Dresden
>>
>
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