[mcstas-users] Guide_gravity Problem
Markus Appel
masolomaster3000 at googlemail.com
Sat Feb 9 23:44:42 CET 2019
Hi,
"it didn't work" is kind of a vague error to work with, but on first
glance your problem might be that the nbounces variable is not reset in
the TRACE section, it will just keep counting up through the simulation.
Check again the example in the manual, there is an Arm component before
the guide with an EXTEND that sets nbounces=0 for each iteration.
Best,
Markus
On 09/02/2019 22:56, Lingnan Shen wrote:
> Hi all,
>
> I now have my reflectivity file working and I'm trying to
> understand how many reflections happened in the guide. I followed the
> example in the component manual in the end of section 9.8.7. It didn't
> work. I attached the .instr and .rfl file to this email.
> Thanks for all the great help.
>
> Sincerely,
> Lingnan Shen
>
> On Sat, Feb 9, 2019 at 2:42 AM Kim Lefmann <lefmann at nbi.ku.dk
> <mailto:lefmann at nbi.ku.dk>> wrote:
>
> Hi Shen,
>
> It is also my understanding that the k value is the momentum transfer.
>
> Sorry, I do not have the time to look into you problem now.
>
> best, Kim
>
>
> On 2/7/19 4:53 PM, ls8vm at virginia.edu <mailto:ls8vm at virginia.edu> wrote:
>>
>> Hi all,____
>>
>> __ __
>>
>> I checked the supermirror_m3.rfl file and it ranges
>> from 0 to 0.09 [Angs-1] so I’m really confused with the k value in
>> the first column of reflectivity file. I thought it represent the
>> total momentum transferred. Can you explain more on “better the k
>> values in the reflectivity file to be around e.g. 1.0 Angs-1.”
>> Does the guide_gravity component have a different definition on
>> reflectivity file? My actual source wavelength ranges from 0 to 10
>> [Angs].____
>>
>> __ __
>>
>> And also for Peter, my actual problem is to optimize a polarizer
>> which is built by stack of supermirror. I’m trying to find a way
>> to get the most transmission through that setup. So I want to
>> calculate the ratio neutron_out/neutron_in. Now it seems that I
>> should just divide the intensity instead of event numbers?____
>>
>> __ __
>>
>> __ __
>>
>> Happy Lunar New Year,____
>>
>> Lingnan Shen____
>>
>> __ __
>>
>> *From: *Peter Kjær Willendrup <mailto:pkwi at fysik.dtu.dk>
>> *Sent: *Tuesday, February 5, 2019 4:20 AM
>> *To: *Lingnan Shen <mailto:ls8vm at virginia.edu>
>> *Cc: *Emmanuel Farhi <mailto:farhi at ill.fr>
>> *Subject: *Re: [mcstas-users] Guide_gravity Problem
>>
>> __ __
>>
>> Hello again, ____
>>
>> __ __
>>
>> __ __
>>
>> A better starting point for understanding Guide_gravity and
>> reflectivity files may be the instrument file Test_Guides which is
>> included with your McStas installation, in combination with one of
>> the example reflectivity files from the data folder - e.g.
>> supermirror_m3.rdl.____
>>
>> __ __
>>
>> Also, for a pencil beam with controllable divergence, an option is
>> to use Source_div.____
>>
>> __ __
>>
>> Hope this helps - otherwise you are welcome to write again,
>> preferably with a good description of what exact problem you are
>> trying to solve. :-)____
>>
>> __ __
>>
>> Best,____
>>
>> __ __
>>
>> Peter____
>>
>>
>>
>> ____
>>
>> On 5 Feb 2019, at 10.12, Peter Kjær Willendrup
>> <pkwi at fysik.dtu.dk <mailto:pkwi at fysik.dtu.dk>> wrote:____
>>
>> __ __
>>
>> Hello Lingnan, ____
>>
>> __ __
>>
>> __ __
>>
>> Agree with Emmanuel. ____
>>
>> __ __
>>
>> Further, the combination of a pencil-beam, i.e. almost
>> non-divergent source and using 500 channels in a rotated
>> Guide_gravity means that transport through the guide becomes
>> close to impossible. ____
>>
>> __ __
>>
>> With regard to your second question you should always consider
>> the transported intensity I. The event count is simply a
>> measure of statistics (of "neutron rays", not “neutrons”).____
>>
>> __ __
>>
>> __ __
>>
>> Best,____
>>
>> __ __
>>
>> Peter Willendrup____
>>
>> __ __
>>
>> __ __
>>
>> On 5 Feb 2019, at 10.01, Emmanuel FARHI <farhi at ill.fr
>> <mailto:farhi at ill.fr>> wrote:____
>>
>> __ __
>>
>> Hello Lingnan,
>>
>> Your reflectivity file is given for k=0 to 0.14 Angs-1.
>> This is very small and covers neutrons around lambda=60
>> Angs, which are not even created by your source. Change
>> either the lambda setting at the source, or better the k
>> values in the reflectivity file to be around e.g. 1.0 Angs-1.
>>
>> Cheers, Emmanuel.
>>
>> __ __
>>
>> On 2/5/19 7:17 AM, Lingnan Shen wrote:____
>>
>> Hi all, ____
>>
>> __ __
>>
>> I was trying to learn how to use the
>> guide_gravity component. I tried to define the
>> reflectivity curve but I get zero neutrons at the
>> wavelength monitor in the end of guide. I have
>> attached my .instr and .rfl file. I also found that
>> even if the neutron beam just go through the guide.
>> The detector at the end still see nothing.____
>>
>> Also another question about transmission of
>> certain setup. To calculate the ratio of neutron_in /
>> neutron_out. I want to know how much neutron remained
>> after passing through that setup. Should I use the
>> flux or the events count?____
>>
>> __ __
>>
>> Sincerely,____
>>
>> Lingnan Shen____
>>
>>
>>
>> ____
>>
>> _______________________________________________
>>
>> mcstas-users mailing list
>>
>> mcstas-users at mcstas.org <mailto:mcstas-users at mcstas.org>
>>
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>>
>> --
>>
>> Emmanuel FARHI, \|/ ____ \|/
>>
>> Spectroscopy Group Institut Laue-Langevin (ILL) Grenoble ~@-/ oO \-@~
>>
>> 71 av des Martyrs,CS 20156,38042 Grenoble Cedex 9,France /_( \__/ )_\
>>
>> Work :Tel (33/0) 4 76 20 71 35. Fax (33/0) 4 76 48 39 06 \__U_/
>>
>> _______________________________________________
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>> https://mailman2.mcstas.org/mailman/listinfo/mcstas-users____
>>
>> __ __
>>
>>
>> Peter Kjær Willendrup
>> Forskningsingeniør, Specialkonsulent
>> Næstformand for DTU Fysik LSU
>>
>> DTU Physics____
>>
>>
>> <image001.gif>
>>
>>
>> Technical University of Denmark
>>
>>
>> <image002.gif>
>>
>>
>>
>> Department of Physics
>> Fysikvej
>> Building 307
>> DK-2800 Kongens Lyngby
>> Direct +45 2125 4612
>> Mobil +45 2125 4612
>> Fax +45 4593 2399
>> pkwi at fysik.dtu.dk <mailto:pkwi at fysik.dtu.dk> ____
>>
>> __ __
>>
>> __ __
>>
>>
>> Peter Kjær Willendrup
>> Forskningsingeniør, Specialkonsulent
>> Næstformand for DTU Fysik LSU
>>
>> DTU Physics____
>>
>>
>> cid:b6339554-7f28-441d-9f31-5944f811397c at win.dtu.dk
>>
>>
>> Technical University of Denmark
>>
>>
>> cid:e108e480-fcab-46e2-9531-b38165079572 at win.dtu.dk
>>
>>
>>
>> Department of Physics
>> Fysikvej
>> Building 307
>> DK-2800 Kongens Lyngby
>> Direct +45 2125 4612
>> Mobil +45 2125 4612
>> Fax +45 4593 2399
>> pkwi at fysik.dtu.dk <mailto:pkwi at fysik.dtu.dk> ____
>>
>> __ __
>>
>> __ __
>>
>>
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