[mcstas-users] Guide_gravity Problem

[Peter Kjær Willendrup]

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



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Emmanuel FARHI,                                           \|/ ____ \|/
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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]



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