Divergence_monitor

[Kim Lefmann]

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Date: Tue, 17 Nov 1998 14:52:10 +0100 (CET)
Subject: Re: Divergence_monitor
In-reply-to: <199811161115.MAA24308 at fys-hp-1.risoe.dk>
To: Kim Lefmann <kim.lefmann at risoe.dk>
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Hello Kim,

thank you for the quick answer!

> I am glad to hear that you are working on McStas. I hope that you
have had good progress in the past two weeks.

Thanks, I have to say yes! The system is easy to use as soon as you got used 
to it. And getting used to McStas took less then a week which is not
much regarding the complexity of the matter! So keep up the good work!

I also have to confess that I still cannot use the graphics because
the installation of PGPLOT makes some trouble I don't understand.

>  The question about the coupling between the position and 
divergence I do not understand fully: Of cource if you illuminate a
plane with a point source, there will be a correlation between the
position and divergence (to take a simple example), but the detector
does not care about that, it simply calculates the angle between the
neutron path and the detector normal, whereever the neutron intersects
this plane. 

Ok, this answers my second question. I was thinking of the following:
We have a rather short neutron guide (11.5m) with rather short
wavelengths. So we don't expect a really isotropical angular and
spatial distribution of neutrons at the end of the guide. There should 
be a large correlation between the angle of the neutrons trajectory
and the coordinates, where the neutron hits the detector. And that of
course is important for the further optics! This is why I thought of a 
more complex detector, which gives you the angular distribution
depending on the coordinates. But I can approximate such a detector by 
using several neighboured divergence_monitors.


Best wishes,

Georg

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