McStas

[Kristian Nielsen]

> Date: Wed, 25 Aug 1999 14:23:22 +0200
> From: "P. Horn" <horn at ill.fr>

> Hello!
> 
> At working with McStas i found a bug in the component Monochromator at
> line 59. The instrument definition i attached to this e-mail should
> reproduce the error or not.

You did not mention exactly what the problem you experienced was, but I
assume it was that some neutrons were reflected, even though the
scattering angle was far off the Bragg angle?

I tried running your example using the components of McStas version 1.1
(which version were you using btw? If unsure, "mcstas --version" will
tell you). This gives the (correct) scattered intensity of zero; however
it does scatter the neutron with a weight of zero, which is not really
desirable. Was this the problem you had in mind, or did you see
something else?

The problem mentioned above will be fixed in the next version.
Furthermore the Monochromator component has been replaced by new and
much better implementation (which will be included in the next
release). I can send that (or a fixed Monochromator.comp component) to
you if you like?

> Something else:
> What else monitors are existing now? 
> I have only seen the official and unofficial components on your
> McStas-pages.

I have a 2D divergence-position detector that has not yet been put on
the unofficial page. Not sure if there are any others.

> I have written a Monitor wich gives a 2D-output of the energy an the
> vertical divergence. Do you want it?

Yes please! I would very much like to put it on the web page so that
others could benefit; we already have a good number of people using
McStas. If I can get documentation for the component I would also like
to include it in the next release.

Thanks for the report and your interest,

 - Kristian.

--
Kristian Nielsen        kristian.nielsen at risoe.dk
Risø National Laboratory
Condensed Matter Physics and Chemistry Department
Tel. +45 4677 5515   Fax +45 4677 4790