McStas and monochromators

[JAMES, Michael]

> -----Original Message-----
> From:	Kristian Nielsen [SMTP:kristian.nielsen at risoe.dk]
> Sent:	Monday, 11 October 1999 22:45
> To:	JAMES, Michael
> Subject:	Re: McStas and monochromators
> 
> > Date: Mon, 11 Oct 1999 09:49:29 +1000
> > From: "JAMES, Michael" <mja at ansto.gov.au>
> 
> > A colleague mentioned that he thought that a new flat monochromator component had been developed
> to
> > account for secondary extinction.  I have searched for this component and have turned-up a
> blank.
> > Also have you heard of any similar components that account for variations in reflectivity with
> > wavelength ?
> 
> We do have a new monochromator in development, and it is close to
> finished, but not completely finished yet unfortunately. I could send
> you some code, but given that there are still unresolved issues and no
> documentation yet I am not sure that it would be useful, unfortunately.
> 
> The component is designed to handle multiple scattering events inside
> the crystal, and should correctly handle secondary extinction as well as
> wavelength dependency. I think the main error compared to a real
> monochromator is in the modelling of the mosaicity. A gaussian mosaicity
> is assumed with a large number of small microcrystals. This assumption
> may not be valid in real mosaic crystals.
> 
>  - Kristian.
	[JAMES, Michael]  

	Dear Kristian

	It sounds like you are making some good progress on the new monochromator.  I would be very
interested in testing a version of it as soon as you think it is in a reasonable state.

	Regards

	Michael James