[mcstas-users] intercomparison between McStas and SIMRES

Jan Saroun saroun at ujf.cas.cz
Wed Aug 19 17:46:54 CEST 2009

Hello Tom and Peter,

I think the problem is the theta-scale. I suppose DTT on the Peter's 
result is the full scattering angle, while the data shown by Tom are on 
Bragg angle (=DTT/2) scale. If you correct for this, the two profiles 
are very close. Also the intensity scale is not MUCH different, we 
should check first the input data for the monochromator and sample in 
order to resolve this. I attach the curves simulated by SIMRES with the 
two methods I have mentioned earlier (theta-scan and resolution function).


Peter Willendrup wrote:
> Hello Tom, Jan,
> I agree with Jan, you need to perform a scan in 2\theta. I have 
> modified Tom's instrument slightly - optimizing it slightly - and 
> performed the proposed scan. Please find attached both the 
> instrumentfile and the resulting peak profile. It now looks much more 
> like your result from SIMRES, but a bit more broad.
> A closer study of SIMRES parameters in comparison to the McStas 
> component parms will very likely resolve this discrepancy. As Jan also 
> mentions, intensity agreement is a bit more complicated. :)
> Best regards,
> Peter Willendrup

Dr Jan Saroun 
Nuclear Physics Institute
Academy of Sciences of the Czech Republic
25068 Rez near Prague
phone: 420-2-66173140 phone/fax: 420-2-20940141
mailto:saroun at ujf.cas.cz

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