How do you define signal to noise in powder diffraction? I have seen this term 
used several times, but I have not found a definition so far with regard to 
powder diffraction per se. 
I have just done two runs on a Panalytical one with 0.04 soller slits and one 
with 0.02 (both with a CuKa1 premonochromator) both for about 9 hours. The 
strongest peak for the 0.02 case is 2700 counts, half width 0.08 degrees and a 
background of 25 counts. The same peak with the 0.04 slits  has 70000 counts, 
half width 0.11 degrees and a background of 700 counts.


Mike Glazer

-----Original Message-----
From: Van der Lee [mailto:[EMAIL PROTECTED] 
Sent: 18 February 2008 16:36
To: rietveld_l@ill.fr
Subject: Re: advice on new powder diffractometer

Leonid Solovyov wrote the following on 18/02/2008 16:27:
>> Yes it is mainly down to the Soller slits, there was a very large 
>> thread on soller slits somewhere in the Rietveld archives about this 
>> discussion. I think the down side of changing the soller slits is a 
>> move away from the optimum FWHM that can be obtained?
> 
> Changing sollers from 0.04 rad to 0.02 or 0.01 reduces the asymmetry, 
> the FWHM and the intensity, so the peak shape and the resolution 
> become more optimal but the intensity is sacrificed.
> 
>

However, the signal to noise ratio becomes better with 0.02/0.01 rad sollers 
compared to 0.04 rad

Arie


--
***************************************************************************
A. van der Lee
Institut Européen des Membranes
CNRS - UMR 5635
Université de Montpellier II - Case Courrier 047 Place E. Bataillon
34095 MONTPELLIER Cedex 5 - FRANCE

Tel :  33 (0) 4 67 14 91 35
Fax : 33 (0) 4 67 14 91 19

Website X-ray scattering facility ICG/IEM:
http://www.iemm.univ-montp2.fr/xrayweb/main_uk.html
****************************************************************************


Reply via email to