Now, now no need to be prickly To be fair to Julian he didn't ask what the polarization was - he asked how it was calculated. Given that Goebel mirrors are graded multilayers (i.e. not a fixed diffracting angle) it's a fair question and one I asked myself in 2001. As the 'minute quote' demonstrates with the lack of d-spacing, etc, the value of 0.999 seems to have been picked from thin air
The experimental (as opposed to theoretical) methodology for determining polarization was posted on the CCP14 website many moons ago by Bob Von Dreele http://www.ccp14.ac.uk/solution/gsas/graphite_monochromator_and_gsas.html I also used the same sort of methodology for a focusing mirror. That requires a little bit of lateral thinking to cancel out the effect of capillary absorption - answers on a postcard! Pam -----Original Message----- From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf Of Artem Babaryk Sent: Sunday, 06 April, 2014 4:21 PM To: Julian R Tolchard Cc: rietveld_l@ill.fr Subject: Re[2]: Polarization factor por Ge (111) monochromator Dear Julian, Here is a minute quote following the link to the excerpt from the Rielveld Mailing list archive I've posted below: "Monochromator Wavelength [Å] Material Reflection /d/-spacing [Å] 2/θ/_m [°] POL ... All mirrors All wavelengths - - - - 0.999 " Just be attentive... Cheers, Artem 06.04.2014 23:00, Julian R Tolchard <julian.r.tolch...@ntnu.no> >Whilst we are on the topic - is the polarization factor from a Göbel mirror >calculated the same way as for a mono? > > > ________________________________________ > From: rietveld_l-requ...@ill.fr [rietveld_l-requ...@ill.fr] on behalf > of Artem Babaryk [baba...@bigmir.net] > Sent: 06 April 2014 20:56 > To: Josu Friedrich > Cc: rietveld_l@ill.fr > Subject: Re: Polarization factor por Ge (111) monochromator > > Dear Josu, > > Somethimes browsing the Rietveld list archive I'm strengthening myself > that there is nothing new under the sun... > > So, look there: > > http://www.mail-archive.com/rietveld_l%40ill.fr/msg05129.html > > Best, > Artem > > 06.04.2014 20:11, Josu Friedrich <josue.friedr...@gmail.com> > >Good afternoon, > > > > Does anyone know the polarization factor for an incident beam germanium > > (111) monochromator used in a Panalytical XPert Pro diffractometer? > > > > Many thanks, > > Josue
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