I seem to remember i asked the same question about Goebel mirrors last year. The outcome of that, from the list and a private comm or two, was that they are theoretically challenging to calculate because they effectively act as a series of monochromators with varying acceptance angles.
The good news is that the acceptance angle is so low that you'll be fine just assuming that there is no polarization. I did try refining the polarization on a standard from our focusing Mo instrument, and it refused to budge from zero. jools ________________________________ From: [email protected] [[email protected]] on behalf of Leopoldo Suescun [[email protected]] Sent: 03 June 2015 16:54 To: Matthey, Björn Cc: Davide Levy; [email protected] Subject: Re: polarization Dear Björn, Since the Goebel mirror uses diffraction it should require the same polization factor than a crystal monochromator. http://www.ccp14.ac.uk/ccp/web-mirrors/dirdif/xtal/documents/equipment/d8/accessories/goebel.html you can get the equations from: http://reference.iucr.org/dictionary/Lorentz%E2%80%93polarization_correction Hope this helps, Leo 2015-06-03 10:39 GMT-03:00 Matthey, Björn <[email protected]<mailto:[email protected]>>: Dear all, what is he right factor in case of a laboratory diffractometer with „ sealed tube or rotating anode source” and especially for a goebel mirror? Thank you in advance Björn Matthey -- Mit freundlichen Grüßen | Best Regards Björn Matthey Fraunhofer-Institut für Keramische Technologien und Systeme, IKTS Dresden Dipl.-Ing. Björn Matthey Keramografie, Phasenanalyse / Ceramography, Phase Analysis Winterbergstraße 28, 01277 Dresden, Germany Telefon +49 351 2553-7973<tel:%2B49%20351%202553-7973> Fax +49 351 2554-280<tel:%2B49%20351%202554-280> mailto: [email protected]<mailto:[email protected]> http://www.ikts.fraunhofer.de Von: [email protected]<mailto:[email protected]> [mailto:[email protected]<mailto:[email protected]>] Im Auftrag von Leopoldo Suescun Gesendet: Mittwoch, 3. Juni 2015 15:31 An: Davide Levy Cc: [email protected]<mailto:[email protected]> Betreff: Re: polarization Dear Davide, The polarization factor depends on the incident X-rays not on the type of detector. If your radiation comes from a sealed tube or rotating anode source without monochromator there is no polarization of light and the factor is 0.5, the use of a filter does not change the polarization state. If you have an incident beam monochromator it depends on the material of the monochromator (or better on the diffraction angle). If you are using synchrotron radiation you will need something in the range 0.95 to 1 depending on the optics of the beamline. I hope this helps, Leo 2015-06-03 5:56 GMT-03:00 Davide Levy <[email protected]<mailto:[email protected]>>: Hi to everybody, Which polarization correction is better to use in GSAS for data collected with a linear detector without monochromator? thanks Davide ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]<mailto:[email protected]>> Send commands to <[email protected]<mailto:[email protected]>> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -- Dr. Leopoldo Suescun Prof. Agr (Assoc. Prof.) de Física Tel: (+598) 29290705<tel:%28%2B598%29%2029290705>/29249859 Cryssmat-Lab./Cátedra de Fisica/DETEMA Fax: (+598) 29241906<tel:%28%2B598%29%2029241906>* Facultad de Quimica, Universidad de la Republica. Montevideo, Uruguay Ahora la cristalografía importa más (www.iucr.org<http://www.iucr.org/>) Crystallography Matters more. -- Dr. Leopoldo Suescun Prof. Agr (Assoc. Prof.) de Física Tel: (+598) 29290705/29249859 Cryssmat-Lab./Cátedra de Fisica/DETEMA Fax: (+598) 29241906* Facultad de Quimica, Universidad de la Republica. Montevideo, Uruguay Ahora la cristalografía importa más (www.iucr.org<http://www.iucr.org/>) Crystallography Matters more.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]> Send commands to <[email protected]> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
