LP_Factor

Przemek_Rzepka

Dear Topas users,

I have always assumed LP_Factor(90) for synchrotron data following the guidance here: https://topas.awh.durham.ac.uk/doku.php?id=lorentz_and_polarisation_factors

However, I recently came across this statement in a technical reference: "For unpolarized radiation v is 90 (e.g. X-ray diffractometers without any monochromator), for fully polarized radiation v is 0 (e.g. synchrotron radiation)." Is this information incorrect?

Additionally, for synchrotron data from non-high-resolution beamlines, is it still safe to assume LP_Factor(90)?

I would appreciate any feedback or clarification on this.

Przemek_Rzepka

Dear Topas users,

In the meantime, I found this old thread: https://topas.awh.durham.ac.uk/flarum/public/d/333-lp-factor which indicates that the numbers in the PDF file: https://topas.awh.durham.ac.uk/lib/exe/fetch.php?media=lp_corrections.pdf should be correct.

I would still like to ask whether, for synchrotron data from non-high-resolution beamlines, it is safe to assume LP_Factor(90)?

I would appreciate any feedback.

Best regards,
Przemek

johnsoevans

I don't have anything specific to add beyond what's in the documents and/or in the Rietveld text Robert, Andreas and I wrote. My only other general advice is that you should always consult the beam line responsible. They will know their instrument and the corrections needed better than anybody else.

Przemek_Rzepka

Dear John,

Thank you very much for trying to help me. Consulting the beamline scientist is always the starting point, but for spectroscopy-oriented beamlines that collect diffraction data as an additional feature, it's not always as straightforward.

Best regards,
Przemek

johnsoevans

Maybe just get their standard data and use that to check corrections?

Przemek_Rzepka

Thank you, John. I will try to do some tests on the standards.