Re: RE: Software re-binned PD data
Hi Tony If you want to have a look at what the uncertainties are doing, then try scanning over a peak a couple of dozen times (maybe with a few different mA settings on the tube, maybe with some different step times) to collect a range of different intensities. The standard deviation of the "raw" counts (not raw CPS) should approximately the square root of the number of counts. If it is different, then something squirrelly is going on. Matthew On Fri, 27 Sep 2019 at 13:46, iangie wrote: > Dear Rietvelders, > > Thanks for your opinions! > The "re-binning" of 1D data was done by my measurement software > automatically, rather than by analysis software. > The CPS is unchanged after its "re-binning". This means, rather than > adding counts of neighboring steps, it is *averaging* my data (sum counts > up then divided by the number of combined bins)! > I have a feeling what my measurement software doing is not correct... > > -- > *Dr. Xiaodong (Tony) Wang* > *Research Infrastructure Specialist (XRD)* > Central Analytical Research Facility (CARF) | Institute for Future > Environments > Queensland University of Technology > > > 在 2019-09-27 10:31:45，alancoe...@bigpond.com 写道： > > Hi Tony > > > > >My I ask is this re-bined data from the measurement software considered > as "raw data" or "treated data"? > > > > I’m not sure what is meant by treated data. Almost all neutron data and > synchrotron data with area detectors are “treated data”. > > > > If the detector has a slit width in the equatorial plane that is 0.03 > degrees 2Th then it makes little sense using a step size that is less than > 0.03/2 degrees 2Th. If rebinning is done correctly (see rebin_with_dx_of in > the Technical Reference) then rebinning is basically collecting redoing the > experiment with a wider slit. > > > > In the case of your PSD then the resolution of the PSD would be the > smallest slit width. If the data has broad features relative to the slit > width then rebinning (or using a bigger slit width) should not change the > results. You could simulate all this using TOPAS to see the difference. > Correct rebinning should not affect parameter errors. > > > > This is a question that is not simple to answer and if there’s concern > then: > > > >1. Simulating data with the small step size and performing a fit >2. And then rebinning with various slit widths and then fitting >3. And then comparing parameters errors and parameter values for all >the refinements should shine light on the area. > > > > I don’t know where but I feeling is that there should be papers on this. > > > > Cheers > > Alan > > > > > > *From:* rietveld_l-requ...@ill.fr *On Behalf > Of *iangie > *Sent:* Thursday, September 26, 2019 1:40 PM > *To:* rietveld_l@ill.fr > *Subject:* Software re-binned PD data > > > > Dear Rietvelder, > > > > I hope you are doing well. > > It is generally acknolwdged that Rietveld refinement should be performed > on raw data, without any data processing. > One of our diffractometer/PSD scans data at its minimal step size (users > can see that the step size during scan is much smaller than what was set), > and upon finishing, the measurement software re-bin the counts to the step > size what users set (so the data also looks smoother, after re-bin). > My I ask is this re-bined data from the measurement software considered as > "raw data" or "treated data"? And can we apply Rietveld refinement on this > data? > > > > Any comments are welcome. :) > > -- > > *Dr. Xiaodong (Tony) Wang* > > *Research Infrastructure Specialist (XRD)* > > Central Analytical Research Facility (CARF) | Institute for Future > Environments > > Queensland University of Technology > > ++ > Please do NOT attach files to the whole list > > Send commands to eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://www.mail-archive.com/rietveld_l@ill.fr/ > ++ > > ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re:RE: Software re-binned PD data
Dear Rietvelders, Thanks for your opinions! The "re-binning" of 1D data was done by my measurement software automatically, rather than by analysis software. The CPS is unchanged after its "re-binning". This means, rather than adding counts of neighboring steps, it is *averaging* my data (sum counts up then divided by the number of combined bins)! I have a feeling what my measurement software doing is not correct... -- Dr. Xiaodong (Tony) Wang Research Infrastructure Specialist (XRD) Central Analytical Research Facility (CARF) | Institute for Future Environments Queensland University of Technology 在 2019-09-27 10:31:45，alancoe...@bigpond.com 写道： Hi Tony >My I ask is this re-bined data from the measurement software considered as >"raw data" or "treated data"? I’m not sure what is meant by treated data. Almost all neutron data and synchrotron data with area detectors are “treated data”. If the detector has a slit width in the equatorial plane that is 0.03 degrees 2Th then it makes little sense using a step size that is less than 0.03/2 degrees 2Th. If rebinning is done correctly (see rebin_with_dx_of in the Technical Reference) then rebinning is basically collecting redoing the experiment with a wider slit. In the case of your PSD then the resolution of the PSD would be the smallest slit width. If the data has broad features relative to the slit width then rebinning (or using a bigger slit width) should not change the results. You could simulate all this using TOPAS to see the difference. Correct rebinning should not affect parameter errors. This is a question that is not simple to answer and if there’s concern then: Simulating data with the small step size and performing a fit And then rebinning with various slit widths and then fitting And then comparing parameters errors and parameter values for all the refinements should shine light on the area. I don’t know where but I feeling is that there should be papers on this. Cheers Alan From: rietveld_l-requ...@ill.fr On Behalf Of iangie Sent: Thursday, September 26, 2019 1:40 PM To: rietveld_l@ill.fr Subject: Software re-binned PD data Dear Rietvelder, I hope you are doing well. It is generally acknolwdged that Rietveld refinement should be performed on raw data, without any data processing. One of our diffractometer/PSD scans data at its minimal step size (users can see that the step size during scan is much smaller than what was set), and upon finishing, the measurement software re-bin the counts to the step size what users set (so the data also looks smoother, after re-bin). My I ask is this re-bined data from the measurement software considered as "raw data" or "treated data"? And can we apply Rietveld refinement on this data? Any comments are welcome. :) -- Dr. Xiaodong (Tony) Wang Research Infrastructure Specialist (XRD) Central Analytical Research Facility (CARF) | Institute for Future Environments Queensland University of Technology++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
RE: Software re-binned PD data
Hi Tony >My I ask is this re-bined data from the measurement software considered as "raw data" or "treated data"? I'm not sure what is meant by treated data. Almost all neutron data and synchrotron data with area detectors are "treated data". If the detector has a slit width in the equatorial plane that is 0.03 degrees 2Th then it makes little sense using a step size that is less than 0.03/2 degrees 2Th. If rebinning is done correctly (see rebin_with_dx_of in the Technical Reference) then rebinning is basically collecting redoing the experiment with a wider slit. In the case of your PSD then the resolution of the PSD would be the smallest slit width. If the data has broad features relative to the slit width then rebinning (or using a bigger slit width) should not change the results. You could simulate all this using TOPAS to see the difference. Correct rebinning should not affect parameter errors. This is a question that is not simple to answer and if there's concern then: 1. Simulating data with the small step size and performing a fit 2. And then rebinning with various slit widths and then fitting 3. And then comparing parameters errors and parameter values for all the refinements should shine light on the area. I don't know where but I feeling is that there should be papers on this. Cheers Alan From: rietveld_l-requ...@ill.fr On Behalf Of iangie Sent: Thursday, September 26, 2019 1:40 PM To: rietveld_l@ill.fr Subject: Software re-binned PD data Dear Rietvelder, I hope you are doing well. It is generally acknolwdged that Rietveld refinement should be performed on raw data, without any data processing. One of our diffractometer/PSD scans data at its minimal step size (users can see that the step size during scan is much smaller than what was set), and upon finishing, the measurement software re-bin the counts to the step size what users set (so the data also looks smoother, after re-bin). My I ask is this re-bined data from the measurement software considered as "raw data" or "treated data"? And can we apply Rietveld refinement on this data? Any comments are welcome. :) -- Dr. Xiaodong (Tony) Wang Research Infrastructure Specialist (XRD) Central Analytical Research Facility (CARF) | Institute for Future Environments Queensland University of Technology ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: Software re-binned PD data
Tony, These days many if not most powder instruments (~100% of those at synchrotron and neutron sources) do some sort of data processing to take raw measurements and convert them to diffractograms that are used in Rietveld. The key for how to know if this is done properly is to ask if any experimental measurement ends up in being used in more than one bin in the final diffractogram. If this rule is broken, such as the mode in FIT2D that smooths patterns by pixel-splitting) then one introduces correlation between points in the pattern and the statistically expected R becomes overestimated (and reduced chi-squared values can drop below 1). That could be handled in theory (using a weight matrix in construction of the Hessian), but no Rietveld code does. Brian On Sep 25, 2019, at 10:40 PM, iangie mailto:ian...@126.com>> wrote: Dear Rietvelder, I hope you are doing well. It is generally acknolwdged that Rietveld refinement should be performed on raw data, without any data processing. One of our diffractometer/PSD scans data at its minimal step size (users can see that the step size during scan is much smaller than what was set), and upon finishing, the measurement software re-bin the counts to the step size what users set (so the data also looks smoother, after re-bin). My I ask is this re-bined data from the measurement software considered as "raw data" or "treated data"? And can we apply Rietveld refinement on this data? Any comments are welcome. :) -- Dr. Xiaodong (Tony) Wang Research Infrastructure Specialist (XRD) Central Analytical Research Facility (CARF) | Institute for Future Environments Queensland University of Technology ++ Please do NOT attach files to the whole list mailto:alan.he...@neutronoptics.com>> Send commands to mailto:lists...@ill.fr>> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++ ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: Software re-binned PD data
Hello, the term "raw data" has become kind of fuzzy in recent times. Most powder diffractometers nowadays are equipped with some kind of linear or area detector. The 1D powder pattern in this case is always the result of some integration, merging, and binning. I would take "raw" to mean that major corrections like absorption or Lorentz-Polarisation should not be applied beforehand. In particular, removing the background was done in old times quite a lot, making it hard to judge the real quality of the data. Yours, Daniel Többens Am 26.09.2019 um 05:40 schrieb iangie: Dear Rietvelder, I hope you are doing well. It is generally acknolwdged that Rietveld refinement should be performed on raw data, without any data processing. One of our diffractometer/PSD scans data at its minimal step size (users can see that the step size during scan is much smaller than what was set), and upon finishing, the measurement software re-bin the counts to the step size what users set (so the data also looks smoother, after re-bin). My I ask is this re-bined data from the measurement software considered as "raw data" or "treated data"? And can we apply Rietveld refinement on this data? Any comments are welcome. :) -- *Dr. Xiaodong (Tony) Wang* *Research Infrastructure Specialist (XRD)* Central Analytical Research Facility (CARF) | Institute for Future Environments Queensland University of Technology ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++ -- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V. Aufsichtsrat: Vorsitzender Dr. Volkmar Dietz, stv. Vorsitzende Dr. Jutta Koch-Unterseher Geschäftsführung: Prof. Dr. Bernd Rech (Sprecher), Prof. Dr. Jan Lüning, Thomas Frederking Sitz Berlin, AG Charlottenburg, 89 HRB 5583 Postadresse: Hahn-Meitner-Platz 1 D-14109 Berlin smime.p7s Description: S/MIME Cryptographic Signature
Re: Software re-binned PD data
Tony, if you bin (add) the raw data you can perform Rietveld refinement as if you had taken larger steps. Regards, Alan. On Thu, 26 Sep 2019 at 05:42, iangie wrote: > Dear Rietvelder, > > I hope you are doing well. > It is generally acknolwdged that Rietveld refinement should be performed > on raw data, without any data processing. > One of our diffractometer/PSD scans data at its minimal step size (users > can see that the step size during scan is much smaller than what was set), > and upon finishing, the measurement software re-bin the counts to the step > size what users set (so the data also looks smoother, after re-bin). > My I ask is this re-bined data from the measurement software considered as > "raw data" or "treated data"? And can we apply Rietveld refinement on this > data? > > Any comments are welcome. :) > > -- > *Dr. Xiaodong (Tony) Wang* > *Research Infrastructure Specialist (XRD)* > Central Analytical Research Facility (CARF) | Institute for Future > Environments > Queensland University of Technology > ++ > Please do NOT attach files to the whole list > > Send commands to eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://www.mail-archive.com/rietveld_l@ill.fr/ > ++ > > -- __ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * +33.476.98.41.68 http://www.NeutronOptics.com/hewat TVA FR 79499450856 __ ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
