Tony. If you want the statistics to be the same as for larger steps you should be adding the counts from your PSD channels, not averaging them. That said, with an x-ray PSD you perhaps have so much intensity that uncertainties in your refined parameters due to counting statistics may be small compared to systematic errors, so it may not be important that your PSD averages adjacent channels instead of summing them. Perhaps the PSD manufacturer chose averaging to make the data look better:-) Alan.
On Fri, 27 Sep 2019 at 07:45, iangie <ian...@126.com> 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 <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 <alan.he...@neutronoptics.com > > > Send commands to <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/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > -- ______________________________________________ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * <alan.he...@neutronoptics.com> +33.476.98.41.68 http://www.NeutronOptics.com/hewat TVA FR 79499450856 ______________________________________________
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