[Ifeffit] Ifeffit Digest, Vol 184, Issue 21

Carlo Segre segre at iit.edu
Thu Jun 28 13:20:08 CDT 2018

Hi Edmund and Chris:

I totally agree but for the same reason as Edmund, it is much more 
efficient to let the monochromator and not stop and start all the time. 
Rebinning is useful if you are sure that it works properly.


On Thu, 28 Jun 2018, Edmund Welter wrote:

> Dear Chris,
>> Rebinning is always fraught; I would normally not allow a student to do 
>> it...
> I thought you would say that! ;-) and I share your concern, actually that is 
> the reason why we store ~8600 data points or more for a scan of 1200 eV. 
> Don't mess with the raw data! But 8600 (or 22000...) is a significant 
> oversampling. We could simply measure for a certain longer time per point, 
> than read the counters and store the values. The results turned out to be 
> less good, some weird technical reason. We could also sum up n points and 
> divide the result by n, so that we would end with 8600/n data points in the 
> final data file. In most cases that would certainly be ok, but information 
> would be irretrievably lost.
> But, at some point one has to reduce the number of points and make use of all 
> the counts that were collected within a certain reasonable interval like 0.5 
> eV or 0.05 Ang-1. But it looks as if artifacts might arise from doing it 
> twice, first explicitly by using Athena's rebin function and than again 
> implicitly by mapping the data onto the 0.05 Ang-1 grid.
> Cheers,
> Edmund

Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498            Fax: 312.567.3494
segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org

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