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SAS Intensity standardization

  • Subject: SAS Intensity standardization
  • From: "John D. Barnes" <john.barnes@nist.gov>
  • Date: Fri, 4 Dec 98 20:50:21 -0500
Dear Friends;

     First of all I would like to thank the many people who have replied 
to my earlier posting regarding possible interlaboratory test programs 
for SAS. I should mention that there have been a couple of different 
propoals along this line since the IUCr SAS Commission was formed in 
1996. These never got anywhere because there was no formal protocol and 
because they did not address the questions that are really at the core of 
these matters.

     On the basis of some recent correspondence with one of my friends I 
have decided to proble a little more deeply into the genral questions 
surrounding our ability to characterize precision (and perhaps, to some 
extent, accuracy) in generic measurements using SAS techniques.

     I need to gather a little more intelligence on these subjects before 
I try to recruit people for a technical effort of this sort. I therefore 
submit the folowing questions in the hope that people with more 
institutional memory than I have can save us some reinventing of the 

     1. Can anyone provide literature references to studies of 
variability in intensiity measurements since the work of Hendricks under 
IUCr sponsorhip in the mid-seventies?

     2. Please add any items that you can to the following (naive?) list 
of physical observables that depend on the ability to measure scattered 
intensity on an absolute scale:
     a. molecular mass of macromolecules
     b. interfacial areas in two-phase materials
     c. total scattering "invariant" in two-phase materials

     I have omitted items that I (perhaps mistakenly) believe can be 
estimated knowing only relative intensities. I am most interested in 
observavbles that are of practical rather than theoretical interest.

Thank You

Dr. John D. Barnes               email: john.barnes@nist.gov
Natl Inst of Stds and Tech       Voice: 301-975-6786
100 Bureau Drive, Stop 8544        FAX: 301-975-4977
Gaithersburg, MD 20899             URL: http://www.nist.gov/sas
                               or http://www.ctcms.nist.gov/~jdbarnes