[Clas12_verystrange] xi polarization uncertainty plot

[Igor Strakovsky]

Lei,

For the 1st plot - please keep the vertical scale the same for every
plot: 0 to 0.4

Igor

On Tue, 5 Jun 2012 00:32:07 -0400, Lei Guo <lguo at jlab.org> wrote:

> Somehow my email is not going through. Maybe it's because of the  
> attachment.
> 
> The plots are at
> 
> www.jlab.org/Hall-B/secure/g12/lguo/xipol/
> 
> I generated the polarization uncertainties for the xi-, using what  
> Mike gave me (which are the counts of xi- as a function of Egamma, and  
> angles in the cm frame). I did a simple exercise, assuming the  
> polarization being 10% or 30%, and estimated the statistical  
> uncertainty.
> 
> The formula I used was P=(-2/alpha)(Npos-Nneg)/(Npos+Nneg). What Mike  
> gave me was the Ntot=Npos+Nneg in each bin. I assume the Npos and Nneg  
> was measured independently without correlation. Then it can be shown  
> that
> the error was |dP|=(2/alpha)*sqrt(Npos*Nneg*Ntot)/(Ntot**2).
> 
> The results are in the two attached plots. The first one xipolErr.pdf  
> are for all energy bins. The second one xipolErrEg8250.pdf is for the  
> Egamma=8.25GeV bin.
> 
> Please let me know if you notice anything wrong, and have suggestions  
> for improvement.
> 
> Thanks a lot!
> 
> Lei
> 
> 
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Igor Strakovsky, SAID CNS The George Washington University
Tel: 703-726-8344(NV),202-994-4742(FB),Skype: igors1945_2
Fax: 202-994-3001(FB),Emails: igor at va.gwu.edu, igor at jlab.org