[b1_ana] Evening Update

[O. A. Rondon]

Hi Elena,

It looks like the rates without the cuts in x are just integrated over
the full spectrometer acceptance.

I think we do need to define x bin sizes, because the full x range of
the spectrometer includes regions of very different physics. For
example, for the x ~ 0.1 point, the bin cannot go too far above x ~ 0.2,
which corresponds to correlation lengths that are too short to be
related to shadowing. Similarly, if the next point, x ~ 0.3, is wider
than delta x = x_high - x_low ~ 0.2, it will average over the supposed
cross over region.

What I suggest is dividing each spectrometer setting into bins of fixed
x size. Bins of the same x but different Q^2 can then be combined. We
don't expect much of a Q^2 dependence, so integrating over Q^2 should be
OK. But integrating over wide x ranges would just dilute any x
dependence there may be. This is also what HERMES did.

Cheers,

Oscar


Elena Long wrote:
> Good evening,
> 
> I've realized that in the plots I've been showing thus far, I've included an arbitrary cut of plus/minus 0.1 for each x point shown on Azz. Removing this cut increases our rate by about a factor of two. I've also added, in grey, the total acceptance of the spectrometer and colored in blue and red, the physics acceptance (W>2). Patricia noted that we could also park the HMS at a high x point for the entire run period, so I've added that point as well.
> 
> Please note that on Azz and b1d, the central x values for the two highest points will shift to the left. I'm still working on what the central values for those points actually are, weighted to the acceptance cuts, but you can get a sense of it from the kinematics plots (especially theta_e').
> 
> https://hallcweb.jlab.org/wiki/index.php/Elong-13-05-01-Azz-Method-2#Removed_arbitrary_x_cuts
> 
> Take care,
> Ellie
> 
> --------------------------------------------
> Elena Long, Ph.D.
> Post Doctoral Research Associate
> University of New Hampshire
> elena.long at unh.edu
> ellie at jlab.org
> (603) 862-1962
> 
> 
> 
> 
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