[Sane-analysis] Updated wiki section on single arm pions

[Whitney Armstrong]

Hi Oscar,

Thank you for update. I have a few questions.

Does your version-3 of EPC, which includes OConnell's multi pion
addition (which we'll call version-2), simply switch between the two cross sections?

The thing that keeps confusing me about OConnell's version-2 is that he integrates the bremsstrahlung spectrum
from Wiser and not the monochromatic photo-production cross section. 
Since the Wiser Code is a fit to the bremsstrahlung cross section, doesn't the photon cross section have to be unfolded from that data? Skimming over his thesis, there is mention of doing a subtraction, but I am not sure it was ever done with success. 
Here is the thesis http://quarks.temple.edu/~whit/papers/photo-production/Wiser_thesis/

Also, I was not sure about the "per Equivalent quanta", which after some digging around various papers, I found is just the average photon energy of the bremsstrahlung beam (from the threshold to the beam energy) divided by the the beam energy, Q = <k>/E0
Is this just a way of normalizing the measured bremsstrahlung photo production cross sections so that they can be compared to each other, independent of the electron beam energy used to produce the photon beam?
I don't understand how this would do the deconvolution unless it is some approximation...

Either way, I am not sure that OConnell properly used the Wiser fit, but might be missing something.

Do you have a copy of the GPC code? 

Cheers,
Whit



On Fri, Jan 10, 2014 at 04:31:09PM -0500, O. A. Rondon wrote:
> I've updated my SANE wiki section on inclusive pions
> https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Inclusive_pion_and_nucleon_electroproduction
> 
> I've expanded the discussion of pion production via Deltas, clarifying
> the epc*.f code cutoff of this contribution above 500 MeV/c pion
> momentum, and added two plots comparing the cross section with and
> without the Delta .
> https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Delta_cutoff/no_cutoff
> 
>  For pion momenta above 500 MeV/c, Wiser seems to be the only
> parameterization that is based on high momentum data, so extrapolating
> the Delta part of epc can lead to substantial overestimates. A
> comparison of Wiser to actual pion photoproduction data (Yerevan) is
> available on the same wiki section.
> 
> The assumption that is made when using Wiser to estimate SANE's pion
> inclusive yields is that pion photoproduction from our electron beam's
> bremsstrahlung in our 4.6% X0 target (for p.f.=0.6) is the dominant
> mechanism to produce high momentum pions.
> 
> It looks like other processes would be negligible at the values of
> p_pi > ~ 1000 MeV/c that are required to produce pairs with
> E_cluster > 700 MeV, but it would be great to have some comparison with
> actual single arm pion electroproduction. In any case, it doesn't seem
> like other pion production models would work for the momenta we want.
> 
> Cheers,
> 
> Oscar
> 
> 
> 
> 
> 
> 
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