[G12] similar study of eloss in g11

[Lei Guo]

HI, Craig,

Nathan Baltzell did a very comprehensive study of eloss for g11. What  
I recall is that he uncovered quite a few mistakes here and there,  
mostly on the gsim side,  by comparing the delta_P (momentum change)  
as a function of various variables (vertex positions, theta, momentum,  
etc) using both real data and simulation. I think you already have the  
all the info now. It might be worthwhile now to make sure that we did  
eloss correctly, by checking the delta_p's as a function of z, theta,  
p, and it should be similar to what gsim has, if we are doing eloss  
correctly.

Personally, I still think the low mass might come from the shifted  
electron beam energy.

Lei



On Sep 14, 2011, at 6:45 AM, Craig Bookwalter wrote:

> Hi folks,
>     I've posted a few more things to the wiki in relation to our
> discussion Friday about the issues I'm having with energy loss and the
> mass of the neutron being too low:
>
> http://clasweb.jlab.org/rungroups/g12/wiki/index.php/Charged_3pi_event_selection#Neutron_Mass
>
> Specifically, Mike Paolone and I each did our own eloss corrections  
> to a
> common set of events and I find our corrections to be identical. In
> addition, I've examined a sample of p pi+ pi- events and when I
> reconstruct the proton via missing mass off the pi+pi-, I see a  
> similar
> underestimation of the mass of the proton.
>
> Feel free to ponder this til Friday, or respond now via the list if  
> you
> so desire. Any ideas are welcome.
>
> --cb
>
>
> -- 
> -------------------------------------------------------------------------
>  Craig Bookwalter			FSU Office:  (850) 644 3808
>  Department of Physics			JLab Office: (757) 269 5465
>  Florida State University		craigb at hadron.physics.fsu.edu
>  Tallahasse, FL 32306			craigb at jlab.org		
>
> "Tower, this is Ghostrider requesting a flyby."
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>
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