[G12] similar study of eloss in g11

[John Price]

John Goetz and I looked into this some time back.  My recollection is
that we determined that the energy loss card in GSIM has no effect
whatsoever.  Energy loss is *always* applied, regardless of the setting
of the FFREAD card.

John

On Wed, 2011-09-14 at 09:19 -0700, Lei Guo wrote:
> I agree with you. MC data should also be able to tell us how much the  
> neutron peak will be moved due to eloss. It seems to me that the shift  
> in the data -- excluding the effect of the electron beam energy --- IS  
> too big.
> 
> Lei
> On Sep 15, 2011, at 3:03 AM, mpaolone at jlab.org wrote:
> 
> > I thought that gsim removes energy from the tracks depending on what
> > materials they pass through, then you must run eloss in your  
> > analysis to
> > recover what gsim removed.  I also think that gsim removes energy  
> > from the
> > tracks by default, and you have to turn off a switch somewhere to  
> > get rid
> > of that functionality if you want to.  I am not a gsim expert, and if
> > anyone else has a different understanding, please correct me.
> >
> > -Michael
> >
> >
> >> I don't recall a conclusive answer as to whether or not GSIM data
> >> requires eloss to be applied (see attached).
> >>
> >>
> >> On 09/13/2011 02:41 PM, Lei Guo wrote:
> >>> 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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> >>>
> >>> **************************************
> >>>       @
> >>>      /    *
> >>>     /   ___  ___  Lei Guo _______________________
> >>>    L_O_/ ____ Florida International University____/_/
> >>>        \   |             Physics Dept., CP 212
> >>> /  /
> >>>     /    \ |             Miami, FL 33199
> >>> /                       /  /
> >>>    /  I_/ \  ____ USA _____ /______/__________/  /
> >>>   /   /     L                /              /
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> >>>  /   /                       /              /
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> >>> /_/__________/______/______/__________/_/
> >>> 305-348-0234(o)
> >>>
> >>> **************************************
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >> --
> >> -------------------------------------------------------------------------
> >>  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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> >>
> >
> 
> **************************************
>         @
>        /    *
>       /   ___  ___  Lei Guo _______________________
>      L_O_/ ____ Florida International University____/_/
>          \   |             Physics Dept., CP  
> 212                       /  /
>       /    \ |             Miami, FL  
> 33199        /                       /  /
>      /  I_/ \  ____ USA _____ /______/__________/  /
>     /   /      
> L 
>                  /              /              /                       /  /
>    /   /                       /              /              /                       /  /
>   /_/__________/______/______/__________/_/
> /_/__________/______/______/__________/_/
> 305-348-0234(o)
> 
> **************************************
> 
> 
> 
> 
> 
> 
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-- 
John W. Price
Professor and Chair of Physics
CSU Dominguez Hills
310-243-3403