[Frost] tagger sag

[Sungkyun Park]

Hi Michael,

My understanding is that we do not worry about the problem of the tagger sag in FROST data.
When we make the cooking file, that problem is corrected.

I make a same plot made at g8b. 
The first plot is about E-id vs E{true photon beam} - E{measured photon beam} 
The second plot is about E{measured photon beam} vs E{true photon beam} - E{measured photon beam}

These plots are made in topology #gamma p -> p #pi+ #pi- (all detected) and the updated eloss correction is applied.
E{measured photon beam} is the initial photon energy.
E{true photon beam} is the photon energy after kinematic fitting.
I used 0.05 as the confidence level cut. I used only a run 55570 in period 3. The electron beam energy of period 3 is 1.645 GeV. So The energy range of E{measured photon beam} is from 0.33 GeV to 1.56 GeV.
When we compare plots in CLAS-NOTE with plots attached with this email, FROST data do not have any problem of the tagger sag.

Sung
Florida State University


----- Original Message -----
From: Michael Dugger <dugger at jlab.org>
Date: Wednesday, June 9, 2010 1:04 
Subject: [Frost] tagger sag
To: frost at jlab.org

> 
> Hi,
> 
> I know that the study Sungkyun performed was to help verify the 
> eloss 
> momentum corrections, and I think that this is a reasonable way to 
> look at 
> his study. However, this sort of study is also very useful in 
> determining 
> the tagger sag. Since the eloss correction is not as pronounced for 
> the 
> Carbon and CH2 targets, these targets can give us a good picture on 
> the 
> tagger sag situation.
> 
> If you look at the CLAS note:
> http://www1.jlab.org/ul/Physics/Hall-B/clas/public/2009-030.pdf
> 
> Fig. 5 on page 6 shows the tagger sag correction to be on the order 
> of 
> 0.5% for g1c data. For g8b data, the sag correction was between 0.2 
> to 
> 1.0% (Fig. 6 page 7). This means that we need to look for energy 
> effects 
> on the order of 0.1% to be sure that the tagger sag is not an issue.
> 
> For g8b it was found that the tagger sag correction was important 
> in 
> obtaining reasonable pulls for the FSU kinematic fitter (see table 
> 1 on 
> page 7).
> 
> One way to get a better look at the energy study is to use:
> [E_calculated - E_measured]/E_measured
> instead of
> E_calculated/E_measured.
> 
> Since Mike Williams used this sort of parametrization for g1c (and 
> I 
> did the same for g8b), we can more easily compare results between 
> the 
> different run periods to see if the shape of the energy correction 
> distributions look similar. The tagger sag has a "signature" three 
> bump 
> pattern that should be clearly visible once we get to the 0.1% level.
> 
> -Michael
> _______________________________________________
> Frost mailing list
> Frost at jlab.org
> https://mailman.jlab.org/mailman/listinfo/frost
> 
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