[Frost] pi0 mass

[Michael Dugger]

Sung,

Thanks for the information. For energies below E_gamma/E_e = 0.7 the mean 
of pulls look fairly good. Perhaps the pi+ momentum pull is a bit high and 
the pi- lambda pull is too low. Overall, this looks promising.

I think your right, the momentum corrections for the higher energies look 
like they need to be refined some more.

The thing that concerns me the most is the problem of having a z-vertex 
dependence in the photon energy correction. We will never get an 
analysis through committee having a target dependent photon energy 
correction. (I'm starting to sound like a broken record. Sorry.)

It looks like you have been busy.

When you feel like you have preliminary energy/momentum corrections, 
please feel free to share them so that we can start testing the 
corrections using different analyses.

Take care,
Michael

On Mon, 4 Oct 2010, Sungkyun Park wrote:

> Hi, Michael.
>
> I checked why the pulls in the high energy have a bad condition.
> To check these,  I make the six kinds of pull distributions.
>
> Plot:
> ELoss: http://www.jlab.org/Hall-B/secure/g9/sungkyun/IMG/Oct0410/Check_Pull_ELoss_AllTarget_Sit04.gif
> MomC: http://www.jlab.org/Hall-B/secure/g9/sungkyun/IMG/Oct0410/Check_Pull_MomC_AllTarget_Sit04.gif
>
> Notes:
> In ELoss plots, there are three kinds of pulls.
> RED -> After ELoss and FSU EC
> BLUE -> After ELoss, FSU EC, and E_{gamma} / E_{e} < 0.7
> GREEN -> After ELoss, FSU EC, and E_{gamma} / E_{e} > 0.7
> In MomC plots, there are three kinds of pulls.
> RED -> After ELoss, FSU EC, and MomC
> BLUE -> After ELoss, FSU EC, MomC, and E_{gamma} / E_{e} < 0.7
> GREEN -> After ELoss, FSU EC, MomC, and E_{gamma} / E_{e} > 0.7
>
> If you want to know the means of each number in x-axis, click the
>   http://www.jlab.org/Hall-B/secure/g9/sungkyun/X_axis.html
>
> In ELoss plots, The Eloss in high Energy(Green), the Eloss in low Energy(Blue), and the Eloss in all energy(Red) have the similar
> patterns.10, 20, and 30 ( mean of photon pull of proton, pi+, and pi-, respectively) have good position. However, 2, 5, and 8 are
> big. These parts are related of lambda angle. I think these lambda angles parts are fixed after applying magnetic field correction.
> Before applying FSU MomC, there are not the major problems.
>
> In MomC plots, The Eloss in high Energy(Green) has a bad condition. Especially, the positions of 1, 4, 7, 10, 11, 14, 17, 20, 21, 24,
> 27, 30 are bad in Green point. These numbers are related of pulls of mom and photon of proton, pi+, and pi-.
>
> I think the wrong positions of photon pulls are happened after applying FSU MomC.
> The FSU-MomC is worked very well in low energy. In high Energy, this is not enough.
> I need to check FSU MomC in high energy more.
>
> Do I make some plots of the preliminary energy corrections and pi0 mass maden before applying FSU MomC to  fellow FROST collaborators?
>
> Best Wishes
>
> Sung
>
> Florida State University
>
>
>
>
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>>
>> ----- Original Message -----
>> From: Michael Dugger <dugger at jlab.org>
>> Date: Friday, October 1, 2010 4:37 pm
>> Subject: [Frost] pi0 mass
>> To: frost at jlab.org
>>
>>>
>>> Hi,
>>>
>>> I am seeing differences in the pi0 mass when I plot the pi0 yield
>>> as a
>>> function of massX as opposed to massX^2.
>>>
>>> Because to CLAS resolution issues, the best way to plot the pi0
>>> yield
>>> distribution is how Sung has (massX^2).
>>>
>>> For the g1c and g8b data, we extract pi0 yields using massX^2. We
>>> do this
>>> to make sure we are not losing pi0 events due to the yield being
>>> "pinched"
>>> off at massX<0. I did not think that this "pinching" effect would
>>> change
>>> the mass centroid of the pi0 peak by much. In the plots using
>>> massX, the
>>> pi0 mass is being shifted upwards by ~10 MeV for Butanol, and ~4
>>> MeV for
>>> CH2.
>>>
>>> Plots:
>>> massX CH2:       http://www.jlab.org/~dugger/g9/g9a/tmp/mXCH2.gif
>>> massX^2 CH2:     http://www.jlab.org/~dugger/g9/g9a/tmp/mXsqCH2.gif
>>> massX Butanol:
>> http://www.jlab.org/~dugger/g9/g9a/tmp/mXButanol.gif> massX^2
>> Butanol:
>>> http://www.jlab.org/~dugger/g9/g9a/tmp/mXsqButanol.gif
>>> Notes:
>>> The only correction applied is eloss
>>> BLACK-> no Carbon subtraction;
>>> RED-> scaled Carbon;
>>> Blue-> Carbon subtracted
>>>
>>> Results:
>>> massX from massX CH2 plot = 142 MeV
>>> massX from massX^2 CH2 plot = 138 MeV
>>> massX from massX Butanol plot = 150 MeV
>>> massX from massX^2 Butanol plot = 140 MeV
>>>
>>> This is good news :) The pi0 mass situation is not as bad as we
>>> have previously thought. Instead of the masses being different
>> for
>>> the
>>> Butanol and CH2 targets by 8 MeV, they are only different by
>> about
>>> 2 MeV.
>>>
>>> The difference between the pi0 mass as measured by massX
>>> distributions as
>>> opposed to massX^2 distributions is being driven by CLAS momentum
>>> resolution. This might explain why Hideko sees such large
>>> differences in
>>> the pi0 mass as a function of CLAS angle.
>>>
>>> For E_gamma/E_e, Sung is seeing pi0 masses for the Butanol and
>> CH2
>>> targets
>>> that are within 5 MeV of each other using photon energy
>> corrections
>>> that
>>> (look) to be similar for each target. There is a good chance that
>>> the 5
>>> MeV might be attributable to differences in the Carbon
>> subtraction,
>>> the
>>> lack of background contributions being part his pi0 fit routine,
>>> and
>>> differences in the photon energy correction.
>>>
>>> Since we can not have a target dependence in the photon energy
>>> corrections
>>> it would be good to see the pi0 mass for the Butanol and CH2
>>> targets when
>>> the photon energy correction is made to be identical to each target.
>>>
>>> Sung, can you make your preliminary energy and momentum
>> corrections
>>> available to fellow FROST collaborators? It would be good to
>> check
>>> the
>>> consistency of pi0 mass results between different groups.
>>>
>>> Take care,
>>> Michael
>>> _______________________________________________
>>> Frost mailing list
>>> Frost at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/frost
>>>
>