[Frost] New ELoss correctons

[Michael Dugger]

Hi,

There is no doubt that there are problems that must be addressed. There is 
a communication issue (that I apologize for), and there is the more 
serious issue regarding the eloss/tagger/momentum corrections. At this 
stage, we do not have reasonable corrections.

The communication problem: The Butanol pi0 mass that I 
I stated was "about 155 MeV". I have just rerun the code over the entire 
2.478 MeV data set and get the mass of pi0 of 158 MeV.

I said that the CH2 pi0 mass was 132 MeV. It is now 133 MeV (when using 
the full 2.478 MeV data set).

One thing to note: I am using a momentum cut for protons of 350 MeV/c. 
This is a common type of cut for CLAS protons.

>From what I can tell, the preliminary tagger correction is too large. I am 
working on determining why my results are not correct.

There is also some sort of problem with eloss that we do not yet 
understand. This problem is most easily seen in the Butanol pi0 mass.

Sungkyun stated that his pulls did not change by much when using the new 
eloss. I disagree. Some of his CH2 pulls have become much worse with the 
new eloss!

Determining the eloss/tagger/momentum corrections for FROST are 
proving to be more challenging than for a simple hydrogen target. Much 
more difficult than I would have anticipated.

We have serious problems.

Good news:
I have been in communication with Brian Vernarsky and he is currently 
looking at the tagger correction. With luck, we can get at least two 
groups to agree on the tagger correction.

Below is a table of my fit results:

------------------------------

CH2 pi0 without preliminary tagger correction:

mass = 1.32655e-01 +/-  5.77997e-04
width = 3.17648e-02 +/-  7.47824e-04

CH2 pi0 with preliminary tagger correction:

mass = 1.48137e-01 +/-  5.01902e-04
width = 2.82804e-02 +/-  6.79126e-04

------------------------------

CH2 eta without preliminary tagger correction:

mass =  5.46010e-01 +/-  5.43345e-04
width =  5.01823e-03 +/-  3.50958e-04

CH2 eta with preliminary tagger correction:

mass =  5.50062e-01 +/-  4.89531e-05
width = 2.03782e-03 +/-  2.14987e-04

------------------------------

Butanol pi0 without preliminary tagger correction:

mass = 1.57548e-01 +/-  1.30123e-04
width = 3.75916e-02   1.68128e-04

Butanol pi0 with preliminary tagger correction:

mass = 1.71000e-01 +/-  1.15874e-04
width = 3.44353e-02 +/-  1.60955e-04

------------------------------

Butanol eta without preliminary tagger correction:

mass = 5.50800e-01 +/-  1.28918e-04
width = 7.91745e-03 +/-  1.82985e-04

mass = 5.54747e-01 +/-  1.23859e-04
width =  7.11401e-03 +/-  1.09526e-04

------------------------------

-Michael


On Fri, 13 Aug 2010, Sungkyun Park wrote:

> Hi Michael,
>
> I have made some pull distribution using new ELoss Correction.
>
> In the first page of Check_ELoss.pdf,
> The first column is made by old ELoss Correction (updated at May2510)
> The second column is made by new ELoss Correction (updated at Aug1110)
> The first row is for butanol and the second row is for CH2 target.
> These plots are made in topology gamma p -> p pi+ pi- and 4 runs in period7.
> And I have not applied any momentum correction in these plots.
>
> In the second page of Check_ELoss.pdf,
> The left plot is made using old ELoss and the right is using new ELoss.
> The x-axis has the unit of GeV^2.
> The mean of gaussian fitting by new ELoss is 0.02404 Gev^2
> That is, my pi0 mass is 155 MeV.
> This plot is made from the topology gamma p -> p X.
> I remember you found about 135 MeV as the pi0 mass.
>
> After applying new ELoss Correction, i have not experienced many change in my pull and pi0 mass.
>
> Best Wishes
>
> SungKyun Park
> Florida State University
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