[Frost] Meeting follow up

[Michael Dugger]

Franz,

The momentum include eloss.

I restrict the figures to less than 80 degrees in the figures. The plots 
go up to 140 degrees. The polynomial is fit to the theta region between 
0.0 to 140.0 degrees. For angles greater than shown, the scale factors 
drop more rapidly. I only show up to 80 degrees because the larger 
angles don't play a part in gamma p -> p X reactions.

I don't know for sure why the scale factors behave the way they do.

We will have to figure out what momentum cut is reasonable for the FROST 
data.

Take care,
Michael



On Fri, 19 Nov 2010, Franz Klein wrote:

>
> Mike,
> do I understand correct that the momenta in slices1.gif & ~2.gif are momenta 
> from tracking (no eloss)?
> I am surprised that the scale factor is that small for low momentum protons 
> in forward direction. My suspicion is that the phase space for protons from 
> butanol is still distorted at this momentum range, i.e. the momentum cut 
> should be more like 400 MeV than 350 MeV.
> The other (minor) observation is that the polynomial tends to got down a 
> large angles. I would say, the scale factors are quite constant (except the 
> very forward direction).
>
> Your procedure is a very promising approach!
>
> Thanks
> Franz
>
>
> On Fri, 19 Nov 2010, Michael Dugger wrote:
>
>> 
>> Hi,
>> 
>> I have put some example code on the phase space dependent scale factors at
>> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Mike%27s_analysis_page#Phase_space_scale_factors_.28version_1.29
>> 
>> I have the requested scale factor plots:
>> 
>> Reminder: The reaction is
>> gamma p -> p pi+ pi- Y,
>> where massY^2 < -0.1 GeV^2
>> and the scale factors are simply equal to the NumberOfEvents_from_Butanol
>> divided by NumberOfEvents_from_Carbon
>> 
>> 
>> Proton TBTR scale factors:
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices1.gif
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices2.gif
>> 
>> where the y-axis is the value of the scale factor, the x-axis is theta lab
>> angle, and the value of the fixed momentum is shown clearly on each panel.
>> 
>> For momentum above ~600 MeV/c the scale factors might be well represented
>> with a zero-order polynomial. For momentum below ~550 MeV/c, there is a
>> strong momentum and theta dependence.
>> 
>> Pi+ TBTR scale factors:
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices1pip.gif
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices2pip.gif
>> 
>> These look good. We can probably use the negative Mass^2 scale factors
>> for the pi+ reaction :)
>> 
>> MVRT scale factors:
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices1mvrt.gif
>> http://www.jlab.org/~dugger/g9/g9a/tmp/sfSlices2mvrt.gif
>> 
>> These look much better than the Proton TBTR scale factors, but not as good
>> as I expected. There is still a strong momentum and theta dependence for
>> momentum below ~500 MeV/c. This might be due to low angle and low momentum
>> protons having difficulties "swimming" through the target.
>> 
>> Take care,
>> Michael
>> _______________________________________________
>> Frost mailing list
>> Frost at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/frost
>> 
>
> ===============================================================
>                  Franz J. Klein, Associate Professor
>                  CUA, Department of Physics
>                  Washington, DC 20064
>  office: Hannan Hall 206          phone: 202-319-6190
>  or: Jefferson Lab,CC F-243       phone: 757-269-6672
> ---------------------------------------------------------------
>