[Halla_pi0] pi0 meeting

[richard lindgren]

Hi Cole and Doug,
Nobody called at 2:30 when we got in the room at 2:30. Only Khem and I showed up.
Khem and I went over the 1d and 2 d plots comparing the data and simulation. He renormalized the plots in each kinematics by summing over all the counts in one file and use the total counts in each file to set the scales. 

Below are plots of data (black) and simulation (blue) from 0.2 to 0.5 GeV /c. Ignore the green and teal curves.  The first plot corresponds to what khem call target angle = to -0.3 rad or about -17 degrees and the 30' th plot  is +0.3 or +17 deg  ---- roughly spanning the vertical opening of BigBite. There are 30 plots or 0.6 rad /30 =0.02 rad increment per plot or about 1 deg.

I ignore the first 5 and last 5 plots in each group since those are near the upper and lower edge of BIgBite where fringe fields are not accounted for in the simple dipole approximation. Also statistics are lower in those plots. Overall the simulation and data are in pretty good agreement. I plotted the data this way to emphasize the momentum dependence. I would like to think that the remaining disagreement in the  momentum dependence is  due to the MAID model since Khem is integrating over all W at least up to 30 MeV. I suggest two things. 

(1) He first lower W to just 10 MeV above threshold and repeat the simulation with MAID expecting the cross section dependence be better predicted.
(2)  Then run it again using the DMT model and repeat the simulation again to see how the two models affect the results.

 I also suggest that he reduce the bin size by 2 and plot only 15 panels instead of 30.

I also notice that in general usually the simulation is higher than the data at low momentum and lower than the data at high momentum. Maybe this is also due to the model. This generally mainly shows up at angles which correspond to the edges of the BB spectrometer.

Below are 4 groups of the extreme kinematics  from which I base these conclusions. 

Similar results can be obtained from looking at the phi dependence. 

 HRS    BB  
12.5    43.5
12.5    54.0
20.5    43.5
20.5    54.0


 HRS = 12.5 degrees   BB=43.5 degrees
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 12.5_43.5_abcissa_0.2-0.5_GeV.tiff
Type: image/tiff
Size: 331716 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/halla_pi0/attachments/20110822/91cc5423/attachment-0004.tiff 
-------------- next part --------------




HRS =12.5  BB=54 deg


-------------- next part --------------
A non-text attachment was scrubbed...
Name: 12.5_54.0_abcissa_0.2-0.5_GeV.tiff
Type: image/tiff
Size: 331356 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/halla_pi0/attachments/20110822/91cc5423/attachment-0005.tiff 
-------------- next part --------------
 





HRS =20.5   BB=43.5
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20.5_43.5_abcissa_0.2-0.5_GeV.tiff
Type: image/tiff
Size: 346972 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/halla_pi0/attachments/20110822/91cc5423/attachment-0006.tiff 
-------------- next part --------------



HRS = 20.5  BB=54.0

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20.5_54.0_abcissa_0.2-0.5_GeV.tiff
Type: image/tiff
Size: 356202 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/halla_pi0/attachments/20110822/91cc5423/attachment-0007.tiff 
-------------- next part --------------







-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 4940 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/halla_pi0/attachments/20110822/91cc5423/attachment-0001.bin