[Sane-analysis] Minutes of Dec 15 SANE Analysis Meeting

[Narbe Kalantarians]

_*James:*_ Looking at asymmetries with kinematic binning calculated by 
Narbe. Looked at parallel runs.  The (average) Q^2 bins of 3 and 4 
[GeV^2] seem reasonable and the delta peak can be seen. The upper-most 
bin of 5[GeV^2] seems to not have that much statistics. Might re-bin, 
but want to see how the physics asymmetries look first.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Binned_Asymmetries#First_Look:_12.2F15.2F2010
Updated beam polarization tables. Found out, from Dave Gaskell and Mark, 
that the dips seen in the quantum efficiencies were not real. Replaced 
those with averaging  before and after readings.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Beam_Polarization_Per_Run#Erroneous_QE_readings.2C_QE_correction:_12.2F15.2F2010


_*Luwani:*_ Looking at energy distributions for electrons and neutral 
pions. The ratio of photons to electrons seems to be higher than 
expected. Sorted neutral pion distributions by helicity. Also looked at 
the 2 photon energies for the neutral pion final state. Will check cuts. 
Hovhannes thinks there might be some multiple counting.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Elections_and_pi0_plots


_*Narbe:*_ Looking at cluster distributions with the GEANT-MC, mainly 
positions, but also angles and energy (everything dated Dec 10 and 
later). At first look(files with extension 'wrong'), saw an uneven 
distribution between RCS and Protvino blacks, in that the RCS blocks 
seems to have significantly less populating. There was also a huge gap 
with no populating at all for almost 20-25% of the RCS blocks. Along 
with Hovhannes, found that the block-size selection in the code was 
being determined with the wrong index. This fixed the empty gap issue, 
but not yet the large difference in populating between the 2 block 
types. Seems like there is an offset on the RCS blocks. Will check code 
and find bug(s).
http://twist.phys.virginia.edu/~narbe/SANE/analysis/GEANT/acceptance/v5/5.25/?C=M;O=D


_*Whit:*_ Developing an event display for looking at data. This plots 
tracks and gives diagnostic plots relevant to the detectors. Has 
something working and willing to let whoever is interested try it out. 
In progress, but should be done fairly soon.
Mentioned that some 'checksum' ought to be applied to the (raw)data 
files being copied/cached over from the silo. This would be useful in 
checking for files that corrupted in the caching over at times.


_*Hovhannes/Mark/Oscar:*_ Looking into the issue of the target's 
magnetic field. It seem that in the GEANT-MC the field is possibly in 
the opposite direction. This means that the tracks are being bent in the 
opposite direction of where they should be. Hovhannes ran MC with field 
directions of +/-80 and 100 degrees. In this context, looking 
downstream, positive implies left of beam and negative  right of beam. 
Oscar ran his stand-alone code and noticed that the beam has the same 
deflection for +80 and -100, but opposite for -80.
http://www.jlab.org/~rondon/sane/analysis/asym/a80_4.7_2/?C=M;O=D
Suggested cut on theta (for BETA) ~+40 ± ~1 deg and look at the 
deflections GEANT gives for scattered electrons of 1.714 GeV for +80 and 
-80 and compare with his bdl numbers. The idea of whether the target 
assembly might have been rotated to actually +100 degrees was discussed 
but it seemed unlikely due to the likeliness of the HMS acceptance being 
block by one of the coils.
http://www.jlab.org/~rondon/sane/mtg13/sane_2007_0330.pdf (see slide 6).


As always, please let me know if I missed anything, or if I made any 
mistake(s).

Next meeting (/last one of 2010/) will be Wednesday December 21st at 
3:30pm. For the next meeting, the students giving talks for the Winter 
Hall-C meeting on January 14/15 of 2011 will go over their presentations.

 
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