[Sane-analysis] Minutes of Sept 29 Analysis Meeting

[Narbe Kalantarians]

_*Hoyoung(From Sept 28):*_ Taking closer look at runs that have been 
giving suspiciously low packing fractions. These are perpendicular 
4.7GeV runs. Adjusting the HMS MC to use the exact same beam 
energy/position and HMS momentum setting improved agreement between data 
and MC, but the packing fraction only increased by ~1%.
Will look at one of these suspect runs (72828) in 2 halves to see if we 
can find something onsetting.
Asking MCC to check their archiver for any happenings during this part 
of the data taking (helicity status, IOC trips, ...)
Oscar suggested for Hoyoung to look at the HMS asymmetries to see how 
these compare with the those from BETA.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Hykang#2010.2F09.2F20


_*Hovhannes:*_ Looking at positron contribution. Looking at deltaX(hit 
in Tracker - straight-track hit) for some reconstructed energy bins. In 
the plots, the blue curves represent electrons, pink=>positrons, and 
yellow=>accidentals/background. The deltaX not being centered at 0 might 
be from shifting of the Tracker itself. Sees that contribution decreases 
exponentially as energy increases. Requiring 2 clusters, which is part 
of good event ID, already decreases the pair symmetric background some 
initially.
Will look at this as a function of polar angle (theta) with fixed energy 
and check using the GEANT to see what is expected.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Positron_contribution


_*Jon:*_ Looking at BigCal energy resolution. Used a process found in a 
NIM article(cited in link) looking at decaying pi0-> 2 photons, fixing 
the energy of one cluster and varying the energy of the other cluster. 
These clusters were mostly in the RCS part of BigCal. Used 6 Carbon runs 
for this study. Including the low energy (E'<0.5GeV) causes some bias 
because the NN doesn't work at that range.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/JrmEResolution


_*James:*_ Looking some more at swimming hits from BigCal to the Tracker 
using the integrated Bdl method. Using the perpendicular data for this. 
This is a work in progress. 
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Particle_Tracking_to_Front_Tracker%2C_Target#Tracking_to_Target_with_Bdl:_9.2F29.2F2010
Updated perpendicular asymmetries, using different Q2 and W bins. It 
seems that the perpendicular data has 1/3 the events seen in the 
parallel data.  Will try using geometrical cuts to see if there is some 
part(s) of BigCal with lower efficiencies.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Raw_Asymmetries#Updated_plots.2C_Multithreaded_Analysis:_9.2F29.2F2010


_*Anusha:*_ Comparing data with MC for NH3 runs. This is specifically 
using the HMS, using Eric Christie's MC. Does not see hardly any elastic 
events in the MC. Is working on finer momentum binning to see if some 
come out with the radiative corrections.
https://hallcweb.jlab.org/experiments/sane/wiki/index.php/MC_with_NH3


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

Next meeting will be October 7th at 15:30.
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