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<u><b>Hovhaness:</b></u> Studying the pair symmetric/positron
background, looking mostly at the 5.9GeV perpendicular data (runs
72488-72500). Sees a small contribution (~4-8% @ E > 0.5GeV).
Looking at invariant mass spectrum for pi0s, reconstructing for
positrons, saw that the pi0 mass was off, centering around 100MeV.
Swimming these specific pi0's back to somewhere in the Cerenkov (about
80 +/-5cm downstream from target) the mass is centered more towards the
correct value. The suspicion is that this could be from something in
the Cerenkov, perhaps the LED, its support structure, and/or mirror
edge (from flipping open). Will try implementing this structure into
the GEANT to see if it gets reproduced.<br>
Looking at distance between cluster tracks as a function of pi0 mass
and requiring that Lucite fires (both sides of TDC) seems to eliminate
the pi0 mass peak. This implies that the Lucite wasn't firing that much
meaning that what is being seen is mostly photons. This will require
more investigation.<br>
Looking at positron asymmetry for background contribution. They seem
sizable but would be smaller with dilution (~50+%) being taken into
account. These also include the beam and target polarization, which may
need to be taken out and make it even smaller.<br>
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<br>
<u><b>James:</b></u> Revisiting front tracker studies, where he was
projecting hits in BigCal back to the front tracker. Used most recent
replay engine, with updated neural network taking slow raster into
account. The results don't seem much different from last time. The
tracking agrees well for the varying methods up to the radius of the
tracker, but diverge after that. This will take some more looking into.<br>
<a class="moz-txt-link-freetext" href="https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Particle_Tracking_to_Front_Tracker%2C_Target#Revisiting_Front_Tracker:_9.2F15.2F2010">https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Particle_Tracking_to_Front_Tracker%2C_Target#Revisiting_Front_Tracker:_9.2F15.2F2010</a><br>
Updated scaler table, adding information about the scalers 508 and 536,
as well as b1trig and b2trig (calculated by dividing the prescalers out
of the values in the gen files).<br>
<a class="moz-txt-link-freetext" href="https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Dead_Time#Update_to_Scaler_Table:_9.2F15.2F2010">https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Dead_Time#Update_to_Scaler_Table:_9.2F15.2F2010</a><br>
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<u><b>Jon:</b></u> Went through the Carbon runs to check for helium
content. Did this by looking at the top and bottom target chip resistor
resistances. Generally a resistance of 1200 Ohms or below indicates a
warm target, and a resistance higher than 1300 Ohms indicates the
presence of liquid helium. Prepared spreadsheet that gives the relevant
information. This will be very helpful in the packing fraction effort.<br>
<a class="moz-txt-link-freetext" href="https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Carbon_Run_List">https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Carbon_Run_List</a><br>
<div>Checking livetimes calculated from variables in the ntuples
relating to the helicity triggers. This is basically a sanity check to
make sure things are working correctly. g_hel_pos(neg) is used in the
analyzer code(sane_ntuple_keep) to count triggers positive and negative
beta2 triggers. btrigp(n) is used in CTP to count the same thing. These
in combination with the gscaler(510 or 538) values are used to
calculate the livetimes. They
should (and appear to) output the same numbers, so the report template
and the ntuple should give the same values for livetimes.<br>
<br>
<br>
As always, please let me know if I forgot something or if I made any
mistake(s).<br>
<br>
Next meeting will be Sept 22.<br>
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