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<h1 class="firstHeading">Minutes of the February 9 meeting</h1>
<h3 id="siteSub">From Lowqwiki</h3>
<p>Present: Rafayel, Bayram, Stepan, F.-X., Hovanes, Yohann
</p>
<p>On the phone: Raphael
</p>
<p>Notes by Hovanes
</p>
<p><br>
</p>
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<h2>Contents</h2>
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<li class="toclevel-1"><a href="http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#RTPC_reconstruction_after_noise_reduction">1 RTPC reconstruction
after noise reduction</a></li>
<li class="toclevel-1"><a href="http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#Study_of_the_RTPC_cathode_radius">2 Study of the RTPC
cathode radius</a></li>
<li class="toclevel-1"><a href="http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#Cherenkov_SPE_calibrations">3 Cherenkov SPE
calibrations</a></li>
<li class="toclevel-1"><a href="http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#DC_Calibrations">4 DC Calibrations</a></li>
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<h2> RTPC reconstruction after noise reduction </h2>
<ul>
<li> After implementing the noise reduction discussed by Raphael
during the precious meeting new files were cooked. </li>
<li> <a href="http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/DQ_1"> Raphael's studies</a> showed that there was noticeable
improvement in the number of events. </li>
<li> For proton data there is a peak at Δφ=0 which may correspond to
electrons.
</li>
<li> For helium data the peak at Δφ=0 is very small.
</li>
<li> Stepan suggested to study where in z this peak comes from. If
it was from scattering on the target windows then it could be some
recoil fragment from nuclear break-up. </li>
</ul>
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<h2> Study of the RTPC cathode radius </h2>
<ul>
<li> Yohann studied the <a href="http://www.jlab.org/%7Eperrin/bow_cath/">efects of
changing the radius of the RTPC cathode on the drift path</a> using
MAGBOLTZ.
</li>
<li> He concluded that a 5mm change would translate into a 20%
modification of the phi angle. </li>
<li> We do not have a very good feeling how much the cathode could
be deformed. May need to ask the engineers to figure out the
deformation dues to the electrostatic force and due to pressure
difference. </li>
<li> Yohann also looked at the <b>sdist</b> versus distance
along the z-axis to see if he can see an effect there since the part in
the middle would be displaced by the largest amount. The results so far
were not very conclusive. </li>
<li> Stepan suggested to make 1D plots of slices in z with fine
binning to see the <b>sdist</b>-distribution at each z-position.
</li>
</ul>
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<h2> Cherenkov SPE calibrations </h2>
<ul>
<li> Mairizio developed a procedure to calibrate the single
photoelectron peak position using the data. </li>
<li> The procedure works because of presence of triggers unrelated to
the CC pretrigger.
</li>
<li> Maurizio put the new numbers into the database and link to the
main runindex. </li>
<li> The uncertainties were by a factor of five larger that from the
calibrations using dedicated CC calibration runs. </li>
<li> Hovanes will compare the new numbers with the numbers from
the October's calibrations to decide hoe to proceed with the CC
calibrations. </li>
<li> The plots from the calibrations can be seen at <a href="http://www.jlab.org/%7Eungaro/maureepage/proj/Cerenkov/cc_periods/eg6.html">Maurizio's CC calibration page</a>.
</li>
</ul>
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<h2> DC Calibrations </h2>
<ul>
<li> Bayram showed plots from the first DC calibration round. </li>
<li> Fits went successfully, except there seems to be a problem in
one of the supoerlayers of sector 5 where Tmax seems to be different
from the other sectors. Bayram will discuss this with Pawel or Mac. </li>
<li> Bayram did not have privilege to write into his own
calibration database. Hovanes needs to get Bayram a write access to
calib_user database.
</li>
<li> We need to cook some data after Bayram's constants are in the
database.
</li>
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