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-------- Original Message --------
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<th align="RIGHT" valign="BASELINE" nowrap="nowrap">Subject: </th>
<td>Delta++ remarks</td>
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<th align="RIGHT" valign="BASELINE" nowrap="nowrap">Date: </th>
<td>Thu, 14 Apr 2011 09:23:18 -0400</td>
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<th align="RIGHT" valign="BASELINE" nowrap="nowrap">From: </th>
<td>Ralf Gothe <a href="mailto:rwgothe@gmail.com"><rwgothe@gmail.com></a></td>
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<th align="RIGHT" valign="BASELINE" nowrap="nowrap">To: </th>
<td>Lewis Graham <a href="mailto:graham@physics.sc.edu"><graham@physics.sc.edu></a>,
<a href="mailto:lgraham1985@gmail.com">lgraham1985@gmail.com</a></td>
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Dear All,<br>
<br>
After reading the committee remarks and our corresponding text
again, we would indeed suggest to change our text (see below), which
is indeed more accurate and should suffice as a response to the
committee. <br>
<br>
Cheers,<br>
<br>
Lewis and Ralf<br>
<br>
The overall normalization of the experiment was checked using the
d(gamma, pi−Delta++)n reaction with the detection of the pi+pi−p
final state. The cross section of this process is expected to be
mostly dominated by the photoproduction off a quasi-free proton
gamma p ->pi− Delta++. Although final state interactions (FSI) contribute
to this process, we do not expect their impact to be significant
within the precision required for this purpose. Using the same analysis
and assumptions, the measured cross sections for d(gamma,
pi− Delta++)n obtained from the current data was compared to
p(gamma, pi−Delta++) cross section from a different CLAS run period
where these trigger<br>
inefficiencies were not present. The cross sections from these two CLAS
data sets for the photon energy range of 4.5 GeV < E < 5.0
GeV differed by 9% − 14%. The agreement of our measurements with the
published data on gamma p -> pi−Delta++ from SAPHIR at Egamma=2.5
GeV [39] is better than 10%, which indeed indicates that FSI contributions are
negligible . A more detailed analysis of the d(gamma, pi−pi+p)n reaction
and its cross sections is under way [Lewis 11]. Based on
these comparisons, we have assigned the normalization uncertainty
for the presented data to be 15%.<br clear="all">
<br>
-- <br>
<div>Prof. Ralf W. Gothe</div>
<div>Department of Physics and Astronomy</div>
<div>University of South Carolina</div>
<div>Columbia, SC 29208</div>
<div> </div>
<div>Phone: 803 777 9025</div>
<div>Fax: 803 777 3065</div>
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