[Clas_cascades] Fwd: Delta++ remarks

[Lewis Graham]

-------- Original Message --------
Subject: 	Delta++ remarks
Date: 	Thu, 14 Apr 2011 09:23:18 -0400
From: 	Ralf Gothe <rwgothe at gmail.com>
To: 	Lewis Graham <graham at physics.sc.edu>, lgraham1985 at gmail.com



Dear All,

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.

Cheers,

Lewis and Ralf

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
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%.

-- 
Prof. Ralf W. Gothe
Department of Physics and Astronomy
University of South Carolina
Columbia, SC 29208
Phone: 803 777 9025
Fax: 803 777 3065


-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/clas_cascades/attachments/20110414/3c536e82/attachment.html