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GEn Analysis Meeting for March 28, 2007
Follow the link below to access the plots provided for the meeting:
http://hallaweb.jlab.org/experiment/E02-013/mtg/2007mar28
Rob Feuerbach
I've been concentrating on the dilution factor of protons making their way into our neutron sample due to interactions (ie: physics) in the materials before the veto. Right now we (Sergey and I) are concentrating on the hydrogen data sample, which gives us a clear way to evaluate the probability to observe a neutron when a proton left the target, denoted by Cnp.
Interestingly, the ratio of observed neutrons to protons changes with the luminosity, as seen in http://hallaweb.jlab.org/experiment/E02-013/mtg/2007mar28/feuerbac/Rnp_hydrogen.ps. The "normalized" proton and neutron yields, where the effective charge used in the normalization is Q * ElectronicLT * DaqLT, is shown in http://hallaweb.jlab.org/experiment/E02-013/mtg/2007mar28/feuerbac/ylds_hydrogen.ps. It appears we are "losing" protons at the higher luminosity, while the neutron yield is rather flat.
The same trend in the ratio is seen in the Nitrogen runs 4583 and 4585. For these runs the target pressure changed from 24psi to 149psi, such that the luminosity changed by a factor of 6.
Also, more and longer hydrogen runs from Kin 3 have been processed, such that they SHOULD be sufficient for calibrating the ND and scintillators. Please use them, and inform me if there are any issues. Minor improvements to the scripts to run/submit the jobs to the farm have been made to make it easier to switch between datasets. After verifying I have reasonable starting points for Kin 1 and 2, I'll process a couple of files from each of them as well.
Finally, a "corrected" plot compared to what was shown at the collaboration meeting can be found at http://hallaweb.jlab.org/experiment/E02-013/mtg/2007mar28/feuerbac/gen4.eps. Mistakes in the error calculation of the plot shown at the collaboration meeting were found, and a first pass correction for the finite acceptance has been taken into account. The contribution from the GMn shifts the observed asymmetry by ~15% down to get the value of GEn shown here. Understanding the uncertainties on this correction is on my list of important issues.
