[Clas_cascades] Notes phone conference June 30

[Elton Smith]

Online: Elton, Kijun, Hovanes, Zhiwen, Ralf, Haiyun, Lewis  <br>
Notes by Elton. <br>

# Announcements: Hovanes was in Detroit to give a talk
# [[Update 7-30]] (Lewis)
## Last comparison between eg3 and g11 showed good agreement. A bug was
found in the analysis that selected Trig Bit 6 events. This bug was
corrected, but affected the extraction of the trigger efficiencies and the
data in a similar way, so the resulting cross section did not change very
much
## Ralf: To obtain a systematic error suggests the following procedure
##* Fit the ratio of eg3 and g11 data sets relative to Kijun's fitted
average
##* Select the appropriate energy region (for now use 2<Eg<5 GeV)
##* Use the difference between the fitted ratios to determine the
systematic error
##* Normalization document will be updated. The conclusion of the document
will be a table summarizing the trigger efficiencies and corresponding
systematic error.
## Kijun: From the plots that determine the trigger efficiencies, the
error bars were very uniform and expect larger variations due to
statistics. Lewis: The error is dominated by the fitting error that comes
from extracting the Delta++ yield. The statistical error is small on this
scale
# Zhiwen
## [https://mailman.jlab.org/pipermail/clas_cascades/2009-July/000003.html
Missing files]. About 1% of the golden run sample is left uncooked. Should
we recover thse?
## Hovanes noted that the Fedora Core8 executables could only be rebuilt
with changes. Therefore cooking these files would necessarily be with a
slightly different version of the code.
## It was decided not to recook.
## Discussion: There was some discussion of possibly processing another
skim. Zhiwen would be interested in a ppi+pi- skim without the cut on
missing mass to look at pK0 events.
## If we decide to do this, Zhiwen should use the claseg3 account to
compete with other CLAS cooking.
## Zhiwen should send Hovanes his public key so he can be added to the
claseg3 ssh file.
# [[KSigma update July 30 2009 | Gflux Study]] (haiyun)
## The gflux*Eg (which should be approximately flat) falls rapidly below
Eg<2 GeV. Note that the tagger range is 1.15<Eg<5.5 GeV.
## The rates in the tagger counters reaching to about 3 MHz, seem to be
saturating for the low energies, yielding evidence that the fall of the
gflux below 2 GeV is due to dead time in the counters. Therefore, if cross
sections are to be measured below about 2 GeV, the dead time corrections
will have to be studied in some detail.

List of items for next meeting:
# Draft note on normalization (Lewis)
# Trigger bits. Histogram K+Lambda yields integrated over all ST counters
shows a flat distribution for the corrected Bit6 rates, but a jump in the
rates for Bit 5. This does not reflect individual ST histograms, so is
likely a bug. Hovanes will investigate.


Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite # 16
Newport News, VA 23606
elton at jlab.org
(757) 269-7625
(757) 269-6331 fax