Patricia
Solvignon reported on target analysis:
Patricia continued
to look into the lifetime difference between JLab and UVa by
reanalyzing the UVa data for Pinocchio.
Patricia found the same results for
Pinocchio that UVa did. Compared
with JLab, the UVa AFP loss is larger, but the
uncorrected lifetime at UVa is still
larger than JLab's uncorrected lifetime. Lifetime
measurements on cells measured previously
at JLab agree with new measurements.
More work is required to understand
the differences.
Patricia has
been using a Lorentizian fit to obtain the target chamber temperature
from the RTD values with a 3% relative
error. The error for the temperature test is
either < 1% by averaging several
tests together, or 6.5% by using propagation of
errors. Patricia and Kevin will
look into the error from propagation.
Patricia looked
at effects of the RF on EPR polarimetry. No visible shift was
found in the frequency.
Vincent Sulkosky
discussed the target lab status:
Vince reported
on the equipment status for the experiment. Coherent 2 was
shipped back to be repaired, and a
fan was ordered for Kepco 3. Also a field
mapping system was designed and built
to map the holding field in the presence
of the septum magnets. The system
will be tested in the target lab.
Field mapping
results with an iron plate next to the scattering chamber were
reported. No large gradients
were seen in the crude field map, which helped to
confirm that it is possible to use
a field clamp to reduce gradients from the septum
magnet.
Vince presented
his results on final checks on the Ice cone cell flux model. Results
from the model appear to be consistent
with the shape of the cell. The signal to flux
ratio for water signals was calculated
for several water calibrations. The ice cone
cell ratios agree with standard cell
ratios.
The wall thickness
measurements done at JLab for Patton were presented. The
thickness along the cylindrical and
cone parts are fairly uniform.
Alexandre
Deur gave an update on the cell status for E97-110:
Twenty-one
cells have been produced, but only 2 good cells have been made. One
of which has blown up (Victor).
There are also three marginal cells (lifetime < 35
hours), which could be used.
Plus there is a new cell which needs to be tested.
At the last
collaboration meeting, over working of the glass was believed to be a
reason for the low production of good
cells. But since then, no good cells have been
made. A list of possible suspected
problems has been made, and it is possible that
more than one is the culprit.
Al Tobias
gave an update of the UVa target system:
Al compared the procedures used to make standard cells for previous
experiments
and the procedures used now for ice cone and thin-walled cells.
Two of the issues
are the way the Rb is handled and cell volume measurements.
There is concern
that contamination is being left after the volume measurement, so
the measurements
will be stopped for future cells. For target development the
procedures used
in the past will be implemented for new cells.
The laser for wall thickness and pressure broadening has been repaired.
The NMR/EPR systems are capable of full polarization measurements.
Improvements
have been made measure polarization in both pumping and target
chambers .
Todd Averett
gave an update of the W&M target system:
Todd gave
an overview of recent cell production at W&M. The last good cell
made
was last fall (Sergei). Vanna
(ice cone) was recently made and will be tested. The cell
was filled without using the gas getters,
since Todd found an increase in the amount of
hydrogen, when he turned the getters
on.
Surface characterization
will be done at JLab on unblown glass and samples from
an ice cone cell next week.
The new torlon
oven at W&M is ready for use. Pick-up coils have been made
for
both upper and lower chambers of the
cell. Paul (ice cone) was tested and a lifetime
of 2.7 hours was found, which agrees
with JLab's and UVa's measurements.
Gordon Cates
discussed the cell production problem:
Gordon commented
that there are two possible sources to the cell production
problem. The two possible causes
are specific to ice cone cells and not specific to ice
cones. Gordon wanted to remind
the collaboration that both possibilities need to be
covered.
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