Small Angle GDH Meeting
October 18, 2002




 
    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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