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    User name brads/doug

    Log entry time 19:55:41 on April 07, 2008

    Entry number 230579

    This entry is a followup to: 230551

    keyword=Balloon work (late entry)

    During the controlled access in the morning Doug and I refilled the two balloons and investigated the gas flow through the flangle volume.

    Both balloons were deflated enough that there was several inches of air between it and the chamber gas-plane for the bottom-most 10--12" of the front and back chamber. A camera has been installed so we can monitor the balloon status from the counting house (see other entry).

    The flangle gas flow is a little confusing. We tried putting an outflow bubbler on the system to see if any helium was actually being vented through the "vent" line. The answer is no. We had to crank the inflow pressure way up (several inches of water at least -- it was off-scale the available meters) to get even a slow bubble rate in the outflow bubbler. That tells us that helium is going in and leaking out somewhere... After trying a few things without success we removed the outflow bubbler and returned the gas configuration to its original state. The inflow was set to roughly 1 cfm and we're assuming/hoping that that will keep the flangle volume full of helium. (The volume can only be roughly a cubic foot so it's hard to imagine 1 cfm is insufficient, even if there is a huge leak...)

    A copy of this log entry has been emailed to: lindgren@jlab.org