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    User name Al Tobias

    Log entry time 20:55:43 on September 08, 2010

    Entry number 332118

    keyword=VCG1P02=9x10-9 Torr: Hall A Compton Cavity Vacuum Status

    Abdurahim & I are done baking out the Hall A Compton Cavity vacuum (after three days over the weekend). Yesterday (Tues), we turned on its two ION pumps and closed off our turbo. After pumping overnight with the two IONs, the vacuum at VCG1P02 is about 9x10-9 to 1x10-8 Torr.

    In the meantime, for the two gates valves that close off the Compton Cavity region from the rest of the Compton Chicane, the cables that connect to the gate valve remote controls in the Hall A tunnel are disconnected to prevent any accidental opening of these valves to the higher vacuum regions of the Compton Chicane beampipe.

    Note: the vacuum in the Compton Chicane beampipe both upstream and downstream of the cavity is high (5x10-4 and 10-2 Torr?) and their ion pumps are off. We don't know why, but this is the case and I am informing everyone of this. - AL

    A copy of this log entry has been emailed to: nanda@jlab.org, rahim@jlab.org, tobias@jlab.org, smythe@jlab.org, folts@jlab.org, camsonne@jlab.org