[Halla_running] [New Logentry] Hall A Status and plans - Tuesday, November 11

[gaskelld at jlab.org]

Logentry Text:
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We are currently in Restricted Access for repair of the cryotarget, and opportunistic repair/improvement of the LHRS vacuum.

The LHRS entrance window and gasket were removed and replaced by the Hall A techs. Things have pumped down pretty nicely, and Jessie tells me that as of about 1 hour ago, the vacuum was in the high 10^-4 range, sometimes fluctuating up to the low 10^-5. This is already somewhat better than we were seeing before the fix. Hopefully, after continued pumping overnight, the vacuum will approach the desired target (mid 10^-5).

The target group has discovered today that there was actually a pretty significant leak in loop 1 (the 4 cm cell). This leak is large, and there is no spare 4 cm cell, so we will have to proceed without a 4 cm target over the near term. The target group will look into having a new cell fabricated. The longer cells may have small leaks, but they might be small enough to be tolerable and give us a serviceable target.

Tomorrow (Wednesday) the target group will install the longer cells and start to pump down the scattering chamber. We may have good enough vacuum to begin work with solid targets sometime on SWING shift. Cryotarget cooldown could happen, at the soonest, on Thursday. 

For tomorrow, I would like to stick with the original plan of having the shift leader (only) in the Counting House  for DAY shift, and then restart full shifts on SWING.  We will likely lock up the hall early on SWING shift.

Another issue we dealt with last night was the beam dump ion chambers. I have not yet heard an update on this topic. Hopefully this will be resolved before we want to lock up the hall tomorrow.

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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3305952
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