[Hallb-engineering] Possible leak

Steve Christo christo at jlab.org
Fri Dec 3 06:17:16 EST 2010

At about 4:10 pm yesterday, the pressure in the Saclay target vacuum 
jacket suddenly rose from the low e-7 range to the mid e-5 range. The 
target was in steady state empty mode when it occurred. It is not 
possible at this time to determine whether the leak is from the outside 
or from the internal helium circuit. The target or H2 circuit are not 
leaking. Over the past 12 hours the pressure has increased slowly from 
3e-5 to 4.5e-5 mbar. The pumps are running and should not be strained at 
the current pressure. The target is now full and we should expect a very 
large spike in pressure that will probably trip off the pumps when the 
target is emptied due to vaporization of ice from the warming surfaces.

Brian informs me that there there will be an opening today. It would be 
prudent, at the very least, to install the large turbo pump station on 
the vacuum jacket during the opening. I am, technically, on vacation 
today but will be available by phone (804-854-3169) or pager 
(757-584-7178) and will come in to help if needed. I would appreciate it 
if Denny and/or David could install the turbo pump when the hall opens. 
I will consult with Dave this morning to plot a course of action.

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