[Bteam] Beam studies opportunity Monday-Wednesday

[Jay Benesch]

Hall A is down for a target change Monday to Wednesday so, as Arne 
points out, it's likely that the machine will be available for beam 
studies during a lot of that period because of the new/old vacuum 
problem in hall C.

-------- Original Message --------
Subject: 	Re: [Q-weak] We are off till Monday (at the very least)
Date: 	Sat, 16 Apr 2011 14:32:39 -0400
From: 	Arne Freyberger<freyberg at jlab.org>

In the likely event that we have no program monday, tuesday we need to
pull together a set of beam studies. Spata, mott should be prepared to
go on monday if qweak is not able to take beam.

Arne Freyberger
Director of Accelerator Operations
Jefferson Lab


-----Original message-----

     *From: *Jay Benesch <benesch at jlab.org>*

     Subject: *Fwd: [Q-weak] We are off till Monday (at the very least)

     FYI

     Also, Silviu Covrig is being consulted on how low to set the target
     heat
     load until Monday.

     Jay

     -------- Original Message --------
     Subject: [Q-weak] We are off till Monday (at the very least)
     Date: Sat, 16 Apr 2011 14:16:15 -0400
     From: Hall C Electronic Logbook
     To: q-weak at jlab.org



     Link: http://hallcweb.jlab.org/hclog/1104_archive/110416141615.html

 
------------------------------------------------------------------------


     User name Gericke


     Log entry time 14:16:15 on April 16, 2011


     Entry number 228836

     keyword=We are off till Monday (at the very least)

     After consulting with Greg Smith, Dave Gaskell, and Andy (through Dave)
     and getting the results from RadCon, it has been decided that we will
     have to wait till Monday to access the situation again.

     We asked for beam off until then.

     Time line summary:

     ~9:00 am: MCC starting to have trouble giving beam to both hall C and A
     at 95 uA into hall A. So beam went on and off a couple of times
     (it is not at all clear if this is part of the problem).

     ~11:00 am: After having beam back for an hour or so, the vacuum
     started to go bad quickly during another set of beam
     on-off periods (not sure if this is the cause of the
     current problem, but the vacuum spikes before the turbo
     died completely seem to be correlated with the beam on-off
     periods).

     https://hallcweb.jlab.org/hclog/1104_archive/110416123449.html

     Thanks to Dave Gaskell the 16 inch valve downstream
     of the scattering chamber was closed immediately.

     ~11:30 am: Dave Gaskell and I went to the hall to see if the pump
     controller had died. Two other controllers were swapped
     in without success. The controller reported failure (red
     failure light) and pressing the STOP button did not result
     in the expected stop condition light to turn on. Instead,
     the controller continued to display the red failure light.

     ~12:00: RadCon measured 95 mR just beyond the fence, which is only
     a fraction of the distance to the pump. So the radiation
     levels at the pump will be a few hundred mR.

     Jay believes that this is not (just) a pump problem, but
     that this was ultimately caused by another leak near the
     bellows or possibly in the water cooled exit window.

     Also see his log entry here:

     https://hallcweb.jlab.org/hclog/1104_archive/110416114044.html


     A copy of this log entry has been emailed to: q-weak at jlab.org