[BTeam] [New Logentry] Supplemental LASO log

[freyberg at jlab.org]

========  SUPPLEMENTAL LASO LOG [1]  ===========================================


Lognumber 3277931 [1]. Submitted by freyberg [2] on Fri, 03/28/2014 - 15:37.



+---------------+--------------------------+
|Logbooks:      |BTLOG [3]                 |
+---------------+--------------------------+
|Attached Files:|Latest ORFP procedure  [4]|
+---------------+--------------------------+


Arrived this morning to relieve Tiefenback and Yves who worked over night to 
establish a sound setup. They had a good steup through pass-2, but were stuck 
at 
that point due momentum instability. Upon arrival they were in the middle of 
dealing with this periodic energy changes when I arrived and the source proved 
difficult to identify. The RF-power guru's arrived at 7am and identified a 
railed cavity 1L02-2 that had no phase control. With this repaired 
dispersion/CS 
tuning resumed and progress in completely pass-3 by noon was almost 
accomplished.

I benefited greatly from the work of Yves and Mike (and all the rest who have 
gotten us to this point), specifically they identified that *too strong* of an 
RF kick during dispersion minimization. To get the required kicks, they 
instructed me to only use *1* RF cavity during fOpt and 30Hz. This tended to 
yield consistent results between fOtp and real-time 30Hz, which was very 
comforting to me.

At one point in the process, an old veriosn of ORFP made its way into my hands 
and some time was lost working with the *wrong knobs*! Please make sure you are 
working from Rev. 13b2 of ORFP (attached). Do not use an older version, do not 
rely on the color coding of the screens.

Even with the correct knobs, I found it very challenging to get the CS match 
into Arc6. Dispersion suppression went smoothly, but there was no traction on 
CS 
X or Y with the nominal knobs. I then made the decision to move forward without 
a CS match into Arc6, reasoning a mis-match in Arc6 is after the fact. I am 
wiling to entertain arguments as to why this is the worst decision in the 
history of 12GeV CEBAF.

We then move to the Hall-A dumplette, we found the line was in a totally 
mis-configured state, supplies off, magnets off-loop, magnets mis-configured. 
We 
steered up the line, put LAM1C on design. Minimized steerers as best as 
possible. And started a documentation effort, all-saves, viewer tour, aperature 
check.
At the time of this writing, an aperture check to the Hall-A dumplete is in 
progress. Lots of transverse aperture, energy aperature data is being collected 
now.

Several times this afternoon, trucks travelling down the South Linac trip off 
the C100s in the South very frustrating. but for the most part the Accelerator 
has been up more than it has been down!!!! This has been absolutely crucial to 
making progress.

At 3pm I met with the Hall-A users. The tentative plan is to continue our 
effort, if we can re-establish beam to Hall-A by midnight, they have a program 
that can use less than 10microAmperes over night. Saturday, if we are in a 
position to support it, we will see how high we can go with CW. Sunday Owl, 
Hall-A will be back to low beam current. Sunday day the Hall would like to do 
Moeller, so in the morning the LASO (Joe Grames) will assist/lead setting the 
Wien Filter and after that the hall will start the Moller program. This means 
Yves will have to come in well before his nominal Swing Supplemental Shift. I 
hope we will be in a position to not need Supplemental LASO on Sunday Swing, if 
not I need a volunteer.

[1] https://logbooks.jlab.org/entry/3277931
[2] https://logbooks.jlab.org/user/freyberg
[3] https://logbooks.jlab.org/book/btlog
[4] https://logbooks.jlab.org/files/2014/03/3277931/optics_restore_proc_13b2.pdf
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