[Bteam] Status

[Arne Freyberger]

Colleagues,
     Around 1am Saturday morning beam  transport to Hall-C became 
problematic.   After searching for problems in the C-line, Reza was 
called in to check the Injector.  Reza spent several hours and 
ultimately was able to delivery up to 125microAmps out of the injector 
to Hall-C.  The compton rate looked the acceptable at that point.  
Within minutes of achieving this  accomplishment, the compton rates 
increased by a factor of three.  None of the nominal knobs  restored the 
good compton rates.

In the end, this was the best we could do today.  But we need to develop 
a plan to restore 150microAmp capability.    While Hall-C is not happy, 
I am not pushing to resolve this problem on Sunday.  But might want to 
set something up for Monday.  I'll be in a better position to gauge the 
urgency tomorrow morning.

The main limiting factor right now are BLM trips in the injector  region 
and high compton rates.   QE is down to 0.5%, but not that bad.  
Interception in the front end is not that bad, it is mostly scraping 
downstream of apertures.

It was frustrating to sit there and observe the compton rates rise and  
not see any direct cause and to be powerless to reign it in.

We will have a meeting sometime on Sunday to discuss the path forward.  
Let me know your availability, at a minimum  Optics-on-call, Gun and 
Injector  need to be involved in forming the plan.  In the meantime, 
read the elogs, bring up your favorite screens and see if you can find 
anything obviously wrong with the machine.


Arne

-- 
Director of Accelerator Operations
Jefferson Lab           Office: (757) 269-6268
12000 Jefferson Avenue  Cell:   (757) 876-6289
Newport News, VA 23606  Email:  freyberg at jlab.org