Back in action

[Brendan Kiburg <kiburg@npl.uiuc.edu>]

Hello again, 
 We have more good news to report.  We recleaned the fischer and made sure
it had silicon paste.  We replaced DN-13 and the RED LED was working
again.  The beamline produced an excellent vacuum in a very short time (~4
hours) and so we were able to start testing the muon on request mode
around 4 pm.  We have now verified that the kicker is working properly in
vacuum, with the pickup signals as well as with our detectors.

There is really every indication that we have resolved this issue and
restored the kicker to a working state.  We are now taking production
kicked mu+ data only 1 shift after we removed the vacuum to begin repairs,
so we are quite happy about that.  We plan to monitor the kicker signals
and make occasional accesses to verify the LED status and display
voltages.

Thanks again for all of the external support.  Please feel free to follow
any future developments on the kicker as well as the mucap experiment via
our electronic logbook on http://kaon.physics.berkeley.edu:8080/run9 . 

Best regards,

Brendan and Peter

On Fri, 2 Dec 2005, Peter Kammel wrote:

> Dear Peter, dear Brendan,
> 
> Congratulations for your findings. I am very impressed how you
> worked out a thoughtful plan, communicated with the experts on every
> details and made the right decisions. That was not so easy, considering
> that you are already exhausted by your other run duties.
> 
> Many thanks to all the remote experts for their enormous help and
> careful thinking up to 3AM. This was really excellent teamwork.
> 
> I don't see why we would need the collimator for MuCap.
> 
> Good luck
> 
> Peter
> 
> 
> 
> On Fri, 2 Dec 2005, Brendan Kiburg wrote:
> 
> > Dear Colleagues,
> >   This morning we discussed with the hallendienst our plans.  They
> > explained that due to time constraint, we should not first look in the
> > top/down access ports, but rather we should move or wait until Monday.  We
> > decided to move and they disconnected the kicker.
> > 
> >   As the upstream bellow was removed, the SU identified that the
> > collimator was no longer in position.  He said that it was at already at
> > an angle relative to vertical (~45 degrees), and that it fell
> > further when they removed the bellows.  
> > 
> >   Based on what the SU told us, we fully believe the collimator
> > was in electrical contact with the upstream deflector plate and the
> > beampipe at the time of opening.  We remeasured the resistance between the
> > fischer connector in HV1 and ground and obtained >20 MOhm , so the short
> > appeared to be gone.  At air, we reconnected the power and ground and
> > turned on HV2 as a control in the fixed frequency mode.  We
> > then ramped up the voltage on HV1 and found no breakdown and we were able
> > to achieve +9 kV on HV2 and -9 kV on HV1. We note that
> > there was no Red LED on card 13, but we concluded yesterday this is a
> > problem with the optical fiber and not a problem related to the
> > breakdown.  This was our reasoning for stopping at 9 kV for the time
> > being.
> > 
> >   As a result of our findings, we believe there is clear evidence the
> > collimator was responsible for the breakdown.  We have removed the
> > collimator, as there was damage to the nylon ends inserted in the set
> > screws.  We made the working decision to return to vacuum without
> > inserting the collimator, but we have left open the option of reinserting
> > it as early as next wednesday if we see significant evidence that we need
> > it for beam quality.
> > 
> >   We are currently pumping the beamline, which will take on the order of 8
> > hours.  We can then verify that everything still works, and continue with
> > our measurement program.  If there are any further problems, we will
> > communicate them to all of you.  We will send another email later tonight
> > when we have verified the repair was succesful.  Thanks for all the
> > efforts and communication; we appreciate it.
> > 
> > With guarded optimism,
> > 
> > Brendan and Peter
> > 
> 
> Peter Kammel  /  pkammel@uiuc.edu
> Department of Physics, Loomis Laboratory
> University of Illinois at Urbana-Champaign
> 1110 West Green Street, Urbana, IL 61801 
> Tel (217) 333-5424 / Fax (217) 333-1215   
> 
>