Re: Kicker news (good)

[Michael Barnes <barnes@triumf.ca>]

Dear Brendan and Peter,

Congratulations: I am very pleased that the breakdown is caused by
something as simple as the collimator falling out of place and that it is
not a "wear out" mechanism of the Fischer socket.
Look forward to hearing that everything is confirmed to be working later.

Re card 13: please check the backplane to ensure that the connections to
the fast grading capacitors are not shorting against the terminals on the
back of the blue connector (this can easily occur during voltage grading
and would cause the red LED not to be lit). Otherwise, as we concluded
yesterday, it is probably the fibre optic cable.

Best regards,
Mike

> 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
>
>