The logic behind having the slits retract when ARF (the Automated Ring Fill
software) is disabled, is to minimize the time required to reestablish
beam in the ring.
Often ARF is disabled, the hall is opened for work, then 10 hours later
some random Chief attempts to inject beam into the ring and can not. There
are 100s of things that can cause this problem and the most common involves
RF or magnets. Only after doing all the obvious trouble shooting would
the crew check the slits and find them inserted. This wasted beam time and
every Chief, including myself was bitten by this same oversight. The
simple solution
to the problem was to have the slits retract when ARF is disabled. Since we
can't deliver production beam without ARF, there seemed no point in leaving
the slits in when not required by the experiment. Likewise, the slits
can be
inserted manually by the crew when ARF is not required.
ARF was modified to include this feature over a year ago and we have not
lost
any beam time due to the "slit in" problem since. The issue of rebooting
the HV control software ioc was not considered at the time and I'm surprised
this wasn't an issue before.
However, we will remove this "slits out on disable" feature from the
software.
We now have the mode selector in EPICS, so we can provide a sophisticated
alarm to alert the crew that the slits are inserted at inappropriate
times and avoid
the "slits in" problem by a new method. The new code will probably be ready
sometime next week or sooner if possible.
Shannon
Adam Jon DeGrush wrote:
>I agree w/ Tancredi. It doesn;t make much sense.
>
>
>
>On Thu, 19 Feb 2004, Tancredi Botto wrote:
>
>
>
>>Hi, indeed the slits move out after you reboot the hv IOC for the
>>simple reason that the autofill is not enabled. From my perspective,
>>I failed to understan why.
>>
>>Maybe we should fix this. Shannon ?
>>
>>
>>
>>>i think that, last week during one of my shifts, i was the first person to
>>>experience the mass HV tripping. during a later shift (with Jason), we
>>>once again experienced it. it turned out that, both times, the mass HV
>>>tripping occurred right after we rebooted the ioc (via ./BOOT). the
>>>problem during those shifts was that after a reboot, the slits were going
>>>out but the GUI (on dblast13) said that they were still in. we had CCR
>>>verify this (ask Jason; he was there).
>>>
>>>if HV problems still exist, it may have something to do with the slits
>>>going out after an ioc reboot. i asked adam about this, and he said that
>>>the slits should be independent of rebooting the ioc. perhaps this isn't
>>>the case. or perhaps the slit problems during my shifts were just
>>>flukes...
>>>
>>>aaron
>>>
>>>
>>>
>>
>>
-- Shannon Krause Accelerator Operations Group Leader MIT Bates Linear Accelerator Center 21 Manning Rd. - P.O. Box 846 Middleton, MA 01949, USA617-253-9206 krause@mit.edu
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:30 EST