|
29 April 2003 |
Location |
Phone Number |
Access Code |
|
WH-2 NE |
865-673-6703 |
334823 |
Progress Updates and Issues
- Upstream Beamline
- Targets
- TPC - Time Projection Chamber
- Magnets
- CKOV - Cerenkov
- DC - Chambers
- TOF - Time of Flight
- RICH - Ring Imaging Cerenkov
- ECAL - EM Calorimeter
- NCAL - Hadron Calorimeter
- Gas Systems
- DAQ - Data Acquisition
- MC - Monte Carlo
- Installation
- MC7 - Enclosure and Counting House
- Meetings
- Project Management
Leon Beverly:
At some point in time, all parts of the E907 apparatus that are deemed to have some type of hazard will be reviewed by a committee chaired by Win Baker. Each potential hazard will have to be identified and mitigated to minimize the likely hood of a future problem.
Attached are two items:
- ESH_Review_List_v2.xls (Excel), listing each system that needs an evaluation for the presence of a particular hazard. I have made an attempt to identify applicable hazards. Each system manager should review all parts of their system, make corrections and return to me.
- ESH_QA_Review_Status_v2.doc (Word) that will be used to track the status of each item in the review process. Again review the list and forward me corrections or additions.
An example of a review item will be any systems that used low voltage power supplies to feed custom (not commercial) electronics. Each system manager will need to prepare a system block diagram which indicates full capacity of power supplies, wire sizes and fuse locations. If you have not prepared such a document you should think about it, sketch it and forward to me.
Documentation for many of the systems that have "mechanical" hazards will come from the MD design drawings, if done by Fermilab engineers.
Please respond as soon as possible with any correction or additions to the attached. Also prepare any system documentation that will be useful to the review committee.
Holger Meyer:
How about training that people may need? If someone from a university comes here to cable up a HV system, do they need to take some electrical safety training before? How would they find out? (This used to be a pain at Brookhaven.)
Leon Beverly:
All collaborators will have to take a certain amount of training. I believe the needed training is determined by PPD & ES&H.
Leon Beverly's meeting summaries in italics.
BEAM - Beamline
UBL - Upstream Beamline Detectors
BCKOV
Terry Tope:
At the meeting the question came up of pressure vessels. I thought about it, and the beam CKOV's are NOT pressure vessels. The lab follows the ASME code. It's not considered a pressure vessel if the maximum differential pressure the vessel can see is less than 15 psi. So at full vacuum we are slightly below the 15 psi differential rating and are not a pressure vessel. If we set the over pressure relief at 2 psig, all we have to do is prove the relief is adequate for the amount of gas we can put in (probably my job) and won't allow the vessel to reach 15 psig. So theoretically we can go up to 15 psig as long as our relief is adequate and not be a pressure vessel.
As a hopefully irrelevant side point there is a funny situation that can arise. If you have a vessel that you want to relieve at 1 psig but it is surrounded by a vacuum jacket, then it's a pressure vessel because the differential pressure it sees is greater than 15 psi. So it has to be stamped as an ASME pressure vessel and it needs a code stamped relief valve. But code stamped relief valves are not available below about 13.75 psi because the test method is based on sonic flow and sonic flow does not occur below this differential pressure.
But FESHM 5033.1 talks about vacuum window safety and it says an engineering note has to be prepared for all vacuum windows unless window failure is fully contained within the volume of the beam pipe on either side of the window. So we may have to do something for safety on this issue?
TGTW - Target Wheel
CTGT - Cryogenic Targets
NTGT - NuMI (MINOS) Target
Peter Barnes:
Last week we managed to repair most of the leaking connectors and to install the cathode plane. In the process we broke four things (two connectors, two O-rings). We repaired one connector, we have a workaround for the second, and the O-riings will be repaired when we move the TPC from the clean room.
In detail:
Connectors:
- 8 potted connectors installed,
- 3 remaining connector holes taped over, *
Gaskets:
- 2 broken O-rings not fixed yet, *
Cathode connections:
- Internal cathode wire repaired,
- External HV cable connected at TPC, not at power supply,
- Ground cable connected at TPC, power supply rack, and conduit.
Gas:
- Nitrogen purge started on 4/24.
*'ed items should be adequate for nitrogen purge and HV test.
Raja will test the cathode voltage at the end of this week.
ZipTrack
JGG - Jolly Green Giant
Rosie
DC1-4 (E690 Chambers)
DC5 & DC6 (Iowa Chambers)
Andre Lebedev:
Sparking PMT's of the RICH.
DESCRIPTION:
The problem seems to be caused by the fact that PMT's lose vacuum. Once they have air inside and HV is applied, such a tube will spark (could happen a number of times, but probably not too many), and die.
I established that by taking the tube which I knew had sparked, scraping off the paint and the wave-shifter. Then I did the same to another (probably working, but we had to have a sacrifice) tube, and it was apparent that only one of the tubes had any photo-cathode coating left. The front face of the tube that I took out of the array was absolutely clear.
I tried to confirm my "discovery" by looking at another tube that Sasha Kozhevnikov labelled as "HV problem/Tube disc" (there are 3 like that, all "NEW", i.e. they were ok in 1998, but not in 2001). Its face was also clear. I tried another one which was labelled "No signal; NEW". It's face looked fine.
Unfortunately, it is impossible to tell (at least I cannot think of a way) whether the cathode is there or not without destroying the shifter. Therefore, it is likely that while commissioning the RICH we will be scraping off some wave shifter on working tubes. Question: does FNAL have a facility which would allow us to recoat the PMT faces with a waveshifter?
SOLUTION:
Once we have all the HV supplies (almost certainly by May 7), we'll bake PMT's at high voltage which is slightly above nominal (say, +50V) for 24 hours or so. All tubes which have already lost vacuum will spark their lives away. We will identify PMT's from which we do not have a signal, replace them, and repeat the first step until we establish that the number of non-working channels is sufficiently small (or we run out of tubes to replace).
This way we will destroy a minimal number of electronics channels. Presumably, PMT's will continue to lose vacuum and die at some rate. Given that Sasha identified 36 new problems after ~3 years and the fact that he claimed that SELEX lost ~100 channels due to sparking, that rate should be minimal, and therefore we do not have to worry about protecting the input to the electronics. If we determine other sources of sparks, we'll come up with a different strategy.
CONCERN:
How long can we keep the RICH work stand? That is, how late can the drift chamber be mounted onto Rosie?
Mark Messier:
I've set up a phone conference to talk about the MIPP software:
Friday May 2, 1-3 Central Time
phone number = (201) 368-8643
participant code= 558591Agenda:
TOF Simulation: Tim B.
Slow control and Bfield status: Holger M.
Package updates etc. AllIf you have items you'd like to contribute please send them to me.
Alignment
Peter Barnes:
An edited short (QuickTime, 2'38") of the MIPPCam pictures is on the MIPP web.
The next call will be Tuesday, 6 May 2003, at 1:00 PM CDT in WH-2NE, Snake Pit.