|
24 June 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's meeting summaries in italics.
BEAM - Beamline
UBL - Upstream Beamline Detectors
BCKOV
TGTW - Target Wheel
CTGT - Cryogenic Targets
NTGT - NuMI (MINOS) Target
Holger Meyer:
The field in the JGG is quite inhomogenous. The TPC works best if charge from the Tracks drifts down to the readout plane without seeing any transverse component of B-field. This is not completely possible due to the inhomogeneities. The question then arises how to minimize these transverse B effects. We can align the TPC such that the center of the TPC the E-field in the TPC and the B-field are parallel (i.e. the B-field is normal to the readout plane, assuming that the readout plane is perpendicular to the E-field). Or we could try to minimize some appropriately weighted integral of transverse B components over the volume of the TPC (with the former being the special case of the later in which the weight is 1 at the center of the magnet and 0 everywhere else). At the center of the magnet the transverse fieldcomponents are small compared to other regions well inside the active area of the TPC (as one expects by the almost symmetric setup of the JGG coils.) The fieldcomponents are B(0;0;0) = (-0.00624453;-0.602915;-0.00601322) in the MIPP coordinate system with +x = beam left, +y = up, +z = downstream. These values do not take into account small corrections due to rotations of the probe based on the alignment data of the ziptrack. (It will still take me a while to incorporate that into the final fieldmap and I just have too many other things to do.) This still gives a good estimate of how the field is tilted. Just from 'looking by hand' at a few other spots in the fieldmap, it seems that alignment of the TPC at an angle given by the vector above is at least close to the optimum. So my recommendation is to align with a 1% tilt to negative x and z.
Peter Barnes:
1% tilt sounds gigantic! That's ~2 cm height difference from front to back of the TPC. I don't think we have that adjustment range. Is that at all consistent with the JGG steel (presumably the pole tips)? Are you saying that the probe component axes are perpendicular and that the probe was oriented to better than this tilt, so the tilt is mostly real?
Let me try another metric. What is the magnitude of the transverse field at the perimeter of the TPC on the horizontal plane through the beam axis? If we align so the transverse field at the center is much less, we should be OK.
In any case, I don't think we have to nail down the alignment target right now. It will be easy enough to tweak it closer to the start of our run.
Terry Tope:
The techs cleaned up your TPC distribution rack, put new seals on the bubblers, etc. They were leak checking it and we came to the issue of teflon tape. You said to avoid teflon tape. Its pretty much impossible to avoid having pipe fittings that need some sort of sealant. What about Loctite Hydraulic Sealant? I'm not sure what in the Teflon tape is harmful. I'd like to use this loctite instead unless you find some kind of objection. I know it outgasses some because I was told we don't use it in high vacuum systems.
In the TPC rack we had a low pressure regulator and a relief which have pipe threads and I'd like to keep those components in there.
The mixing rack I setup is stainless, but I'm thinking there are probably at least reliefs that are pipe thread in it. The same goes for the gas shed, there will have to be a few components that are pipe thread and need sealed with something. So what I'm saying is there are various components along the way that are pipe thread and will be hard eliminate. At the meeting I think it was Nickolas that said it should be all stainless. Hopefully he is wrong because we violate that hugely with 500 ft. of copper from the gas shed to the TPC. Maybe its possible to filter out whatever is the problem?
Peter Barnes:
Copper is fine, it just has to be clean, (as does stainless, brass, . . .) I noticed last time I was there that the long tube runs had been cleaned and were drying out, so that's in progress.
I talked to my vacuum techs, and they suggested that we use Torr Seal (Varian?) or Hysil (?). According to them, these are compatible with O-ring systems, and much cleaner than the hydraulic sealants.
ZipTrack
JGG - Jolly Green Giant
Rosie
David Lange:
Ed and I completed what we needed to this trip so that we believe the Ckov is ready for chambers 1 and 2 to be installed. We installed most of the large pmt shields, with only some of the easy ones left to do.
We believe the ckov is currently at a reasonably optimal location wrt the target. We marked the location of the downstream end of the cart and recorded measurements for backup to Virgil's survey.
Around the front window of the ckov is a (we think double) layer of gasket that the drift chamber should sit against. This seal in principle will allow us to keep the front window of the ckov and the chamber separated, which can help account for atmospheric changes which will cause the ckov volume to expand somewhat. We did not need the gasket you [David Miller] gave me. It is under the ckov and should be used to replace the gasket that chamber 1 will be against.
I'm coming back to fnal for Thursday/Friday/Saturday. Will test pmts. Would also work on HV cables if materials exist (and someone can give me a tuturial on how to crimp the connectors). I have 100 cables in total. I'm not quite sure how long they need to be yet. (presumably 48 cables would be about 25 feet and the other 48 would be longer (maybe 40 feet)). Need to talk through the routing with someone who knows where the chamber cables go so I don't assume that I'm using the same space.
Lawrence Pinsky:
On another front, I actually have do have the possibility to send a summer undergraduate physics major (who happens to be my son) up to Fermilab for about 5-6 weeks to help out with the E-907 assembly work. Please let me know if this would be useful and practical.
David Miller:
A Strontium-90 beta gun is in place in the portacamp source cabinet. Holger has one key and I have the other. Kathy Graden has placed an order for more keys. But, for the next month or so, Holger and I will have the only keys available.
If you need to use the source, either of us can give it to you. This assumes that you are source trained. We can actually give you the key itself. Again, only if you are source trained. This training must be completed here at FermiLab. Livermore training is not acceptable here.
If you have any questions or need a different source please contact me.
DC1-4 (E690 Chambers)
Winslow Baker:
This morning, June 20th, there was a meeting in my office to discuss safety issues regarding the discriminator boards that will be used for the drift chambers in E907/MIPP. Attending were Dave Christian, Ed Hartouni, Pierrick Hanlet, Dave Miller, Holger Meyer, Stan Orr and Win Baker.
The question was the necessity and method for fusing these boards. The boards have been used in several previous experiments without any safety problems. It was decided to proceed along two tracks. Stan is getting a quote for having fuses installed. In parallel some boards will be tested to destruction by shorting them out and seeing if fire develops or if the traces act as fuses themselves. This test is scheduled to take place this afternoon in Lab 6 at 3:00 PM.
Pierrick Hanlet:
This morning, Stan, Keith, Win, David, Walt, and I met at the Pole building to work with Walt Jaskierny to test the self-fusing of the discriminator boards.
We shorted a power supply across the largest power trace on the board to test for a worst case scenario. We then ramped the power supply in 5A increments. If the trace would blow at 10A, we would consider the board sufficiently self-fusing. In fact, we ramped the current up to 70A when it finally began to smoke and we terminated the test. From this we concluded that the -5.2V supply on each board needs to be fused.
We need 304 discriminator boards. Assuming a 15% spare, we require 350 boards. I will look into having the work done at IIT under my supervision. Stan is looking into an industrial solution. Pierrick
Peter Barnes:
I thought there was a third possibility, which Leon and I have discussed several times: smoke and thermal interlocks in the discriminator towers that disconnect the AC power. This solution avoids retrofitting many boards.
At the time we were testing the TPC in MTest, this was suggested as an eventual solution to the same problem for the TPC electronics. The suggestion was made by some combination of Rick Hance, Jim Priest, and Win Baker, if I remember correctly.
DC5 & DC6 (Iowa Chambers)
Tim Bergfeld:
I have a couple of questions about the upstream T0 counter for which you are wanting to string the cables. We have one here with four tubes and the question becomes can we get four lines instead of two? Also is it possible/designed to have electronics near the T0 counter? Carl was asking about radition exposures etc. if we were to have electronics in that location?
Peter Barnes:
The most upstream electronics I was planning on is RR01 at the upstream end of MC7. In the final beam and BCKOV design I think this is not quite as far up as the upstream end of the first BCKOV, which is also where the first beam chamber will be. RR01 has lots of NIM and CAMAC space available.
Tim, can you use a local 2229 TDC (in RR01) to get the relative timing of the four PMTs of T0_1, then send just one signal (the OR, maybe, T0_1OR, to get the first hit [on second thought, maybe 2 fold coincidence will be closer to the "true" T0_1 time?]) down a single wire to the main TOF TDCs to get the absolute timing between the two stations? You could do the same for T0_2 in RR03, which would be the second wire to the main TOF TDCs.
In fact, you could even feed the T0_1OR into RR03, and just send T0_2OR to the main TDCs, using just a single wire in each segment. This may be too many TDC jitters stacked up though.
In any case, we need to have access to T0_1OR in the vicinity of RR03 (or RR06) to form the low momentum beam PID for the trigger.
David Asner:
Three TDC crates haved been delivered to MC-7. I have checked the 4298's and a few 4291's in my test setup and all modules work as advertised. Our minimal test at LLNL appears to have been in sufficient. We have 1 4299 and 1 dedicated TDC crate with only 1 TDC. Unfortunately I am currently unable to readout multiple TDC's in a single TDC crate or multiple TDC crates daisy chained together. I have brought sufficient hardware back to LLNL to bring our complement of TDC electronic to 1 4299, 2 4298's and 2 4291's. I will add the CAMAC crate from Lange's office and solve the current hardware impass next week.
The branch cable extender that Bob Jones' crew is working on was not completed before I left FNAL on Friday. Work has clearly started as I saw the work in progress on the bench.
Alignment
The next call will be Tuesday, 1 July 2003, at 1:00 PM CDT in WH-2NE, Snake Pit.