From wagner@fnal.gov Tue Oct 16 11:36:53 2001 Date: Tue, 16 Oct 2001 09:55:35 -0500 From: Bob Wagner To: ambrose@fnal.gov, Morris Binkley , mukherjee@fnal.gov, orejudos@fnal.gov, burkett@cdfsga.fnal.gov Subject: Updated COT fix list Plans for October access (updated 10/16/01) ----------------------------------- 1.High Voltage work. 2.Electronics work. 3.Insulation work 4.Survey (possibly move?) work ******************************************************************************* 1. High Voltage work: ---------------------------- {Note: Normal capmeter reading for sense is 5.6 to 5.8nf and for potential is 2.5 to 2.7nf. In all cases, nearest neighbor cells should also be checked BEFORE and AFTER making the modifications. Twice we found that nearest neighbor ribbon cable connections had been jostled. } Note that this is a high prority list, consisting of known or possible high voltage breakdown and/or high voltage connection problems. SL1-106-11, SL4-227-05 are known missing high voltage connections that are also known breakdowns. SL7-138-05 is a known breakdown with likely good connections. SL1-064-10, SL8-445-01 and SL8-445-11 have connection problems (YMon "low occ" and Dave-pulse "DTH = 150"), but no known breakdowns as yet. The remaining problems are either "high occ" or "high mult" in YMon, but look fine in Dave-pulse. In the past these have always turned out to be strictly readout problems, and the lack of "Dave-pulse" was likely due to a difference in "cuts" or some intermittent behavior. These include SL1-151-01 ("high mult" = 3.5), SL3-061-01 ("high occ"), SL7-233-0 ("high mult" = 3.2). Note that SL8-105/105-09 is a special case where both S9's were disabled, but only one caused the breakdown. We hope to determine the bad one near the end of the shutdown when Ar/Ethane flow is resumed. -SL1-064-10 (B,324,14-06-0) (USE): -->YMon "Low Occ" and Dave-pulse "DTH = +150". Signature of missing HV connection, so check with capmeter. The cap reading was previously checked "ok" in May, so it may be intermittent. -SL1-106-11 (C,473,16-03-1) (LSE): -->There is a trip in quad c (cells 106-108). Cell-106-11 has YMon "low Occ" and Dave-pulse "High DTH" indicating a disconnection, so we should check this with the capmeter and hopefully fix the problem. The quad d S11 trip as yet has no candidate. -SL1-151-01 (D,691,19-20-3) (LNE): --> YMon "High Mult" (3.5), but Dave-pulse says ok. First look with Spy. -SL3-061-01 (B,194,02-12-2) (UNE): -->YMon "High Occ", but Dave-pulase says ok. First look with Spy. -SL4-227-05 (D,579,18-17-3) (LNE) : --> Bad cap connection (lots of other HV problems with cell). BACKGROUND (from September access): Before removal, HVDB (SN ?) caps measured S0 = 8.2, S2 = 8.5, S3 = 8.6, S4 = 8.5, ***S5 = 7.6***. After removing the HVDB, all wire measured about 615nf (including known +40nf offset) = ASD cap + 40nf wire capacitance, EXCEPT S5, which measured 80 - 40nf offset = 40nf. This means that S5 is disconnected at the ASD motherboard, either at the hot cap leg or the ground leg. We did not come across this when previously working with this cell (intermittent??). Given that we have no power to check things out after working on the ASD end before the EAST plug closes, we decided to just proceed with the planned work and hope that things last until the October shutdown. Tieing S5 to the P6 voltage should dramatically reduce the trips, since it was infrequently tripping at the normal S5 voltage. Anyway, the 300ohm resistor was removed from S5 and it was jumpered to P6. After reinsertion, S0 = 8.15, S2 = 8.45, S3 = 8.52, S4 = 8.53, S5 = 7.96, P0 = 2.91, P2 = 2.88, P3 = 2.91 and P4 = 2.90. The reading for P6 was normal, since S5 does not see the ASD capacitance. ACTION: In addition to the above, a new problem shows up in YMon: 227-8 is completely dead, but this is a TDC problem. Something is really odd with this cell. Anyway, the first thing to do is determine the source of the 227-S5 missed connection (ASD MB or ASD DB). My guess is that we will decide to crack open the ASD MB. Aseet suggests that if we need the stringing engine, a temporary seal can be made with tacky tape until it can be set up. -SL7-138-05 (B,233,03-18-1) (USW): --> Trips in cell 138. Tie S5 to P6. -SL7-223-00 (C,375,05-21-3) (USW): -->YMon "high mult" = 3.2, but Dave-pulse ok. First look with Spy. -SL8-104-09 and SL8-105-09 (A,178,12-05-2) (UNE): -->Trip previously disabled. BACKGROUND (from September access): Cell 104: HVDB (SN 2332) caps measured ok before removal. S9 had it's 300 ohm resistor removed and was jumpered to P10. After re-insertion, P10 = 2.8nf and S9 = 8.1nf, which is ok. Cell 105: HVDB (SN 2351) caps measured ok before removal. S9 had it's 300 ohm resistor removed and was jumpered to P10. After re-insertion, P10 = 2.8nf and S9 = 8.3nf, which is ok. ACTION: Toward end of access. Just before Ar/Et flow, reinsert resistor to (say) cell 104. See if we have trips at full voltage. If do, change 104 to 105. We know that this trip occurs without beam, so this should be a conclusive test. -SL8-445-(01 and -11) (D,708,19-06-0) (LNE) : -->YMon "low occ" and Dave-pulse "DTH = 150". Check with SPY and capmeter for connection problem. ******************************************************************************* 2. ELECTRONICS WORK: ----------------------------------------- -SL6-LNW QDR short to -3v due to washer. Dave said that "null-noise" indicates that possibly both TREFE and TREFO are affected. He believes the washer is now trapped between the CV board and the extrusion. -SL2 microcoax miscabling: Swap cells 24/25 with 26/27 (A,046&047,01-16-2&3) (UNW). -->MIcrocoax miscabling. Fix and undo the "compensating" swap at the TDC. In addition to the above, the following is a list of "cell level" readout problems which stick out like a sore thumb in the YMon. All have corresponding problems in Dave-pulse. -SL2-071-(08 & 11) (B,325,04-06-1) (USW): -->Dead in Dave-pulse, "low occ" in YMon. -SL6-096-(8-11) ( (B,236,03-14-0) (USW): -->Hot in Dave-pulse and "high occ" in YMon. At HV ribbon connection. -SL7-050-(8-11) and -051-(6-11) (A,089,01-03-1) (UNW): -->Hot in Dave-pulse and "high occ and high mult" in YMon. -SL7-372/373-(5-11) (D,658,08-02-2) (LNW): -->Hot in Dave-pulse and "high occ" and "high mult" in YMon. -SL8-116 to118-most channels (A,192,13-19-0&1) (USE): -->Extremely hot cells (worst in chamber). These have been worked on extensively with no luck. -->BACKGROUND: Put ferrite core on flat cable at TDC input with no effect. -->5/14/01: Microcoax well seated and latched, ASDQ angle brackets well solder and screws tight, lateral staggering of ASDQ pins had no effect on noise, HVDB and HVDB Fcage grounds fine (adding Cu tape had no effect). Last gasp is adding ferrite core to SL8 quad A HV ribbon, but we have never noticed any improvement in upper quadrants by doing so in the past. Removing ASDQ Fcage seemed to have no effect on the noise. This is the noisiest area on the YMon list, and it does not want to budge. -->5/15/01: Tried ferrite core on quad A SL8 HV ribbons only - no effect on noise. Removed core. -->TRY?: This is at the end of one of the longest DAC voltage runs. I believe one can bump up the DAC voltage a bit by removing (or reducing) a series resistor? Also could try replacing the ASDQ. -SL8-197-(8-11) (B,320,15-18-0) (USE): -->Hot in Dave-pulse and "high occ" in YMon. -SL8-199-(9,10,11) (B,321,15-18-1) (USE): -->Dead in Dave-pulse and YMon. -SL8-271-(9,10,others) (C,429,16-16-1) (LSE): -->Noisy in Dave-pulse. "high occ" in YMon. -SL8-363-(0,1,3) (D,583,18-09-3) (LNE): -->Noisy in Dave-pulse. "high occ" and "high mult" in YMon. ******************************************************************************* 3. "INSULATION WORK" -------------------------------------- BACKGROUND: East side: The inner cylinder area is such a rat's nest, that it was difficult to see any way to effectly add insulation. We decided to punt until October. Aseet was able to see 3 of the 4 ID temperature monitors (all but the one on the bottom north) and came up with a way to better assure that they are measuring the endplate temperature and not the ambient. First, the 592 was attached to the plate using CA (superglue), then it was covered with spray polyurethane foam. Slightly more foam made it onto the 592 than Aseet's fingers. West side: Aseet was again able to see only 3 of 4 592 temperature monitors on the COT endplate ID, so the upper north monitor was not insulated. The other 3 were insulated using the polyeurathane foam. These 592s were securely attached to the endplate with RTV, so CAing was unnecessary. ACTION: I recommend skipping the mylar trube, but attempt to install the bubble insulation of the endplate ID. Because things are such a rat's nest, we will need that advice of silicon cabling experts as to what can and cannot be moved. ******************************************************************************* 4. SURVEY and possibly move COT: ------------------------------------------------------------- In order to get the SVT "in range", the SVX has to move up by 2 to 4mm. If it is impossible to move the SVX, we may have to move the COT. Sounds like move the enitre central detector is completely impractical. ******************************************************************************* Possible Insulation projects: -------------------- 1. Al/bubble wrap around ID. Kourosh bought a new roll, 2' x 25'. ID of COT inner cylinder: 31.756", pi*ID=99.764"=8.3'. This would essentially "complete" the insulation of the COT can: 1) Extrusion + FCage + ASD heat on endplate surface, 2) Al/bubble wrap to ISL and annular pieces, 3) Al/bubble wrap and heaters around ISL). 2. Mylar tube to block convection (Kourosh?). Need OD of ISL (with wrap): 64cm + 2 * 1/4" = 25.2" + .5" = 25.7", ID of COT: 31.76". 1/2(31.76-25.7)= 3.0". If we oversize by 1/2" --> tube diameter would be 3.5". Butt and tape (wide Kapton) two 5' long tubes together during installation. 3. Pipe wrap (Mike?) - where possible and easy. -- have to unwrap when doing COT work below. Phone numbers --------------------- Ken (8630, LRP 722-0582, Home: 365-2241) Kourosh (8630, 5215, 978-1958) Karen (3377, 8630, Cell: 508-0117, Home: 365-5585) Michelle (3377, Home: 393-0861) Wanda (3377) Ines (3377) Dave Erikson (3366, 8630, LRP:266-8728): Wojciech (3366, Home: 630-783-9462 ) Tools and equipment required: -------------------------------------------- - Capmeter (2) and DVM (2) (check) - Two pliers for HVDB ribbon connectors (check) - Hex screwdriver for HVDB screws (check) - Spy for alternative connection checks (check) - Kapton tape (both 4" and 1") and copper tape?? - Ordinary needle nose (2), scissors, cutters (2), flashlights (2)??-- - Al/bubble wrap and mylar tubes (check). - Baggies and duct tape (check)