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Report dal Technical Coordinator

Detailed report by Anna Colaleo on gas leak issues, repairs, and solutions for various chambers, connectors, and gas circuits in the detector system. Investigations and repairs summarized for different types of leaks encountered during maintenance. Gas flow equalization mechanisms explained with observations and fixes provided by the technical team.

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Report dal Technical Coordinator

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  1. Report dal Technical Coordinator Anna Colaleo

  2. A.Colaleo Detector Status: gas leak problem W+ 1, W+2, W-1 : 12 chambers with gas leak replaced W0 one chamber has a serious leak we will try to operate in open mode. Gas leak tests redone on W0, W+1, W+2 (Claudio Viviani) (in 1.5 months!) Several connections re-done. 2 new chambers with gas leak: RB4 settore 1 W+1 (SISTEMATO provvisoriamente) RB4 settore 8 W+2 (?)

  3. A.Colaleo Chambers with problems System cannot handle the red cases (chamber does not keep any pressure). For the black cases it is possible to compensate the leak with the higher flow.

  4. A.Colaleo Gas circuit To equalize the gas flow between two gaps we use polycarbonate T and L junctions with flow reducers. Tygon tubes connect T and L connectors to the gas inlets. A –L connector B- T connector C- Gas inlet D- gap frame Backward Double gap Gas inlet D A Gas inlet B Forward Double gap Gas inlet C T and L connectors with Steel 316L Micro-cylinder inside

  5. W+1 We found the following problems: • In one chamber we found a broken gas inlet (polycarbonate, glued on chamber) in the gas input circuit of the forward gap. Chamber repaired. 2) In one chamber we found a broken "L" connector (connecting two external pipes) . The connector was in gas input circuit of the backward gap . Chamber repaired. 3) In one chamber we found a broken "L" connector (connecting two external pipes) . The connector was in input circuit of the backward gap . We also found a broken “T” connector in the gas output circuit . Chamber repaired. 4) In the two chambers with small leaks we found that the frame of the gap (polycarbonate glued on the gap) presented a small leak, that we could only localize by the gas sniffer. We could recover the second double gap in both chambers (we keep them as spares).

  6. CH 47 (W+1 RB1 out/9) Broken "L" connector (connecting tygon and polyetilene pipes). The connector was in gas input circuit of the backward gap . Chamber repaired. Polyetilene pipe Backward Double gap Service block Forward Double gap

  7. CH 206 W+1 RB3/5 A) Broken "L" connector (connecting tygon and polyetilene pipes). The connector was in gas input circuit of the backward gap . B) Broken “T” connector in the gas output circuit. Chamber repaired. . A Polyetilene pipe Backward Double gap B Service block Forward Double gap

  8. CH 92 (W+1 RB2 in/11) One gas inlet (polycarbonate, glued on chamber) in input to the forward gap was broken. Chamber repaired. Polyetilene pipe Backward Double gap Service block Forward Double gap

  9. Two chambers had a small leak in both cases in the frame of the gap (polycarbonate frame glued on the gap) . The leaks were localized with a gas sniffer. We could recover the second double gap in both cases (we keep them as a spares) CH125 (W+1 RB4-2500/10 )  DG Back GAP UP CH 235 (W+1 RB1in/10 )  DG forw GAP UP Backward Double gap Service block Forward Double gap Leak here

  10. W+2 We found the following problems: 5 chambers with big leaks in the frame of the gap (polycarbonate glued on the gap) always about 20-30 cm from the gas inlet. One of them presented also gap deformations and broken gas inlet

  11. CH134 (W+2 RB4-2000/11 left ) CH 118 (W+2 RB3/11 left) Big leak in the frame of gap Back UP Backward Double gap Forward Double gap

  12. CH114 (W+2 RB3/3 left ) Big leak in the frame of Forward GAP UP Backward Double gap Forward Double gap

  13. CH 65 (W+2 RB2/3-11 out right ) Big leak in the frame of Forward GAP UP Backward Double gap Service block Forward Double gap

  14. CH 82 RB2IN left / 11 Several problems: 1) Found Double gap back deformed and up gap detached from down gap in both sides 15 cm Backward Double gap 15 cm Forward Double gap Service block

  15. 2cm

  16. 2) Two big leaks in backward double gap 3) Broken gas inlet in forward down gap One gas inlet (polycarbonate, glued on chamber) in input to the forward gap was broken. Big leak in the frame of backward up gap Backward Double gap Backward Double gap Forward Double gap Service block Big leak in the frame backward down gap

  17. W-1 We found: Two chamber with broken “T" connector (connecting two external pipes) . The connectors are in input circuit of the forward gap . Chamber repaired.

  18. CH 7 (W-1 RB3) CH 352 (W-1 RB2/3) Broken “T" connector (connecting tygon and polyetilene pipes). The connector was in gas input circuit of the forward gap . Chambers repaired. Polyetilene pipe Backward Double gap Service block Forward Double gap

  19. NOTE: Leak tests have been performed in all chambers during construction phase, at ISR, after coupling, before and after installation. A difference between input flow and output flow in some flow cells in the gas racks was observed already during MTCC. But the instability of calibration of flow cell system in the gas racks prevented us to rely on the flow cell readout. Also the good performances of the chambers during MTCC, local commissioning and Global Runs did not help to discover the problem. A.Colaleo Flow cell readout for W+2 rb3 settore 11 Input flow output flow MTCC sx5 UXC

  20. Planning per l’ISR • Necessario assemblare le doppie gap buone in modo da avere camere spare pronte • Sistemare il materiale di recupero (elettronica, capton , meccanica) • Mettere in ordine l’ISR.

  21. A.Colaleo UXC Hardware BARREL Status Missing LV modules and 4 MAO expected in March. Now we move MAO from tower to tower in order complete the commissioning

  22. A.Colaleo USC55 hardware BARREL Status HV modules not all in place! We move from one easy crates to the other in order to test the chambers. All modules will be at CERN in March

  23. Tower Cabling for MAO and EASY CRATES RPC cables in all Wheels have bad path because the connector in MAO is in opposite side with respect to the power distribution box . Solution: remake the cabling passing the cable under the rack. Material ordered. Example: WB+1 Front side Back side Ricablaggio sulle torri e sistemazione dei cavi di HV in S1 entro Marzo (tecnici Napoli)

  24. Link system installation • YB+2,+1, 0 - commissioned from USC; • YB-1,-2 - all LBBs with boards installed, all cabled; • YB-1 - commissioned now; • YB-2 - to be commissioned; • YE+3,+1 - LBBs installed and cabled, no boards installed; • YE-1,-3 - LBBs installed, no boards installed, cabling started: • YE-3 to YE-1 mini chain cabling done, • LBB LV cabling done, • Control, Trigger, TTC cabling to be made. • Enough modules for barrel and endcap installation, BUT lack of spare modules - need to fix broken modules or small production! Maciek Kudla, CERN, CMS week, CMS Joint RPC/Trigger Meeting 27.02.2008 24

  25. Trigger installation (1) • UX-US cables (YE+3,+1,YB+2,+1, 0, YB-1,-2) installed; • UX-US cables (YE-1,-3) - waiting for installation; • USC trigger cabling - • TTC, GMT, DCs, Slink cables - done; • TC(11), TC(9), TC(1) - installed and cabled, • TC(10), TC(2), TC(0) - will be installed without TBs this week, • the rest of TCs and TBs will be installed in April, • DCC cables (TBs to DCC_PP and DCC_PP to DCCs) - installed, • Splitter cables delivered CERN, cabling in April; Fully cabled TC Maciek Kudla, CERN, CMS week, CMS Joint RPC/Trigger Meeting 27.02.2008 25 25 25

  26. Trigger installation (2) • Trigger Boards (TB): • 17 installed in USC; • 105 delivered to Warsaw + 5 waits for missing components in factory), • 8 - tested, • 69 – ready to be tested, • 16 optics to be installed in UW lab; • last 7 will be delivered to Warsaw this week; • mid of April - delivery of TBs to CERN. • Trigger Crates (TC): • 3 - installed now in USC, • 3 - will be installed in USC during this week; • one TC send to Wiener to be repaired; • the last 6 will be installed and cabled in USC staring mid of April. Maciek Kudla, CERN, CMS week, CMS Joint RPC/Trigger Meeting 27.02.2008 26

  27. A.Dimitrov Tower Test • Detector performance procedure, using the final RPC-Trigger system: • Connectivity Test • Strip Connectivity Test – dead strips • FEB – LB Connectivity Test – swapped cables • Noisy FEB • Threshold Scan • Noise rate as a function of HV and threshold. 4/ 5 Wheel tested. W-2 to be tested next week

  28. F. Loddo • Installation of RBC boards on the detector towers: done • Cabling of negative wheels: this week • Installation of TTU boards in USC55: 1 out of 3 (can cover up to 2 wheels) • The installation will be completed as soon as full production of Trigger Boards (Warsaw) will be delivered • TTU is under testingBUT: • always in conflict with RPC Trigger activities and Tower test • since July 2007, TTU could use the system for few days only • DCC problems prevent to validate the implemented algorithms • We succeeded to take data yesterday evening. Data are been analyzing RPC Technical Trigger Status

  29. F. Loddo To be done: • Validate the implemented algorithm using any readout • At sector level • Tower level • Wheel level • Study the timing calibration for cosmic muons • Xcheck with DT trigger • Coupling with Global Trigger • Provide Trigger for any cosmic run, May Global Run and CMS startup Need automatic data analysis and DQM ready (at the moment only 2-3 people can see the data)

  30. Awaiting full commissioning In sequence : 60 degree sector on YE+1 (i.e. 6 RE1/2 & 6 RE1/3) then rotate 60 degree sector on + end cap (i.e. 36 RPC on YE+1 & YE+3) Prerequisites : • Readiness of final UXC RPC gas system • Installation and connection of end cap Link Boards • Borrow AC/DC, HV, LV PS from barrel (CAEN delivery late) • Finalize missing cables (power and DCS) inter racks and crates • Finalize connectors on HV umbilical cables in USC • Control PC • Manpower • Other tasks: • HV distribution boxes • Assembly, test and installation of 6 high eta RE1/1 (see S.Park) • Finalize the FW specific software FIRST COMPLETE BARREL COMMISSIONING

  31. A.Colaleo Commissioning status and plan We are using the final LV power system from S4 on W+2, W+1, W0, W-1

  32. Local commissioning Essendo legati alle trigger board installate possiamo iniziare con i 4 settori delle torri near (settori 2-3-10-11). Studio efficienze, correnti, cluster size, noise rate, noise profile con TTU trigger . Necessari turni su questi item : fornite per favore la vostra disponibilita’

  33. R. Guida Schedule for completion - update Status Supplier: ok Mixer: ok Humidifier: ok Purifiers: commissioned, at the moment not in use Pre-distribution and pump: ok Final distribution: ok(back-up system to be adjusted) Pressure Transmitter on the detector: only negative Endcap missing CERN Gas group responsability Commissioning status Positive end (W0 included) completely commissioned. Final distributors connected to the final system. Some fine tuning has to be done on the back-up and purge lines. Infrared analyzer installed and operational Then we are ready to use the final mixture.

  34. Status A new ELOG entry has been submitted: Logbook : RPC Author : Roberto GUIDA , mailto:roberto.guida@cern.ch Type : Other Subject : CMS-RPC YB+2 under gas with final gas system Logbook URL : https://cmsdaq.cern.ch/elog/RPC/671 ================================= Dear all, all the RPC on YB+2 are connected to the final gas system since yesterday late afternoon. The system is in fill mode and the total flow from the mixer is about 450 l/h. Mixture composition (R134a 96.2%, iC4H10 3.5 %, SF6 0.3 %). Humidifier On, but not stable. Exhaust module forced in run mode with YIC5003 forced closed (in order to use also the MFC). The pressure in the chambers is: rack 78 (YB+2 top part) +0.2 mbar rack 73 (YB+2 bottom part) +0.2 mbar Alarm for chamber pressure are HH 0.7 mbar, LL -0.7 mbar. Cheers, Mar, Andrea, Roberto Needed temporary procedures and tools to correlate current and gas information (Plamen)

  35. RPCs on final gas system: • 4 sectors on W0 will be connected to the final gas system .These sectors will operate in fill mode (i.e. open mode) for at least one month in order to verify the RPCs performance : • noise rate and noise profile (every 2 hours) • Efficiency • Currents and working point take data continuously • During that test also the performance of the Purifier modules will be checked working with the exhausted mixture. • Once we will be confident with the system (gas mixture, humidity stability and purifier performance) we will switch to run mode (closed loop mode) with some high percentage of fresh gas (starting from ~50%). Same procedures for data taking Gas parameter monitoring in DCS We are preparing the software in order to have all the information about the gas system in the RPC-DCS together with the information about the detector performances. For the moment we are reading the gas parameter from the PVSS of the gas system (Claudio, Roberto, Giovanni) DSS interlock to the detector high voltage in case of gas system stop. It is foreseen an hardware signal generated in each gas control rack in case of problem with the gas system. This signal has to be configured and connected to the CMS-RPC high voltage system. Most probably it will be ready in one month

  36. R. Guida Pending problems: Flow-cells issue. In the final distribution, the supply and the return flow per each channel is read-out by means of flow-cells. The flow measurement was expected with a precision at the level of few %, while we have some channels with input-output difference at the level of 30 %. We are trying to evaluate the problem (we just finished the commissioning of the positive end). One example: In order to start we will adjust the reading taking into account the measured difference.

  37. R. Guida Closed loop at ISR: history • From the end of 2006 a dedicated test has been set-up for the re-circulation study • However, many problems appear: • pump failure (Jan07) • Bad quality of the R134a cylinders after a change in the supplier (Mar-Sept07) • All the R134a cylinders analyzed since June 07 with the Gas Chromatograph: • 6 cylinders < 500 ppmvol “air” • 3 cylinders ~ 4000 ppmvol “air” • 4 cylinders >> 30000 ppmvol “air” (plus unknown component/s) • Since September all the cylinders arrive with an “air” concentration < 1000 ppm • 3. Saturation of the purifiers followed by more than one month of operation in open mode in order to recover the detectors (Nov07-Jan08) • 4. Abnormal amount of air in the closed loop after the Christmas shutdown (Jan-Feb08). Found several weak points due to old o-ring. The problem has been fixed last week. • 5. New closed loop cycle started on 25/2/2008

  38. R. Guida-S.Bianco Master Planning for closed loop ISR • 25/2 Closed Loop running with saturated filters • 3/3 Currents start increasing • stop CL • regenerate filters, take samples of used filters • restart CL, • check air-tightness of 3 gas gain monitoring gaps, connect 3 gas gain monitoring gaps to closed loop • 24/3 Currents start increasing • stop CL • take samples of used filters, install new filters, • install sampling flasks, install F- specific electrodes • restart CL, start gas sampling • 15/4 Currents start increasing • Stop CL • Take samples of used filters, regenerate filters, resume sampling • May • Start Gas and filters sampling with individual purifiers 3 cycles in 2 months? We are already not on schedule and this plan does not take in account the chamber recovering time

  39. Gas Gain Monitor (conceptual design) S. Bianco USC5 UXC5 VENT RPC TRIG1 RPC TRIG2 Slow Ctrl GC, p/T/RH/Ph MONITOR VENT RPC PAD MON1 RPC PAD MON2 RPC PAD MON3 VENT RPC PAD MON4 RPC PAD MON5 CMS RPC PAD MON6 PURIFIERS REFERENCE half wheel lines VENT RPC PAD REF1 C2H2F4/SF6 /i-C4H10 /H2O RPC PAD REF2 VENT RPC TRIG3 RPC TRIG4 SGX Bldg

  40. S. Bianco Gas Gain Monitoring System tests • System operational at ISR, working on integration with DCS • Tests on sensitivity of charge and avalanche/streamer ratios for working point changes • Good sensitivity in avalanche-to-streamer transition regions • Run with (0% SF6) --> (0.3% SF6) last week, analysing results Time schedules for the tests ?

  41. Equipment management database All elements (chambers, racks, Easy crates, modules etc) must be integrated in the official CMS database (CMS labels, bar code). Construction database must include references to all internal elements (ex. FEB, Control boards) . Need to update the information as soon as possible. Construction databases must be: either 1) Linked to the CMS official database (Stephane Bally) and we have to guarantee the maintenance of it for CMS like (RPC responsible for that) Or 2) integrated in the CMS database (no need to maintain in the future). Need to take a decision about those possible solutions. RPC responsibles for the construction database should contact Stephane Bally in order to implement one of this solution.

  42. Conclusions and comments • Barrel installation almost completed and local commissioning ongoing: since May07 4/5 wheels commissioned • Final gas system ready in PT5, but we have to work only with safe procedures (DCS, DSS). • We can start new commissioning phase to check the chamber performance with TTU trigger . TTU trigger not fully operational since readout problems prevent to validate the implemented algorithms : first good data took 10 days ago. Intensive program to fully validate the system in next 10 days maximum. Need automatic data analysis and DQM ready (at the moment only 2-3 people can see the data). • We have to define the standard operation procedure and start to apply them in order to be ready for data taking during Global Run. • ISR and GIF tests for the closed loop system: need realistic schedule

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