Slide 1

Summary of the technical stopactivities on collimators (w17, 2012) O. Aberle 07/05/12

Main activities during the last technical stopTDI.4R8

Collimator roller screw replacement

TIM intervention/observationsMay 7th, 2012O. Aberle CWC2TDI.4R8TDI.4R8: New x rays have been taken on:Up and downstream beam screen transition jaw extremity.Result: No change since the last scan in January. Stable conditions after the 144 bunches dumping.The parking settings of TDI.4R8 should be changed from 37 to 55 mm during physics, as in Pt. 2.

May 7th, 2012O. Aberle CWC33TDI.4R8Result: No change since the last scan in January. Stable conditions after the 144 bunches dumping.The parking settings of TDI.4R8 should be changed from 37 to 55 mm during physics, as in Pt. 2.

May 7th, 2012O. Aberle CWC4

25.01.2012, source25.04.2012, source25.04.2012, tube4Looking at the 2 LVDTs (RU-RU2)

Clear symmetric drift of the 2 LVDTs indicating a possible deformation of the right jaw of TDI in point 8. intensityRURU22012TDI observations and beam measurements, C. Bracco

130th LMC Meeting held on 25 April 2012 May 7th, 2012O. Aberle CWC5Looking at the 2 LVDTs (RU-RU2)

Same LVDT feature in 2011 and 2012. However, not seen in 2011, as limits were twice larger (0.5s) than in 2012 (0.25s).

intensityintensityRURURU220122011TDI observations and beam measurements, C. BraccoMay 7th, 20126ConclusionWe see a drift of the TDI LVDTs mainly during physics jaw position outside interlocks (0.25 s) when back at injection setting (already observed last year but tolerances more relaxed)Symmetric drift for the 2 LVDTs located at the 2 sides of the motors jaw deformation?Measurements with beam indicate a possible deformation towards the beam (safe side) of the order of 0.5 s Angular scan on the cold jaw did not show any evident change.Not always clear correlation between LVDT drift and beam condition need more statisticNot clear correlation between LVDT drift and jaw deformation need reference measurement with cold jaw (right after TS, no angular scan) repeat measurements with warm jaw (including angular scan) Once we define if and by how much the TDI jaw is deformed and the correlation LVDT/jaw setup thresholds accordingly to insure protection in case of miss-injection (TDI grazing) Still to be understood the cause of the warming up when the jaws are at 55 mm (high order modes?), are we heating the jaw or the full structure? (N.B. after opening TDI jaws from 20 mm to 55 mm vacuum improved but there was no clear evidence of improvements in heating) Works ongoing!!TDI observations and beam measurements, C. Bracco130th LMC Meeting held on 25 April 2012 May 7th, 2012O. Aberle CWC7Collimator roller screw replacementElogbook 22/04/2012 00:16:45 22/04/2012 00:46:43 00:29:58Collimator Hardware TCSG.5L3.B1 Collimator stuck; won't drive to injection settings. - The TCSG.5L3.B1 failed to go correctly to injection settings after the collimator setup ( suspected problem with roller screw), and required piquet reset. Normally this collimator should not be included in the active set until the hardware problem is fixed.

Performance loss on axis B. First steps lost during the week end, recovery with simple resetting. Within 3 days the situation was degrading a lot. The axis, and therefore the collimator had to be disabled in parking position after regularly loosing steps.This triggered a systematic sound check with the TIM in point 3. The noise profile off all 16 out of 18 collimators have been registered, a list of conspicuous collimators has been delivered for further inspection.In parallel, torque measurements have been performed on most of the collimators, in reducing the motor current until steps are lost.These values have been compared with original data taken during commissioning campaigns.

All suspicious collimators have been checked and validated for operation in situ.

May 7th, 2012O. Aberle CWC8Collimator roller screw replacementThe roller screw on TCSG.5L3.B1 had to be replaced due to mechanical wear. There is a clear correlation between a high torque value and the noise pattern."SEM observations and EDS analyses of debris found in a roller screw from a LHC TCS collimator tablehttps://edms.cern.ch/document/1212253/1The roller screw is still in the RP buffer zone and will be analysed as soon as possible.

A second roller screw was found, based on the noise recording. The torque measurement did not yet indicate problems.Affected is the axis A on the TCP.6R3.B2. The screw showed signs of wear and was exchanged preventively.

Collimators in Pt. 3, 5, 7 and 8 have been crosschecked with visual inspection. No further case has been found.

All collimators are commissioned and ready for operation.

May 7th, 2012O. Aberle CWC9Collimator roller screw replacement

May 7th, 2012O. Aberle CWC10Dust and debris in the end cap and the housingSome dry screws regreasedCollimator roller screw checkMay 7th, 2012O. Aberle CWC11Collimator Functional NameCollimator CERN nameTCSG.5L3.B1TCS025TCDIH.29465TCDI212TCLIA.4R2TCLIA002TCP.6R3.B2TCP103TCSG.6L7.B2TCS019TCDIH.20607TCDI207TCTH.4R5.B2TCT301In combination of acoustic check and torque measurement a good indication for problems can be found, but:

TCP.6R3.B2 not detected with torque measurement

Collimator with the problemMay 7th, 2012O. Aberle CWC12TIM interventionMay 7th, 2012O. Aberle CWC13Set up and tuning of TIM in Point 3: ~ 5 h.This can be faster with final parameters, around 2 h.Sound recording of 16 collimators during 6 h (night, no access).Remote control from the CCC with data analysis in parallel.Visual inspection with camera will be useful in the future.

TIM exercise - Sound inspection of the collimators in S34 (23/24 April 2012)

Microphone

Roller screw

TCSG.5L3.B1_L_IN_OUT TCLA.A5R3.B1_L_IN_OUT

Faulty (the initial one):Normal:TCP.6L3.B1_L_IN_OUTTCP.6R3.B1_L__IN_OUTSuspicious:

EN/HE - EN/STICollaborationO. Aberle CWC14Courtesy R. Folch, B. FeralOutlookMay 7th, 2012O. Aberle CWC15Improve the sound and image quality for the TIM, very powerful tool for the future.Reference sound recording of all collimators.Improve the accessibility to the screw (cap).A regular check during long breaks and shut-downs with re-lubrication of the screw.Automatic motion cycles during LS1 to be planned.