m Alignment Status & Outlook

CMS m Alignment 20-Dec-2010IFCA HEP Group Why Align? IFCA m alignment group

Current alignment

IFCA alignment 2010 highlights

Summary & Outlook

20-Dec-20101IFCA HEPWhy align?Physics and mechanical cases for alignment20-Dec-2010IFCA HEP22Physics Case for Alignment

20-Dec-2010IFCA HEP3 CMS will study physics at the TeV scale Precise m reconstruction in the TeV momentum range requires alignment of DT/CSC chambers to a precision ~ few hundred mm Well aligned MU system improves pT resolution for pT > 200 GeV/c3Why Align20-Dec-2010IFCA HEP4

Chamber resolution ~200 mmuseless unless chamber positionsare known to a similar precisionSub-mm precision for a detector which is: large (notice the person in the figure) heavy (12,500 tons) compact has large B (4T) has hostile radiation environmentVery hard task4Mechanical Case for AlignmentSolenoid is COLOSALHuge magnetic forces (~10K tons) displace, rotate and deform yoke elements by several mmYoke elements are HEAVYGravitational distortions observed at the level of several mmYoke wheels/disks are movablePosition reproducibility for such large & heavy structures expected at the mm level at bestThermal instability effects might contribute at the sub-mm levelAlignment system must track these effects after CMS is closed and magnet energizedTight spatial confinementLarge dynamic range to trace large displacementsTolerance to large (3.8 T) magnetic fieldsTolerance to large radiation exposure20-Dec-2010IFCA HEP5Example: effect of magnetic forces

20-Dec-2010IFCA HEP6Displacements and deformations between B = 0T and 3.8T

0 T3.8 T~DZ(LD-AR) ~DZ(YE+1-Tracker)Final closure of disk from detector closureuntil after large B-field is appliedElastic deformation of disk25-Aug25-Aug21-Nov21-Nov6Example: gravitational compression20-Dec-2010IFCA HEP7

CMS y-axis6 mm-6 mmNominal vs Surveyed DT positions w.r.t. wheel center14 m6 mm6 mm7Link System: an IFCA/CIEMAT project

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r-f planesr-f plane8Alignment Ring20-Dec-2010IFCA HEP9

9CMS Muon Alignment System20-Dec-2010IFCA HEP10

LDARDCOPSASPDsMABSLMLink lineYE+1YB+210Who works for alignment at IFCA?Past and present colleagues participating in the muon chamber alignment effort

20-Dec-2010IFCA HEP11IFCA Alignment GroupCoordinacin de CMS muon alignment: an IFCA taskGervasio (now), Teresa (before)Diseo, construccin, calibracin, instalacin, commissioningTeresa, Ivn, Pupi, Mar, Amparo, Alicia, Javier G., Gervasio, David DAQ, LV, integracin DCS, data chain, automationJavier G., GervasioCOCOA reconstructionCelso, Javier B., Mar, TeresaTrack-based alignment, internal DT alignment:Luca, Pablo (now ETH), PupiValidacin SA segments and muon re-recoLuca, AliciaLiason for DPG and AlCaLuca (now), Pablo (before)Liason for alignment muon triggersJavier F. (Oviedo)Procesado de PG, construccin de alignment DBLuca

20-Dec-201012IFCA HEPIFCA alignment: ISR20-Dec-2010IFCA HEP13

IFCA alignment: ISR20-Dec-2010IFCA HEP14

IFCA alignment: CMS20-Dec-2010IFCA HEP15

IFCA alignment: CMS20-Dec-2010IFCA HEP16

Current alignment status20-Dec-2010IFCA HEP17Current Barrel AlignmentOptical alignment of DTsMB1/2/3 aligned in single full COCOA reconstructionNo more splitting into super-sectorsBetter use of redundancy: more robust against data loss (MAB +1_9 was lost 29-May-2010)MB4 added in a separate step to resulting rigid structureSmaller COCOA model, faster runningMAB calibration in MB4 region less precise: better to decouple from overall barrel structure

Resulting rigid barrel is thenPositioned using Link MABsFinal position/orientation with respect to tracker corrected using global tracks

PG vs 0T alignment comparison:localX RMS 430-700 mm for all wheelslocalY RMS 800-1200 mm for all wheels

20-Dec-201018IFCA HEPBarrel Alignment: PG vs 0T

Fit with sin-curve:

0.73-0.57*sin((sector-2.4)*PI/6)Wheel position correctedEntries37Mean0.008 mmRMS0.625 mm

0.57mm0.13mrad Correction:For the average radius of 4.5m=20-Dec-201019IFCA HEPBarrel Alignment: SA Validation

Identical performance as current alignment. 20-Dec-201020IFCA HEPCurrent Endcap AlignmentSequence of alignment steps:PG pre-alignmentlocal x, y, z, fx, fzDisk displacement (local z) and bending (local fx) from optical system SLM lines and LinkAlignment in fy from collision tracks (new)CSCs within rings using beam halo overlaps + PG to fill in holes due to missing dataReplaces rf and fz from PGYE disk alignment using collision tracks (new)Keep internal chamber structure intactDetermine global x, y, fz

20-Dec-201021IFCA HEP2010 Alignment Highlights Track-based DT alignment: saw tooth problem solved Poster: all constants delivered on-time for reprocessing General: improved m reco at low and high Pt Improved internal DT chamber description Link improvements (in backups)ASPD vs Temp add MAB inclinometers to geometry reconstructionautomated data taking and conversion to root Outstanding issue: TB HW differences CMS Award

20-Dec-2010IFCA HEP22Saw tooth problem20-Dec-2010IFCA HEP23Large, unexplained correlation between Dx residual and the F position of the hitin all sectors, stations and wheels.Due to the local coordinate convention the blue and yellow chambers have opposite sign. Not a real effect.

CRAFT10Wh:0 St:1 Se:8,9,10,11,12This dependency was identified as a different p scale for low and high p muons.This curve motivated a selection of muons with Pt > 100 GeV in alignment, losing most of the statistics.

Saw tooth solution20-Dec-2010IFCA HEP24DT APEs are set to huge value, tracker track is then extrapolated (in principle with zero muon system bias) and residuals are used to align. This was not true for the RPCs!! As a consequence the RPCs (which are not aligned) were contributing to the refit. It was not a pure extrapolation from the tracker.

Without RPC

With RPCSame sample, code, conditions the only difference is that the RPC is or not consideredSaw tooth solution20-Dec-2010IFCA HEP25Residuals are now much wider It is obvious, we are not counting the piece of information of the RPC.The mean of the residuals displaces with the momentum => now we know why we needed a Pt>100 GeV cut.The effect decreases with the momentumAs long as the sagitta of the track approaches the intrinsic resolution of the RPC it does not contribute so heavily.

Without RPCWith RPCPt>10 GeVPt>50 GeVPt>100 GeV20-Dec-2010IFCA HEP26

These are the muon alignment constants*for all DT (barrel) and CSC (endcap)chambers(internal DT alignment of layers and SLsNOT shown)

They were validated and delivered timely for data reprocessing.

Their effect on muon reconstruction is shown ahead.* Corrections applied to nominal chamber positions in CMS reconstruction Alignment Effect on m Reco

Split cosmics: Gaussian sigma as a measure of the core resolution. Improves a bit at high pT (>200 GeV/c)

Improvement also at lower pT in dimuon mass resolution (note: improvement is mostly due to new endcap alignment which had larger changes, see backup)20-Dec-201027IFCA HEPA problem: Tracks vs HWSystematic TB-HW differences have not been resolvedWork is in progress to understand thisOverall ~4/5 mm end-to-end effectSectors 1,7 have low statistics for cosmic tracks

20-Dec-201028IFCA HEPAnd the 2010 prize goes to 20-Dec-201029IFCA HEP

Our Pablete! For his outstanding contributions to muon alignment!

Thank you! Jo to, I so japi!!Esta noche me emborracho que me lo he ganao!Summary & OutlookSeveral improvements in all fronts:Hardware: full barrel reconstruction and separate treatment of MB4, link temperature corrections and inclusion of inclinometer data, best ever agreement with PG at 0T, slight improvements in endcap disk displacement and bendingTrack-based: solved long-standing saw-tooth problem increased statistics by lowering Pt cut, new alignment in fy, improved data coverage for ring overlaps, new disk alignment using collision tracksNew alignment slightly improves muon reconstruction with respect to previous alignment (from March) at low and high momentumImprovements expected in 2011:Must understand cause of barrel TB vs HW differencesHigh priority, since this is the major remaining source of systematic uncertaintyOngoing tests: endcap transfer lines, Link YB2-YE1 connection + Global muons MU-TK connection vs MB1-ME12 overlapping tracks, cosmic endpoint analysis, Boosted Zs?

Additional refinements are in the queue for optical systemsLink: include tilt meters in reconstruction, finish systematic studies Endcap: finish transfer line analysis and also for track-basedStandalone muon barrel alignmentDetailed studies of global muon residualsInclude SLM and TL information in addition to PG for track-based endcap alignment

20-Dec-201030IFCA HEPBack-up slides20-Dec-201031IFCA HEP32AR Lasers: big variations

This 2 mm trend is excluded by all other measurements If not due to a real movement, study systematic effect Dedicated 4-day run with lasers ON2 mm !20-Dec-2010IFCA HEP33Link Improvement: AR Lasers vs TemperatureThis change is NOT an artifact of the ASPD profile fit:the laser spot actually moved:

T(AR)=13.7C(March)T(AR)=16.5C(May)20-Dec-2010IFCA HEP34First: AR-LD distance vs TempSmall changes due to (small) day/night temperature variations?

Ignore 25 mm effects untillarger effects are under controlCorrelation with T is clearContact sensor is very preciseand attached to 3.7m Al profile20-Dec-2010IFCA HEP35ASPD/LaserAR vs TempSame structure, much larger (x10, non-mechanical!) magnitudeCorrelation with T is clear(only 0.6 change in this 4-day run)

300 mm nair(T) : lasers not straight lines! dX/dT ~ R (MAB_T > MAB_B) implies directional change, not physical movement 20-Dec-2010IFCA HEP36ASPD/LaserAR vs TempIndeed, correlation is clear and T-dependence is large: correcting it can take us from 300 mm to ~50-100 mm, closer to expected ASPD resolution of ~50 mm

300 mm100 mm20-Dec-2010IFCA HEP37An exampleRunDateAR+ TAR- TComment134Jan 201014.415.00T, collimate AR lasers, excellent residuals152Mar 201013.716.83.8T, good residuals (600 mm) 190May 201013.816.93.8T, agreement with 152, good residualsAs an example, take ONLY ONE measurement from runs 188 and 190(separated only by 2 days with NO field change in between)20-Dec-2010IFCA HEPRun #TempRaw XRaw YCor. XCor. Y18816.5-9.47-8.12-8.60-8.5119013.8-8.38-8.58-8.63-8.47(mm)2.7-1.090.460.03-0.04ALL corrected hits show similar significant improvementLink Improvement:Including MAB inclinometers20-Dec-2010IFCA HEP38In this table one sees the Angle Z of the MABs according to PG, the tilt variation between r32 (B=0T in CRAFT09) and r134 (first reading at B=0T in Jaunary 2010), the deduced Angle_Z for the MABs and the actual COCOA fit without taking into account the tilts and with them included:MABPG Abs.()Tilt (rad) r134 vs r32Deduced ()Fit r134 () wo tiltsFit r134 () with tilts19514.4153.214.41514.42714.41625574.363-70574.32374.34674.325315134.274-656134.236134.319134.24315194.141-11194.140--75254.304-578254.271--135314.401-42314.399314.361314.396

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20-Dec-201043IFCA HEPGlobal PositionDetermine the MU position with respect to TK using tracksInput:New internal tracker alignmentNew internal optical barrel alignment70K global tracksOutput:Global Position Record for Muon System!GPRs:Trackertranslation = (-0.09, -0.11, -0.17) cmEuler angles = (0, 0, 0) mradUNCHANGED (by choice)MuonsTranslation (0.0826, 0.0109, -0.0006) (0.1424, 0.1962, -0.0031) cmRotations (-101, -76, 789) (40, 24, 753) mrad around x,y,z axisChanges are due to different anchoring to Link MABsby Alexander Spiridonov20-Dec-201044IFCA HEP