The alignment of the lhc during the shut down 2008 2009
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The alignment of the LHC during the shut-down 2008-2009. D. Missiaen. Outline. Repair of sector 34 Maintenance alignment Roll angle measurements Vertical smoothing of the LHC Horizontal smoothing of the LSS Case of the LSS with experiments Conclusions. Repair of sector 34.

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The alignment of the LHC during the shut-down 2008-2009

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The alignment of the lhc during the shut down 2008 2009

The alignment of the LHC during the shut-down 2008-2009

D. Missiaen


Outline

Outline

  • Repair of sector 34

  • Maintenance alignment

    • Roll angle measurements

    • Vertical smoothing of the LHC

    • Horizontal smoothing of the LSS

    • Case of the LSS withexperiments

  • Conclusions

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Repair of sector 34

Repair of sector 34

A measurement of the position « after incident » wasdone

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Repair of sector 341

Repair of sector 34

  • A zone of 700 m of 39 dipoles and 14 quads

    • Fiducialisation

    • Alignment of BPM in quads

    • Beamscreen and Tubes positioning on both types

    • Main difficultywas to re-start an activitystoppedtwoyearsbefore

      • « Fiducialisation » benchesweredismantled

      • Motorized system without maintenance

      • Software not running

      • Interface to databasehad to beupdated

    • After a re-learningcurve, whole job done in 3-4 months

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Repair of sector 34 2

Repair of sector 34 (2)

  • Initial alignmentdonewith respect to the geodetic network

    • NOT the normal procedure

    • BUT geodetic network wasstill consistent withmagnets

    • Accuracyobtained 0.3 mm at 1s.

  • Local smoothingdonedirectly on fiducials on areas of 100m. => OK to the interconnection team

    • Offsets to a stretchedwire – Digital levels

    • Accuracyobtained 0.15 mm at 1 s.

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Vertical smoothing of sector 34

Vertical Smoothing of sector 34

  • 49 magnetsrealigned (22%)

  • No more in the damaged area thanelsewhere

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Horizontal smoothing of sector 34

Horizontal smoothing of sector 34

  • 41 magnetsrealigned

  • MB.B29L4.E:1.5 mm

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Alignment maintenance

Alignment Maintenance

SU alwaysclaimedthatitwilltaketwo to threeshut-downs to have the « best smoothed» position of the magnets

This was an opportunity to startwith the improvementcampaigns

All magnetswereunder cold conditions

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Roll angle measurements

Roll angle measurements

  • Mvtsbetween 2008 and 2009

  • For eachsector :

    • Avgis close to 0

    • Stdevisbetween 0.06 and 0.09 mrad

    • 55 magnetsrealigned

    • S34 : stdev = 13mrad, 100 magnetsrealigned

  • S67: q8r6 moved due to concreteslabproblem

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Vertical smoothing

Vertical smoothing

  • Absolute vertical shape

  • Closure +2.4 mm

  • Not fixed on the deepreferences

  • Pb withconcreteslab in LSS6

  • Hole of S78

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Sector 78

Sector 78

  • The wellknown « LEP hole » of 2mm per yearre-appeared in 2009

  • Weshould have leftitlikethatbecauseitissmooth but finallyitwasdecided to realigned to the theoretical position

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Vertical smoothing1

offset

Length of the window

Vertical smoothing

  • The relative position of the magnetsis more important for the beamthan the absolute one

  • The deviationsw.r.t a smoothcurve, much more significant, werecalculatedwith PLANE

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Horizontal survey of lsss

Horizontal survey of LSSs

  • Straight lines of 500 m on each part of the IP from Q8Ln to Q8Rn

  • 4 of them are equipedwith permanent monitoring systemsbecause of the obstacle of the Experiment and of the low beta quadrupoles

  • The aimwas to link

    • the standard arc with the LSS

    • The LSS to the low beta quads

      Beforethese areas become radioactive

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Horizontal survey of lsss1

Horizontal survey of LSSs

  • Methodology

    • Long stretchedwire of 160 m with an overlap of almost 100m

    • Measurementsissuedfrom permanent sensors values

  • Calculations

    • Q2Ln considered as fixed point, Q2Rn orientation point

    • Radial corridors of 1 mm at the vicinity of the Q8s in order NOT to make a stepat the junction

    • Add relative position of « standard » and « permanent monitoring » fiducials

    • Residualswerebetterthan 0.1mm. Someinconsistenciesbetweenmeasurements of different types and accuracies

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Horizontal survey of lsss1 2 5 and 8

Horizontal survey of LSSs1, 2, 5 and 8

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Conclusions

CONCLUSIONS

  • Leveling and roll angles allowed the detection of unstable areas (sector 78, LSS6R, etc)

  • The vertical smoothing of all LHC sectorsimproved the relative accuracy to betterthan 0.1 mm at 1 s

  • Horizontal smoothingwith long stretchedwireswas a success

  • Horizontal position of the low beta quads wasimproved

  • A huge effort to measure and to realign but itisworthit

  • LHC willrununtil the end of 2011, then a hugeshut-down in 2012 and part of 2013. A rythm of a shut-down everythreeyearswillbeadopted

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


Conclusions1

CONCLUSIONS

IWAA2010, 13-17 Sep. 2010, DESY Hamburg


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