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STARTSLIDE
ALIGNMENT OF THE NEW TRIPLETS Hélène MAINAUD
DURAND
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INTRODUCTION
Overview

1. The alignment functions
2. The status of these alignment functions
3. Some improvements, proposals for the alignment of
   the new triplets

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INTRODUCTION
The alignment functions
F0 Fiducialisation F1 The alignment of one
inner triplet w.r.t to the main elements of the
corresponding arc and LSS F2 The alignment of
the experiment w.r.t. to one inner triplet F3
The alignment of one triplet w.r.t. the other
inner triplet (left/right side) F4 The
alignment of the quadrupoles w.r.t each other
During 3 periods of alignment - first or
initial alignment - monitoring beam on -
maintenance of the alignment beam off
Functions and periods still valid for the new
triplet
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INTRODUCTION
The status concerning these alignment functions
F0 Fiducialisation

• Fiducialisation determination of the
  coordinates of the fiducials according to the
• mechanical / magnetic axis of the magnet
• According to the baseline fiducialisation in
  warm and cold conditions performed
• by Fermilab (a sample of the whole production of
  Q1 and Q3 tested at cold, all Q2
• tested at cold), and a simple control at CERN
• Reception procedure changed after several
  problems (transport by trains, spider problems,)
• ? decision to apply the same geometrical
  metrology on the triplet quadrupoles as
• on the other cryo-magnets
• - measurement of the position of the fiducials
  w.r.t. to the mechanical
• and magnetic axes at CERN
• - measurement of the position of the tubes at
  each extremity w.r.t. to the fiducials
• - measurement of the position of the beam tubes
  and the associated BPMs.
• ? Accuracy expected 0.1 mm (1s) using Laser
  Tracker

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INTRODUCTION
The status concerning these alignment functions
F0 Fiducialisation ? status

• Accuracy after fiducialisation 0.1 mm, but in
  the tunnel 0.2 to 0.3 mm (??)
• The supporting system appears to be unstable in
  radial, vertical and longitudinal
• during transport, and a longitudinal
  displacement of the cold mass of 6 mm is possible
• The reference points on the cold masses are not
  easily accessible, and do not allow
• a precise determination of the tilt, when they
  have not been removed!
• In some cases, the longitudinal position of the
  beam tubes did not meet the requirements
• of the technical specification which led to the
  displacement of the cryostat once aligned,
• and to the fact that some jacks are out of range
  before the first beam.

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INTRODUCTION
The status concerning these alignment functions
F1 The alignment of one inner triplet w.r.t to
the main elements of the corresponding arc and LSS

• During the first or initial alignment, 2 steps
• Alignment w.r.t to the geodetic network
• relative planimetric alignment accuracy between
  3 consecutive points 0.3 mm (rms)
• relative accuracy in altitude between 3
  consecutive points 0.1 mm (rms)
• Smoothing
• relative alignment accuracy 0.1 mm (1s) in
  radial
• relative alignment accuracy 0.1 mm (1s) in
  vertical
• During the maintenance beam off only the
  smoothing is carried out.

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INTRODUCTION
The status concerning these alignment functions
F1 The alignment of one inner triplet w.r.t to
the main elements of the corresponding arc and
LSS ? status

• During the smoothing measurements, some problems
  were encountered
• a difficult access to the fiducials, hidden by
  the monitoring systems equipment
• no angle measurements possible only wire
  measurements could be performed
• jacks already in their end of range concerning
  longitudinal displacements (5R)
• The specification seems to be met concerning the
  accuracy of the positioning in
• planimetry and altimetry.

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INTRODUCTION
The status concerning these alignment functions
F2 The alignment of the experiment w.r.t. to
one inner triplet F3 The alignment of one
triplet w.r.t. the other inner triplet
(left/right side) F4 The alignment of the
quadrupoles w.r.t each other
Positioning of one triplet w.r.t the other
(RAD/LEV) 0.1 mm /0.1 mm rms for IR1 and
IR5 Positioning of one triplet w.r.t. the other
(RAD/LEV) 0.2 mm/0.1 mm rms for IR2 and
IR8 Stability of the positioning of one
quadrupole inside its triplet a few
microns. Due to high radiation doses and
stringent alignment tolerances implementation of
alignment systems and motorized jacks.
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INTRODUCTION
The status concerning these alignment functions
The alignment systems for monitoring

• A combination of two alignment systems HLS
  (Hydrostatic Leveling System) based
• on the principle of the communicating vessels,
  and WPS (Wire Positioning System) based
• on offsets measurements, using capacitive
  technology.
• Remote electronics located in UPS galleries. The
  sensors have been validated under
• irradiation test facility.

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INTRODUCTION
The status concerning these alignment functions
The alignment systems for monitoring ? Status

• Alignment systems installed and commissioned on 5
  triplets (1L, 2R, 5R, 8L, 8R)
• Position given by the sensors is coherent with
  the position calculated by the standard
• instrumentation (stretched wires, optical
  leveling, LTD measurements)
• Invar measurements are not available on both side
  of ATLAS or CMS (first results
• expected in three weeks)
• Main problem encountered EMI interferences on
  the sensors readings
• The invar rods support is not designed to cope
  with longitudinal displacements of the
• quadrupoles higher than 2mm, once installed.
• The boreholes in which are installed the invar
  rods were not drilled properly they
• are not straight and ovalizing over years.

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INTRODUCTION
The status concerning these alignment functions
The motorized jacks

• For schedule matters, we decided to use standard
  LHC cryo-magnets jacks (with slight
• modifications) and to motorize them (range of
  the motorization 2mm, resolution of
• a displacement a few microns).
• The inner triplet review pointed out that there
  was an over-determinated longitudinal
• restraining of the triplet because of the
  combination of the jacks fixed to ground and
• the tie-rods.
• ? once the triplet is pre-aligned and smoothed
  dismounting of the longitudinal
• adjustment mechanism
• Bumpers are added on each side of the triplet in
  order to block the triplet longitudinally.

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INTRODUCTION
The status concerning these alignment functions
The motorized jacks ? Status

• The longitudinal position of the triplet is
   floating  when tie-rods are removed and
• the longitudinal adjustment mechanism is not
  reinstalled. The quadrupole Q2 is held
• by the tie-rods and can not be adjusted
  differently.
• Since the beginning of the project, the jacks
  have to cope with loads that are far higher
• or lower than expected. Last example a load of
  more than 14 tons is applied on at least
• 3 central jacks (triplet 2R, 1L, 1R).

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INTRODUCTION
Some improvements, proposals for the new triplet
Concerning the cold mass and fiducialisation

• To perform fiducialisation under cold conditions
  at CERN (cold bench needed)
• To be sure that there will not be any
  displacement of the cold mass in process of time
• use of a dedicated system, which would monitor
  the displacements of the cold mass
• inside the cryostat during key phases (from the
  fiducialisation to the installation in the
• tunnel, during the pressure or vacuum tests and
  cool down).
• A strict compliance to the technical
  specification concerning the position of the cold
• mass and the beam tubes.
• To install references on the cold mass better
  than the existing ones (with redundancy,
• better repartition, non-detachable, easily
  accessible). These references would allow a last
• control after installation of the quadrupole.
• On a rigid cryostat, better positioning of the
  fiducials (we could for example adjust
• the fiducials dedicated to the monitoring
  during the fiducialisation) and of the
• jacks interface on the cryostat. ? To tighten
  the mechanical tolerances of the cryostat.
• The jacks interface on the cryostat will have to
  be improved.

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INTRODUCTION
Some improvements, proposals for the new triplet
Concerning the alignment

• Before the dismounting of the  old  triplet, we
  need to re-determine the local
• geodetic network, in order to keep the good
  geometry and colinearity of the triplet,
• and apply it to the new one.
• The link between the two triplets, through the
  boreholes and the UPS galleries must
• be kept in order to have a good colinearity of
  the triplets. For that, the fiducials
• will be needed in front of the boreholes, and at
  this place the cryostat will have to be
• reinforced. According to the layout of the
  magnets, the boreholes will perhaps have to be
• enlarged.
• The standard methods performed (offsets to a wire
  and leveling) for the initial
• alignment must be kept, but some space for line
  of sights must be protected, especially
• in case of the installation of shielding around
  the triplet.
• Concerning the maintenance of the alignment,
  knowing that the access in the area will
• be restrained, one idea for an optimization
• - to install an HLS sensor linked to the
  triplet network, far in the tunnel, which
• will allow to connect the triplet to the LSS in
  vertical

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INTRODUCTION
Some improvements, proposals for the new triplet
Concerning the alignment

• To monitor the longitudinal position of each
  quadrupole
• To perform the tests on the triplet once the
  alignment systems are installed, in order to
  monitor the displacements.
• To exchange the position of the monitoring
  /standard fiducials, in order to access
• easily to the standard fiducials during the
  measurements. (not possible now because of the
  DFBX).
• The design of the reinforcement on the cryostat
  must be performed in such a way that the
  fiducials are as close as possible from the
  cryostat, and are not hidden by the
  reinforcement.
• Integration of all the equipment volumes as soon
  as possible in the 3D layouts of the area, in
  order to avoid last minute interfaces (vacuum
  equipment was not in the 3D layouts), and taking
  into account the access to equipment.

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INTRODUCTION
Some improvements, proposals for the new triplet
Concerning the jacks

• To know as soon as possible the layout of forces
  applied on the triplet, for all configurations of
  test, in order to chose the jack which will suit
  the best, and if possible avoid the tie-rods.
• To increase the range of displacement of the
  jacks.

• Some question marks the remote repositioning
  (to be tested in 2 weeks) and the rigidity and
  flexibility of the interconnections during these
  displacements.