1. ALIGNMENT OF THE NEW TRIPLETS
STARTSLIDE
ALIGNMENT OF THE NEW TRIPLETS
Hélène MAINAUD DURAND

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

3. The alignment functions
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

4. The status concerning these alignment functions
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

5. The status concerning these alignment functions
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.

6. The status concerning these alignment functions
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.

8. The status concerning these alignment functions
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.

9. The status concerning these alignment functions
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.

10. The status concerning these alignment functions
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.

15. The status concerning these alignment functions
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.

16. The status concerning these alignment functions
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.

18. The status concerning these alignment functions
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).

19. Some improvements, proposals for the new triplet
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
jack’s interface on the cryostat.  To tighten the mechanical tolerances of the cryostat.
The jack’s interface on the cryostat will have to be improved.

20. Some improvements, proposals for the new triplet
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

22. Some improvements, proposals for the new triplet
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.

23. Some improvements, proposals for the new triplet
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.