Alignment systems in ATLAS: Monitoring of the bedplates ETH Zürich, 02/09/2014 Hélène Mainaud Durand

ATLAS

HLS = Hydrostatic Levelling System Based on the principle of the communicating vessels Free surface of a water network provides the reference frame Fluid = demineralized water + biocide additive Different technologies in order to measure the vertical distance to the water surface : capacitive, ultra sonic, optical

HLS : capacitive technology Resolution: 0.2 μm Range: 5mm Repeatability: 1 μm Based on Fogale Nanotech capacitive technology [1], they were developed for ESRF (European Synchrotron Radiation Facility) in France, in 1987, in order to perform the permanent vertical alignment of the Storage Ring. Sensors were then upgraded when used at CERN and KEK.

Monitoring of a large infrastructure: ATLAS with HLS

Monitoring of a large infrastructure: ATLAS with HLS

Origin of seisms perturbing HLS readings in 2005

Monitoring of the installation of one detector: calo barrel

Monitoring of the installation of calo barrel USA C M US BED

Alignment systems in LHC: Monitoring of the low beta quadrupoles ETH Zürich, 02/09/2014 Hélène Mainaud Durand

Monitoring of Machine Experiment Interface Alignment tolerances are getting increasingly tighter Last genereation and future accelerators ask for monitoring Most critical area of accelerator are final focus magnets Limit exposure of personnel to radiation (ALARA) Sensors need to be radiation hard and to resist high magnetic fields

System monitors the co-linearity of focusing magnets Systems based on capacitive sensors HLS, WPS and DOM Electronics seperated from sensors Positioning of one inner triplet to the other at ±0.1 mm Relative precision inside one triplet few μm level

HLS, WPS and DOM Sensors HLS: Monitoring a ‘large’ plane water surface (communicating vessels) Resolution : 0.1μm, repeatability : 1 μm Range: 5 mm or 10 mm WPS: Monitoring a ‘long’ direction, 2D measurements conducting stretched wire (carbon peek) Range: 10 mm by 10 mm DOM: Monitoring a ‘short’ distance within distance and calibrated invar rod Range: 10 mm 100 mm

WPS and DOMS

Installation in LHC tunnel Dirk MERGELKUHL - 14.07.2014

Motorized jacks for focus magnets Manual adjustment is time consuming ALARA – As Low As Reasonably Achievable Magnets are adjustable remotely using jacks, stepper motors, reducer, angular encoders, CERN made DAQ system Load sensors on top of jacks (magnet ~ 15 t)

Adjustment of final focus magnet Short term monitoring during adjustment Adjustment in two steps Displacement of 220 μm wthin 5 μm (HLS+WPS)