STABILISATION AND PRECISION POINTING QUADRUPOLE MAGNETS IN THE COMPACT LINEAR COLLIDER S. Janssens, P. Fernandez Carmona, K. Artoos, C. Collette, M. Guinchard The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD * ULB Scope: Compact Linear Collider (CLIC) 2 Lepton collider complementary to LHC Linear due to energy loss in turn 1 chance for collisions CLIC: Vert. Beam size 1nm at ip Hor. Beam size 40 nm at ip For high collision rate Scope: CLIC 3 The main beam accelerator: Accelerating structure: To accelerate the beam Quadrupole magnets: Mass kg Length mm 200 T/m To focus the beam after accelerating structures Problem: Misalignment of quadrupoles due to: Ground motion External forces (watercooling, ventilation,) Result: Beam-Beam offset (missing each other) Beam growth (fewer collisions) Accelerating structure Stabilisation Requirements Goal for 3992 CLIC Main Beam Quadrupoles: Stability vertical magnetic axis 1.5 nm int. 1Hz Stability lateral magnetic axis 5 nm int. 1 Hz 4 Type 4: 2m, 400 kgType 1: 0.5 m, 100 kg A. Samoshkin Additional requirements: Modify position of quadrupoles: Range 5 m Increments 10 to 50 nm Precision 0.25 nm Available Space Compatibility alignment Transportability Stray magnetic fields + radiation DNA 2 nm Characterisation ground vibration 5 Cultural noise -Human activity -Incoherent -Highly variable Earth noise - Coherent Micro seismic peak -> Sea waves Reduced by Method 1: Beam based feedback Deeper tunnel 2-5 nm int. 1Hz Reduction needed 0.7% Courtesy of J. Pfingstner Current study 18 Vibration sensor requirements: Resonance frequency: 5 Hz +/- 1 Hz Maximum overshoot d max : 2 Spurious modes: >100 Hz Sensitivity: [V/ m] Operating temperature: C Temperature sensitivity: 1 m/C Humidity: 20-80% Radiation level Gy/year Stray magnetic fields Maximum defined noise curve based on simulations PACMAN subjects 19 Increasing range of actuators to mm: Reduce time between realignment Increase robustness against temperature changes Larger range to use quadrupoles as dipoles With similar precision! Required redesigns: New actuator/New combination of actuators New guidance system Adapted relative measurement system A. Samoshkin Conclusions 20 A feedback + feedforward system with stiff piezo actuator was chosen to cope with external forces on the system to the nano metre level. It was demonstrated with models and in a test bench that it is technically feasible to stabilise and position a mass better than the required level at 1Hz. A concept design of the stabilisation support based on the validated actuator pair with is being constructed. Spares