Topics on Vibration Issues Report from Nanobeam 2005 Topics on Vibration Issues Alessandro Bertolini DESY

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Topics Ground Motion Studies (DESY) Cold Quadrupole Vibration Measurements (BNL) Interferometric Position Sensors (Oxford et al.) Active vibration suppression (LAPP-Annecy) Comments

Ground Motion Studies Ramila Amirikas for Motivation Study the impact of ‘cultural noise’, f >1 Hz, at several accelerator laboratories & synchrotron light sources Site comparison for future accelerators Use of the same equipment and data analysis software for every site to get comparable data set

Ground Motion Studies Ramila Amirikas for Weekday and Weekend Comparison Seismic Station HERA – WL745

Ground Motion Studies Ramila Amirikas for Site comparison and characterization

Ground Motion Studies Ramila Amirikas for Corresponding integral spectrum

Ground Motion Studies Ramila Amirikas for Peak-to-peak data as an additional information on a site

Ground Motion Studies Ramila Amirikas for Peak-to-peak data as an additional information on a site

Ground Motion Studies Ramila Amirikas for Visit the website and download the vibration data

Cold mass vibration at RHIC Animesh Jain for Experiment Measure the relative motion between the cold mass and the cryostat cold mass accessible via viewports evaluate the effects of flowing He a spare RHIC quadrupole at 4.5 K have been tested

Cold mass vibration at RHIC Animesh Jain for 1 nm/Hz

Cold mass vibration at RHIC Animesh Jain for Experimental setup

Cold mass vibration at RHIC Animesh Jain for Experimental setup

Cold mass vibration at RHIC Animesh Jain for Instrumentation Fiber optic differential interferometer Mach-Zender heterodyne interferometer with access to both the beams a DSP extract relative velocity and displacement between the two targets noise 1.5 nm RMS integrated from 1 Hz

Cold mass vibration at RHIC Animesh Jain for

Cold mass vibration at RHIC Animesh Jain for

Cold mass vibration at RHIC Animesh Jain for Summary The measurement shows a small increase in the horizontal motion at a few frequencies with the cryogenic flow No evidence of a systematic increase of the vertical motion of the cold mass with respect to the cryostat encouraging for the use of superconducting quadrupoles in ILC My comments The measurements look polluted by some experimental “bias”, as confirmed by the authors in a ‘offline’ discussion Stiffer optical head stand may have to be designed

The STaFF Project David Urner for Fast Beam-Beam Feedback Receipe Measure with IP BPM’s the beam misalignment A DSP triggers fast stripline kickers to adjust beam pointing Latency goal: 140 nsec (3 iter.) JAL proposal Measure the relative motion of the cold masses Use the fast beam-beam feedback kickers to steer the beams, instead to move the quadrupole The relative motion data provide additional, alternative, independent input channels for the DSP-fast kicker system G. White (QMUL/SLAC)

The STaFF Project David Urner for JAL Philosophy “Measure the relative motion of the quadrupoles interferometrically” “The cold mass must to be accessible, even the QD0 which is expected to be hosted in the detector” “Lines-of-sight required, maybe in region of muon system”

Reference Interferometer The STaFF Project David Urner for JAL Distance meters Frequency Scanning Interferometer for precision DC alignment at micron level (LICAS heritage) Hardware-sharing Michelson interferometer for fast motion sensing at nanometer level (still debugging) Laser Reference Interferometer DAQ Wavelength: 1550nm Scanning speed: 40nm/sec Distance Meters Optical Amplifier

The STaFF Project David Urner for JAL Straightness monitor to be tested at ATF-KEK Use Michelson distance meters for 6 degrees of freedom relative position measurement The relative position information is transferred by the “reference” (black) triangle Optical layout simulation set “challenging” constraints on beam pointing (about 100 nrad) Ceiling node 2 Ceiling node 1 A B Floor node

Active stabilization studies Benoit Bolzon for brand new activity on the learning curve aim to actively control the vibrations of the quadrupole coil assembly Capabilities Vibration isolated platform heritage of CLIC studies (see the picture) Conventional and electrolytic seismometers FEM of mechanical structures for modal analysis

Active stabilization studies Benoit Bolzon for Perspectives Build a simplified mock-up of the quadrupole coil assembly Numerical modal analysis Simulations to optimize inner support design and materials Active control simulations

Final Comments Site choice looks crucial as well as technical noise sources not included in site characterization: we can’t be marginal ! Full-Active vibration suppression inside the FF Cryostat (Annecy) looks extremely hard! Optical anchor-like systems still to be demonstrated in the “crowdy” detector area and they are very tricky (personally I don’t like something which is not inertial..) Fast Beam-Beam Feedback is promising (waiting for ATF tests), but if it’s not able to take charge of the whole business ?