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

2. Latest preview of Final Focus Hardware

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

4. 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

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

6. Ground Motion Studies Ramila Amirikas for
Site comparison and characterization

7. Ground Motion Studies Ramila Amirikas for
Corresponding integral spectrum

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

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

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

11. 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

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

13. Cold mass vibration at RHIC
Animesh Jain for
Experimental setup

14. Cold mass vibration at RHIC
Animesh Jain for
Experimental setup

15. 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

16. Cold mass vibration at RHIC
Animesh Jain for

17. Cold mass vibration at RHIC
Animesh Jain for

18. 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

19. 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)

20. 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”

21. 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

22. 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

23. 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

24. 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

25. 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 ?