1. Active isolation Target : a low cost dedicated table
Laurent BRUNETTI
LAViSta Team
LAPP-IN2P3-CNRS, Université de Savoie, Annecy, France &
SYMME-POLYTECH’SAVOIE, Université de Savoie, Annecy, France

2. Transfer function of ~1 between the floor and the support
2 possible approaches
The choice depends on the coherence of the ground motion and the tolerances.
Rigid support : ATF2 approach
Active isolation : CLIC approach ?!
Rigid bloc
Use of beeswax in order to obtain a very good transmission of the floor vibrations.
The study of an efficient but expensive industrial solution
Transfer function of ~1 between the floor and the support
Beeswax
No beeswax (fixed on the fllor) 2

3. The principle 4 active and passive feet
4 coupled feet
Behavior of the feet when the table is off (passive part) : 3

4. Requires active isolation Δf Passive isolation is efficient
The previous stage
A small and elementary mock-up : an association of active and passive isolation
The passive layer :
Requires active isolation Δf
Passive isolation is efficient
Resonant frequency of the rubber
 Active layer : tested in simulation, but not very adapted for efficient tests. 4

5. The approach The assumptions :
Possibility to integrate active isolation
Active isolation
A rigid structure can be considered
Possibility to integrate passive isolation
Passive isolation
The requirements which are not completely defined (study in progress) :
The number and the location of the magnet supports.
The type and the design of the magnet.
 From these considerations, an intermediary stage was carry out. 5

6. The build prototype An association of active and passive isolation :
Possibility to adapt a support in order to place a mass or a magnet prototype
The active isolation
Active isolation
A rigid structure ( a concrete of 290 Kg and 610x530x350 mm)
Passive isolation
The passive isolation 6

7. Expected results about fo < 15 Hz
The passive isolation
The product :
The specification :
Produced by Wattelez
Expected results about fo < 15 Hz
The results :
Transfer function
~55 Hz
- No feet (concrete block placed directly on the floor with beeswax)
- With passive feet 7

8. The passive isolation Tests and results : 24 bricks of 8 kg
~12 – 14 Hz
Transfer function
No feet (concrete block placed directly on the floor with beeswax)
With passive feet – no load : 290 Kg (55Hz)
With passive feet – 16 bricks : 420 Kg (50Hz)
With passive feet – 24 bricks : 500 Kg (45Hz)
~45 Hz 8

9. The status Solution n°1 : Solution n°2 : Investigations : Wattelez
Paulstra
The principle is different and it seems that it allows to obtain a lower eigenfrequency.
Solution n°2 :
To build a new one (some ideas were proposed)
Investigations :
It requires to check if the passive part doesn’t have a bad influence in the others directions….
Possibility to use the Guralp sensors of CERN ?
TMC table OFF 9

10. - A stacking of PZT patches – (APA)
The active isolation
A triangular table with PZT actuators :
3 actuators, so an ISO positioning.
The actuators can be managed simultaneously (1 sensor) or independently (3 sensors).
A mass or a magnet prototype can be placed.
Cedrat actuators :
Force = 102 N
Maximal displacement = 76 μm
Resolution = 0,8 nm
- A stacking of PZT patches – (APA)
 Will be tested in closed loop when the problem of the passive isolation is solved. 10