1. Io ILIAS - STREGA MEETING
Fulvio Ricci
Dipartimento di Fisica, Università di Roma La Sapienza
&
I.N.F.N. Sezione di Roma
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

2. Io ILIAS-STREGA meeting
The VIRGO-CRYO tasks
The final goal of VIRGO-cryo is the construction of full scale prototype of a suspended test mass at cryogenic temperatures
The final goal is reached by merging the activity of task C1 and C3 during the last (4th) year of the project
Task C1 : main activity ==>>the cryogenic payload ( lower part) -->> “Roma La SAPIENZA”
Task C3 :main activity ==>>the cryogenic super-attenuator (upper part) -->> “INFN PISA”
There are several items in common between C1 and C3 also during the first part of the project : for example the development of sensor and actuators at low temperature, the simulation software …..
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

3. Io ILIAS-STREGA meeting
Frossati G., Leiden University, Leiden, The Netherlands
Gammaitoni L., INFN Perugia
Gennai A., INFN Pisa
Giazotto A., INFN Pisa
Giordano G., LNF INFN, Frascati
Guidi G., INFN Firenze/Urbino
Hello P., LAL-Orsay IN2P3/CNRS
La Penna P., EGO
Losurdo G., INFN Firenze/Urbino
Majorana E., INFN Pisa
Marchesoni F., INFN Perugia
Martelli F., INFN Firenze/Urbino
Mazzoni M., INFN Firenze/Urbino
Milano L., INFN & University Federico II, Napoli
Palomba C., INFN Roma
Passaquieti R., INFN & University of Pisa
Passuello D., INFN Pisa
Perniola B., INFN Firenze/Urbino
Punturo M., INFN Perugia
Puppo P., INFN Roma
Rapagnani P., INFN & University La Sapienza, Roma
Ricci F., INFN & University La Sapienza, Roma
Stanga R., INFN Firenze/Urbino
Vetrano F., INFN Firenze/Urbino
Vicere' A., INFN Firenze/Urbino
Vocca H., INFN Perugia
Acernese F., INFN & University Federico II, Napoli
Babusci D., LNF INFN, Frascati
Barone F., INFN Napoli & University of Salerno
Barsuglia M., LAL-Orsay IN2P3/CNRS
Bizouard M.A., LAL-Orsay IN2P3/CNRS
Brisson V., LAL-Orsay IN2P3/CNRS
Braccini S., INFN Pisa
Bradaschia C., INFN Pisa
Brocco L., INFN & University La Sapienza, Roma
Calloni E., INFN & University Federico II, Napoli
Cattuto C., INFN Perugia
Cavalier F., LAL-Orsay IN2P3/CNRS
Cella G, INFN & University of Pisa
Cuoco E., INFN Firenze/Urbino
Dattilo V., INFN Pisa
Davier M., LAL-Orsay IN2P3/CNRS
DeWaard A., Leiden University, Leiden, The Netherlands
De Rosa R., INFN & University Federico II, Napoli
Di Fiore L., INFN Napoli
Di Virgilio A., INFN Pisa
Dominici P., INFN Firenze/Urbino
Eleuteri A., INFN & University Federico II, Napoli
Ferrante I., INFN Pisa
Fidecaro F., INFN Pisa
Frasca S., INFN & University La Sapienza, Roma
Frasconi F., INFN Pisa
Contact persons: Fulvio Ricci Stefano Braccini )
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

4. Io ILIAS-STREGA meeting
R&D on Cryogenics
Liquid helium
Refrigerators
hybrid system
1) Study of the refrigeration system
- noise
- refrigeration power
2) Suspension compatibility: thermal conduction and acoustic quality factor Q measurements
3) Sensors at low temperatures
- accelerometers and position sensing devices
- actuators
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

5. Gravitational Wave group of the University of Rome La Sapienza &
ILIAS activity of the
Gravitational Wave group of the
University of Rome La Sapienza &
INFN Roma 1
L. Brocco, S. Frasca, G. Martinelli, M Perciballi, C. Palomba, P. Puppo, P. Rapagnani, F. Ricci, E. Serrani
The main R&D activities to achieve the realization of a full cryogenic suspension (task C1)
are focused on
Modification of a cryogenic facility hosting a new PTR refrigeration system for the mirror cooling
Low temperature monitor of the additional noise generated by the refrigeration system
Heat absorption measurements of the mirror substrates
Development of sensors and actuators for the position control of the mirror that are
compatible with the cryogenic environment
e) Design and construction of a suspension last stage protype for a cryogenic environment
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

6. Io ILIAS-STREGA meeting
An alternative way to cool down without liquid helium: the new generation of Cryocoolers
First stage
A "low frequency” Pulse Tube Refrigerator (PTR) or "G-M style" pulse tube cryocooler, is a variant on a Gifford-McMahon (GM) cryocooler. PTR operate at low frequencies, typically <5 Hz. They use a conventional oil-flooded G-M compressor and a valve set near the cold head to convert the continuous flow of helium from the compressor to a low frequency pressure wave. The cold head itself has no moving parts. Because of their low frequency and high pressure ratio (up to 5:1), these cryocoolers are best suited to low temperature applications, and are competitive with GM cryocoolers at temperatures below about 65 K. Typical efficiencies are in the range of 4 to 9% of Carnot cycle.
Second stage
Benefit
- Ideal for applications that require efficient operation
No moving parts in cold head.
Minimal vibration, low acoustic noise.
- High stiffness cold head allows mounting of heavy loads
without extra structural support
- High efficiency. 2 to 3 times higher efficiency than GM cryocoolers for loads load temperatures between 55 and 120 K.
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

7. Io ILIAS-STREGA meeting
PTR Integration in the Rome cryogenic facility
PTR
ready for
cooling
Cold head of
Pulse Tube Refrigerator
Vacuum chamber for
hosting the payload
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

8. Io ILIAS-STREGA meeting
The Rome cryogenic facility: acoustic insulation of the compressor station for PTR
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

9. Io ILIAS-STREGA meeting
First cooling test with PTR and a mirror sample: the thermal contact resistance
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

10. Io ILIAS-STREGA meeting
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

11. Elastic dissipation study at low temperature: the case of CaF2
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

12. Io ILIAS-STREGA meeting
Experiment setup
Scheme
Ring down method
Excitation
Hammer
Transducer
PZT on suspension
CaF2 sample
50 x 25 mm
Multiple loop suspension of NbTi
Setup side view
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

13. Results on a small sample of CaF2
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

14. Io ILIAS-STREGA meeting
Work to be done
- PT Refrigeration system : noise characterization to be completed in the low frequency region
In 8 weeks from now, we will start to set up the installation that includes the vibration compensation system
( we hope in the financial support of INFN Commissione II)
- New mirror suspension to reduce the thermal resistance which will be coupled to an elastic holder at 4K
Q measurements on CaF2 sample of 10 cm in diameter.
Parallel activity: study of an alternative design based on sub-cooled superfluid helium (at pressure of 1 bar)
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

15. Io ILIAS-STREGA meeting
Vibration measurements performed on the CRYOMECH refrigerator with piezo-accelerometers at low temperature
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

16. Io ILIAS-STREGA meeting
Displacement noise of the cold stage
Sensor noise
Vertical displacement
Horizontal displacement
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

17. Vibration free cryostat: modification of the Rome cryogenic facility
Conceptual scheme
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

18. Io ILIAS-STREGA meeting
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

19. Io ILIAS-STREGA meeting
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

20. C3 TASK To build an anti-seismic mirror suspension
with mechanical performance similar to VIRGO Superattenuators
and equipped with items for the extraction of the heat absorbed
by the mirror because of the impinging beam (< 1 W)
C3 task
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

21. Main Idea: Superattenuator mechanical filters coupled
with high thermal
conductivity stripes not affecting mechanical performances
Al / Cu
~1 m
~ 40 cm Z Y
30 cm x
1 cm
C3 task
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

22. Preliminary tests of strips has been already performed
1x1x70 cm Aluminum
l=60 cm
Set of stripes
Negligible Stiffness, Negligible effects on Q (measured)
Enough thermal conductivity at 4 K (on paper)
C3 task
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

23. Io ILIAS-STREGA meeting
Two possible strategies
COLD FINGER
Very Soft
Joint
Cryostat
COLD FINGER
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting
C3 task

24. Possible Improvement (valid for both strategy)
A Superattenuator of reduced size
(Prototype assembled for tests at Pisa INFN laboratories)
The new system exhibits less cryogenic incompatible items
(no magnets, no glue, no viton,…..) and could be used at 4 K
with minor modifications
C3 task
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting

25. Io ILIAS-STREGA meeting
Conclusions
We need to clarify the contribution of the various institution to the VIRGO cryo tasks
Specific meetings have to be organized
The experimental activity is already started at least in two labs
- Cooling strategy, excess noise and thermal resistance have been identified to be the preliminary topic of this R&D acivitys -
12th May2004
Fulvio Ricci
Io ILIAS-STREGA meeting