1. ET- WP2, Thermal noise issues Fulvio Ricci Assergi (L’Aquila) Laboratori Nazionali del Gran Sasso, February, 9th 2008

2. WP2 - Mission Pave the road to get the sensitivity of a GW detector as near as possible to 1 Hz, by seismic and thermal noise  Passive and active seismic attenuation  Low dissipation materials for mirror suspensions  Cryogenics: safety and noise compatibility in the underground environment

3. Next ET- WP2 workshop 26-27 February 2009 @Sapienza - University of Rome http://agenda.infn.it/conferenceDisplay.py?confId=1047 http://agenda.infn.it/conferenceDisplay.py?confId=1047 The workshop will be devoted to the thermal noise issues in GW future detectors. We will review the thermal noise models for advanced detectors and thermal noise issues for ET. A large part of the meeting will be devoted also to the upper suspension configuration.

4.  Tasks and involved Groups  Definition of substrates and coating properties at low temperature: Groups: LMA, Glasgow, INFN- Firenze/Urbino, INFN-Genova, INFN- Perugia, INFN-Padova/Trento……… Science team: Jena, Trieste(Cantatore)………  Design of Upper Suspensions: Groups: INFN-Pisa, EGO………  Design of Lower Suspension Mechanics: Groups: INFN- Roma1,INFN-Firenze, INFN-Perugia, INFN-Pisa, Glasgow…….  Design of Cooling System: Groups: INFN- Roma1, INFN-Roma2……..  Design of Lower Suspension Sensing and Actuation: Groups: INFN-Roma2, INFN-Napoli, INFN-Padova/Trento, INFN- Roma1…… Science Team: Genova (Vaccarone)……..  Design of Lower Suspension Fibers: Groups: Glasgow, INFN-Firenze/Urbino, INFN-Perugia, INFN-Pisa……… Major impact on ET Infrastruc tures Major impact on ET Infrastruc tures

5. 10 -19 10 -20 10 -21 10 -22 10 -23 10 -24 10 -25 Credit: M.Punturo LIGO Advanced LIGO/Virgo (2014) Virgo GEO-HF 2011 Einstein Telescope 1 10 10 2 10 3 10 4 Frequency (Hz) Ad LIGO/Virgo NB [Hz -1/2 ] Frequency [Hz] Assuming a Sensitivity Target for ET LIGO VIRGO

6. 6 Design of the cooling system The upper part is thermally insulated by thermal screens Cryo-Compatible Superattenuator design Tanks to R. Passaquieti

7. The Pulse Tube Cryogenerator Second stage First stage Compressor High pressure lines Lenght up to 20 m

8. Typical Performance of a double stage PT cryogenerator (PT 405)

9. The Prototype of Cryogenic Payload installed at the EGO West hall @1.5 km

10. Payload detailss Marionette Reaction Mas 100 kg Aluminums Marionette 100 kg s. steel and tungsten Mirror Reaction Mass ~20 kg aluminum Mirror (silicon (20 kg) Frame ~40 kg saluminum Cinese hat Titanium Ti6Al 4V

11. Cooling is started

12. Preliminary Displacement Spectra Room Temperature: Pulse Tubes OFF Mirror Temperature 126 K: Pulse Tubes ON

13. How to overcame the problem.on the way - Active damping of the harmonic excitations

14. 14 The Free Vibration Cryostat and its control chain Slide 0 S. Caparrelli, et al. Rev. of Sci. Inst. 77, 095102 (2006). T. Tomaru et al. Cryogenics, 44 (2004). ( Passive vibration insulation system for the cryocooler) i

15. 15 Vibration of the cold head reduced (@T=4K) The vibration reduction scheme works, but we need to improve it. The sensing will be modify to reduce the noise floor at closed loop. displacement noise density

16. The alternative scheme based on the production of Supefluid Helium

17. Cryostat design based on the so-called Claudet bath principle

18. Cryogenic Infracture Requirements The PT solution

19. Cryogenic Infracture Requirements The superfluid Helium solution

20. Further studies are needed PT solution – Increase the active damping efficiency – Increase the length of the high pressure lines – Increase the refrigeration power Superfluid helium solution - evaluation of the noise impact of the cryogenic facility - thermo acoustic insulation of the long transfer lines

21. Upper part suspension …..see the presentation of Adalberto Giazotto

22. LCGT project It is a 3km Fabry-Perot MI with a power recycling scheme and equipped with a broadband RSE. The laser power is 150W Main mirrors made of sapphire are cooled at 20K. A SPI impedes the refrigerator- vibration. It is built underground at Kamioka. Two independent interferometers are installed in one vacuum system. The main target is the coalescence of BNS, which can be detected 1.2-27.8 events per year at confidence level of 95% for mass 1.4Msun and S/N=10. Data Taking Starting in 2012 Cost: 132 M$ (without salaries and maintenace) Thanks to Prof. Kuroda - ILIAS Meetng