1. STREGA C2:Cryogenic suspension system for advanced resonant detectors (5 MIN) Task -C2: development and construction of advanced cryogenic system for resonant detectors; The double task of removing the heat from the antenna resonator while keeping it mechanically isolated from the environment is similar to the one that will be encountered in the cooling of the interferometer mirrors. Although the ultra cryogenic detectors have been successfully operated, further advances in cooling and/or isolating the antenna can be achieved via finite element modelling and experimental tests. Objective: - Two 1.2 ton spheres with their cryogenic suspension assembled and measurements of mechanical quality factor and thermal noise at low temperatures performed. Participants: INFN * -Istituto Nazionale di Fisica Nucleare MiniGRAIL-Leiden University – LION Institute of Physics * Involved labs: Ferrara, Firenze, Genova, Frascati, Legnaro, Napoli, Padova, Perugia, Pisa, Roma 1, Roma 2, Trento, Urbino

2. STREGA C2:Cryogenic suspension system for advanced resonant detectors (5 MIN)

3. STREGA C2:Cryogenic suspension system for advanced resonant detectors (5 MIN) Cooling MiniGRAIL 78 mK after 37 days. Heat leak of about 50 microW- Hydrogen? Internal stresses?

4. STREGA MiniGRAIL MaterialCuAl6% Diameter = 0.65 m MassM = 1150 kg Resonant freq. f = 3160 Hz Goal temperature ~ 20 mK Expected sensitivity h~10 -20

5. STREGA Vibration Isolation System

6. STREGA Vibration Isolation System

7. STREGA Vibration Isolation System 30 dB around 3 kHz 70 dB around 3 kHz

8. STREGA Vibration Isolation System

9. STREGA Vibration Isolation System

10. STREGA Vibration Isolation System

11. STREGA Vibration Isolation System

12. STREGA To 50 mK shield To mixing chamber Cryogenics Thermal anchoring suspension To still shield

13. STREGA Cryogenics Thermal anchoring suspension

14. STREGA C2:Cryogenic suspension system for advanced resonant detectors (5 MIN)