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Ultra-cryogenics for advanced resonant detectors (C2). G.Frossati Kamerlingh Onnes Laboratory Leiden, The Netherlands. Second ILIAS-GW Meeting October 24-25 2005 Palma de Mallorca. Sensitivity. Minimum detectable energy T eff =T/ Q +2T N. Need ~0.05; Q~2x10 6 : T~30 mK.
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Ultra-cryogenics for advanced resonant detectors (C2) G.Frossati Kamerlingh Onnes Laboratory Leiden, The Netherlands Second ILIAS-GW Meeting October 24-25 2005 Palma de Mallorca
Sensitivity Minimum detectable energy Teff=T/Q +2TN Need~0.05; Q~2x106: T~30 mK
SQUID noise decreases with T 0.38 0
ROG SQUID • Double SQUID made of a sensor d.c. SQUID, developed by the Institute of Photonic and Nanotechnologies of CNR, and a commercial Quantum Design d.c. SQUID as a preamplifier. • Open input and in open loop configuration:28hbar at 4.2 K and 5.5hbar at 0.9 K. • Feedback network :37hbar in closed-loop open-input 4.2K. • With a high-Q resonant input load :70hbar at 2 K.
Next: 33 ton sphere ? Project together with the Roma group to be submitted to INFN hQL≈4x10-24/√Hz hQL≈4x10-23/√Hz
Cooling from 300K Fill liquid helium
Forced flow MiniGRAIL 1.3 +1 ton N2 1200 L 800 L He
ROG-Leiden-Geneva project: to be submitted to INFN SFERA 33 +7 ton 20000 N2 14000 L He ! Use 4 GM cryocoolers for pre-cooling from 300K to 20K Use 4 PT410 for cooling to 4K and for the dilution refrigerator GM600 (Cryomech) 1200W at 250K PT400 60W at 60K and 1W at 4.2k Heat to remove ~70J/gm ~2.8x109J Cool-down time ~2 weeks to 4k
1k POT HEAT FLOW Dilution Refrigeration; Schematic view CIRCULATION SYSTEM STILL • HEAT EXCHANGER • MIXING CHAMBER TMC HEAT ABSORPTION REGION
Pulsed tube dilutionrefrigeratorJoule Thompsonheat exchanger replaces the 1K pot: No need for Helium bath PTR 50K 4K JT Heat exchanger 600 mK 60 mK Mixing Chamber 10 mK
Strain sensitivity MiniGRAIL f=1000 Hz f=100 Hz f=10 Hz 2m CuAl6% sphere