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Task M2 – Advanced Materials and Techniques for Resonant Detectors. Motivation : Reduce thermal noise contribution to the acoustic detector noise budget. Task M2 – General Strategy. A) Reduce thermal noise power spectrum.
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Task M2 – Advanced Materials and Techniques for Resonant Detectors Motivation : Reduce thermal noise contribution to the acoustic detector noise budget.
Task M2 – General Strategy A) Reduce thermal noise power spectrum • Find the materials with the lowest mechanical and/or electrical dissipation and suitable to be cooled down at cryogenic temperatures (Mo,Be,SiC,CuAl,….) • Find the assembling and joining procedures that preserve the Q-factor of the material (explosion welding, silica bonding…)
Task M2 – General Strategy B) Reduce the relative contribution of thermal noise (i.e. increase the transducer efficiency a) For the capacitive transducer: a is proportional to the Electric bias field For the optical transducer: a is prop. to the laser Power1/2 time the Finesse Surface treatments, two faces transducer,..
Task M2 – Advanced Materials and Techniques for Resonant Detectors Main outcomes : • Low temperature measurement of the mechanical Q, thermal expansion and heat capacity of several materials (Mo,Be,CuAl,SiC…). -Find joining procedures (electron beam, explosion beam welding, silicate bonding) and surface treatment which preserve high Q-factors . - Low temperature measurement of dielectric losses. - Construction and test of high sensitivity and of low loss capacitive and optical displacement transducers
Task M2 – Advanced Materials and Techniques for Resonant Detectors
M2.1 - Construction of first CuAl, SiC and Be resonators Working groups Rog, Auriga LNL,Leiden Apr04-Sep04 “Pure” resonators Transducer resonators Mo Be CuAl (ROG,Leiden) Hot Isostatic Pressure (ROG,LNL)
M2.1 - Construction of first CuAl, SiC and Be resonators Working groups Auriga LNL, IFN C/SiC resonator: status Best geometry under investigation “..The size of the structures that can be manufactured is limited by the scale of the currently available facilities (3mx3mx4m)...”
M2.3 -Low T and low frequency, Q measurements on CuAl, SiC and Be Working groups Leiden, Auriga LNL, IFN, ROG Apr04-Sep05 First results for CuAl resonators: Q300K=20000, QLN2=(3-5)x104, QLHe4=(5-10)x105 For the other materialsmeasurements will be done at LNL: the last stage of suspension has to be designed and tested with high Q resonators Optical read-out (ready) Capacitive read-out (for metal samples)
M2.3 -Low T and low frequency, Q measurements on CuAl, SiC and Be LNL Cryogenic test facility, optical readout
M2.2 -Construction of Optical and Capacitive transducers Apr04-Sep04 Optical Transducer: Working groups Auriga Fi,Pd,LNL Construction of the optical transducer is complete Only Resonator Assembled Low T Q-factor measurements in the TTF
M2.2 -Construction of Optical and Capacitive transducers Optical Transducer: Next step (Spring 2005) Up-grading
M2.2 -Construction of Optical and Capacitive transducers Apr04-Sep04 Capacitive Transducer: Working groups Leiden, Rog Many Capacitive transducer has been constructed • Rosetta Transducer, CuAl, gap 15 mm, freq= 3200 Hz • Double face transducer, Al5056 , freq=920 Hz ROG • Rosetta Transducer • Drum Transducer + Bolt free assembling Leiden MiniGrail Transducer
T= 5 K M2.4 Test of a metallic transd. on a resonant sphere Oct04-Dec05 Working groups Leiden, ROG SQUID output PSD Thermal noise dominated at 5K MiniGrail
M2.5 Effect of the dielectric coating on the thermal noise Apr05-Dic05 Working groups Rog,IFN, Leiden, Auriga LNL • Electric losses: measure of the electrical quality factor of a cryogenic LC resonator. The dielectric under investigation fills the capacitor gap. Sensitivity of the existing apparatus (IFN) d=10-6. • Mechanical losses: measure the quality factor of transducers having dielectric coating. The available facilities are ROG, Leiden, LNL
M2.6 - Experiments on limiting bias electric fields in the capacitive transducer Working groups Leiden, IFN, Auriga LNL Oct04-Dic05 • Typical value for operating detectors 10-15 MV/m • Best result 25MV/m Leiden-MiniGrail July 2004 • Test of surface treatment on small sample (goal 100 MV/m). Experimental set-up (ready) Samples (ready) • Al5056 • Diameter 3 cm • Single point diamond turning (optical quality) • Dielectric coating (if need) still to be done
M2.9 - Q of silicate bonding on SiC at low T (as part of improving fabrication processes) Working groups Auriga LNL, Virgo MAT, IGR MAT Apr05-Dec05 Assemble the resonators using silicate bonding and then measure the mechanical quality factor Silicate Bonding
Task M2 – Advanced Materials and Techniques for Resonant Detectors Conclusions • Almost all the objective of the first 6 months as been obtained. • According to the time schedule the second part of the program has begun.