T3 considers two aspects of the thermal noise The problem of the interrogation area of the test mass. Small interrogation area means large fluctuations because of the higher modes contribution An average over higher order modes is needed ==> Wide area transducers The problem of the rejection of the non quadrupolar modes. These modes do not carry signal information but can spoil the detector bandwidth Suitable arrangement and connections of the transducers on the detector can reduce these effects Techniques to achieve a fine balancing of the sensitivity of the transducers are needed. STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes

STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes DUAL resonant mass detector concept spheres or cylinders Nested high cross section resonators M. Cerdonio et al., Phys. Rev. Lett. 87 (2001) M. Bonaldi et al., Phys. Rev. D 68 (2003)

DUAL resonant mass detector concept STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes measurement of the differential motion of the resonators No resonant transducers

STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes DUAL resonant mass detector concept measured quantity: X = x 1 +x 2 -x 3 -x 4 Selective read out

FF STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes DUAL resonant mass detector concept Displacement Gain Factor >10 First internal resonance > 5 kHz Optical or Capacitive or Microwave readout Mechanical amplifier

STREGA kick-off meeting, May 2004, Cascina Introduction T3 Development of selective read out schemes The T3 issues will be faced by studying, designing and if possible realizing transducer prototypes based on three displacement transduction methods: optical, capacitive, and microwave. evaluating, also with FEM analysis, the noise of a DUAL detector which employs one or more of these transduction methods Groups involved CNRS (LKB Paris) IFN (Trento) INFN (AURIGA LNL Legnaro, PACO Genoa, LENS Florence)