ILIAS meeting Mallorca 2005 V. Fafone Viviana Fafone INFN - LNF Future plans for resonant detectors

ILIAS meeting Mallorca 2005 V. Fafone CERN RE 5 LNF INFN MiniGrail Leiden LNL INFN

ILIAS meeting Mallorca 2005 V. Fafone Used to improve suspension system design Wideband readout design New devices and methods are now available Superconductive amplifier sensitivity improved by a factor of 100 Optical and parametric readout for acoustic detectors Methods to develop large masses (100 ton) New high cross section materials Readout systems: FEM analysis: Test masses:

ILIAS meeting Mallorca 2005 V. Fafone EXPLORER WIDENING THE BAND… NAUTILUS 2001 AURIGA

ILIAS meeting Mallorca 2005 V. Fafone 3· No veto applied The duty cycle is limited mainly by cryogenic operations and for most of the time is about 90% The apparata show constant performances. The data are not affected by human activity in the lab. NAUTILUS DATA TAKING DURING 2005

ILIAS meeting Mallorca 2005 V. Fafone EXPLORER - 5 April 2005 – a working day 1h starting 1am 1h starting 11am night day

ILIAS meeting Mallorca 2005 V. Fafone Noise budget is well understood T eff ~ 2mK h ~ Present limit from amplifier noise reference signal Present Status of EXPLORER

ILIAS meeting Mallorca 2005 V. Fafone Very good agreement with noise predictions all these noise sources will scale with temperature one-sided S hh Present Status of AURIGA

ILIAS meeting Mallorca 2005 V. Fafone To improve sensitivity: We need to improve the peak spectral sensitivity -Increase M: large and/or multimode detectors -Reduce T/Q : ultracryogenics. Low-loss materials We need to increase the bandwidth -Increase the coupling of the e.m. transducer -Reduce the noise temperature of the amplifier (double SQUIDs)

ILIAS meeting Mallorca 2005 V. Fafone S h for 0.1K, parametric transducer (m = 1 kg) T eff ≈ 6  K, sensitivity < 1· /√Hz over about 50 Hz. S h for 0.2K, capacitive transducer M3 - R. Parodi INFN Genova

ILIAS meeting Mallorca 2005 V. Fafone TOWARDS MORE POWERFUL AND SENSITIVE ACOUSTIC DETECTORS

ILIAS meeting Mallorca 2005 V. Fafone “…This paper suggests the following scenario for future detector development in this field: In the medium-term, the realization of a spherical detector, to be proposed now to the funding agencies, In the longer term, research toward wideband resonant detectors using Dual Detection techniques. GWIC Scenario for future detectors in the resonant-mass field

ILIAS meeting Mallorca 2005 V. Fafone GWIC Scenario for future detectors in the resonant-mass field A spherical detector can make use of the state of the art readout technology, developed for the bars and for MiniGrail, profiting from a larger mass and from the omnidirectional nature of the spherical detectors. Such a detector could have a sensitivity competitive with VIRGO and LIGO in the 1 kHz region. And since it allows full sky coverage during all observation time, and determination of the source direction, it can have an important role in a coordinated coincidence search. Since the principles of operation and technology are well understood, a funding proposal could be prepared soon. Research and development work on wideband resonant detectors using Dual Detection techniques is valuable because it offers the potential for a detector having unprecedented sensitivity in the band 1 to 7 kHz. …”

ILIAS meeting Mallorca 2005 V. Fafone sensitivities in the prospective GEO The sphere has a quality factor due to the isotropy not shown in the plot adv LIGO/adv VIRGO

ILIAS meeting Mallorca 2005 V. Fafone Thanks its five quadrupolar modes, equally sensitive to gravitational waves: Properties of spherical detectors: a summary… Reconstruction of the metric tensor (polarization states and arrival direction) Omnidirectionality Multi-frequency capability Testing different metric theories of gravity

ILIAS meeting Mallorca 2005 V. Fafone The experimental situation 1.MiniGRAIL -Fast cooling of large masses (60 mK already achieved) -Investigation of new material (CuAl 6%) - Q’s, effect of the suspension and trx fabrication - Coupling of transducers with the sphere

ILIAS meeting Mallorca 2005 V. Fafone 2. TIGA experiments TIGA arrangements TIGA experiments The experimental situation

ILIAS meeting Mallorca 2005 V. Fafone To allow the detection and identification of GW signals it is useful to complement the IFO network with an advanced resonant-mass observatory Added value Duty cycle Sky coverage Instruments based on different principles Strategy: Realization of a Resonant-mass GW Observatory Complementing the IFO Network VIRGO - SFERA 2mfirst hybrid observatory

ILIAS meeting Mallorca 2005 V. Fafone The short term proposed detector: SFERA 2 m dia, CuAl M = 33 tons f1 = 1.0 kHz f2 = 1.9 kHz The Collaboration INFN (I) University of Geneva (CH) University of Leiden (NL) Cost ~ 3 MEURO

ILIAS meeting Mallorca 2005 V. Fafone Mixing chamber Sintered heat exchanger 50 mK plate still Joule-Thomson heat exchanger 3 He pumping tube 50 mK radiation shield 700 mK radiation shield 4 K radiation shield Continuous heat exchanger Pulse tubes 80 K radiation shield C2 - G. Frossati, Leiden

ILIAS meeting Mallorca 2005 V. Fafone At the final sensitivity an underground location will be probably necessary, to avoid cosmic ray noise M6 - G. Mazzitelli, INFN - LNF

ILIAS meeting Mallorca 2005 V. Fafone If funded in January 2006 Assembling and tests during Commissioning at the beginning of 2008 Science Run at the beginning of 2009 SFERA

ILIAS meeting Mallorca 2005 V. Fafone DUAL detector is based on new ideas 1 – Wideband transducer: read displacement signal between two massive resonator - M. Cerdonio et al. Phys. Rev. Lett (2001) 2 - Selective readout: only GW sensitive normal modes must be measured - M. Bonaldi et al. Phys. Rev. D (2003) Avoid resonant bandwidh limit and thermal noise contribution by the resonant transducer Reduce overall thermal noise by rejecting the contribution of not useful modes Dual R&D: a full open bandwidth acoustic detector INFN and Dept of Physics: Firenze – Legnaro - Padova – Trento - Urbino

ILIAS meeting Mallorca 2005 V. Fafone Measurement of differential deformations of two nested resonators Intermediate GW broadband Dual: Main Concept 5.0 kHz π Phase difference The inner resonator is driven below frequency The outer resonator is driven above resonance

ILIAS meeting Mallorca 2005 V. Fafone Mode selection strategy 2-D Quadrupolar filter: X=X 1 +X 3 –X 2 –X 4 Capacitive transducer design Large interrogation regions Geometrically based mode selection Reject high frequency resonant modes which do not carry any GW signal Bandwidth free from acoustic modes not sensitive to GW Also FFP optical scheme F. Marin et.al, Phys. Lett. A 309, 15 (2003)

ILIAS meeting Mallorca 2005 V. Fafone Mo Dual 16.4 ton height 3.0m 0.94m SiC Dual 62.2 ton height 3.0m 2.9m Q/T=2x10 8 K -1 Evaluated sensitivity (SQL) Antenna pattern: like 2 IFOs colocated and rotated by 45° M. Bonaldi et al. Phys. Rev. D (2003)

ILIAS meeting Mallorca 2005 V. Fafone a deep revision of the resonant detector design DUAL is based on AND a challenging R&D on readout systems Timeline R&D: Detailed design: (Some topics are tackled within STREGA)

ILIAS meeting Mallorca 2005 V. Fafone Broadband amplification (5.0 kHz) Displacement gain factor about 10 Negligible intrinsic thermal noise Compliance Leverage type amplifier Selective readout system for DUAL: mechanical amplification stage Capacitive readout Electric Field Optic readout Fabry-Perot mirrors T3 - P. Falferi, IFN Trento

ILIAS meeting Mallorca 2005 V. Fafone Progress towards a wide area optical readout Usual cm-long cavities have small spot size (  1mm) → higher order acoustic modes of the real system contribute to the noise M1 M2 M3 M4 D Phys. Lett. A 309, 15 (2003) To average out the noise, we need a spot size > 10 cm !!!! Folded Fabry-Perot: FFP relative shot noise limited displacement sensitivity: constant relative freq. noise due to Brownian noise  1/ N relative freq. noise due to rad pressure noise  1/N 2 effective increase of spot size T3 - P. Falferi INFN Firenze

ILIAS meeting Mallorca 2005 V. Fafone Apparatus for High voltage breakdown study Bias voltage in the 100 MV/m range M2 - J.P. Zendri, IFN Trento Goal: 10 8 V/m Achieved: 10 7 V/m Measurement of V.B. of aluminum polished surfaces of cylindrical samples Two axis adjustment - surface finishing effect - electrodes conditioning procedure - effect of dielectric films Linear vertical stage

ILIAS meeting Mallorca 2005 V. Fafone Test mass material characterization Low temperature measurements of the Q factor of ceramic materials M2 - J.P. Zendri, INFN Legnaro

ILIAS meeting Mallorca 2005 V. Fafone