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STREGA legacy for ET

STREGA legacy for ET. Michele Punturo INFN Perugia. STREGA target. The STREGA mission is the development of the technologies needed to reduce the thermal noise in the GW detectors by a factor 10 respect to the advanced detectors design The target is the 3 rd generation detectors

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STREGA legacy for ET

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  1. STREGA legacy for ET Michele Punturo INFN Perugia STREGA & ET - 4th ILIAS-GW general meeting

  2. STREGA target • The STREGA mission is the development of the technologies needed to reduce the thermal noise in the GW detectors by a factor 10 respect to the advanced detectors design • The target is the 3rd generation detectors • STREGA is born as European (FP6) support and glue for the R&D activities already (and independently) started by the different GW research group in Europe STREGA & ET - 4th ILIAS-GW general meeting

  3. ET • Einstein GW Telescope • Design study submitted to the European Commission under the 7th Framework Programme • Project in the negotiation phase • Conceptual design of a 3rd generation GW interferometric detector • Fully dedicated session tomorrow • Cryogenic suspension is one of the keywords of the possible design of ET • No R&D activity expected inside the ET DS projects • Obviously the outcomes of STREGA are of fundamental importance for the ET design phase STREGA & ET - 4th ILIAS-GW general meeting

  4. 1st generation 2nd generation 3rd generation ? -19 10 -20 10 -21 10 -22 10 -23 10 -24 10 -25 10 1 10 100 1000 10000 Sensitivity evolution Seismic Shot Noise Thermal Noise STREGA contribution STREGA & ET - 4th ILIAS-GW general meeting

  5. Reduction of the thermal noise • Reduction of the suspension and bulk thermal noise • New materials at cryogenic temperature • Jena University research on CaF2 substrates • http://www.ego-gw.it/ILIAS-GW/documents/London_Talks/2nd_day/Jena-Nawrodt.ppt • Glasgow University research on Si substrates and blades • INFN (Fi, Pg, Pi) measurements on Si fibres STREGA & ET - 4th ILIAS-GW general meeting

  6. Advantages of the cryo-suspensions S.Reid et al. • Reduction of the Brownian thermal noise • <X2>~T • Reduction of the thermo-elastic noise • <X2>~T2 • Some “magic” behavior of special material M.Alshourbagy et al. STREGA & ET - 4th ILIAS-GW general meeting

  7. Problems of a Cryo-Suspension • A GW detector has many noise constrain that make very difficult the realization of a cryo-suspension • STREGA started the first studies of the compatibility of the cryo-technologies with a GW detector suspension system • Low noise cryo-cooler (Roma 1) STREGA & ET - 4th ILIAS-GW general meeting

  8. … problems of a cryo-suspension • Realization of a full Si Payload • Extraction of the large amount of heat deposited by the high power laser light circulating in the FP cavities • EGO R&D activity with STREGA collaboration • EGO, INFN Pi, et al. • http://www.ligo.caltech.edu/docs/G/G050529-00/G050529-00.ppt STREGA & ET - 4th ILIAS-GW general meeting

  9. Coatings • Coating thermal noise will be dominant in the 2nd generation GW detectors • Groups participating to STREGA are studying the possible scenario in a 3rd generation detector • Coating loss measured in a single layer doped tantala coating applied to Si cantilever substrate Cobalt doped tantala (LMA production) on FS substrate (F. Travasso et al.)

  10. Escaping from the coating problem • Problems due to high power laser and transmittive optics • Reduce the coating thickness • High reflectivity grating waveguide coatings • Use a different approach: • Full reflective optics and grating coatings http://wwwcascina.virgo.infn.it/collmeetings/presentations/2006/2006-10/TNworkshop/burmeister_tnws_ego06.pdf STREGA & ET - 4th ILIAS-GW general meeting

  11. Studies in Glasgow on silicate bonding of silica in relationto the Advanced generation and future GW detectors Settling time experiments Bond structural properties Bond mechanical & thermal properties SEM SEM k measurements Firenze/Glasgow Above plot showing settling time as a function of temperature for silica-silica bonds Above plot showing two bonded silica cylinders, studied before and after silicate bonding. TEM Activation energy:Ea = 0.545 eV permolecule of OH− AFM S. Reid et al.,PLA 363 341-345 (2006) Experiments suggest that the level of loss associated with silicate bonding may lie:fbond ~ (0.3→1.2)×10-1 TEM (81±4) nm 7.9 GPa

  12. Direct thermal noise measurement • An interferometer devoted to direct measurement of thermal noise in fused silica suspensions and composite structures built using hydroxy-catalysis (silicate) bonding has been realized in Glasgow • Mike Plissi e al. • Excess noise from the reference cavity is currently limiting the thermal noise measurement • Work in progress STREGA & ET - 4th ILIAS-GW general meeting

  13. STREGA legacy for ET • The WITCH is not dead, hence it is too early to talk about legacy • ET is a conceptual design study • Any R&D budget is included in ET design study, but in the proposal it is stated that ET will benefit of the R&D activities already active in Europe • STREGA must act as the solutions supplier for ET • STREGA people must enter in the ET Science Team • Discussion after this session STREGA & ET - 4th ILIAS-GW general meeting

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