1. WG3 Report Michele Punturo Harald Lück

2. WG3 composition Co-Chairmen M.Punturo INFN Perugia, Italy H.Lück MPI für Gravitationsphysik, AEI, Hannover, Germany Appointed Participants K.Strain IGR, Glasgow, Great Bretain R.Flaminio EGO, Italy-France V.Fafone INFN Frascati, Italy M.Bonaldi IFN-CNR and ITC, Trento, Italy D.Enard EGO, Italy-France L.Gottardi Leiden University, Leiden, The Netherlands

3. Role of WG3: the proposal WP3: An European Strategy for Future Antennas –Plan the enhancement of the performances of the European gravitational wave detectors and to organise their collective operation. –Objectives: To determine scientific objectives that could be attained through short term improvements, optimisation and association of detectors now available in Europe. To establish the bases for integrating existing and future gravitational wave detectors in a coherent network. To draft a plan for a European network of gravitational wave detectors at the 2010 horizon

4. WG3 the meetings We organized a meeting every 3 months –8-9 July 2004, Virgo site, Cascina, Italy –21-22 October 2004, GEO site, Hannover, Germany Next meeting: –27-28 January 2005, Auriga site, Legnaro, Italy All the meeting documentation is available on the web: –http://www.ego-gw.it/ILIAS-GW/N5-WP3_meetings.htmlhttp://www.ego-gw.it/ILIAS-GW/N5-WP3_meetings.html

5. WG3 the method To organize the discussion and reach our objectives, we first defined a list of items that are affecting (or will affect) the current (future) GW detectors –Low frequency noises Advanced suspension systems Mirror substrate materials Coatings –High frequency noises High power lasers Signal recycling –Technical noises Reduction below the fundamental noises –Thermal compensation Thermal lensing in the main mirrors Cavity finesse tuning Advanced light injection optics

6. … WG3 the method –Co-located interferometers Coherence between the detectors –Advanced non-interferometric detectors Materials and geometries Advanced transducers (resonant or non-resonant) Read-out schemes –High or low frequency sources (WP2 interaction) –Possible schemes for future detectors Following and updating this strategy we organized our meetings –In each of them we invite experts of the subjects under discussion to present (directly or via phone/video conference) their opinion or experience

7. Cascina, 8-9 July First meeting –Devoted to the presentation of the activities of each research group –Status of each detector –Organization of short and middle term objectives –Discussion on the integration of the WP3 activities in the “merging” process between the European GW collaborations

8. Hannover, 21-22 October Second meeting – Visit of the GEO detector –High power laser research in GEO Strong interest by Virgo members Almost mature technology for “short term” upgrade –Mirror Substrate research in LSC Evaluation process still under development –Highlights on GEO High Frequency Design under development –Co-located interferometers Better understanding of the LIGO experience Many inputs for “short upgrades” in current GW detectors –Highlights on advanced Virgo design Presentation of the discussions inside the Virgo collaboration –Dual Detector Presentation of the ideas and of the progress in the design of a broadband resonant detector

9. Next meeting, in Legnaro In the Hannover meeting we identified some of the items we need to discuss in the next meeting Legnaro (Auriga site) 21-22 January 2005: –Signal recycling techniques, from GEO to future experiments –New ideas on mode cleaner realization –Thermal compensation in high power interferometers –Read-out schemes in future resonant antennas –…

10. Deliverables & Conclusions We are full filling the requests of the proposal No delay is foreseen Some improvement to be implemented: –Stronger relation with the other groups WP1 & WP2 –Increase the number of participants to the group, inserting other physicists that are involved in experiment upgrade –Deeper involvement of the WG3 in the discussion “internal” to the experiments about detectors evolution