The views of Virgo collaboration groups on upgraded/advanced Virgo Michele Punturo on behalf of the Virgo Collaboration

Why we have to think to an advanced version of Virgo

What we want to do Shot noise First, reach it!

Seismic noise The mechanical performances of the Virgo SuperAttenuator are already compliant with the requirements of a second generation interferometric GW detector Few upgrades are needed to make the SA compatible with the new payload New filter 7 design needed to improve the functionality of this component during assembly and operation and in relation to mirror contamination prevention Control noises must be reduced with an upgraded version of the control system (R&D Pisa and Annecy)

Suspension thermal noise Suspension thermal noise can be reduced through the realization of a monolithic fused silica design An attempt of a “semi-monolithic” design have been published by the Perugia-Virgo group in 1996 GEO demonstrated the feasibility of the monolithic FS design

Monolithic FS suspension 0.5 mm diameter suspension fiber Long R&D activity (in Virgo and in collaboration with GEO-Glasgow) arrived now to an engineering phase Technical problems to be solved: New payload design Higher SA control security constrains Electrostatic Actuators (or Dielectric reference mass) Activities in Perugia and Rome R&D in controls in Pi and Annecy R&D activity in Napoli Already used in GEO

Mirror thermal noise Mirror thermal noise will be one of the largest enemy of the “future” sensitivity It derives from the super-position of 4 effects Brownian vibration of the Bulk Thermo-Dynamical fluctuation of the bulk Thermo-Dynamical fluctuation of the coating Thermo-refractive fluctuation on the coating

How to assault the problem Bulk Brownian: Choose the better material (FS) Design the better geometry Reduce the excess losses PG R&D on substrates Na R&D on electrostatic actuators PG-Fi/Ur R&D on thermal noise FEM ESPCI optical characterization of new substrates SMA-Lyon R&D on Coatings PG R&D on direct thermal noise measurement in membranes OCA ideas on flat Beams SMA-Lyon activity on MexHat

Shot Noise Two main evolution paths High power lasers Signal Recycling European Collaboration ILIAS: GEO-Hannower R&D in Nd:YAG high power lasers R&D of the OCA group in fiber lasers and Disk Lasers R&D Activity at LAL in collaboration with Ligo on SR R&D in thermal compensation (To Be Started)

Shot Noise possible reduction

Parallel activities Time Scale? Several activities have been started and if successful will contribute to an upgraded/advanced design of Virgo Adaptive optics for an advanced ISYS (Na-OCA) Hollow Fiber Mode Cleaner (OCA) New control philosophy based on remote computation (Na) Crystalline Silicon suspension fibers (Fi/Urb – Pi – Pg) TWIN BEAMS Two laser beam in the Virgo Pipe Possible with “controllable” impact on infrastructure Positive experience in LIGO-S3 no coherence between the two Hanford ITFs Positive experience from TAMA measurement of Scattered Light Expected seismic correlated signal (scaled to Virgo) 10-20-10-19. Investigation activity started in the ILIAS framework and in EGO Time Scale?

In the FP6 framework +1 year GW experiments evolution 2004 Virgo 2005 Initial LIGO 2006 2007 GEO Adv. LIGO 2008 Advanced Virgo 2009 2010 2011 EGO FP6design study EGO Engineering design, Financing and construction 2012 2013 2014 EGO !! LISA High Frequency GEO Resonant detectors Upgraded Resonant detectors Tama LCGT In the FP6 framework +1 year

Virgo Internal Organization Virgo just (30-09-2004) defined a group that must coordinate the development of the advanced design: P.Hello, G.Losurdo, B.Mours, M.Punturo and A.Vicerè Periodic restricted meetings will be organized to define a standard advanced Virgo design Periodic plenary meetings will be organized to receive the feedback from the R&D progresses in the collaboration and update the advanced Virgo design Our commitment is to have an official design for the next STAC meeting This group will benefit of the interactions with the ILIAS framework Next WG-3 meeting, Hannover 21-22 October 2004 Next General ILIAS meeting, Paris 5-6 November 2004 The VESF framework First VESF meeting 9-10 December 2004