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

2. Why we have to think to an advanced version of Virgo

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

4. 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)

5. 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

6. 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

7. 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

8. 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

9. 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)

10. Shot Noise possible reduction

11. 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)
Investigation activity started in the ILIAS framework and in EGO
Time Scale?

12. 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

13. Virgo Internal Organization
Virgo just ( ) 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 October 2004
Next General ILIAS meeting, Paris 5-6 November 2004
The VESF framework
First VESF meeting 9-10 December 2004