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FS Suspension for Virgo+. Michele Punturo On behalf of the Thermal noise working group of Virgo+. Scientific Motivation. The reduction of the Suspension thermal noise will improve the sensitivity at low frequency:. Scenarios. Many effects to be considered: Mirror thermal noise (see curve b)
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FS Suspension for Virgo+ Michele Punturo On behalf of the Thermal noise working group of Virgo+
Scientific Motivation • The reduction of the Suspension thermal noise will improve the sensitivity at low frequency:
Scenarios • Many effects to be considered: • Mirror thermal noise (see curve b) • Newtonian Noise (compare curve c and a)
Virgo Commissioning Plan • The Virgo collaboration defined the evolution of the commissioning for the next two years Science Run 1 Science Run 2 Noise hunting Noise hunting ITF Shutdown ITF restart 03 06 09 03 06 09 01/2008 01/2006 01/2007
2008: Virgo+ upgrade • FS suspension • Huge engineering effort • To upgrade the ITF at the beginning of 2008 a well detailed plan must be defined • VIR-PLA-DIR-4700-109 • 4 tasks: Mechanical Realization of a prototype Control test of the prototype Definition of the mounting procedures Production of the 4 payloads
Task #1 • Realization of a Static payload • Fibre production • O2-H2 facility under completion in Cascina (H.Vocca) • CO2 laser facility in delay (June 2006) • Upper clamp design • New component to be designed to connect the FS fibre to the Steel marionette • Lower clamp design • “Ears”: large experience in GEO within the LSC • Suspend a dummy test mass • In progress in Perugia • Steel Marionette • Similar as much as possible to the current Virgo design • Dielectric reference mass • Eddy current issue • Able to accommodate current Virgo coils • Full payload realization
Task #2 • Mechanical response characterization and control test • Setting up the position sensing apparatus • Virgo “local control” design • New marker design exploration • Setting up the digital control chain • Virgo “local control” design • Error signal calibration and diagonalization + Mechanical TF measurements • Decoupling of the different D.O.F. • Payload control • Virgo “local control” design • Frequency dependent driving matrix to compensate for nasty couplings • Monolithic payload robustness tests
Task #3 Ceramic glue Silicate bonding • Definition and test of the mounting procedures • Mirror preparation procedures • Realization of a new design for magnet glueing. • Direct painting of the markers on the mirror (?). • Spacers bonding before coating (?) • Payload assembling and transportation procedures • Definition of the procedures for payload assembly. • Realization of a test prototype in clean room. • Test of the transport and hanging procedures
Task #4 • Production of the four payload components • Preparation of the four mirrors • Currently three Susprasil substrates are available. They are used as spare of the current Virgo mirrors, but can be coated and used for Virgo+ (one of them must be used as PR because it have a small defect that can reduce the Q). Obviously 3 other mirrors must be produced (2+1 spare). The four mirror for Virgo+ must be coated with the best coating available (in terms of optical and mechanical performances) in such a may to reduce the dissipation due to the mechanical losses in the Tantalum. The possibility to paint the markers (if needed) directly on the coating must be investigated. • Preparation of the four marionette • Defininition of the procedure for marionetta series production: construction, material tests, assembly, mechanical and electrical tests before coupling with the monolithic suspension and reaction mass, storage space and structure • Preparation of the four reference masses • Defininition of the procedure for RM series production: • construction, assembly, mechanical and electrical tests to be performed before coupling with marionetta and mirror, storage space and structure • Assembling of the four payloads • The four payload will be assembled as soon as we are ready to mount them (no storing seems possible).
Infrastructures • To be compatible with the commissioning plan, new infrastructures are needed • Experimental area for the fiber production • Two (or one large) clean room in the 1.5km building • Experimental area for the payload assembling • Time schedule and the success of this operation are related to the quick availability of these infrastructures • EGO is investigating for this large effort • Meeting the 19th of January in Cascina