Design study for 3rd generation interferometers Work Package 1 Site identification and...
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Design study for 3rd generation interferometers Work Package 1 Site identification and infrastructure Jo van den Brand e-mail: [email protected] Tübingen, October 9, 2007
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Transcript of Design study for 3rd generation interferometers Work Package 1 Site identification and...
Design study for 3rd generation interferometers Work Package 1 Site identification and infrastructure
Jo van den Brand
e-mail: [email protected]
Tübingen, October 9, 2007
LISA
Rüdiger, ‘85
Improved sensitivity compared to LIGO and Virgo
– Sensitivity below 10-24 m/sqrt(Hz)
– Ultra-low frequency cut-off
Underground site
Multiple interferometers
– 3 interferometers; triangular configuration?
– 10 km long arms
– 2 polarization + redundancy
Design study part of FP7 & ILIAS
Site identification issues: science
LISA
Seismic displacement noise
Seismic displacement noise – Driven by wind, volcanic, seismic activity
– Ocean tides, cultural noise (e.g. humans, cars)
– Ground-water variations
– Complicates operation of ITF, certainly in future designs with high finesse cavities
– Active control systems, seismometers feedback to mirrors
Underground
– Surface and compression waves
– Die exponentially with depth
Surface waves
Compression waves
Courtesy: G.Cella
LISA
Experience: CLIO – Prototype for LCGT
LISA
Experience: underground interferometers
LISM: 20 m Fabry-Perot interferometer, R&D for LCGT, moved from Mitaka (ground based) to Kamioka (underground)
Seismic noise much lower:
Operation becomes easier
102 overall gain103 at 4 Hz
LISA
Gravity gradient noise
Gravity gradient noise
– Time varying contributions to Newtonian background driven by seismic compression waves, ground-water variations, slow-gravity drifts, weather, cultural noise
– Determines low-frequency cut-off
– Cannot be shielded against
Counter measures
– Network of seismometers and development of data correction algorithms
– Analytical studies: G. Cella
– Numerical studies
Figure: M.Lorenzini
LISA
NN reduction in caverns
Reductionfactor
Cavern radius [m]
Spherical CavernG.Cella
5 Hz10 Hz20 Hz40 Hz
NN reduction of 104 @5 Hzwith a 20 m radius cave
106 overall reduction (far from surface)
(Compression waves not included)
102 less seismic noise x 104 geometrical reduction
Compression waves: R. De Salvo
LISA
Ultra soft vibration isolation: sensitivity at low frequency
Upper experimental hall
Credit: R.De Salvo
50-100 m tower to accommodatelong suspension for low frequency goal
Ellipsoidal/spherical cave fornewtonian noise reduction
10 km tunnel
Working group 2
LISA
Other criteria
Site selection and evaluation– Site availability and acquisition risk
– Acquire land rights in reasonable time frame
– Scientific suitability
– Various noise sources
– Construction suitability
– Geological conditions (topography, hydrology)
– Environmental considerations
– Legal issues
– Earthwork costs (local soil waste, labor costs)
– Operations suitability
– Supporting technical infrastructure (local University support)
– Nearby communities (travel time, schools, etc.)
– Operation costs (power, utilities, etc.)
– Risks from environmental sources or future development – Future developments (noise sources)
– Earthquakes, etc.
LISA
ILC, NLC, Tesla, VLHC, Muon Source – Site requirements
LISA
Dusel in USA: NSF – July 10, 2007 – 15 M$ study
LISA
Site identification
Gran Sasso
Salt mines
Geological issues
– Collaborate with earth science community
– Roma 3, VU Amsterdam
– Perform seismic measurements
– Salt mines, granite
– Geotechnical site reports
– Existing mines / tunnels
– Horizontal site access
Cost issues
– Excavation costs
– Equipment costs
– Crushed rock disposal
Infrastructure
– Vacuum, cryogenics
LISA
Logistics for FP7
Define detailed strategy in first WP1 meeting
LISA
FP7 foreseen resources
• 44 kEuro travel • 1 postdoc for 3 years, 1 postdoc for 2 years• 30 kEuro for external work
LISA
Summary
Site selection for 3rd generation ITF – Underground site
– Seismic activity, gravity gradient noise
– Numerous technical issues
Collaborative design study– Interest expressed by
– Caltech - LIGO
– CNRS - Annecy
– EGO
– Florence
– GEO600
– Gran Sasso
– Nikhef / VU
– Pisa
– Roma 1, 3
– Start regular meetings (as soon as EC formalities are completed)
– First meeting at Gran Sasso (E. Coccia)(Underground Lab. Community)
Contact me: [email protected]
LISA
Gravity gradient noise
Gravity gradient noise
– Time varying contributions to Newtonian background driven by seismic compression waves, ground-water variations, slow-gravity drifts, weather, cultural noise
– Determines low-frequency cut-off
– Cannot be shielded against
Counter measures
– Network of seismometers and development of data correction algorithms
– Analytical studies: G. Cella
– Numerical studies
Figure: M.Lorenzini
LISA
Possible strategy
Join the N2 network `Deep Underground Science Laboratories: DLnet (0.8 MEuro)’.
