Einstein Telescope Design Update

Einstein Telescope Design Update Workshop at Glasgow, September 2017

• Karsten Danzmann:
• David Shoemaker: aLIGO experience in the context of ET
• Sheila Rowan: Worldwide co-ordination towards a 3G network
• Jo van der Brand:
• Salvatore Vitale: 3G Science overview
• Michele Punturo: Overview of the ET design and next steps on the ET roadmap
• Harald Lueck:gwic_3g_rad_glasgow.pptx
• Stefan Hild: Slides for starting of discussion
• Humboldt Foundation (not given due to illness): Slides
• Dr Barden-Lauefer, Dr Huntebrinker: Leibniz University Alumni overview and opportunities
• Joe Galloway: Slides on ITN, EJD and joint doctorates in general

All GraWIToN Early Stage Researchers present at the ET update meeting gave a four minute presentation of their PHD project.
The best presentation (judged by a jury of supervisors) got a certificate:

• ET design study
• ET-D sensitivity data: total sensitivity: Matlab-figure, Matlab mat
• ET-D LF noise budget: Matlab fig
  
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• ET-D HF noise budget: Matlab fig
  
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• Still LF the key feature? — Science case difference between 2Hz cut-off and 10Hz cut-off. What will be covered by LISA already? What else to we get from LF apart from BBH? Thomas, David.
• Length argument: Infrastructure (ultimate noise limit, long-term capability) vs detector (short term + cheaper)?
• Michele: The two things we have to decide within the next two years: Underground or not? And triangular or not?
• Is ET a brand? Is it what we want to be? Is it important or a hindrance in global coordination?
• Steps needed towards ESFRI roadmap (level of maturity/TDS?)

• Science case difference between 2Hz cut-off and 10Hz cut-off? Tomek, David
• Lessons learned from KAGRA so far in terms of materials?
• Lessons learned from KAGRA so far in terms of sensors and actuators?
• What do we lose if we abandon triangular footprint vs longer L?
• What do we lose if we abandon the xylophone (because might not be necessary in global network)? What cost reduction to we get? Stefan
• Tube diameter to small currently for proper scattering mitigation?
• Optimum arm-length? is there a sweet spot from beam divergence, mirror dimensions available, energy stored in suspensions?
• What an estimate for the classical noise budget of an 3G detector? (Useful for optimisation)
• Is it of any use if a single ET has good LF sensitivity but no other detector has similar sensitivity in this frequency range?
• Do we need sky localisation capability?

• Unordered List Itemmodify to two floor design. Con: lose flexibility of infrastructure
• a-LIGO pre-isolation and compact SUS.
• Warm and cold sensors and actuators.
• up to date list of what is available in terms of materials (sapphire, silicon, composite masses?) today Giles,
• SPI: options for central ifo?
• improvement of seismic sensors, tiltmeters
• actuators for minimal cross-coupling (act only in the desired direction)
• violin mode sensors and dampers
• think about ALL modes of long suspensions Norna
• Need to look anew into cryo-suspension techniques. 1.5m last stage.
• SPI?

• (Michelson vs speedmeter etc) what is the decision path? decision point can be late as they all fit into the same infrastructure
• LG33 availability of optics, TCS, do we need LG33 ? rely on better coatings? review investigations since ET DS. Jerome
• squeezing higher order modes
• coatings review Stuart, Peter
• substrates review of materials and performance Harald
• PIs Anna, Andreas, Daniel
• TCS: Better wavefront sensors, better actuators? Need for TCS in “voyager” design?
• alternatives to xylophone design? what do we need? what do we gain?
• update options for optics surface, surface figure, scatter. Derive cavity losses (10km) from this
• squeezing losses in FC. Actuating BW of FC. Actuating on surface figure of FC to reduce losses and improve MM.
• adaptive mode matching
• quantum noise of ET LF Haixing
• what parameters do we have to push to get to CE sensitivity? Haixing
• problems with increasing beam size

• derive site preference from geology and noise sources (cities)? Is it possible?
• minimum set of measurements for validating site. Improve understanding of damping of different materials at sites. Michele
• cryogenics. Cooling power –> disturbances. liquid He “from above”. safety issue?
• self made seismic noise: level, counter-measures Nikhef
• Identify any potential cost savings on vacuum?
• facilities for producing large cryo substrates –> GWIC 3G R&D

Working group meeting: Michele Punturo, Jo v/d Brand, Tamas Novak, Peter Van, Niels van Bakel

• requirements of calibration accuracy
• Telecon 6 Oct

• Conclusions and Observations of the meeting
• ET telecons