et- wp2, thermal noise issues fulvio ricci assergi (l’aquila) laboratori nazionali del gran sasso,...
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ET- WP2 , Thermal noise issuesFulvio Ricci
Assergi (L’Aquila)
Laboratori Nazionali del Gran Sasso, February, 9th 2008
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WP2 - Mission Pave the road to get the sensitivity of a GW detector as near as possible to 1 Hz, by seismic and thermal noise
Passive and active seismic attenuation
Low dissipation materials for mirror suspensions
Cryogenics: safety and noise compatibility in the underground environment
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Next ET- WP2 workshop26-27 February 2009
@Sapienza - University of Romehttp://agenda.infn.it/conferenceDisplay.py?confId=1047
• The workshop will be devoted to the thermal noise issues in GW future detectors. We will review the thermal noise models for advanced detectors and thermal noise issues for ET.
• A large part of the meeting will be devoted also to the upper suspension configuration.
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Tasks and involved Groups
Definition of substrates and coating properties at low temperature: Groups: LMA, Glasgow, INFN- Firenze/Urbino, INFN-Genova, INFN-
Perugia, INFN-Padova/Trento………Science team: Jena, Trieste(Cantatore)………
Design of Upper Suspensions: Groups: INFN-Pisa, EGO………
Design of Lower Suspension Mechanics:Groups: INFN- Roma1,INFN-Firenze, INFN-Perugia, INFN-Pisa,
Glasgow…….
Design of Cooling System:Groups: INFN- Roma1, INFN-Roma2……..
Design of Lower Suspension Sensing and Actuation:Groups: INFN-Roma2, INFN-Napoli, INFN-Padova/Trento, INFN-
Roma1…… Science Team: Genova (Vaccarone)……..
Design of Lower Suspension Fibers:Groups: Glasgow, INFN-Firenze/Urbino, INFN-Perugia, INFN-
Pisa………
Major impact on
ET Infrastruc
tures
Major impact on
ET Infrastruc
tures
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10-19
10-20
10-21
10-22
10-23
10-24
10-25
Credit: M.Punturo
LIGO
Advanced LIGO/Virgo (2014)
Virgo
GEO-HF2011
Einstein Telescope
1 10 102 103 104
Frequency (Hz)
Ad LIGO/Virgo NB
[Hz -1/2 ]
Frequency [Hz]
Assuming a Sensitivity Target for ET
LIGOVIRGO
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66
Design of the cooling systemDesign of the cooling system
•The upper part is thermally insulated by thermal screens
•The upper part is thermally insulated by thermal screens
Cryo-Compatible Cryo-Compatible Superattenuator Superattenuator designdesign
Cryo-Compatible Cryo-Compatible Superattenuator Superattenuator designdesign
Tanks to R. Passaquieti
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The Pulse Tube Cryogenerator
Second stage
First stage
Compressor
High pressure linesLenght up to 20 m
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Typical Performance of a double stage PT cryogenerator (PT 405)
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The Prototype The Prototype of Cryogenic Payload installed at the EGO West hall @1.5 kmof Cryogenic Payload installed at the EGO West hall @1.5 km
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Payload detailss
Marionette Reaction Mas100 kg Aluminums
Marionette100 kg s. steel and tungsten
Mirror Reaction Mass~20 kg aluminum
Mirror (silicon (20 kg)
Frame~40 kg saluminum
Cinese hatTitanium Ti6Al 4V
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Cooling is started
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Preliminary Displacement Spectra
Room Temperature: Pulse Tubes OFF Mirror Temperature 126 K: Pulse Tubes ON
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How to overcame the problem.on the way- Active damping of the harmonic excitations
How to overcame the problem.on the way- Active damping of the harmonic excitations
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1414
The Free Vibration Cryostat and its control chainThe Free Vibration Cryostat and its control chain
Slide 0Slide 0
S. Caparrelli, et al. Rev. of Sci. Inst. 77, 095102 (2006).
T. Tomaru et al. Cryogenics, 44 (2004). ( Passive vibration insulation system for the cryocooler) i
S. Caparrelli, et al. Rev. of Sci. Inst. 77, 095102 (2006).
T. Tomaru et al. Cryogenics, 44 (2004). ( Passive vibration insulation system for the cryocooler) i
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Vibration of the cold head reduced (@T=4K)Vibration of the cold head reduced (@T=4K)
The vibration reduction scheme works, but we need to improve it.The sensing will be modify to reduce the noise floor at closed loop.
displacement noisedensity
€
ΔxOL
ΔxCL
=117 @ 1Hz
€
Δx = 29 μm / Hz[ ] @1 Hz
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The alternative scheme based on the production of Supefluid HeliumThe alternative scheme based on the production of Supefluid Helium
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Cryostat design based on the so-called Claudet bath principleCryostat design based on the so-called Claudet bath principle
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Cryogenic Infracture RequirementsThe PT solution
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Cryogenic Infracture RequirementsThe superfluid Helium solution
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Further studies are needed• PT solution
– Increase the active damping efficiency– Increase the length of the high pressure lines– Increase the refrigeration power
• Superfluid helium solution- evaluation of the noise impact of the cryogenic facility - thermo acoustic insulation of the long transfer lines
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Upper part suspension
• …..see the presentation of Adalberto Giazotto