Materials and Cooling Techniques

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Materials and Cooling Techniques

• G. Frossati, A.de Waard, L.Gottardi and O.Usenko
• Kamerlingh Onnes Laboratory
• Leiden, The Netherlands

ESF exploratory workshop Toward a 3rd
generation European Gravitational Wave
Observatory Perugia, 21-23-Sept. 2005
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Sensitivity
Minimum detectable energy TeffT/?Q 2TN
For a SQUID noise energy of one quantum
Need??0.05 Q2x106 T30 mK
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material properties

• Dissipation is mainly caused by the mobility of
  defects
• defects freeze out at low temperature
• Q-factor increases with reducing temperature

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H for several spheres
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MiniGRAILCryogenics The dilution refrigerator
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MiniGRAILCryogenics
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Next 33 ton sphere ?

• Project together with the Roma group to be
  submitted to INFN

hQL 4x10-24/vHz
hQL4x10-23/vHz
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Cooling from 300K
Fill liquid helium
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Forced flow
MiniGRAIL 1.4 ton N2 1200 L 600 L He
SFERA 33 7 ton 40000 N2 20000 L He !
Use 4 GM cryocoolers For pre-cooling from 300K
to 20K 4 PT410 for cooling to 4K and for the
dilution refrigerator GM600 (Cryomech) 1200W at
250K PT400 60W at 60K and 1W at 4.2k Heat to
remove 70J/gm 2.8x109J Cool-down time 2 weeks
to 4k
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Liquid mixtures of 3He and 4He
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Dilution Refrigeration as an upside-down
evaporation
VAPOR
LIQUID
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Dilution Refrigeration Schematic view
CIRCULATION SYSTEM
? STILL

• HEAT EXCHANGER

• MIXING CHAMBER

TMC
? HEAT ABSORPTION REGION
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Pulsed tube dilutionrefrigeratorJoule Thompson
heat exchanger replaces the 1K pot No need for
Helium bath
PTR
50K
4K
JT Heat exchanger
600 mK
60 mK
Mixing Chamber
10 mK
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Strain sensitivity
MiniGRAIL
?f1000 Hz
?f100 Hz
?f10 Hz
2m CuAl6 sphere