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Materials and Cooling Techniques

G. Frossati, A.de Waard, L.Gottardi and O.Usenko

Kamerlingh Onnes LaboratoryLeiden, 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 Teff=T/Q +2TN

N B NE = k T =1 h with = 3KHz

For a SQUID noise energy of one quantum

-7NT 1.5×10 K Need~0.05; Q~2x106: T~30 mK

-21effQL 2

-23

kTΔL 3 ×10 m (M = 1 ton)

Mω

h 5 ×10 / Hz

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0.01 0.1 1 10 100

104

105

106

107

108

Q

T (K)

Staal CuSn(20%) CuBe(10%) Al5056 CuAl6% CuNi(5%)Al(9%)Fe(5%)

material properties

Dissipation is mainly caused by the mobility of defects

defects freeze out at low temperature

Q-factor increases with reducing temperature

www.minigrail.nlH for several spheres

100 1000 10000

1E-23

1E-22

1E-21

1E-20

Str

ain

sens

itivi

ty (

h)

Frequency (Hz)

h CuBe 5%(0.65,1.0,1.5,2.0,3.0 m) h CuBe10% h CuAl 6% LIGO adv.

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MiniGRAILCryogenics; The dilution refrigerator

still(700 mK)

50 mKplate

mixingchamber(10 mK)

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MiniGRAILCryogenics

www.minigrail.nlNext: 33 ton sphere ?Project together with the Roma

group to be submitted to INFN

hQL ≈4x10-24/√Hz

hQL≈4x10-23/√Hz

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Cooling from 300K

Fill liquid helium

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Forced flow

MiniGRAIL 1.4 ton

N2 1200 L600 L He

SFERA33 +7 ton40000 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 250KPT400 60W at 60K and 1W at 4.2k

Heat to remove ~70J/gm ~2.8x109JCool-down time ~2 weeks to 4k

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Liquid mixtures of 3He and 4He

)/56.exp(85.0

4.94.810648.0

3/24

323

TTX

TTX

0

0.5

0.50.25 0.75 1

2.0

1.5

1.0

3He concentration

T (

K)

Superfluid 3He/4He

Normal 3He/4He

-line

Two-phase region

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Dilution Refrigeration as an upside-down evaporation

VAPOR

LIQUID

QQ

Q Q

3He out

3He in

dilutedphase

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Dilution Refrigeration; Schematic view

CIRCULATIONSYSTEM

STILL

HEAT EXCHANGER

MIXING CHAMBER

STILLQ

HEAT ABSORPTION REGION

1k POT

HEAT FLOW

MCQ

STILLQ

TMC

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Pulsed tube dilutionrefrigerator

Joule Thompson heat exchanger replaces the 1K pot: No need for Helium bath

JT Heat exchanger

PTR

Mixing Chamber

50K

4K

600 mK

60 mK

10 mK

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www.minigrail.nlStrain sensitivity

2m CuAl6% sphere

f=1000 Hz

f=100 Hz

f=10 Hz

MiniGRAIL