arlettedewaard lucianogottardi giorgiofrossaticgwp.gravity.psu.edu/lisa/presentations/dewaard.pdf...

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Kamerlingh Onnes LaboratoryLeiden UniversityThe Netherlands

Arlette de WaardLuciano GottardiGiorgio Frossati

http://www.minigrail.nl

www.minigrail.nl

Kamerlingh Onnes LaboratoryLeiden UniversityThe Netherlands

Collaboration with:

RomePadovaSão Paulo

Twente


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• Large cross section compared withtraditional bar detector with L~5D

• Determine direction andpolarization (TIGA)

• Very short cool-down time• Cheap (< € 500k / antenna)

• Omni-directional

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Material CuAl6%

Density ρ = 8000 kg/m3

Diameter Φ = 0.65 m

Mass M = 1150 kg

Sound velocity v = 4000 m/s

Resonant freq. f = 3160 Hz

Operating temperature ~ 20 mK


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Sphere+ 6 transducers

7 damping stages

Dilution refrigerator


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T = thermodynamic temperature

β -1 = the ratio of the energy deposited into the detector andthat converted into electromagnetic energy in the transducer

Q = mechanical quality factor

TN = noise temperature SQUID

NN

Neff TQ

T

QT

TTT 2

2122

2

1

+≈

+≅

ββ

Minimum detectable energy kBTeff:


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NN

Neff TQ

T

QT

TTT 2

2122

2

1

+≈

+≅

ββ

HzhTkE NBN 3160with1 === νν

SQUID noise energy (quantum limit):

KT N 105.17−×≅


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NN

Neff TQ

T

QT

TTT 2

2122

2

1

+≈

+≅

ββ

KT N 105.17−×≅

710−<Q

T

β

β ~ 0.1 expected

Q ~ 107mKT 20~

measured



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mRl

kgMm

s

s

195.06.0

1150

====

sfml

kTH eff 24

21

40

2

min0

−×≈

=π

The Fourier transform H0(f ) of a burst h(t) of duration τgconsidered constant within the bandwidth ∆f assumingSNR=1 is:


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200 HffS h ∆= π

For SNR = 1:

2/10 )()(

~ −= HzfSh h

HzQT

Tff

N

2242

17.021

0 ≈

+=∆

ββwith


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4.7×10-231.5×10-224.7×10-224.3×10-211.3×10-214.3×10-20h0

230224224∆f

0.10.10.1β

4.5×10-74.5×10-64.5×10-5Teff

1.6×10-71.6×10-61.6×10-5TN

1 hυ10 hυ100 hυEN

Quantum limitAdvancedInitial goal

2/10 )(

−HzfS h


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MiniGRAIL

MiniGRAIL

∆f ~ 10% f


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MiniGRAIL narrow band

MiniGRAIL

∆f ~ 10% f

MiniGRAIL narrow band

∆f ~ 1% f


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MXylophone of spherical detectors

From 1 – 3 kHz:10 detectors with ↓ = 0.65 → 2 meters

∆f ~ 10% f

MiniGRAIL


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Xylophone of narrow band detectors

∆f ~ 10% f∆f ~ 1% f

MiniGRAILMiniGRAIL narrow band


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Arrays of spherical detectors

MiniGRAIL3 spheres CuAl6%

100 spheres100 spheres (↓ =1.2 m)


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Beryllium sphere

MiniGRAIL

Beryllium (↓ =2 m)


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• Cryogenics• Suspension• Transducer development


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• Repair leak in cryostat and testdr with continuous heat exchangers

• Install sintered heat exchangersand cool below 50 mK

• Test double stage SQUIDat low temperature

• Measure thermal noise MiniGRAILwith capacitive transducer


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→

→_____________________________

→

2Mvn


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2Mvn

1800

6537

7516

8000

2500

Density(kg/m2)

12000

5400

4668

4000

5400

Soundvelocity (m/s)

Crosssection

Diameter(m)

Material

38.83.06Be

2.61.38CuBe10%

1.41.19CuBe5%

0.71.02CuAl6%

11.38Al5056

Several spheres at 2 kHz


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3155 3160 3165 3170 3175

Frequency (Hz)


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0,01 0,1 1 10 100104

105

106

107

MiniGRAIL (φ = 65 cm)MicroGRAIL (φ = 17 cm)

Temperature (K) Tmin= 1.8 KelvinQmax= 950 000

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silver epoxy

WBW3k piezoCu wire↓ =400µm


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Nitrogen Dewar

Copper tube

N2

Roots 1200

Roots 250


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27 hours !


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Thermal anchoring of the massesof the suspension

To 600 mK plate

To 50 mK plate

To mixing chamber (20 mK)


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600 mK platestill1 K plate 1 K pot

50 mK plateMixing chamber


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Attenuation > 40 dBper stage 1

234567

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flat Nb coil2 stage SQUID

3 mode system


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Nb film Twente

Imax stored ~ 4 A

Icrit Nb film ~ 6 A

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Padova(2 stage )

Twente(2 stage)

Carelli(2 stage)

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