Status of MiniGRAIL

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Status of MiniGRAIL

• 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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Advantagesof Spheres

• Large cross section compared with a traditional
  bar detector
• Omni-directional
• Determine direction and
• polarization (TIGA)

• Short cool-down time
• Relatively cheap
• Toroidal modes could be used as vetoes for non-GW
  signals.

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MiniGRAIL
www.minigrail.nl
Material CuAl6 Diameter ? 0.68 m Mass M 1400
kg Resonance freq. 2850/3050 Hz Aimed temperature
20 mK QL sensitivity h4x10-21 QL spectral
amplitude h4.5x10-23
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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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MiniGRAIL
Initial goal Advanced Quantum limit
EN 100 h? 10 h? 1 h?
TN 1.5?10-5 1.5?10-6 1.5?10-7
Teff 4.2?10-5 4.2?10-6 4.2?10-7
? 0.1 0.1 0.1
?f 224 224 230
h0 3?10-20 9.5?10-21 3?10-21
4.5?10-22 1.6?10-22 4.5?10-23
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MiniGRAILCryogenics
cryostat
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Kamerlingh Onnes LaboratoryUltra-low temperature
lab
MiniGRAIL cryostat
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MiniGRAILSeismic isolation
50 dB
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MiniGRAILCryogenics
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Closed Membrane Capacitive Transducer
CuAl6

• Advantages
• Compact design
• Easy to make

d30 micro m VBIAS up to 500 V
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New one or two-modes transducer
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Very low noise amplifier 2-stage SQUID
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MiniGRAIL sensitivity - run 6
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MiniGRAIL sensitivity - run 6
Run 6
T 5 K
? 700 h
Q 105
M 200 g
C 1.1 nF
Vbias 200 V
Run8
T 80 mK
? 100 h
Q 106
M 400 g
C 1.5 nF
Vbias 300 V
Teff 40 ?K
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MiniGRAIL sensitivity - comparison
MiniGRAIL run6
MiniGRAIL expected run 8
NAUTILUS / EXPLORER
AURIGA
GEO 05
LIGO S3
Initial target large interferometers
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Run 8 resonance spectrum at 200V
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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