www.minigrail.nl

The Spherical Detector MiniGRAIL

Science run 1

Kamerlingh Onnes Laboratory Leiden, The Netherlands Arlette de Waard www.minigrail.nl

Properties of gravitational waves

L+∆L

Deformation Force field of a ring www.minigrail.nl

Gravitational wave detectors Laser interferometers

Cascina (Pisa), Italy

3 km km 3

10-9 mbar laser GEOw60w0w.minigrail.nl Duitsland

VIRGO, Italie 3 km

LIGO, USA Hanford 2x4 km, 1x2km

TAMA300, Japan

Livingston

AIGO, Australia www.minigrail.nl

LISA (Laser Interferometer Space Antenna)

Is scheduled to fly in 2012 www.minigrail.nl

Gravitational wave detectors Resonant detectors (Bars)

NAUTILUS Rome-Italy

Material=aluminium vsound = 5400 m/s Length=3meter Mass=2300kg freq~900 Hz T=100mK h~1.5×10-19 www.minigrail.nl Explorer Auriga, Italie Zwitserland

Allegro, USA

Niobe Nautilus, Italie Australie www.minigrail.nl

Gravitational wave detectors Resonant detectors (Spheres)

• Large cross section compared with a traditional bar detector • Omni-directional

• Determine direction and polarization (TIGA)

• Additional veto by monitoring other modes (monopole mode / toroidal modes)

• Very short cool-down time

• Relatively cheap www.minigrail.nl

TIGA positions Determine direction and polarization of gw

(2,2) (2,-2)

(2,1) (2,-1) TIGA positions

5 Quadrupole Modes (2,0) www.minigrail.nl MiniGRAIL The Netherlands

Large Hollow Sphere Mario Schenberg, Brazil R&D in progress by ROG Italy / MiniGRAIL www.minigrail.nl

MiniGRAIL

Material CuAl6%

Diameter Φ = 0.68 m

Mass M = 1300 kg

Resonance freq. f = 2900 Hz

Temperature ~ 20 mK

NF sensitivity 4x10-22 Hz-1/2

QL sensitivity 4x10-23 Hz-1/2 www.minigrail.nl How to measure

a displacement of

10-20 meter ??

Reduce noise Mechanical amplification (seismic/thermal) and and very low noise avoid dissipation amplifier www.minigrail.nl

MiniGRAIL 108 material properties

107 Dissipation is mainly caused by the mobility of Q defects 106

→ defects freeze out at low temperature 5 Staal 10 CuSn(20%) → CuBe(10%) Q-factor increases with Al5056 reducing temperature 4 CuAl6% 10 CuNi(5%)Al(9%)Fe(5%) 0,01 0,1 1 10 100 T (K) www.minigrail.nl

MiniGRAIL Seismic isolation

amplification

attenuation www.minigrail.nl MiniGRAIL Seismic isolation

1 1 2 5 3 2 4

6 5 6 3 7 7 4 www.minigrail.nl

MiniGRAIL Seismic isolation

~ 50 dB www.minigrail.nl

Kamerlingh Onnes Laboratory Ultra-low temperature division

MiniGRAIL cryostat www.minigrail.nl

MiniGRAIL Cryogenics

Liquid N2 77K (-196 ºC)

Liquid He 4K (-269 ºC)

Dilution refrigerator (10 mK)

cryostat www.minigrail.nl Cool-down 2000 kg using a forced helium flow

Roots 1200 N2

Roots 250

Cu tube

N2 dewar www.minigrail.nl

Cool-down time MiniGRAIL www.minigrail.nl MiniGRAIL Cryogenics; The dilution refrigerator

still (700 mK) 50 mK plate

mixing chamber (20 mK)

Tgoal = 20 mK Tmin run 7A = 65 mK www.minigrail.nl

Principle of mechanical amplification

M ∆x = 2 ∆X m 2

M1 M2

∆ ∆ X2 x www.minigrail.nl

Mechanical Amplifier (transducer)

Capacitive transducer

+ + + + + + + + + +

Isolating layer (Teflon) ∆x

1 C ∝ ∆ x www.minigrail.nl

Closed Membrane Capacitive Transducer

CuAl6% electrode mass (~ 200 g) spring

membrane

Advantages: d~30 micro m • Compact design VBIAS up to 500 V • Easy to make www.minigrail.nl

2-stage SQUID read-out

transformer QD dc SQUID DROS

cold damping www.minigrail.nl

Comparison between SQUID-based read-out

2-stage SQUIDS www.minigrail.nl

Future improvements: Advanced sensor SQUIDs

QD dc SQUID New Twente SQUID

input feedback

µ Lin = 1.7 H www.minigrail.nl

Cryogenic run 7 with 3 capacitive transducers

Transformer boxes

Capacitive transducers www.minigrail.nl

MiniGRAIL sensitivity - run 6

Run 6 T 5 K ε 700 ' Q 105 M 200 g C 1.1 nF 1.5 x 10-20 Vbias 200 V www.minigrail.nl

Sensitivity current detectors

MiniGRAIL run 6

NAUTILUS/EXPLORER GEO

AURIGA 3 LIGO S

s e interferometer Initial target larg www.minigrail.nl

1-mode transducer

electrode

1.5 kg

membrane mass Stycast 2850 FT www.minigrail.nl

2-mode transducer

mass 2 Al5056 20 gram

1.5 kg

mass 1 CuAl6% www.minigrail.nl

MiniGRAIL data acquisition system www.minigrail.nl

MiniGRAIL expected sensitivity 7

Run 7 T 80 mK ε 100 ' Q 106 M 400 g C 1.5 nF

Vbias 400 V

4 x 10-22 µ Teff = 40 K www.minigrail.nl

Sensitivity current detectors

MiniGRAIL run 6 Run 7a started MiniGRAIL November 6 run 7 2004 NAUTILUS/EXPLORER GEO

AURIGA 3 LIGO S Run 7b will start February 2005 s e interferometer Initial target larg www.minigrail.nl

Signals detected by the two cylindrical detectors Nautilus and Explorer

~800 km

Explorer Nautilus www.minigrail.nl EXPLORER-NAUTILUS 2001 data analysis s t n e v

De uring 2001 EXPLORER f o r and NAUTILUS were the e b m only two operating u N resonant detectors, with the best ever reached sensitivity (h=2x10-19). www.minigrail.nl

EXPLORER-NAUTILUS 2001 data analysis www.minigrail.nl

R&D by ROG/MiniGRAIL Future detectors

Resonant detectors

SPHERES

TAMA cryogenic projects Laser interferometers Clio, LCGT

CRYOGENIC MIRRORS

VIRGO cryostat www.minigrail.nl

Sensitivity future detectors

MiniGRAIL QL