www.minigrail.nl The Spherical Gravitational Wave 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.