STATUS OF EXPLORER AND NAUTILUS Massimo Visco for

STATUS OF EXPLORER AND NAUTILUS Massimo Visco for ROG Collaboration INFN – LN Frascati, LN Gran Sasso, Sez. Roma 1, Roma 2 and Genova Universities “La Sapienza” and “Tor Vergata” Rome, L’Aquila, Geneve CNR – IFSI and IFN Roma CERN - Geneve GWDAW 9 - December 15 th, 2004

G. W. ANTENNA EXPLORER CERN - GENEVA Bar Al 5056 M = 2270 kg L = 2. 97 m Ø = 0. 6 m n. A= 915 Hz @ T = 2. 5 K Cosmic ray detector G. W. ANTENNA NAUTILUS LNF - FRASCATI Bar Al 5056 M = 2270 kg L = 2. 91 m Ø = 0. 6 m n. A= 935 Hz T=130 m. K - dilution refrigerator Cosmic ray detector GWDAW 9 - December 15 th, 2004

GWDAW 9 - December 15 th, 2004

DATA TAKING DURING THE LAST 14 YEARS EXPLORER 1990 91 92 93 94 95 96 97 98 99 00 01 02 03 04 h from 10 -18 to 4· 10 -19 NAUTILUS 96 97 98 99 00 01 02 03 04 h from 10 -18 to 3· 10 -19 GWDAW 9 - December 15 th, 2004

EXPLORER STATUS • EXPLORER was upgraded in 1999. After a tune-up period, it has been on the air since 2000 with a duty cycle close to 85%, excluding 6 months in 2002 and 3 months at the beginning of 2004. • From March 2004 it has been working with an effective temperature around 4 m. K corresponding to h = 5 · 10 -19. The sensitivity can be increased modifying the electrical field in the transducer. • This year we will not to interrupt the data taking during the winter closure of the CERN. GWDAW 9 - December 15 th, 2004

NAUTILUS STATUS • It has worked in the past run from 1999 to March 2002. The duty-cycle in 2001 was about 80% and the effective temperature smaller then 5 m. K corresponding to h = 6 · 10 -19 • After a hardware upgrade, NAUTILUS has resumed operations in March 2003. In this phase it is working at 3. 5 K with a duty cycle larger then 85 %. The effective temperature is around 1 m. K corresponding to h ~ 3 · 10 -19 • Further improvement is possible changing the experimental parameters. GWDAW 9 - December 15 th, 2004

EXPERIMENTAL CONFIGURATION L 0 Li Small gap capacitive transducer Superconducting matching transformer High coupling dc-SQUID Al 5056 mt = 0. 75 kg nt= 916 Hz Ct = 11 n. F E = 2. 6 MV/m Lo=2. 86 H Li=0. 8 H K=0. 8 Ms = 10 n. H fn= 3 · 10 -6 Fo/ Hz GWDAW 9 - December 15 th, 2004

ROG GROUP TRANSDUCER Gap 10 m 12 cm Teflon insulators Antenna Pb washers • “ROSETTE” SHAPED Resonating disk GWDAW 9 - December 15 th, 2004

The transducer mounted on the antenna GWDAW 9 - December 15 th, 2004

WIDENING THE BAND Old readout New readout Increasing the Bandwidth of Resonant Gravitational Antennas: The Case of Explorer PRL 91, 11 (2003) GWDAW 9 - December 15 th, 2004

(-1/2) EXPLORER and NAUTILUS December 11 th, 2004 GWDAW 9 - December 15 th, 2004

DATA TAKING DURING 2004 EXPLORER 5 · 10 -19 NAUTILUS 3· 10 -19 GWDAW 9 - December 15 th, 2004

NAUTILUS OPERATIONS DURING October 2004 Duty Cycle 85 % Liquid Helium Refillings GWDAW 9 - December 15 th, 2004

EXPLORER OPERATIONS DURING October 2004 Liquid Nitrogen Refilling Liquid Helium Refillings Duty Cycle 85 % GWDAW 9 - December 15 th, 2004

GAUSSIANITY EXPLORER NAUTILUS 12 hours of data on Sept 4 th, 2004 GWDAW 9 - December 15 th, 2004

SEARCH FOR VARIOUS SOURCES • CONTINUOUS: – From the GC, 95. 7 days EXPLORER hc = 3 • 10– 24 - frequency interval 921. 32 921. 38 Hz (P. Astone et al. Phys. Rev. D 65, 022001, 2002 ) – From all the Sky, 2 days EXPLORER hc = 2 • 10– 23 - frequency interval 921. 00 921. 76 Hz (P. Astone et al. , proceedings GWDAW 2002 – ROG – A. Krolak and collab. ) – New analysis in progress • STOCHASTIC SOURCES: – Crosscorrelation of EXPLORER and NAUTILUS data over 10 hours in a band of 0. 1 Hz in 1997 GW(920. 2 Hz) < 60. (P. Astone, et al. , Astron. and Astrophys, 351, 811 -814, (1999). ) – The common bandwidth now can reach 10 Hz: a new upper limit 1 is possible GWDAW 9 - December 15 th, 2004

• BURST SIGNALS: GW detectors • Together with the other detectors of IGEC collaboration: no GW bursts above h 2 10 -18 corresponding to 0. 01 M⊙ in the GC (International Gravitationl Event Collaboration, Phys. Rev. D 68, 022001 (2003)). • P. Astone et al. : “Study of coincidence between resonant gravitational wave detectors”, Classical and Quantum Gravity, 18, 243 -251, (2001). • P. Astone et al. : “Study of the coincidences between the gravitational wave detectors EXPLORER and NAUTILUS in 2001”, Classical and Quantum Gravity 19, 5449 -5463 (2002). • The analysis of the data taken by the two experiments during 2003 and 2004 is in progress. The data are available for coincidence analysis with the other experiments. GW - ray detectors • Analysis over 47 GRB (Beppo. SAX) (95% probability): no signals with h>6. 5· 10 -19 for a time delay within 5 s, and with h>1. 2· 10 -18 for a time delay within 400 s. (P. Astone et al, Physical Review D, 66, 2002 102002). • Analysis of 387 GRB (Beppo. SAX and BATSE) upper bound of h=2. 5· 10 -19 in a time window of 10 s (astro-ph/0408544) GW – cosmic ray detectors • Search for small signals (P. Astone et al. , Physical Review Letter, 84, (2000)14 -17) • Detection of unexpected large signals (P. Astone et al, Phys. Letters B 499, Feb 2001 16 -22) (P. Astone et al, Physics Letters B 540 179 -184 (2002)). GWDAW 9 - December 15 th, 2004

Correlation between cosmic rays and signals in the antennas Ev/day integral distribution 100 Expected Explorer 2002 >600 P m 2 Explorer 2003 Nautilus 1998 Nautilus 2000 -2001 Nautilus 2000 T<1 K Nautilus 2003 10 1 0. 01 0. 001 0. 1 1 Events amplitude - Sqrt(K) 10 GWDAW 9 - December 15 th, 2004

TIME RESOLUTION AND EVENTS FROM COSMIC RAYS - EXPLORER 2003 =5. 7 ms Selection of small events 4 <SNR (amplitude) <6 GWDAW 9 - December 15 th, 2004

MINIGRAIL – NEW RUN November 2004 Ø 68 cm - 1. 4 ton 3 k. Hz T=72 m. K New cryogenic run with 3 capacitive transducers and SQUID read-out. GWDAW 9 - December 15 th, 2004

Strain sensitivity (Hz)-1/2 MINIGRAIL GWDAW 9 - December 15 th, 2004