1. STATUS of BAR DETECTORS G.A.Prodi - INFN and University of Trento International Gravitational Event Collaboration - 2 ALLEGRO– AURIGA – ROG (EXPLORER-NAUTILUS)

2. outline updates on performances of detectors current organization of IGEC-2 recent and current observations plans for future joint observations target performances of detector upgrades

3. burst sensitivity, rms [Hz -1 ] IGEC-1 S hh of IGEC-2 detectors IGEC-1

4. Mode 1 870 Hz Mode 2 916 Hz frequency stationary performances: time-frequency plots ALLEGRO Time (10 hours)

5. frequency stationary performances: time-frequency plots AURIGA Time (10 hours) Mode 1 866 Hz Mode 2 915 Hz Mode 3 956 Hz

6. Mode 1 905 Hz Mode 2 927 Hz frequency stationary performances: time-frequency plots EXPLORER Time (10 hours)

7. frequency stationary performances: time-frequency plots NAUTILUS Time (10 hours) Mode 1 927 Hz Mode 2 942 Hz

8. preliminary duty cycles of detectors in 2005 ALLEGRO:95% AURIGA: 90% after suspension upgrade (may 19 th 2005) 45% before “ “ EXPLORER:83% NAUTILUS: 90% epoch vetoes are still being defined… the IGEC-2 observatory have been in at least three-fold coincidence operation for most of 2005 - tests show that detectors are affected by a very low rate of noise outliers - work in progress on comparison and cross- validation of the detectors results, based on raw data exchange: talk by Francesco Salemi in “Detector Characterization”

9. TRIGGERED SEARCHES by Gamma events Search for bursts in coincidence with 387 GRBs (BeppoSAX and BATSE): cumulative upper bound of h = 2.5 · 10 -19 in a time window of 10s P.Astone et al. (ROG Collaboration), Phys. Rev. D 71, 042001 (2005) - Search for gw ringdown in coincidence with the Dec 27 2004 giant flare from SGR 1806-20: upper limit which invades part of the parameters’ region of existing models in the AURIGA bandwidth Baggio et al. (AURIGA collaboration), Phys.Rev.Letters 95, 081103 (2005)

10. 149 days upper limit assuming a gaussian pulse  = 0.1 ms ROG: BURST SEARCH on 2003 data time coincidence analysis per sidereal hour on 2003 data of EXPLORER and NAUTILUS excluded the rate-amplitude region formerly indicated by a similar analysis on 2001 data P.Astone et al. (ROG Collaboration), Proc. Amaldi 6, (2005)

11. IGEC-2 coordination of observation times: - IGEC-2 groups are planning the interruptions of the observation time to maximize the time coverage (i.e. to keep at least 3 out of the 4 detectors in coincidence operation at all times). see our schedule: https://sam.phys.lsu.edu > IGEC2 calendar IGEC-2 run coordinators: W.Johnson (chair), V.Fafone (deputy), L.Taffarello - IGEC-2 provides real time information on detectors status to other experiments. AURIGA and ROG basic information can be automatically queried via web pages. see for instance: www.auriga.lnl.infn.it > present status in the near future, we plan to add real time information on the achieved sensitivity to standard transient signal waveforms - investigation started on the feasibility and effectiveness of an Early Warning System (in the footpath of SNEWS) see poster by R.Terenzi and R.Sturanihttps://sam.phys.lsu.edu www.auriga.lnl.infn.it

12. IGEC-2 search for bursts data are available since may 2004-present. Observation will continue at least for yr 2006. priority to the anaIysis of the last semester (May.-Nov.2005), since AURIGA improved its duty cycle and up to the start of LIGO S5. Data exchange is planned by end of 2005. New: blind data exchange for a blind data analysis: Rigid time shifts has been secretly added by each group and will be circulated only when the analysis procedure is agreed in detail Network analysis based on IGEC-1 experience: use a priori information to improve the network search (signal template, testing source locations, common search thresholds on amplitudes, etc.) –Nfold-time coincidence search with adapting order N –a priori control of false dismissal (conservative bound). –Data selection, time coincidence search and accidental coincidence estimation in the footpath of IGEC-1 Scientific coordinator: G. Prodi; vice-coordinators: W.Johnson and M.Visco

13. Expected performances of IGEC-2 Triple coincidences: 10 6 time shifts, no accidentals on 9.3 days false alarm rate 10 -21 /Hz high statistical significance in case of gw candidates Double coincidences: lower false alarm rates than for IGEC-1 rate [year –1 ] search threshold dashed region excluded with probability > 90% expected upper limit improvement by IGEC-2 1 month 1 year IGEC-1 upper limit

14. STOCHASTIC BACKGROUND SEARCHES by BARS & INTERFEROMETERS - ALLEGRO & LIGO S4: first stochastic results from a hybrid observatory see talk by John Whelan et al. (LSC) in “Stochastic searches” - VIRGO & INFN BARs: playground h(t) data exchange using VIRGO C6 and C7 commissioning runs to test analysis procedures on real data see poster by G.Guidi, G.Cella et al. (AURIGA, ROG & VIRGO) Expected SNR 4 per unit bandwidth, integration time and  gw

15. BURST SEARCHES by BARS & INTERFEROMETERS AURIGA & LIGO S3: first burst analysis from a hybrid observatory. Mainly of methodological relevance, based on a cross-correlation search on LIGO data triggered by AURIGA candidate events. Tuning phase completed. see poster by F.Salemi et al. (AURIGA & LSC) VIRGO & INFN BARs: characterization of network efficiency and comparison of coincidence search methods on real data (VIRGO C6 & C7) see poster by G.Guidi et al. (AURIGA, ROG & VIRGO) efficiency for cos-gaussian 900Hz Q9 uniform polarization and sky distribution AURIGA&H1&H2 coincident operation: 74 hr estimated false rate 0.5  Hz AURIGA sets overall efficiency h rss50% this search  2x LIGO only search

16. T = 0.12K, double gap transducer (11  m and Q=1.5·10 6 ) double SQUID (L 0 =2.5 H, k=0.7). T eff ≈ 7  K SQUID noise saturation at 200 mK taken into account. current Quality factors are assumed increased bias field inside transducer AURIGA NAUTILUS EXPECTED SHORT TERM PROGRESSES: cooling to 0.1 K

17. FINAL REMARKS growth of the efforts towards joint observation between bars and interferometers; The hybrid observatory is useful when aiming at a gw detection. Benefits: - improved the time coverage in burst searches - improved statistical significance of a gw candidate (if it falls within the reach out of bar detectors) - increased physical information on the gw direction from arrival times additional amplitude information solution of the inverse problem - more discrimination against disturbances Limits: lower reach out of bar detectors good opportunities in the medium term with ultracryogenic resonant detectors

18. extra slides

19. SQUID energy resolution  (  ) vs year — in the detector ● coupled to a LC resonator two stage LHe T ultracryogenic AURIGA 0.1 K Detector T eff  4 T n

20. Detection efficiency for bursts Maximum detection efficiency for transients with flat Fourier amplitude at the detector frequencies (  900 Hz) Efficiency of the AURIGA  matched filter for Sine-Gaussian waveforms: S-G central frequency [Hz] SNR   matched filter SNR SG filter matched to the Sine-Gaussian computed for the AURIGA detector Q SG - 2

21. Arrival time estimation AURIGA arrival time estimation for  signals by Monte Carlo injections of software signals IGEC-2 is not yet able to measure light time delays among detectors - 2

22. Exchanged candidate events amplitude histograms of exchanged events EXPLORER NAUTILUS AURIGA Event counts Event amplitude H [Hz] - 2

23. Self correlograms of exchanged events Histograms of the time lags among events of the same detector: much more “Poissonian” than in IGEC-1 AU EX NA 50 seconds - 2

24. cross correlograms of exchanged events Histograms of the time lags among all events from two different detectors: Poisson model as in IGEC-1 AU-EX AU-NA EX-NA - 2