STATUS of BAR DETECTORS

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. IGEC-1 IGEC-1 burst sensitivity, rms[Hz -1] Shh of IGEC-2 detectors

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

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

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

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

8. preliminary duty cycles of detectors in 2005 ALLEGRO: 95%AURIGA: 90% after suspension upgrade (may 19th 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 byFrancesco Salemiin “Detector Characterization”

9. Search for bursts in coincidence with 387 GRBs (BeppoSAX and BATSE): cumulative upper bound of h = 2.5 · 10-19in a time window of 10sP.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 bandwidthBaggio et al. (AURIGA collaboration), Phys.Rev.Letters 95, 081103 (2005) TRIGGERED SEARCHES by Gamma events

10. 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 dataP.Astone et al. (ROG Collaboration), Proc. Amaldi 6, (2005) ROG: BURST SEARCH on 2003 data 149 days upper limit assuming a gaussian pulse  = 0.1 ms

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 calendarIGEC-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.Sturani

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. dashed region excluded with probability > 90% rate [year –1] search threshold Expected performances of IGEC-2 Triple coincidences: 106 time shifts, no accidentals on 9.3 days false alarm rate < 10-4 / yr for H> 10-21/Hz high statistical significance in case of gw candidates Double coincidences: lower false alarm rates than for IGEC-1 expected upper limit improvement by IGEC-2 IGEC-1 upper limit 1 month 1 year

14. STOCHASTIC BACKGROUNDSEARCHES 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 SNR4 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) efficiency for cos-gaussian 900Hz Q9uniform polarization and sky distributionAURIGA&H1&H2 coincident operation: 74 hr estimated false rate 0.5 HzAURIGA sets overall efficiencyhrss50% this search  2x LIGO only search • 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)

16. NAUTILUS AURIGA T = 0.12K, double gap transducer (11 mm and Q=1.5·106) double SQUID (L0=2.5 H, k=0.7). Teff ≈ 7mK SQUID noise saturation at 200 mK taken into account. current Quality factors are assumed increased bias field inside transducer 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 disturbancesLimits: lower reach out of bar detectors good opportunities in the medium term with ultracryogenic resonant detectors

18. extra slides

19. — in the detector ● coupled to a LC resonator ultracryogenic two stage LHe T SQUID energy resolution e (h) vs year AURIGA 0.1 K Detector Teff 4 Tn

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

21. - 2 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

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

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

24. - 2 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