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IGEC 2 REPORT

IGEC 2 REPORT. International Gravitational Events Collaboration ALLEGRO– AURIGA – ROG (EXPLORER-NAUTILUS). OUTLINE OF THE TALK. Introduction to IGEC2 Data analysis methodology Cross validation of data Progress in coincidence analysis. THE NEW IGEC .

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IGEC 2 REPORT

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  1. IGEC 2 REPORT International Gravitational Events Collaboration ALLEGRO– AURIGA – ROG (EXPLORER-NAUTILUS)

  2. OUTLINE OF THE TALK • Introduction to IGEC2 • Data analysis methodology • Cross validation of data • Progress in coincidence analysis

  3. THE NEW IGEC • IGEC 1997-2000 - First experience of extended search of multiple coincidence using data of 5 resonant detectors: ALLEGRO, AURIGA, EXPLORER NAUTILUS and NIOBE. • IGEC2 2004 May  2005 Feb  …A new agreement for a joint search for gravitational waves, now 4 detectors, NOIBE was dismissed. • ALLEGRO, AURIGA and ROG spokespersons unanimously decide actions/agreements. Stronger coordination of joint observations. • The operation are based on a task force, coordinated by G. Prodi, vice-coordinators W.Johnson and M.Visco

  4. A DIRECTIONAL 4-ANTENNAE OBSERVATORY • The four antennas receive an identical signal, independently from the source

  5. DATA ANALYSIS METHODOLOGY • NETWORK ANALYSISfollowing IGEC1on parallel detectors • The IGEC analysis was conceived as a N-fold analysis with adaptive N of parallel detectors. • The analysis is based on lists of candidate events produced selecting with an adaptive threshold data produced by a filter matched to a delta. • The use of amplitude information together with a directional search allows an a-prioricontrol of false alarm and false dismissal • The time window is adapted to SNR • The search parameters are tuned with a blind analysis • The data are cross validated

  6. PROGRESS OF IGEC2 • Exchange of one day of raw data to cross validate the filter pipeline • - cross validate data and characteristic of the single detector • - measure the efficiency of the observatory • Exchange of candidate events for one month of data (December 2004)- blind • - study of the background • - tune of the coincidence analysis pipeline

  7. FROM IGEC1 TO IGEC2 IGEC 1 1997-2000 IGEC 2 2004 - ….

  8. For  signals by Monte Carlo injections of software signals (Auriga) ARRIVAL TIME ESTIMATION For  signals from cosmic ray (Explorer) = 2.3 ms  (s) • The bandwidth improvement of the detectors gives a time resolution larger of about a factor 100 respect to IGEC1

  9. CROSS VALIDATION OF DATA • To aim a cross validation of data one day of raw data was exchanged • The data were filtered with the AURIGA Data Analysis filters • The first step completed is the analysis of ROG antennae, analysis of ALLEGRO in progress • The first results suggest a good agreement between the different pipelines.

  10. Spectrograms Continuous performances of all experiments PERFORMANCES AU 5000 s EX NA

  11. All the detectors show a gaussian behavior DATA QUALITY - SNR OF EVENTS AU EX NA

  12. Few events with SNR>6 in all the experiments DATA QUALITY: DISTRIBUTIONS OF EVENTS AU EX NA

  13. Injected 1800 signals of SNR=6 within 1h DETECTION EFFICIENCY AU EX NA

  14. ~90 % from May 2004 35 % 89 % 86 % OPERATION TIME - DECEMBER 2004AURIGA- EXPLORER- NAUTILUS N DOY • Single 4.63 days • Double 16.43days • Triple 9.36 days

  15. EXCHANGE THRESOLD Percentage of time with the adaptive threshold T smaller than H • The sensitivity is stationary • There is an enhancement of about a factor 3 respect to IGEC 1

  16. AMPLITUDE OF EXCHANGED EVENTS

  17. Histograms of the time lags among events of the same detector: much more “Poissonian” than in IGEC-1 AU - now SELF CORRELOGRAM OF EXCHANGED EVENTS AU 50 seconds EX NA

  18. Statistics of the accidentals are in agreement with the model PRELIMINARY RESULTS OF 2-FOLDS COINCIDENCES EXPLORER NAUTILUS Number of accidental coincidences

  19. PROGRAM FOR NEAR FUTURE • The analysis must be oriented to the detection as we expect from LIGO after S5 an upper limit far from present resonant detectors sensitivity. • Complete the preliminary analysis of cross validation on raw data. • Complete the preliminary analysis on one month of data to tune the analysis pipeline. • Exchange a larger period of data for the final analysis

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