Документ взят из кэша поисковой машины. Адрес оригинального документа : http://zebu.uoregon.edu/~uochep/talks/talks04/grbs_v2.pdf Дата изменения: Wed Mar 17 21:38:36 2004 Дата индексирования: Tue Oct 2 10:37:39 2012 Кодировка: Поисковые слова: cygnus

Isabel Leonor University of Oregon


searched 25 S2 GRBs for coincident G-waves of duration ~1 ­ 10 ms used crosscorrelation method explored data conditioning in the frequency domain, included whitening and phase correction ­ luxury of limited on-source and off-source data to analyze injected signals to study sensitivity of pipeline used playground data with no GRB trigger data analysis code (standalone), injection and calibration scripts, written using Matlab

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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DFT1 condition this segment

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DFT2

data conditioning done in frequency domain data DFTed using 1-second Tukey windows adjacent 1-sec segments DFTed to determine factor for whitening in frequency domain whitening factor = max(DFT1,DFT2)

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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data conditioning process repeated for each second perform inverse DFT to convert back to time domain keep only time segment corresponding to unattenuated section of window crosscorrelation calculated in time domain

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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average over 160 seconds

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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IFO response function results in out-of-phase AS_Q signal decreases value of crosscorrelation time-domain calibration to correct would be great (S. Marka, S. Mohanty, X. Siemens, others) explored phase correction in frequency domain applied phase calibration after whitening stage calculate inverse DFT to go back to time domain
March 14, 2004, Livingston, LA Burst F2F Meeting I. Leonor 6


phase correction increases crosscorrelation significantly for all IFO pairs

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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each search segment is 160-seconds long (less ~1.5 seconds at ends of segment) each 160-second segment pre-conditioned use crosscorrelation windows of length 25 ms each, windows overlapping by half a window length calculate normalized crosscorrelation for each 25-ms second find largest crosscorrelation within each 160-second search segment; find largest abs(cc) for H1-L1 and H2-L1 due to unknown polarization use playground data to test pipeline and estimate sensitivity ­ playground data was long science segment not coincident with any GRB trigger
March 14, 2004, Livingston, LA Burst F2F Meeting I. Leonor 8


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on-source distributions derived from playground data with injections off-source segments were shuffled ­ each search segment from one IFO paired with all segments from other IFO

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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probability for getting median of on-source distribution, given off-source distribution probability takes into account trials in search probability is function of length of crosscorrelation window small window: 1/sqrt(N), more trials large window: more noise integrated

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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valid for 160-second search segments, 25-ms crosscorrelation window playground data Q = 8.9 sensitivity to gaussians:
H1-H2 0.5 ms 1.0 ms 1.10e-20 2.02e-20 H1-L1 8.56e-21 1.49e-20 H2-L1 9.47e-21 1.66e-20

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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25 GRB triggers used
23 for H1-H2 (includes 4 HETE GRBs) 9 for H1-L1 9 for H2-L1

H1-L1, H2-L1 search did not include non-localized IPN triggers (separate search) time delay taken into account for H1-L1, H2-L1 search GRB durations ranged from 0.3 ­ 200 s all on-source segments were clean (no error codes)
Local coordinates of GRB triggers and rms antenna factors for LHO
March 14, 2004, Livingston, LA Burst F2F Meeting I. Leonor 14


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find largest cc for H1-H2 find largest abs(cc) for H1-L1, H2-L1

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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local off-source distribution determined for each GRB trigger each distribution determined from searches within science segments occurring within a few hours of GRB trigger largest crosscorrelation found in each search included in distribution used data segments defined by burst group (J. Zweizig), with last 10 seconds of each segment excluded

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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calculate probability for largest cc found, given off-source distribution measured probability distribution consistent with random distribution no evidence of outliers, significant excess consistent with null hypothesis

March 14, 2004, Livingston, LA

Burst F2F Meeting I. Leonor

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