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Talk overview

S5 calibration status Michael Landry LIGO Hanford Observatory for the LSC Calibration Committee LSC/Virgo Meeting May 22, 2007 Cascina, Italy. Talk overview . Frequency-domain calibration h(f) V3 calibration and review, some gory details Factors a (t), g (t) Validation work for GRB070201

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Talk overview

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  1. S5 calibration status Michael LandryLIGO Hanford Observatoryfor the LSC Calibration CommitteeLSC/Virgo MeetingMay 22, 2007Cascina, Italy

  2. Talk overview • Frequency-domain calibration h(f) • V3 calibration and review, some gory details • Factors a(t), g(t) • Validation work for GRB070201 • Time-domain calibration h(t) • Photon calibrator • High-frequency calibration

  3. Calibration committee • Calibration committee • S. Giampanis, E. Goetz, G. González, M. Hewitson, S. Hild, E. Hirose, P. Kalmus, M. Landry, E. Messaritaki, B. O’Reilly, R. Savage, X. Siemens, M. Sung • Virgo: B. Lieunard, F. Marion, B. Mours, L. Rolland • Calibration review committees • Frequency domain: S. Fairhurst, K. Kawabe, V. Mandic, J. Zweizig • Time domain : S. Fairhurst, K. Kawabe, V. Mandic, B. O’Reilly, M. Sung, S. Waldman • High frequency : K. Kawabe, M. Rahkmanov, R. Savage, D. Sigg

  4. Frequency-domain calibration • We model the DARM loop in MATLAB • Compare this model to measurements of the open-loop gain, electronics in the Actuation and Sensing chains and DC value of the Actuation. • Optical and loop gain are tracked by time-dependent coefficients which are generated on minute or second time scales. • These coefficients are used to propagate measurements at t0 to other times.

  5. + Darm loop DARM_ERR Measure Open-Loop Gain at a reference time t0 G0(f) = A(f)CD0(f)DD(f) h(f,t) = RDERR(f,t)DERR(f,t) DARM_CTRL_EXC DARM_CTRL  DD(f) + A(f) (t)CD0(f) sres=(Lx-Ly)/L s=h(t)+n(t)

  6. Frequency-domain status • Since last L/V meeting: • V3 calibration released (Nov 4 05 – Jan 22 07) • V3 currently being reviewed • http://touro.ligo-la.caltech.edu/~irish/Work/Calibration/S5V3Review/S5V3Review.html • Changes to a machine’s state are reflected in the calibration yielding epochs • L1 • 3 epochs due to servo changes • Roughly 3, 1/2 and 15 months in duration, respectively • H1 • 4 epochs due to servo and DARM gain changes • 3, 4, 4, and 7 months in duration • H2 • 3 epochs due to servo changes • 3, 8, 6 months in duration

  7. H1 H2 Open loop gain model/ measurement comparison L1

  8. H1 ITM comparison • Results of MICH sweeps, corrected for pendulum H1 – Dec 8 06 H1 – Nov 22 06

  9. DC cal histories L1 H1

  10. Factors at reference time : a(t), g(t) L1 – epoch 3

  11. Calibration for GRB070201 • GRB event ostensibly in M31 on Feb 1, 2007 : H1 and H2 locked in science mode • Validate V3 calibration for Feb 1, 2007 • Made V4 calibrations: checked against V3 • Checked Feb 1 IFO configurations against that of V3 reference time • Autocalibration check : check V3 against quasi-independent autocalibrator procedure • Conclude V3 calibration acceptable for GRB070201 • Technical doc T070100-00-W, “Validation of the S5 V3 LHO calibrations for GRB070201” written

  12. h(t) • Description at • http://www.lsc-group.phys.uwm.edu/~siemens/ht.html • S4 review complete • Production of V3 h(t) underway • h(t) in LIGO naturally follows on from frequency domain model • Necessary filters created from h(f) V3 DARM model • Lengthy process (~ month) to reprocess S5 data with updated V3 calibration and produce h(t) : data are on tape • h(t) now employed by all search groups

  13. Photon calibrator • Intensity modulated radiation pressure excites ETM, approximately sinusoidally, at a chosen frequency. • Displacement is estimated with basic physics. Power is deduced from a photo-detector looking at beam pickoff.

  14. H1 ETMY coil actuation coefficients Photon calibrator Actuation coeff. x f^2 Official calibration Frequency (Hz) H1 ETMY coil actuation coefficients determined by the official calibration procedure (blue) and by the photon calibrator (red). The transfer functions have been multiplied by the square of the measurement frequency to flatten the plots. Ratio of ETM coil calibration factors (m/ct) measured using the photon calibrators to those measured using the official calibration technique (mean of values over the frequency range from 50 to 400 Hz).

  15. High-frequency calibration • AS_Q_FAST channels 262kHz sampling rate • Signals digitally heterodyned at 1024Hz (AS_Q_0FSR) and 37.504kHz (AS_Q_1FSR) at 2048Hz sampling rate Introduction • S4 calibration review underway • S5 calibration • Post-S5 measurements to ensure quality

  16. Closing • S5 calibration issues • Many measurements over a long run: multiple epochs, discrepancies to understand. Complicates data production and calibration validation • What to do with short epochs? Data quality flags or special calibrations? • Events like GRB070201 require confidence in online calibration • All calibration flavours will require IFO configuration freezes at the end of S5: suite of measurements, both in control room and on the floor

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