LIGO-G070312-00-I

S5 calibration status Michael LandryLIGO Hanford Observatoryfor the LSC Calibration Committee

LSC/Virgo MeetingMay 22, 2007Cascina, Italy

Landry - L/V meeting, 22 May 2007 2LIGO-G070312-00-I

Talk overview

• Frequency-domain calibration h(f)» V3 calibration and review, some gory details

» Factors (t), (t)

» Validation work for GRB070201

• Time-domain calibration h(t)• Photon calibrator• High-frequency calibration

Landry - L/V meeting, 22 May 2007 3LIGO-G070312-00-I

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

Landry - L/V meeting, 22 May 2007 4LIGO-G070312-00-I

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.

Landry - L/V meeting, 22 May 2007 5LIGO-G070312-00-I

A(f)

DD(f)

(t)C D0(f)

DARM_ERR

+

s=h(t)+n(t)

DARM_CTRL

sres=(Lx-Ly)/L

+

DARM_CTRL_EXC

0

0

1 ( ) ( )( , )

( )( )DERR

D

t ff t

fGR t C

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 loop

Landry - L/V meeting, 22 May 2007 6LIGO-G070312-00-I

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

Landry - L/V meeting, 22 May 2007 7LIGO-G070312-00-I

Open loop gain model/

measurementcomparison

H1 H2

L1

Landry - L/V meeting, 22 May 2007 8LIGO-G070312-00-I

H1 ITM comparison

• Results of MICH sweeps, corrected for pendulum

H1 – Nov 22 06 H1 – Dec 8 06

Landry - L/V meeting, 22 May 2007 9LIGO-G070312-00-I

DC cal histories

H1 L1

Landry - L/V meeting, 22 May 2007 10LIGO-G070312-00-I

Factors at reference time :(t), (t)

L1 – epoch 3

Landry - L/V meeting, 22 May 2007 11LIGO-G070312-00-I

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

Landry - L/V meeting, 22 May 2007 12LIGO-G070312-00-I

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

Landry - L/V meeting, 22 May 2007 13LIGO-G070312-00-I

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.

xexc () 2P cosMc 2

LIGO-G070312-00-I

H1 Xarm H1 Yarm H2 Xarm H2 Yarm L1 Xarm L1 Yarm

Pcal/Ocal ratio N/A 1.16 1.16 1.17 1.14 1.08

Date measured Sept. 28, 06 Nov. 8, 06 Nov. 8, 06 Mar. 16, 07 Mar. 16, 07

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).

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.

H1 ETMY coil actuation coefficients

Act

uatio

n co

eff.

x f

^2

Frequency (Hz)

Photon calibrator

Official calibration

Landry - L/V meeting, 22 May 2007 15LIGO-G070312-00-I

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

0 20 40 60 80 10010

-3

10-2

10-1

100

Frequency (kHz)

Phas

e (

deg

.)

Ifo. response to diff. length variations

exactsingle pole

0 20 40 60 80 100-100

-50

0

50

100exactsingle pole

Landry - L/V meeting, 22 May 2007 16LIGO-G070312-00-I

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