ligo-g030423-00-dm. landry – hanover lsc meeting, august 18, 2003 ligo s2 calibration michael...
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LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
LIGO S2 CalibrationMichael Landry
LIGO Hanford Observatory
Representing the calibration team:Rana Adhikari, Peter Fritschel, Gabriela Gonzalez,
Luca Matone, Brian O’Reilly, Hugh Radkins, Patrick Sutton, Akiteru Takamori
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Current status
• Online calibration with accuracy of ~20% was available with 1 hour latency
• Interim calibration issued with corrected DC calibration
• Final calibration to include hardware measurements: accurate representation of the actuation function
• Additional Wednesday talks relating to calibration include: Brian O’Reilly, Patrick Sutton, Xavier Siemens, and Soumya Mohanty
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Calibration Basics I
R(f): Response Function Scale Factor (from Calibration Line)G(f): Open Loop Gain = C(f)D(f)A(f)
Xi / AS_Q(fi,t) = R(fi,t) = [1 + (t) (t) G(fi) ] / (t) C(fi)
Xi = AS_Q(fi,t) . R(fi,t)
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Calibration Basics II
• We choose a time t0 and measure 0 ,G0 and R0 .
• This allows us to extrapolate to any time t using the amplitude of the calibration line (or lines).
• The amplitude (t) is a function of the alignment, dependent on the carrier power in the arms and the sideband power in the recycling cavity.
• (t) is tracked throughout the science segments.
R(fi,t) = [ 1 + (t) (t) G(fi) ] / (t) C(fi)
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
DC calibrations
• Have redundant measurements, including sign toggling, fringe counting, free-swinging and PZT fine actuator
• Gained confidence with multiple methods during S2; excellent agreement
• Will limit the number of redundant measurements during the S3 run; making some of these beforehand
• Concentrate on reducing error
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
L1 anti-imaging filter
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
New model comparison
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
LHO open loop gains
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Propagating the calibration:
LLO
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Propagating the calibration:
LHOH1
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Contributions to the Error
Magnitude: 2
4
22
4
22
4
2222
1
1
1
1
1
1G
G
G
G
G
G
G
G
G
D
D
A
A
R
R
Phase: 2
4
22222
4
2222
1
1
1
1GDAR
G
GGG
G
G
R(fi,t) = 1 + (t) (t) G(fi)
(t) C(fi)
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Estimating errors in L1 ’s
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Violins in H1
Independent check by
Rachel Berkowitz (SURF), and Fred Raab – modelling of violin modes in H1
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
S2 strains
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
LLO epoch comparsion
LIGO-G030423-00-D M. Landry – Hanover LSC Meeting, August 18, 2003
Conclusions
• Necessary to incorporate more realistic filters in model, i.e. measurements instead of as-designed filter
• Final calibration with errors to be issued by next Monday
• Expectations for S3: same 1hr latency for online calibration, with accuracy as per existing (final) calibration – we learn more each time