1LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Calibration Testing

Patrick Sutton, withMichael Landry, Gabriela Gonzalez, & Brian

O'Reilly

2LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Idea

We have two ~independent means of calibration, which can be compared for consistency.

`Official' calibration: » Measure H, C during dedicated calibration run (hours).

Eg. Done Feb 14-15.

» Fit measured H data to model, derive H, C, Cb for that time.

» Dynamic: Rescale H, C over time using alpha measured from calibration lines; update Cb.

3LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Idea (cont'd)

AutoCalibrator:

» Inject swept sine into ETMX/Y and measure transfer function to AS_Q (minutes).

» Empirical (no use of model) - independent of `official' calibrations up to treatment of actuation function A(f).

» Gives static snapshot of Cb.

Proposal: Use frequent AutoCalibrator sweeps as check on Official calibration.

This talk: show examples for S2

4LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Example: H1

5LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Ratio: H1 Official/AutoCal

6LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

More H1 Sweeps

7LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Example: H2

8LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Ratio: H2 Official/AutoCal

9LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

More H2 Sweeps

10LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Lonely L1 Example

11LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Lonely L1 Example

12LIGO-G030093-00-Z Penn State / LIGO Scientific Collaboration 2003 March 18

Summary: Huh?

See very similar discrepancies between Official and AutoCal calibrations in all three IFOs.

Discrepancy increases with frequency. At 2kHz:» Magnitude: 40%

» Phase: 2 radians

Source unknown; will require further investigation.