aLIGO LHO Logbook

H1 CAL (CAL)

evan.goetz@LIGO.ORG - posted 13:38, Monday 24 October 2016 - last comment - 10:25, Wednesday 26 October 2016(30811)

Amplitude of 331.9 Hz Pcal line reduced

Since the noise of the detector has improved around the 331.9 Hz Pcal injection frequency, we can reduce the amplitude of the injection (current setting 9000 cts for both sine and cosine). I have reverted changes that increased the amplitude of this line (see LHO aLOG 30476). The new amplitude setting is 2900 (for both sine and cosine amplitudes), which is the same as it was before increasing the injection amplitude.

This also brings the total injections to Pcal Y below the threshold (see LHO aLOG 30802). The threshold is 44,000 counts. The current total injection is now 38650.0 counts.

Screenshot of excitation settings attached.

Images attached to this report

Comments related to this report

jeffrey.kissel@LIGO.ORG - 13:45, Monday 24 October 2016 (30812)

Link

Note to self: check the front-end calculations of the uncertainty and coherence of these lines before and after this change after the IFO reverted back to 25 [W] input power. 
Example checks: 
   - do the calculations show the expected decrease in coherence / increase in uncertainty? 
   - how much was the uncertainty / coherence when the SNR was so high? 
   - do we like that level of uncertainty? did it reveal more real optical parameter changes instead of noise?

evan.goetz@LIGO.ORG - 10:25, Wednesday 26 October 2016 (30889)

Link

Delayed update, these changes were accepted in the SDF today (Oct. 26, 2016, ~10:20 PDT).