Reports until 05:24, Saturday 07 February 2015
H1 ISC
evan.hall@LIGO.ORG - posted 05:24, Saturday 07 February 2015 - last comment - 17:38, Sunday 08 February 2015(16544)
1 hour lock at zero CARM offset

Ryan, Lisa, Evan

We have been locked for more than 1 hour with CARM controlled by digital REFL9I (at 0 pm offset) and DARM controlled by ASAIR 45Q. The power buildup is 1100 times the single-arm buildup, giving an interferometer recycling gain of 33 W/W. The REFL_A_LF power is 1.35 ct, compared to 21 ct with the arms held off resonance. This means the interferometer visibility is about 94%.

The new element today was a higher-bandwidth DHARD pitch WFS loop. The loop time constant is a few seconds or so, and is fast enough to suppress the appearance of the microseism in ASAIR 45Q. Next steps are probably to close the analogous yaw loop. Ryan had to adjust ETM differential yaw by hand several times to keep the AS beam reasonably round. Also, Ryan had to add a DC-coupled oplev servo to ETMX L1 pitch in order to keep the optic from drifting.

Details will be posted later.

Comments related to this report
lisa.barsotti@LIGO.ORG - 05:29, Saturday 07 February 2015 (16546)
Link 

These are the plots with the transition to REFL 9I, and a trend of the 1 hour long lock (starting around Feb 7, 12.11 UTC).

In the first plot, the power build up increase around 400 sec is due to the improvement of differential YAW alignment that Ryan did by hand. 

The lock loss happened right after a DARM loop measurement. 

The high wind of the afternoon was totally gone by the time we came back to the site after dinner.
Images attached to this comment
david.shoemaker@LIGO.ORG - 05:31, Saturday 07 February 2015 (16548)
Link 

Congratulations! and thanks for staying up all night once again.
albert.lazzarini@LIGO.ORG - 07:06, Saturday 07 February 2015 (16550)
Link 

Welcome news. Great job. Congratulations to everyone who has helped bring this about.
david.reitze@LIGO.ORG - 09:48, Saturday 07 February 2015 (16553)
Link 

Awesome! Very pleased to see this result. Nice work everyone!
fred.raab@LIGO.ORG - 01:48, Sunday 08 February 2015 (16563)
Link 

Congratulations from Delhi! Nice to see the stability of lock at this early stage. The entire team deserves credit for undaunted persistence through all the tricky issues. Y'all rock.
lisa.barsotti@LIGO.ORG - 17:38, Sunday 08 February 2015 (16567)ISC
Link 

In my previous trends I plotted the wrong POP18 signal (before demodulation), here is the correct signal representative of the sideband power.

Once the arm cavity power increases from ~ 500 to ~1000 single arm power, the sideband power decreases by ~20% in about 10 min.
Images attached to this comment