We started at 14:00 UTC and to not interfere with the ITF and risk to unlock, we manually injected the SQZ. 

• System initial status: ITF LOW NOISE 3; SQZ_MAIN @SQZ_Locked_NO_FC

• 14:28:26 AA loop engaged

We performed a first CC phase scan (Fig. 1-2): 

• 14:39 CC scan started DCP = 195 Hz

• 15:02:21 CC scan ended (fast shutter closed), ITF in shot

• 15:26:15 fast shutter opened

• 15:36:22 ITF in SQZ phi0 = 0.65 rad

• 15:39:19 SQB1 TX angle set to 300 (initially at 310)

• 16:42:58 SQB1 X position set to -3200 (original position)

• 16:47:58 ITF in SQZ

After the first CC scan we realized the magnitude was similar to the last shift (entry #64094) even though there should be a higher level of injected SQZ. We decided to try to improve the magnitude by acting on SQB1_TX and SQB1_X DOFs. We worked on this from 15:39:19 to 16:42:58 UTC. Finally we left SQB1_X as it was and we changed the set point of SQB1_TX from 310 to 330 urad. The fluctuations on the magnitude are reduced (Fig. 3).

We then performed another phase scan (Fig. 4-5)

• 17:05 CC scan started DCP = 195 Hz

• 17:28 CC scan ended (fast shutter closed), ITF in shot

After the second CC scan we realized the SQZ angle is actually around 1.05 rad, so we decided to repeat the SQZ mode acquisition.

• 17:39:53 fast shutter opened, ITF in SQZ phi0 = 1.05 rad

• 17:49:08 CC loop engaged, gain=75000 (glitch between 17:54:50 and 17:56:14)

• 17:58:54 ITF in ASQZ phi0 = 2.75 rad

We were able to get another CC phase scan with DCP setpoint at 225 Hz (Fig. 6-7). Fig. 8 reports also the shot SQZ and ASQZ acquisitions made after the scan.

• 18:11 DCP value set to 225 Hz

• 18:44:11 ITF in shot

• 18:46: CC scan started DCP = 225 Hz

• 19:09 CC scan ended

• 19:15:07 ITF in ASQZ phi0 = 2.7 rad

• 19:22:48 ITF in SQZ phi0 = 0.95 rad

• 19:28 DCP value set back to 195 Hz

Errata corridge: the plot of the squeezing level and the BLRMS of the first CC scan (t_start = 16:52 UTC) was erroneously equal to the one of the second CC scan. I attach the correct plot.

I attach the plots for the two CC phase scans performed during the shift of yesterday. I was not able to produce the BNS range plot for the second scan, which is anyway visible in Fig.4.

The second scan started at 18:11 UTC, with the same duration times of shot and CC scan as of the first one.

This entry is related to the shift of yesterday 13 March

Preparation to the shift:

In the morning Henning set the Mach Zehnder offset at 0.05V. With this the parametric gain increased from 2.7 to 3.03 i.e. the squeezing level generated by the OPA increased from 8.5 to 9.5 dB

After that we checked the clipping in the SQB1 FI and we found about 1% of clipping that was solved moving the RR by -60 steps in horizontal and +30 steps in vertical

We also checked the tuning of SQB1 HWP1 and HWP2 looking the beatnote between the LO and ITF beam on the HD detector and we mimized it. With a precision of 20 steps of the rotators

We measured the level of SQZ and ASQZ on the HD detector and we foundrespectively 5.8 dB and 9 dB. 

Shift:

The interferometer reached Low noise 3 at 13:51:33 and we measured only 1.9 mV of B1 4MHz mag. We expected to see something around 2.14mV  so we started to align.

We easily reached this walue using SQB1 pico and the AA loop. Then we tried to see if we could improve again by moving SQB1 Bench, the retroreflector and the Z direction of the matching telescope +/- 5000 for M33z and M34z.

Once we reached that state 2.12mV of B1_4MHz_mag we did not improve anymore. So we are probably on a local or on the global maximum. (fig1)

After the alignment we performed a CC phase scan:

• 15:39 Shot noise
• 15:48 Shot noise but we noticed an improvement of hrec
• 15:58 we started the scan (shot noise reference 2 min) 1394380724. The real scan started at 1394380849 (fig 2)
• We took 10 minutes of antisqueezing (phase 2.7 rad) at 16:39 and squeezing beetween 16:57 and 17:11  UTC (phase 1rad). (fig 3) 

From the phase scan we can see that we improved the range by about 3 Mpc starting from 51.7 Mpc. We worsened the range with Antisqueezing by about 4.7 Mpc

Tuning of the AA dithering loop

• We started to commissiong the AA dithering loop with M1_X, M1_Y, M2_X, M2_Y dither lines respectively at 20, 25, 30, 35, 40 Hz
• To do it we open the loop, we reset the correction and we start to scan each DOF with a ramp around the working point with 2 V of amplitude and frequency 0.2 Hz
• M1_X phase changed from 0.28 rad to 0.6 rad. Amplitude increased from 1mV to 10 mV
• M1_Y phase changed from 0.28 to 0.75 rad. Dither line ampolitude increased from 1mV to 3 mV
• M2_X phase changed from 0.36 to 0.8 rad. Dither line ampolitude increased from 1mV to 3 mV
• M2_Y phase changed from 0.3` to 0.75 rad. 

After this work the loop was more stable.

Injections and phase scan

• Squeezing injection at 19:16:50
• Shot noise at 19:33 with dither lines on
• Shot noise at 19:44 with dither lines off
• Shot noise at 19:57 with fdither lines on
•  Phase scan at 1394395672 in 1200 s

Fig 3 brms hrec during the on off of the dither line. No particular evidence except the fact that the noise was changing with the evoulution of the frequency noise.

In figure 4 you can see also that the range is increased from 50 to 54 MPc during the phase noise reference (the maximum was reached with dither lines on). 

Figure 5 shows also Hrec with dither lines on and off

Fig 6 you can see the effect of the squeezing in the pahse scan. Unfortunatelly we had a glitch during the maximum ASQZ and the minimum of the range. The SQZ injection increased again the range about 3.5 Mpc starting from 53.2 Mpc

After the scan Nicola left the system in LOW_NOISE_3_SQZ. I checked the stability of the system during the hour of injection. I saw a small degradation of the mag that seems be correlated to the improvement of CMRF. I don't know if it is due to some clipping created by the relative alignment between ITF and SQZ, in any case the range was increasing and the fluctuation was only 1% show it could be also due to a fluctuation of the Squeezer parametric gain

Here thr list of actions performed during the shift:

• The ITF Locked at 14:45 UTC and we took a shot noise reference with the shutter closed ~55 Mpc in the sensitivity
• At 15:20 we open the SQB1 shutter and we measure ~53 Mpc after 
• We work with alignment using SQB1 picomotors and the SQZ to  OMC AA closed we stopped the work at 17:28:50 UTC
• We close the Fast shutter (shot noise) at 17:29 UTC
• We injected SQZ (angle 1.3 rad) at 17:45:30 UTC
• At 17:52:30 UTC we open the AA and we removed the dither line
• We started moving the SQB1 position in particular SQB1 X from -2950 to -2750 um and SQB1 TX from 290 to 300 urad. At the end of the process we had a B1_4MHz_mag 2.03 mV. The initial magnitude was 1.95 mV i.e 4% of increase. The power increased of about 8%. (fig 1)
• We stopped with the clipping removal at 18:30 and we switched of the AA dither lines at 18:30.

Then we checked the CC loop:

• Clean data: 21:26 UTC 2 min (gain 75000 in SQZ phase 1.3 rad)
• Noise Injection 21:39 UTC 2 min with amplitude of 5uV. We measure an UGF og 4.1 kHz
• We saw lines in the CC loop at 3.088kHz and 6.129 kHz
• We open the CC at 21:46:09 UTC
• We close the shutter and we measure the sensing noise at 21:44 UTC
• The CC is limited by sensing noise and the SNR is about 200 (fig 2 and 3)

Then we checked the results of the alignment performing a CC phase scan:

• Shot Noise at 21:56 UTC
• Phase scan 1394230253 (fig 4)
• Phase scan shot 1394230253
• ASQZ 22:38:41 UTC
• SQZ 22:51:00 UTC (fig 5)

The goals of the shift were:

• to improve the alignment between SQZ and ITF removing clipping 
• tune the SDB1 FI HWP to reduce the amount of light sent from ITF to QNR
• measure the CC loop transfer function
• perform a CC phase scan

We left the ITF with SQZ injected in autorelock failsafe details will follow tomorrow