The recovery of QNR system after the electrical blackout was performed on Thursday 18 May and Monday 22.

The following electronic was reswitched on:

1. Squeezer Main Laser, Squeezer CC Laser and EQB1 Subcarrier Laser
2. The 4 DDS box on the rack 5 (restarted off-on to update the IP address): g25squeeze4, g25squeeeze5, g25squeeze5 and g25squeeze7
3. The EQB1, EDB and EQB2 QPDs were restarted, both the BIAS and the Power supply
4. The 80MHz generator for the phase camera+PLL AOM was restarded via g25squeeze2 DAQ BOX
5. The 80 MHz generator used for the Main PLL was re switched on with the following parameters:
   • Frequency 80 MHz
   •  Amplitude 0 dBm
   • Frequency modulation External
   • Frequency modulation DC
   • Frequency modulation slope 44 kHz
6. The 78 MHz generator used for FMODERR loop was restored with the following parameters:
   • Frequency 78.919655  MHz
   • Amplitude pk-pk 0.9V
   • Modulation FM
   • Tuning range 600 Hz
   • Remember to switch on the output and the modulation (both the led below buttons should be on)

Part 1 - The suspended benches and mirrors are controlled again:

On thursday 18 the first action performed was the control of SQB1, SQB2, FCIM, FCEM

• SQB1:
  • we checked in the VIM the position of the DOF and we found that the setpoint in the config file were not updated in particular LC_X -3700 (last position) and LC_Y -550 (last position), we saved in the config file LC_X and we updated online LC_Y (still not saved)
  • we opened the tracking loop (SDB1 was uncontrolled)
  • we closed the angular controls
  • we closed the position controls
• SQB2: 
  • position are checked and are ok
  • we opened the tracking loops
  • closed the angular controls
  • closed te position controls
• FCIM, FCEM: 
  • with a trend we found the last position of FCIM and FCEM MAR_TX and MAR_TY when the cavity was aligned and we set it online
  • we closed the Local controls MAR_TX, MAR_TY and MAR_TZ
  • we closed the position controls of the inverted pendulum

On Monday 22 May we closed again the tracking loops of SQB1 (once SDB1 was controlled) and SQB2 once (NI was controlled). We aligned also the filter cavity maximizing the flashes in transmission.

In the meantime Henning rechecked the squeezer and the BAB was restored. A problem on SQZ Translation stages occured we could not move them anymore (up to now we can not switch from BAB to SQZ)

Part 2 - Recovery of PLLs

• Until the recovery of the INJ system we could only try to lock the CC and SC PLLs:
  • CC PLL: once restarted the CC laser it worked at the first attempt (SQZ_MAIN in LOCKED_PLL_CC _STAND_ALONE)
  • SC PLL: was not working thus we realized that the hardware was still off. Once we also switched off-on the noise eater 2 times and we could lock the PLL at the first attempt
  • MAIN PLL: once the RFC was locked we performed the following actions
    • Try to lock the PLL without succes
    • With the MUX out we checked the value of LO and RF input (looking the EQB1_MAIN_PLL_STATUS). For the LO we had a good signal for RF no. 
    • We disconnected the LO cable and we realized that was the generator. So RF cable is the beat note this means that the beat note was not present
    • We checked the Photodiode EQB1_MAIN_PLL_PD1_DC and PD2_PDC and we realized that a part of the power was missing probably the pick-off of the inj laser
    • ALS was present thus the beam in the fiber was present, thus after some investigation and with the help of Mattieu we realized that probaby the RF generator of the PLL+Phase camera AOM was not restored
    • I reconfigured the channel 1 of the g25squeeze2 DDS at 80 MHz 
    • After that we regained the missing power on the MAIN_PLL_PD1_DC and PD2_DC and the PLL locked at the first attempt

Part 3 recovery of the filter cavity

• Once the three PLLs were locked again we realigned the filter cavity and we relocked it. A huge noise was present thus we forced in the SQZ_CC_Ctrl process the filter0, the FC_Error signal based on GR_PD 
• The Filter cavity relocked but once we engaged the AA the filter cavity misaligned
• After some investigations we realized that no power on EQB1 QPDs was present. Thus we asked to Fabio to check if the QPDs were on after the ENEL Failure. He reswitched on all the QPDs and the AA worked again
• We put a Scan on PLL SC and we unlocked and relocked the cavity until we found SC flashes in transmission
• We maximized the SC flashes in transmission closing the PY_SQZ_IR loop using SC_PLL as actuator
• We closed IR_AA loop
• We manually closed the FMODERR loop and helping it putting a DC offset od 3.2V then we removed it with a120s ramp
• We performed FMODERR and we reached the state FLT_IR_AA_FMODERR_TUNED. We set 0 Hz detuning in SQZ_FLT.ini for FMODERR
• We religned SC into OPA using the SC AA loop
• We maximized the tranmission of the SC into OPA using M21 and M22 with the IR AA closed. We reached again 14.7V of IR transmission BAB+ SC, i.e. 13.6 V of SC and 1.1V of BAB
• We left for the night the filer cavity in loked IR_AA FMODERR_TUNED

Still to do:

• Update the setpoint of SQB1 MIRROR1 and 2 after the blackout
• Update the demodulation phases of SQB1 AA loop with ITF
• Realign the HD detector with SQZ beam
• The reflected beam from FLT seems clipped on EQB1 cam, to be checked
• The SQZ translation stages are still not working