After the switching off of the PR RH 56065, this afernnoon we started the recovery of the ITF.
- First of all we noticed an increase of the temperature on SIB1. This was due to a misalignment of the PR, which we also experienced when the PR RH was switched on. We had to manually correct the position of the PR in order to get it aligned properly. Moreover, we also reverted the movement of the POP of the PR by moving back the dof PR_F7_TY by 10urad. (plot 1)
- We started with the matching of the arms, coming back to the position before swtiching on the PR RH on 13th of May (55847)? The steps are summarized in the table below and in fig. 2
| gps UTC | L1z | CW | direction | |
| 14h04 | 80000 | forward | ||
| 14h27 | 80000 | " | ||
| 14h35 | 40000 | " | #1 | |
| 15h11 | 40000 | " | ||
| 40000 | " | |||
| 15h29 | 20000 | " | #2 | |
| 15h50 | 25000 | " | #3 | |
| 17h07 | 20000 | " | ||
| 17h10 | 20000 | " | #4 | |
| 17h37 | 20000 | #5 | ||
| 18h09 | 70000 | |||
| 18h16 | 40000 | #6 | ||
| 18h38 | 40000 | #7 |
In total we made with L1z 325000 steps forward, ending up with 1.3% mismatch for the west and 2.5% for the North.
- Recovery of the lock acquisition: we had to tune several demodulation phases in CITF even though most of them have now values close to the one used the last lock at carm_null before the switching on of the RH, the 13th May
| DOF | CITF 1f | demod. phase (rad) | CITF 3f | demod. phase dem (rad) |
| PRCL | SIB2_B2_6_MHz_I | 1.3 | SIB2_B2_18MHz_I | -0.95 |
| MICH/SRCL | SIB2_B2_56MHz_I/Q | 1.95 --> 1.8 | SIB2_B2_169MHz_I/Q | -1.95 --> -2.25 |
| BS TX/TY | SDB2_B1p_QD1_V/H_50MHz_I | 1.3/0.9 --> 1.1/1.1 | ||
| PR TX/TY | SIB2_B2_QD2_V/H_6MHz_I | SIB2_B2_QD2_V/H_18MHz_I |
At DARM IR: the DARM demod phase SDB2_B1p_56MHz_I from 1.7--> 3.1 rad and we propagated it through the steps of carm offset reduction. At CARM OFFSET STEP 3 for DIFFp we left B1p_QD2_H/V_56_MHz demod phase 2.4 rad and we adjusted the B1p 56MHz for DARM.
We finally tried to reach CARM NULL 3f but we unlocked.
We noticed that the SDB2_B1p_56MHz_I phase seems to be more stable, as you can see in the 3rdd plot, to be compared with 56029 (the small jump is when we were tuning the phase, but since then it was stable).
We will continue the full recovery tomorrow after the maintenance.
We leave the arms locked on the IR.
