This morning we have made a preliminary analysis of the cause of the unlocks that took place during the weekend. We have excluded the period when Eric went to the laser lab due to the excitation of the suspended injection bench (see entry 41464) and the period of troubleshooting after the problem with the DAQ (see entry 41467) and the manual unlocks.
We have divided the unlocks in two groups, the ones occurred during the lock acquisition and the ones occured when in Low Noise 3.
LOW NOISE 3 | |
08.32.42 UTC / May 19 | Fast Unlock |
11.52.25 UTC / May 19 | Fast Unlock |
14.35.43 UTC / May 19 | Fast Unlock |
16.42.07 UTC / May 19 | DARM? Saturation on B1 DC? |
21.27.14 UTC / May 19 | Fast Unlock |
22.25.37 UTC / May 19 | Fast Unlock |
22.50.56 UTC / May 19 | DAQ |
11.35.48 UTC / May 20 | Fast Unlock |
15.02.38 UTC / May 20 | SSFS oscillation @ 2kHz |
20.39.09 UTC / May 20 | Fast Unlock |
22.47.01 UTC / May 20 | DAQ |
00.25.00 UTC / May 21 | SSFS oscillation @ 2kHz |
This morning we made a "Fast Unlock" manually from Low Noise 3, in order to compare it with the ones of the weekend 12.18.32 UTC.
Time | ITF_LOCK_index | Cause |
08.42.35 UTC / May 19 | 123 | 125 Hz oscillation on DARM |
09.19.27 UTC / May 19 | 119 | SSFS high gain when going to DF |
14.38.56 UTC / May 19 | 40 | West arm locked in a HOM |
14.45.35 UTC / May 19 | 119 | SSFS high gain when going to DF |
16.49.42 UTC / May 19 | 103 | ??? |
16.52.21 UTC / May 19 | 90 | Fast Unlock |
16.56.13 UTC / May 19 | 81 | IMC unlock (misalignment) |
17.02.48 UTC / May 19 | 123 | IMC unlock (misalignment) |
17.25.59 UTC / May 19 | 126 | DARM 27 Hz - saturation? |
17.39.20 UTC / May 19 | 126 | DARM 27 Hz - saturation? |
21.34.11 UTC / May 19 | 119 | SSFS high gain when going to DF |
11.49.05 UTC / May 20 | 119 | SSFS high gain when going to DF |
15.08.21 UTC / May 20 | 40 | Fast Unlock |
15.22.53 UTC / May 20 | 91 | Fast Unlock |
15.23.51 UTC / May 20 | 39 | Fast Unlock |
22.58.45 UTC / May 20 | 126 | DARM 27 Hz - OMC? saturation? |
23.02.28 UTC / May 20 | 102 | DAQ |
From the analysis we made it is interesting to remark that once in Low Noise 3 the most common cause of unlock comes from the IMC. Instead during the lock acquisition we have experienced a wide causes of unlocks (without counting the punctual problems mentioned at the beginning). One well understood is the high gain of the SSFS when reaching DF, we need to adjust better this transition.
We marked in yellow the unlocks that are not yet understood, we will keep on investigating. Also we will keep on studying the Fast unlocks to try to find a cause.