Ibrahim, Sheila, TJ, Camilla, Naoki
Since the +/- pitch alignments of SR3 from 79103 both seem like they will not work, this morning I ran intial alignment for the +Y spot again. After running SR2 align (single bounce, 10W), the power on AS_C NSUM was 0.0219 Watts arriving in HAM6, 5% worse than the 0.023W before Friday (79101). Attached are screenshots of the AS air camera and the sliders after running initial alignment. After PRMI ASC ran, POP18 NORM was 45, POP90 NORM was 48 counts (sliders and camera in PRMI).
DRMI locked with POP18 NORM of 50 counts, so still with 15% less power than last Thursday. We have had a number of locklosses trying to get to DC readout. We saw that again a DARM Offset of 9e-5 causes the ASC to fail and causes a lockloss, so we changed the DARM offset to 6e-5, and made edits to OMC_LOCK to allow it to lock (lowered prominence in FIND_CARRIER to 5, and height to 6, threshold in OMC_LOCKED to 6 instead of 10).
We have been able to lock, with a range of 100Mpc.
Editing to add a comparison of this lock to last Thursday's lock.
The single bounce throughput is (0.219/0.023) = 95% of what it was last Thursday. The optical gain is then expected to be srt(0.95) = 0.97. Right now kappa C is reporting an optical gain of 0.907, 1 hour in to the thermalization, so significantly worse than expected. I think think that this is beyond the range of values where kappa c is a good approximation, so we need to run a calibration measurement soon.
AS_A, AS_B DC, AS_C, and OMC REFL are 86% of what they were last Thursday. Power recycling gain and arm powers are still thermalizing, but may be a bit low. OFI PD A (the one in HAM7, measures rejected beam from the TFP on the side of the OFI closer to HAM6), is lower by 5%, Camilla pointed out to me that the power on this diode changes each time that we move ZM4/5/6, so it's not very reliable for comparisons. OFI PD B, the one in HAM5 that measures the rejected beam from the first polarizer in the OFI, sees more rejected power by 17% than it did on Thursday.
We opened the AS beam diverter and captured screenshots of the image with the normal exposure of 800 and with the exposure lowered to 50.
Since we learned about the lower throughput in full lock (didn't know about that before), we're making whatever we can to assess the performance of H1 with this alignment.
However, this means that we will dump more than 10% of power spike into whatever is absorbing power in the next lock loss. I don't think this is a sustainable way to operate H1. I asked Sheila to reduce the power and unlock after we're done with noise characterization. Calibration is NOT going to be done fully as it involves fixing something that doesn't run as of now, we'll have to skip that.
Attached is a comparison of now (Jul 16) VS 8 days ago (Mon Jul 08), both ~2 hours into 60W lock.
| channels (all OUT_DQ) | Tue Jul 16 | Mon Jul 08 | Now/Before |
| ASC-AS_C_NSUM | 0.583 | 0.702 | 0.830 |
| ASC-OMC_A_NSUM | 0.532 | 0.629 | 0.846 |
| ASC-OMC_B_NSUM | 0.519 | 0.615 | 0.844 |
| ASC-AS_A_DC_NSUM | 50240 | 60769 | 0.827 |
| ASC-AS_B_DC_NSUM | 54311 | 66061 | 0.822 |
| OMC-REFL_A_LF | 571.2 | 687.4 | 0.831 |
Same table but with a new column for our SR3 -P alignment from a 17 hour lock on May29. These values were taken the same as above.
| channels (all OUT_DQ) | May 28 | Tue Jul 16 | Mon Jul 08 | Now/Before |
| ASC-AS_C_NSUM | 0.595 | 0.583 | 0.702 | 0.830 |
| ASC-OMC_A_NSUM | 0.571 | 0.532 | 0.629 | 0.846 |
| ASC-OMC_B_NSUM | 0.538 | 0.519 | 0.615 | 0.844 |
| ASC-AS_A_DC_NSUM | 52000 | 50240 | 60769 | 0.827 |
| ASC-AS_B_DC_NSUM | 55383 | 54311 | 66061 | 0.822 |
| OMC-REFL_A_LF | 675.6 | 571.2 | 687.4 | 0.831 |