MIF (ASC)shinji.miyoki - 15:44 Thursday 05 March 2020 (13339)
Print this report500 kpc[Miyoki, Yamamoto, Yokozawa, Sugimoto]
By adjusting PRMI part alignment (PRM and BS) to obtain LSC-POP_PDA2_RF90_I_ERR_DQ sgnal over 1, we got 500 kpc.
Comments to this report:
shinji.miyoki - 15:48 Thursday 05 March 2020 (13352)
Print this report[Izumi kun comment posted by miyoki]
> Very cool. Do you think this is a consequence of having a good alignment in PRC and MICH?
Truely, I did BS and PRM alignment in order to obtain better "LSC-POP_PDA2_RF90_I_ERR_DQ" value with no confidence about sensitivity enhancement.
Then Actually, better LSC-POP_PDA2_RF90_I_ERR_DQ by this method resulted in better sensitivity. There seems to be related with each other.
Although my this trial was terminated by a big disturbance of ETMX, yokozawa-kun kept the same trial after ETMX recovery, then he got over 500 kpc.
> If that is the case, this could potentially point us to particular type of noise sources such as laser noise (jitter, intensity, frequency), MICH/PRCL feedfoward accuracy and OMC alignment.
Actually, on 4th March early afternoon, Aso-kun took a pretty good alignment of IFO including, beam spot on mirrors, OMC injection. Then, he realized the almost same QPD centering value for OMC for both XY arms, by tuning BS alignment.
Normally, this QPD centering are slightly different with X arm and Yarm individual lock state if non-expert uses a monkey alignment.
This is very important point, I guess, especially BS alignment.
Miyakawa-kun, tried one more boost for ISS just after Aso-kun's alignment, however, no remarkable change of sensitivity at the level of 350 kpc sensitivity.
After that we tried the BS-PRM alignment to obtain better "LSC-POP_PDA2_RF90_I_ERR_DQ" in the night on 4th march, then we got better sensitivity.
In this configuration the ISS has no additional boost that miyakawa-kun tried.
We did not add more boost for Frequency Stabilization System, and don't do more that you pointed out.
> Also, if you are looking for additional kiloparsecs, try engaging the second whitening stage for the OMC DCPD which should give a slight improvement in the noise floor at some high frequencies as suggested by Tomo[1].
>
> [1] http://klog.icrr.u-tokyo.ac.jp/osl/?r=13290
Thank you for your suggestion and hint from akutsu-kun. We would like to try.
However, today's ocean is so violent again. We should wait until today's midnight, maybe.
shinji.miyoki - 15:49 Thursday 05 March 2020 (13353)
Print this report[Nakano kun comment posted by miyoki]
Mmm, we need an ASC or an initial alignment process after the whole lock of PRFPMI.
I’m wondering how the alignment of ARM DoFs effects the sensitivity. Due to the 1 Hz oscillation, the arm cavities cannot be aligned with optimal TRANS power. We often move the ETMY in pitch to avoid the 1 Hz oscillation, and it degrade the TRY power by 20 %. If it’s degrade our sensitivity, we should try the ITMY height adjustment again.
>> Also, if you are looking for additional kiloparsecs, try engaging the
>> second whitening stage for the OMC DCPD which should give a slight
>> improvement in the noise floor at some high frequencies as suggested by
>> Tomo[1].
>>
>> [1] http://klog.icrr.u-tokyo.ac.jp/osl/?r=13290
>
> Thank you for your suggestion and hint from akutsu-kun.
> We would like to try.
> However, today's ocean is so violent again. We should wait until today's
> midnight, maybe.
Several weeks ago, the second stage of the whitening filter cannot be engaged due to its range. At that time, even the OMC itself could not hold to be locked.
Now if I see the error signal of the DARM, the RMS is dominated below 10 Hz, although the DARM UGF is around 100 Hz. We might be able to add another boost in the DARM loop to reduce the residual error signal, and then we might be able to engage whitening filter. My concern is the hand-off to the DC readout with additional boost in DARM loop, since I bet it is difficult to engage whitening after the hand-off.
Also, we improved the lower frequency thanks for the suspension roll-off business. So, it would also help the whitening filter engagement, although I‘m not sure it improve below 10 Hz.
> We did not add more boost for Frequency Stabilization System, and don't
> do more that you pointed out.
There is no additional boost in the CARM loop, but the UGF with the 2 mW REFL PD power is below 10 kHz. We can increase the suppression gain by increasing the REFL PD power. The optimal UGF for CARM loop is around 50 kHz.
shinji.miyoki - 15:51 Thursday 05 March 2020 (13354)
Print this reportMore precisely, the UGF reduction and steep roll off in OMC servo as your suggestions (already automated by Aso kun) and REFL PD power enhancement after OMC locking from roughly 2 to 8 (manual) were applied when we got 500kpc.