aLIGO LHO Logbook

H1 ISC

sheila.dwyer@LIGO.ORG - posted 01:03, Wednesday 19 November 2014 - last comment - 16:15, Thursday 20 November 2014(15156)

DRMI 3F + arm on ALS with 0 CARM offset

Alexa, Dan, Nic, Sheila, Evan

Tonight we made some improvements to our automation, and we reduced the CARM offset with DRMI locked on 3F.

We measured some open loop gains with DRMI 1F + arms off resonance (by 1000 Hz at 532). They seem to have about the same UGF as wihout the arms, for PRCL we change the gain from 22 to 11 when adding arms, and for MICH we changed it from 5 to 4, SRCL we did not change.
We turn on the DRMI ASC, it brings AS 90 positive, then if we leave it on we start mode hopping. For now we are just turning the ASC off once we get a decent build up in AS 90.
We have not changed the ratio between the 3F and 1F signals in the input matrix. Evan got a measurement of the sensing matrix.
Then we decreased the CARM offset without any problems.

Comments related to this report

alexan.staley@LIGO.ORG - 01:07, Wednesday 19 November 2014 (15157)

Link

I have attached DRMI spectra on 1f and 3f with the arms off resonance (1kHz green COMM offset). The first plot is the DRMI 1f configuration; Kiwamu pointed out that one can see the periscope resonances that are present in ALS COMM noise appear in the DRMI signals. The second attachment is of the DRMI 3f configuration, and these noise features are less prominent.

Images attached to this comment

evan.hall@LIGO.ORG - 02:02, Wednesday 19 November 2014 (15158)

Link

Relevant UTC times:

2014-11-19 08:02:45 — DRMI locked on 3f with 1000 Hz_green CARM offset (conversion is 7 pm/Hz_green)
2014-11-19 08:06:00 — Beginning of CARM offset reduction
2014-11-19 08:16:40 — Lock loss
2014-11-19 09:04:00 — DRMI locked on 3f again; second round of CARM offset reduction

lisa.barsotti@LIGO.ORG - 02:41, Wednesday 19 November 2014 (15159)

Link

Great progress! About the ASC, L1 uses REFL_B_45Q -> SRM with bandwidth of 100 mHz ( LLO 13513 ) in the first part of the locking sequence, as AS_RF36_I for SRM didn't work well ( LL0 13358 ).  Here  I see that you are using AS_RF36_I for SRM ASC in DRMI without arms...just checking.

sheila.dwyer@LIGO.ORG - 13:13, Wednesday 19 November 2014 (15175)

Link

Thanks for the information Lisa.

Also, for the record, here are several times that we lost the arm locks last night without a known reason (at least, we didn't think we were doing anything stupid at the time that would have caused the lock loss). All times are UTC, Nov 19, and the lock loss should be several seconds before the time I wrote down.

2:36:27, 3:06:34, 5:58:43, 6:12, 6:25:08, 6:51:07, 7:40:50

evan.hall@LIGO.ORG - 16:15, Thursday 20 November 2014 (15203)

Link

Here is the sensing matrix of DRMI3f with 7 nm (= 1000 Hz_green) CARM offset. I extracted this using the three calibration lines that were injected during the locking period: 131.7 Hz, 6000 ct into PR2; 183.7 Hz, 1000 ct into BS; and 152.9 Hz, 6000 ct into SR2.

In the following table, the first number in each pair is the magnitude (in ct/ct), and the second is the phase.

	PR2	BS	SR2
RF27	7.6(1.2), 3.4(3)°	0.29(6), 151.3(7.8)°	0.07(3), -70(110)°
RF135	12.3(2.0), 139.7(4.5)°	0.7(3), -84(35)°	1.6(4), 6(14)°

Non-image files attached to this comment

radar.pdf