I briefly ran an Optickle simulation to see if we can explain the observed low recycling gain by the 750 ppm Y arm intracavity loss.

According to the result, I am concluding that the loss is the cause of the current low recycling situation.

(Some details)

I set loss of ETMY to 750 ppm such that it does not ruin the SB build up in the DRMI. For the X arm, I assumed a round trip loss of 60 ppm for now. Then I ran the same code as the one I did the day before yesterday (alog 15389).

According to the resultant plots (see the attached), both TRX and TRY went up to only 166 which is close to what we observed yesterday i.e. 140-ish. This corresponds to a recycling gain of roughly 5. Even with this amount of loss, REFLDC dropped to 35% which does not contradict what we observed i.e. 50-ish%. Due to the low TRX and TRY, the CARM signal synthesized by sqrt(TRY +TRY) can be a good linear signal only up to an offset of 15 or so at which point sqrt(TRX+TRY) starts loosing the sensitivity because we are running into the plateau region of TRX and TRY. Indeed we needed to hand the CARM from the sqrt signal to REFL9 at an offset of -15 yesterday.

Interestingly, ASDC does not increase so much between off-resonance and on-resonance points even though we, at the beginning, speculated that differential losses would show up at the dark port as a large contrast defect. So it means that the light at the dark port is still dominated by the 45 MHz SBs which qualitatively agrees with the observed ASDC from yesterday. I am guessing that the reason why the carrier defect is so small is that the power recycling gain is already so low in the first place that the whatever carrier components at the dark also result in a low power.

Sorry, Evan. Fig files again.

DCS Room progress;

Here is a photo from today of the interior wall going up. Trenching work is almost complete - backfill is underway.

After talking with Sheila and Kiwamu this afternoon, I've started trying to make the seismic sensor correction a little easier for non-seismic people. I've made 2 scripts, one for on, one for  off, called HEPI_Senscor_On.py and, imaginatively, HEPI_Senscor_Off.py. They live in the same folder as Hugo's Test_Configuration scripts:  /ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/Common/Misc/Test_Configuration_Scripts. I will work on a wiki page to make this clearer for the operators, but I think currently the operators should run the off script in the morning if there is going to activity in the VEA's or if we have contractors banging on the ground outside the OSB.

To run, go to the folder and type:  ./HEPI_Senscor_On.py or ./HEPI_Senscor_Off.py, as appropriate.

As proposed, WFSA (hard sensor) is fed back to the ITMX and WFSB (soft sensor) to the TMSX.

In the attached, you can see that even when I made a terrible kick such that the transmission dropped below 50%, it eventually came back on its own.

Short lock losses don't kick the WFS out of range, and as of now it is maintaining green transmission between 1.15 and 1.18 for 30 min.

ITMX beam position control (fed back to ETMX) is not implemented yet, but should be easier than WFSs themselves.

Eventually we might be able to change the scheme such that hard is fed back to hard, soft to soft, and then ITM beam position to TMS, but I'm doing it this way as it is easier.

Before doing camera, however, I'll move to Y arm.

This morning, Travis and I removed the Q7 lower structure from the test stand and parked it in it's storage container.  We added the new ground plugs to the 2 extension cables in the box and put the door on it for (hopefully) the final time for a few years.

The upper structure still remains mounted to the test stand, awaiting a storage box to shuffle it over to the near by ISI-storage operation.

We also opened the Q6 Lower Structure box and added the plugs to it's cables.  This box should also be good to go for long term storage as soon as we finish torquing the door on this afternoon.

To fix a security issue, SSLv2 and SSLv3 protocols have been disabled for the DAQ test stand.  The web server was restarted to implement the change.  Various vulnerability test methods show the issue to be fixed.  This should affect nobody.

The Jenkins page still works.

Pressure at which IP4 steps from 7000V to 5000V now the same for both halves of pump and comparable to neighboring pumps

A comparison between the ISC front-end processors at LLO and LHO.

LLO numbers taken from alog 15918.

The contractors for the new DCS room will be working outside causing ground vibration and inside the VPW all day today.

The well pump and water system is back up and running normally.

model restarts logged for Wed 03/Dec/2014
2014_12_03 08:33 h1nds0
2014_12_03 09:38 h1dc0
2014_12_03 09:40 h1fw0
2014_12_03 09:40 h1fw1
2014_12_03 09:40 h1iscex
2014_12_03 09:40 h1nds0
2014_12_03 09:40 h1nds1
2014_12_03 09:41 h1broadcast0
2014_12_03 12:43 h1fw0
2014_12_03 13:32 h1iscex
2014_12_03 13:34 h1broadcast0
2014_12_03 13:34 h1dc0
2014_12_03 13:34 h1fw0
2014_12_03 13:34 h1fw1
2014_12_03 13:34 h1iscey
2014_12_03 13:34 h1nds0
2014_12_03 13:34 h1nds1

no unexpected restarts. Completion of minute trend offloading on fw0/nds0. Completion of code changes for end station ISC models (with associated daq restarts). Conlog frequently changing channels report attached.

Dave O. Elli, Daniel, Kiwamu,

We briefly checked how lossy our arm cavities are by locking the individual arm without recycling.

For the X arm:

ASAIR_A_LF = 1180 cnts when unlocked.

ASAIR_A_LF = 1155 cnts when locked.

For the Y arm:

ASAIR_A_LF = 1180 cnts when unlocked.

ASAIR_A_LF = 970 cnts when locked.

We made a corase estimation of intra cavity loss (or a.k.a round trip loss) for the y arm, which is estimated to be about 750 ppm (!). In the calculation, we did not take a mode-mismatch or RF sidebands into accout. We need a closer look at this arm cavity to see why it is so lossy.

Kiwamu, Sheila, Evan, Lisa, Daniel, Elli, Dave O., Dan, Alexa

On December 3rd 2014, 3:01 UTC we had the IR resonanting in all the cavities. MICH, PRCL, and SRCL were still on the 3f signals; DARM was on AS 45Q and CARM was on REFL 9 I at 0 pm. This is what we did:

• We started with CARM controlled by sqrt(TRX+TRY) and DARM by AS 45 Q.
• With the CARM offset at -15, we measured the UGFs of the DRMI loops: PRCL ~80 Hz, MICH ~ 10 Hz, and SRCL ~ 20 Hz (this was with the reduced gain as Lisa noted in the last alog)
• We then compared the TFs between the normalized REFL9 I signal and the sqrt(TRX+TRY) signal. With a gain of -40, the TF was relatively flat (see TRvsREFL_CARM.pdf)
• We also measured the CARM UGF with the CARM offset at -15 and found that the UGF was ~90 Hz with zero phase margin. We turned up the REFLBIAS gain from 0.8 to 1.5; this brought the UGF to 150 Hz with 25 degree phase margin. We also measured DARM at this point and found the UGF of 16 Hz, with a phase margin of 40 deg.
• With a CARM offset of -15.5 we set the normalized REFL 9I offset such that the output was zero, and then adjusted the input matrix to tranistion from sqrt(TRX+TRY) to the normalied REFL 9I into the REFLBIAS input. Finally, we zeroed the offset. We stayed locked for about 12 min. We repeated this and Evan adjusted the offset around to ensure that we were actually at a maximum power build up in the arm.
• As we locked, REFL LF power went from 75mW to 33mW, and TR QPD sum went from 4 to 143 counts. Meanwhile, ASAIR LF stayed constant. We are missing build up in the arm, and the next step will be to investigate this.
• With CARM on REFL was also took several more transfer functions. The CARM TF looked flat around the UGF. We need to improve this loop. Evan will make an attachement with these pdfs. We also need to transition REFL 9I to the analog signal in the summing node board.
• This is all in the guardian now.
• I have attached a picture for good measure.