This morning the TMS positions to hit the baffle PDs were the same as last night 10001

Alexa moved PR3 by 1.3urad in PIT and 0.7urad in YAW to center the single shot beam on the spot on the camera on ISTC1.  Then we realinged the cavity, moving the ETM pit by hand +3urad in PIT to see cavity flashes around 800 counts. 

We could not engage the PIT and YAW IAL servos at the same time, this would drive the alingment off.  We engaged YAW alone first, this was stable but didn't improve the build up.  When we tried to then egage pit it would drive the alingment off.  Engaging pit by itself first improved the build up, once this had run for a few minutes we could engage yaw.  Now we have around 920 counts on the TRX PD, and -31 dBm beat note power. 

Completed installation of an ITM-X pair of ring heater segments, and associated UHV cables for the lower structure. 
We assume that the upper UHV cable (D1001521) and bracket (D1001756) 
-currently installed on the existing ITM-X upper structure- 
will be (eventually) mated to this lower structure installation. 

Upper RH: 44.9-ohm
Lower RH: 45.6-ohm

Photos are attached.

See also, the following records:

https://dcc.ligo.org//LIGO-T1300463-v21

https://ics-redux.ligo-la.caltech.edu/JIRA/browse/ASSY-D1001838--V7-111
https://ics-redux.ligo-la.caltech.edu/JIRA/browse/ASSY-D1001895--V8-201 
--> the temp sensor head broke off at the time of installation, but free cable secured

Sheila found the two TM ISIs tripped--Looks like a big event hitting the microseisem plus we are having a bit of a wind event.  Sheila was unable to get the ETMx to go up but she was using the 750mHz blends and that may just not work for Lvl3.  We likely need to tailor some blends to work with Lvl3 that don't use the T240s.  I was able to get the ETMx ISI Stage1 up directly to Lvl3 with TCrappy blends as the Bias Position were not far from the targets.  And Stage2 is still using Lvl2 controller with TCrappy blends.

Sheila had no issues getting ITMx back up.  This ISI had been on since Friday 0816utc--not bad.

All HEPIs are operational and running position loops.

The ITMY & BS Appear to be in the same state as I left them last night.  According to the WD last trip time these last tripped about 10:30 & 11:30 yesterday am.  They weren't up during all that time though as we were ignoring them.

As far as the trips on the TM ISIs, there were some significant EQs around the globe in the hour before the trip( such as a 6.9 ~50 minutes before in China), we had elevated winds (no wind monitor at Ends) and running these very aggressive controllers all may have combined to causes these near simultanios trips (8 seconds apart.)

plots attched.

[Stefan, Lisa, Evan, Kiwamu]

Our goal tonight was to get the IR transmitted light centered on the transmon QPDs. A coarse alignment was established. We still need to do a fine alignment with the picomotors.

QPD centering:

We had never aligned this path with the actual IR beam, and neither QPDs had a beam on them. As discussed and suggested in the last integration meeting, we started this mission from a scan of the TMS in order to find an IR beam with the QPDs. Moving the TMSX in an almost random way, we found a beam which was flashing as the carrier light resonated in the cavity. The yaw angle needed to be twisted by roughly 100 urad to get the beam on the QPDs. Then, keeping the flashing beam on the QPD by steering the picomotors (M4 and M14), we steered the TMSX back to the nominal angle. This operation was successful. Then we moved onto a fine adjustment by locking the main infrared light to the arm cavity (the detail of the locking procedure can be found in alog 9644).

The fine tuning was very frustrating. We kept loosing the lock because of the roll mode of MC2 at 40 Hz (see awiki for HSTS resonances ) which then saturates everything and breaks the lock. Plus the spot position on the two QPDs didn't seem to be conversing by moving a combination of the two picomotors. The spot behaved as if the picomotors are degenerate. It is possible that, since the time for tweaking the picotomors was limited by the stability of the locking, we confused ourselves in the rush. This needs to be revisited. Anyway, a good news is that we now have a beam on both the QPDs and therefore we can do the fine adjustment anytime when we get a chance.  Also we did an estimation of the power on the QPD, because we needed to clarify if the beam we saw was the main beam or a ghost. This is summarized in Evan's log (see alog 1006).

Some other things:

Later tonight, I tried to engage the AO path. Though I haven't succeeded. The idea is to have a low cross over frequency which then allows us to (re)insert the notch filter for the 40 Hz roll mode. However the loop was not so stable and everytime when I changed the AO path gain in the common mode servo board it simply broke the lock even if the gain seemed small enough. In addition to it, it became harder to lock approximately after 1:30 am probably due to some angular fluctuation in the arm cavity. I am too lazy to identify what optic is moving, but it is also clearly visible in the green ISCT1 CCD camera. Because of that, the IR locking doesn't stay more than 2 seconds -- the cavity build up in infrared drops extremely quickly due to the angular fluctuation.

[Stefan, Lisa, Kiwamu, Yuta, Evan]

We are trying to center the transmitted X-arm IR on the transmon QPDs, so that we can have an IR alignment reference. The expected power on each QPD is determined as follows:

• 8.8 W into the IMC
• 80% transmission through the IMC
• 3% tranmsission through the PRM (misaligned)
• 50% transmission through the BS
• Power buildup of 2 x 445 / pi in the X-arm
• 5 ppm transmission through ETMX
• 5% transmission through mirror M12 on the transmon table
• 50% power splitting on the beamsplitter on the IR QPD sled

These numbers give an expected power of 3.7 µW on each QPD.

What we measured was about 600 cts for the sum output on each QPD. We can back out the power on the QPDs as follows:

• 2¹⁶ = 65536 counts over a range of 40 V on the ADC
• 1 kΩ transimpedance on the QPDs
• 0.8 A/W for the QPDs

This gives a power of 4.6 µW on each QPD.

J. Kissel, L. Barsotti, H. Radkins, J. Warner, R. Mittleman

What started out as a conversation of "I don't trust the optical lever calibration. The performance can't be that good" turned into "Wow, if we can hold that performance, ASC might be OK..." Excellent work, Jim, Hugh, and Rich. 

Here're some performance measurements of the H1 SUS ITMX and H1 SUS ETMX as measured by the ISI ST2 GS13s and SUS Optical Levers. The ORANGE shows the current performance, which puts the ITMX and ETMX pitch motion at 20 and 50 [nrad] RMS, and a maximum of 5e-8 and 1e-7** [rad/rtHz] at 0.45 [Hz]. I also attach model predictions for this ORANGE optic motion based on the ISI performance, and we can clearly see the ETMX optical lever spectrum is polluted by length-to-angle coupling and is not reporting the actual motion of the optic, so we should not trust Oplev ETMX as a viable pitch sensor when the ISI is performing as well as it is. 

From here on, we need to work on making sure that this performance is consistent. The ground motion (where my only quick indication in the control room is an 80 hour trend of the microseism BLRMS) was consistent between these two better days, so we need to study the performance over longer periods of time to see where we stand in the face of large ground motion.

-------------

I compare three times:
"Controllers" = Isolation Loop Control Filters; "Blends" Isolation Loop Sensor Blend Filters
(2014-02-14 01:00 UTC) TCrappy 
    ITMX HPI -- "Level 1" Controllers; "Pos" (Position-Sensor-Only) Blends
    ITMX ISI -- "Level 3" Controllers; ST1 "TCrappy" Blends (All DOFs), ST2 "100 mHz" XY, "250 mHz" ZRXRYRZ 
    ITMX SUS -- "Level 2.1" Damping Filters, designed 2013-06-14.

    ETMX HPI -- Level 1 Controllers; Position Sensor Only Blends
    ETMX ISI -- ST1 Level 3, ST2 Level 2 Controllers; ST1 TCrappy Blends (All DOFs), ST2 "100 mHz" XY, "250 mHz" ZRXRYRZ 
    ETMX SUS -- Level 2.1 Damping Filters, designed 2013-06-14.

(2014-02-10 01:30 UTC) TCrappy, PRMI Locked
    I *believe* this time is in the same configuration as ORANGE, but I'm not positive. Note, here ETMX was misaligned because team red was commissioning the PRMI. I show the spectra anyway because it's good to see a "dark" spectra.

(2014-01-23 21:00 UTC) T100_N0.44
    The "best" configuration 2 weeks ago, (from LHO aLOG 9546), before we'd fixed the CPS beat frequency combs (see LHO aLOG 9675), and the 0.5 [Hz] comb from the busted T240 cable (see LHO aLOG 9612)"
    ITMX HPI -- "Level 1" Controllers; "Pos" (Position-Sensor-Only) Blends
    ITMX ISI -- "Level 1" Controllers; ST1 "T100mHz_N0.44" blends on XY and "750mHz" ZRXRYRX, ST2 "750 mHz" on all DOFs.
    ITMX SUS -- "Level 2.1" Damping Filters, designed 2013-06-14.

    ETMX HPI -- "Level 1" Controllers; "Pos" (Position-Sensor-Only) Blends
    ETMX ISI -- "Level 1" Controllers; ST1 "T100mHz_N0.44" blends on XY and "750mHz" ZRXRYRX, ST2 "750 mHz" on all DOFs.
    ETMX SUS -- "Level 2.1" Damping Filters, designed 2013-06-14.

There are several things to note, comparing ORANGE measurements against model:
ITMX (A "wire rehang" QUAD)
- Below 0.6 [Hz], the model is dead-on with the optical lever measurement. With a ~30 [m] lever arm, these ITM optical levers have the smallest longitudinal-to-angle, low-frequency, cross-coupling. Nice! This convinces me (in addition the input spectra I'd modelled in LHO aLOG 9734) that the model is a good predictor for the *real* optic motion in this frequency region. 
- Above 0.6 [Hz], (a) we have no idea what that strange fuzz is, and (b) I think both pitch and yaw are ADC noise limited. HOWEVER, I don't understand why the 1-3 [Hz] sensor noise is not visible, if this is the oplev-noise floor. Perhaps the BOSEM sensor noise is better than the stick-curve I use as the input.
- Notice that the BSC-ISI is meeting or beating the aLIGO requirements at all frequencies in this 0.1 [Hz] to 10 [Hz] band. BOOM.

ETMX (A "fiber" QUAD)
- In pitch, I claim that the only motion that is not an artifact of the optical lever sensing are the two bumps between 1-2 [Hz]. Below 0.6 [Hz], the longitudinal-to-angle coupling fundamental to such a short optical lever takes over, and we see mostly longitudinal motion confused for pitch. The remaining bits of the frequency band are electronics / ADC noise of the optical lever.
- This QUAD model DOES over-estimate the first pitch frequency (it predicts it to be 0.56 [Hz], and we've measured it to 0.51 [Hz]), so this, coupled with the L-to-A coupling, is why we don't predict the first pitch mode well at all.
- In yaw, the model prediction is better, especially below 0.6 [Hz] but the remaining spectrum only show hints of the tips of the resonant features.

About the ISI performance:
- Note that both of these chambers still don't have sensor correction. This might help to improve the performance even further in the 0.2 to 0.7 [Hz] band. Nothing amazing, but perhaps another factor of 2 to 3
- We really need a noise budget of the BSC-ISIs to assess what's limiting us in this frequency range. I still have a gut feeling that we're still getting bitten by tilt noise.

Written by Yuta

Xgreen frequency noise spectra from alignment fluctuation (see alog #9429, #9384 for more information) was calculated using oplev spectra of ITMX.
Even if we keep our sideband frequency to be 24.407079MHz and set the demodulation phase to maximize 00 PDH slope, the frequency noise is ~40 Hz in RMS when DC misalignment is 1 urad. Maybe we can work it out without using sideband frequency / demodulation phase tuning technique.

[Method]
1. Get calibrated ITMX oplev spectra (Thanks to Jeff !).

2. Frequency noise from misalignment(HOM) can be written as

fn(t) = k (a(t) + a0)^2

where fn(t) is the frequency noise, k is the conversion factor, a(t) is alignment fluctuation and a0 is DC misalignment. Note that this effect is quadratic and estimated k=1e15 Hz/rad^2 if we keep our setting as is (see alog #9429) and we assume differential angular motion of ITM and ETM.
The spectrum of fn(t) can be calculated using the spectra of a(t) from the following formula.

fn(f) = k^2 * (conv(a(f),a(f)) + 2*conv(a(f),fliplr(a(f)))) + 2*k*a0*a(f)

where conv is convolution and fliplr gives flipped array. conv(a(f),a(f)) gives upconversion term and 2*conv(a(f),fliplr(a(f))) gives down conversion term.
(see this document for derivation if you can read Japanese)

[Result]
1. ITMXOplevspectra.png: Measured ITMX angular motion from oplev. Note that spectra above 0.5 Hz is not measuring the actual motion.

2. HOMfreqnoise_0urad.png: Frequency noise from HOM in the case when DC alignment is perfect. This gives 0.3 Hz RMS.

3. HOMfreqnoise_1e-1urad.png: Frequency noise from HOM in the case when DC alignment is off by 0.1 urad. This gives ~4 Hz RMS.

4. HOMfreqnoise_1e-1urad.png: Frequency noise from HOM in the case when DC alignment is off by 1 urad. This gives ~40 Hz RMS.

Sheila, Stefan

The green arm maximum build-up had been trending down for a while to about 500cts, so we decided to do an arm alignment from scratch today.

Step 1: Baffle PDs
- We used the single shot beam to find the baffle PDs:
         TMS PIT    TMS YAW
  PD1    220.0      -226.7
  PD4    289.3      -288.6
  Center 254.65     -257.6
  
  PD1 is H1:AOS-ITMX_BAFFLEPD_1_VOLTS, and PD4 is actually H1:AOS-ITMX_BAFFLEPD_3_VOLTS 

Step 2: Follow with the arm
- We still had some fringing at the old TMS alignment (P 279.3, Y -245.3 - yes, that's 27urad from the new position...)
- Thus we stepped TMS first in pitch and then yaw, and roughly followed with the ETMX and ITMX.

Step 3: Arm dither: Control ETMX and ITMX instead of ETMX and TMSX
- We changed the feed-back scheme to leave the TMS untouched, and only align the arm to the input beam.
- This was done by feeding back PZT1 dither (DOF2) to ETMX, and PZT2 dither (DOF3) to ITMX.

Step 4: Move PR3 to center the green transmitted beam on the first reference iris on ISCT1.
- The new (good) PR3 alignment is
  PR3 P: -245.0  Y: -253.28

Step 5: Realign the green ISCT1 path
- We aligned the camera (and marked the spot on the monitor), realigned the transmitted green DC PD, and tweaked the COMM beat node up.


With this scheme we got about 915cts of green transmitted light - more than ever.


Step 6 (TBD): Diagonalize the dither drive matrix
- Evan and Yuta will do this soon.

FSS, ISS NOT in nominal range

Output Power is 29.1 W (should be 30 W)
Frontend Watchdog is green
Only warning is 'VB program online'

PMC
locked for 1 day 8 hr
Reflected power is 10% of transmitted

FSS
reference cavity has been locked for 17 min (not good, should be days/weeks)
trans PD threshold is .3 V (not good, should be .9 V)

ISS
Diffracted power is 5.3% (not good, should be 10%)
Last saturation event was 23 min ago (not good, should be days/weeks)

I temporarily installed a modal damping filter on the longitudinal degree of freedom of ETMX. The filter has 32 poles, so it is split between two modules, 'md_part1' and 'md_part2'. I plan to measure ringdown times of the test mass tomorrow using the green cavity signal. This is part of an effort to see what are the fastest possible ringdown times of the test mass with top mass damping. After the test I will remove the filters.

Normally a modal damping filter wouldn't need this many poles, but I decided to include the pitch dynamics in the estimator to get a more faithful reproduction of the 1st longitudinal mode frequency for this test.

Brett and Andres

In an effort to get more data to improve sus models, we locked the top mass down on SR2 and measured spectra of the lower two masses. We then locked the middle mass down and measured spectra on the bottom mass. The data has been committed to the svn at .../sus/trunk/HSTS/H1/SR2/Common/Data.

I will process this data and see if it gives us a model that matches this suspension more accurately.

All ISIs are in Control Lvl3 except for ETMX Stage2 which is in Lvl2.  All Blends are TCrappy where available(only ETMx & ITMx) except for ITMX Stage2 is at 100mHz (Jim--should this be TCrappy?)  The ITMY & BS has 750mHZ blends on Stage 2.  For the BS & ITMY Stage1, T250mHz blends everywhere except the X & Y dofs have T100mHz_0.44 for BS and T40mHz_NO.44 onthe ITMY.