There's been a lot of wondering about the CO2 alignment relative to the center of the optic so we decided yesterday afternoon we decided to step down the CO2 X/Y and look at the centering, and then overnight we stepped down the Ring heaters on both X and Y.  Attached are the contour plots showing that the centering isn't that different between X and Y, but Jenne pointed out that Y is not as good as X, it's off in yaw and so we can probably do more optimization there.  However, this does not capture the effect of miscentering the IFO beam on the test mass which from this ALOG shows that the IFO beam is quite a bit different from the center as well.

I've updated the ITM QUAD overview screen and a few DAC monitor screens such that they're no longer white. This was just an "svn up" of the changes already made by Stuart at LLO -- see LLO aLOG 40729.

jeffrey.kissel@zotws10:/opt/rtcds/userapps/release/sus/common/medm/quad$ svn up
Updating '.':
U    SUS_CUST_QUAD_ITM_OVERVIEW.adl
U    SUS_CUST_QUAD_DAC_MONITOR.adl
A    SUS_CUST_QUAD_ITM_DAC_MONITOR.adl
Updated to revision 17802.

TITLE: 09/21 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 2mph Gusts, 1mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY:

• TCS CO2x laser died last night (Peter said around 11pm PDT) as noted by Jenne.  As I walked in, Jenne mentioned TCSx laser was brought back by Peter.  Jenne now has H1 for alignment/locking.
• Jenne let in the road crack sealer team at 6:50am this morning.
• 5.7 EQ from El Salvador rolled through here around 13:14utc.

Thought this was worth tagging for our DetChar folks.

15:52-15:57:  Genie Lift moved from parking spot just outside the Control Room exterior door down to the Staging Building lower parking lot.  The engine was clearly heard in Control Room and then when it rolled on the rocks it was a little louder.  IMC remained locked (Jeff K mentions since we can hear it, it's high frequency and the suspensions can therefore ride through it.).

Just turned on CO2 Y to 0.7W, since that's what I think we need (at least roughly) for the new ring heater settings.  But, CO2 X looks like it's tripped off, or something.  No power at the laser, according to the screen.

For Yarm, on Tuesday when the ring heaters were set to 50W preloading, at 2W we were using 1.68 W according to the power meter on the table. If we want to use 0W of CO2 when we're fully locked and have 50W injected, I quickly interpolate and find that we want about 0.7W of CO2Y power.  Similarly, it looks like on Tuesday CO2X was putting 1.21W into the chambers, so for the new 30W ring heater settings, I want to set it to 0.5W.  But, CO2X isn't on.

TITLE: 09/20 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY:

Started with alignment and locking as per usual.  Some work on the floor, but mostly regular commissioning.

LOG:

• Contractors before 8am:  asphalt crack person & weed spraying
• 14:53-15:20 EY cleaning Karen
• 14:57-done EX cleaning Vanessa
• 15:38 SEI investigations (re:  ITMy) at racks in CER [FRS11497] (Jim)
• 16:40-17:43 Parking lot (at MY/EY) asphalt work.
• 17:15-17:46 HAM5 tape measure check (Gerardo)
• 18:12 Picking up BS oplev controller (ed)
• 18:38-20:00 ISCT6/SQZ6 work (Nutsinee)
  • 21:41 heading back out (Nutsinee)
  • 21:55-22:39 Terry joining.
• 19:36 Hanford phone call for DRILL for "Take Cover".  This was for surrounding areas & not us.  Terminated at 20:00.
• 20:36-21:02 ISCT1 Comm beatnote alignment on table (Georgia)
• 20:36-21:02 PSL rack IMC measurements (Craig)
• 20:45 fiber pulling from msr to cer (Richard, fil, ed)
• 20:45 Out to ITMy satellite box [FRS11497] (jim)
• 21:30 PNNL tour (hugh)
• 22:44- 23:02 current PSL rack checks (Sheila & Craig)

Sheila, Craig

We investigated the ALS DIFF noise which shows up when the COMM PLL is locked.

We removed the FDD from the COMM PLL path, this did not help.

We moved the COMM VCO physically to another location, this also did not help. 

Next idea is to add a spare Phase-Frequency Discriminator, to have separate COMM and DIFF PFD chassis.

Danny, Stefan

We fitted the ring heater step response that we found in /ligo/home/aidan.brooks/OneArmTest/h2hwsey/2012_08_09_hws_rh_test/matlab_workspace.mat
in the frequency domain. The essential low frequency features are well captured by a
- zero at 5.45e-6Hz
- pole at 1.36e-5Hz
- pole at 6.00e-5Hz

We can therefore design an inverse filter that does not overshoot (high frequency gain equal low frequency gain equal 1) by using
- pole at 5.45e-6Hz
- zero at 1.36e-5Hz
- zero at 6.00e-5Hz
- pole at 1.497e-4Hz

The resulting lens step response is given in plot 1. Note that this inversion essentially shortens the full response to about 2h (at the 5% level), while never overshooting (i.e. there is no negative value problem).
I would imagine that some more tuning could even improve on that.

Terry, Nutsinee

To prepare for the OMC 3MHz locking loop config. LO light is now using PSL LO (we've been using a pick off from our ump laser). PSL LO power going to LO fiber coupler was .3 mW, 13uW measured on SQZT6 going to the HD. Sadly these are somewhat optimized number, could be better with more time spent but probably not necessary. Together with <10uW CLF gives the best 3MHz beat note of 1 dBm.

A few notes from locking throughout the day:

• Remove gain increase in SRC align - causing loops to run away.  The loops converge just fine with the low gain.  Sheila said that she saw this behavior yesterday also. Not sure why, but we'll want to come back to this at some point.
• Locking - PRC gains look *terrible*.  Stefan turning CO2 lasers back to 50W settings, see buildups get better, then returning to low settings to watch if buildups decay.  They do.
• Turned CO2 powers back to the 50W settings.  Still struggling to lock.  We're going to put the ring heaters at settings appropriate for 30W injected power, rather than their current 50W settings.  Hopefully this will make locking easier.
• 3:25pm, turned off CO2 powers, so that we can watch the effect of ring heaters overnight on the HWSs.

Sheila, Jenne, Hang, Danny, Stefan

As Sheila and Gabriele previously reported, the changes in recycling gain due to alignment made the CARM handoff  spotty. The issue is that we go to a certain arm power, but that arm power does no longer corresponds to the same CARM offset when the effective arm loss changed.

In alog 43953 they also hinted at a solution: Also looking at REFL DC (normalized by REFL_DC for large CARM offsets) allows resolving that degeneracy for the last few picometers of ARM offset.

We now tried to implement an effective correction along those lines in Guardian.
Plot 1 shows the theoretically predicted curves for REFL_DC power vs. transmitted arm power for a number of different effective arm losses (50, 75,100, 200ppm). Also shown are markers corresponding to a CARM offset of 1, 3, 5, 10 and 30pm. One can see that spots of constant CARM offset are roughly lying on the diagonal dotted lines. (This approximation gets worse close to resonant, but is likely good enough for our purpose).

The algorithm we put in Guardian does the following:
1) We record the REFL_DC power for large CARM offset (in START_TR_CARM). Call this P0. 
2) We continue going up to an arm power of 800 (our reference arm power Tref).
3) There we read the actual REFL_DC value. Call this P.
4) Now we can calculate the actual transmitted arm power Tact from the ideal (at time of script tuning) arm power Tideal via

1/Tact = 1/Tideal + 1/Treff * [Pref/Pref0 - P/P0]

Here Pref/Pref0 is the power ratio at the time of script tuning. Note that this math corresponds to moving along the diagonal dotted lines on Plot 1 until intercepting the graph for the current arm loss.

5) Finally, the script asks for Tact (instead of Tideal) when doing the final hand-off to REFL RF.

Note that the Guardian actually does the math in terms of CARM_TR_OFFSET which is defined as -sqrt(2*T), i.e.

OFFSETact = - sqrt( 1/[  1/OFFSETideal^2 + 1/OFFSETref^2*( Pref/Pref0 - P/P0)  ]  )

Steps 2-5 all happen in CARM_5_pm.


All code is in Guardian, but due to ALS trouble hasn't been tested yet.

Early this afternoon I adjusted the two mirrors before the COMM beatnote PD. i.e. the mirror that steers the beam onto the diode, and the beamsplitter which combines the x arm transmisison with the frequency doubled PSL. This brought the COMM beatnote up from ~ -16 dB to ~ -9 dB.

This could be aligned better by adjusting the mirror which splits the x arm transmission path between the comm and diff paths, but I wasn't sure how good the PR3 alignment really was so for now this is good enough.

Stefan, Jenne, Danny, TVo

We thought a bit about trying to test how the IFO reacts to different lensing by commonly reducing the CO2 powers.

Attached is a graph of the sideband build ups after turning down the CO2 power in a common way (reducing both by 1.3 Watts), along side of that there is a graph of the AS_A/B which shows any residual differential heating which probably comes from how both CO2 lasers differ in actual spherical power lensing, it seems as though there's about a reduction from 1400 counts to 1136 counts.  There is a Thorlabs power meter right before injecting into the chamber so I believe those values are good, however, if we have one CO2 lasers miscentered, that could be the problem.  

This was all locking PRMI in length only and manually tweaking the alignment to get the best build up.  What this tells us is that the TCS settings we settled on earlier in the week is helping the sideband build ups which isn't surprising because the imbalance in the ring heater powers due to the excess absorption on ITMY is quite high and any compensation in central heating will help your cause.  

Although it not quite clear if we can lock in this reduced common lens configuration, it definitely makes it much harder to reacquire (bordering on impossible).

TITLE: 09/20 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 4mph Gusts, 3mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s
QUICK SUMMARY:

• H1 in IDLE state.  CDS OK, OPS Overview OK.  Jenne arrived to begin alignment/locking.
• 5.4Mexico & 4.5Peru EQs rolled in around 2:30amPDT (9:30UTC)
• Desert Green spraying for weeds.
• End station check/cleaning (reminded to be mindful around racks & BRS)
  • 14:53 Karen @EY
  • 14:57Vanessa @EX

Sheila, Craig, Thomas, Stefan, Gabriele, Jamie, Hang

1. We had some difficulties locking earlier because our recycling gain was low.  We redid the same routine we have been doing when the recycling gain changes of resetting TR_CARM offsets in the guardian state CARM_5_PM (similar to what is described in 43926 ) We changed the CARM ofset at which the TR_CARM gain is increased to 86 from -48 to -40, and the TR_CARM offset at which we transition to REFL9 we changed from -54 to -48.  The goal of this is to keep doing our transitions at the same real CARM offset when the recycling gain changes due to a misalignment or some other problem.  We spent some time thinking about the plots of REFL power vs TR_CARM power in 433444 and comments.  We are thinking that we can make ourselves less sensitive to needing to redo these steps if we implement some code that scales the TR_CARM offset using the REFL power.  Stefan has a proposal for a change to the front end model for TR_CARM to allow us to try this.  
2. We reduced the CO2 power on both ITMs by about 1W each, so that we are now locking with the common CO2 settings that we would expect should be correct for 15W of input power.  The idea was that we are having truoble getting a good contrast defect with the CO2 power that we would need to imitate the cold state.  However, we are less sensitive to errors in the common lensing that in the differential, so we decided to try setting the common lensing intentionally low so that we have less defect from the imperfect CO2.  This did seem to help reduce the very ugly mode we were seeing at the AS port, and caused no problems for locking.  We were able to lock once or twice like this, but lost lock when the soft loops were engaging.  (The soft loops seemed to be working fine, they were increasing the recycling gain). 
3. Earlier tonight we had difficulty with tidal, the Y arm tidal was off which causes the X arm tidal to run away and hit it's integrator. 
4. We've had both our usual intermittent ALS problem with the XARM locking and a new problem where we are unable to lock the Y arm in green. 44068

We are having trouble keeping the Y arm locked in green right now, and according to the optical lever ITMY is having large sudden glitches.  Our difficulty locking might be unrelated to the apparently higher motion of this ISI, which has been moving more that ITMX for 20 days according to the BLRMS. 

The colored blocks on the ISI overview screen seem to indicate that there is a problem with the ISI, and Corey noted that the CPS spectra looked noisy earlier today.  (44061)  

I think that Jim looked into that and I think he and Betsy told me that the problem came and went, indeed.  The first attached screenshot shows a comparison of the 4 BSC ISI BLRMS medms. (ETMX has a known problem, ITMY has only starting having this problem as far as I know.)  Also attached is a time series of some of these BLRMS with a couple of the ITMX channels for reference.  There does seem to be some kind of a problem that might be coming and going on ITMY, this has been the case for at least 20 days (3rd screenshot). 

TITLE: 09/19 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY:

Commissioners working on locking most of the day.  Had issue with ITMx BIO (FIXED), noisy ITMy CPS (maybe fixed?), noisy ITMy oplev (not sure on status), noisy MC1 (not sure on status).
LOG:

• 14:55 Commissioners already working on locking.
• 15:20 Noticed Binary IO issue for ITMx (suspecting software)
• 15:36-15:45 Going on floor to check for mechanical shorts for ITMy (Ed)
• 15:54 End Station cleaning Karen (requested to be mindful around electronics racks & BRS)
  • 15:54-16:35 @EX
  • 16:40-17:06 @EY*---No glitches!  :)
  • *EY is where we have had ISC glitches which have destroyed ALS alignment.  Which sounds like it's relegated to the CER and when an invasive activity is occurring (i.e. accidental unplugging of rack power cable & maneuvering Genie lift).
• 16:23-17:45 ISCT6/rack work (Nutsinee)
• 17:25 Topped off PSL Chiller (Corey)
• 17:32 HVAC welding at VPW (Mark)
• 17:33-done Checking ITMy oplev again (Jason)
• 17:46-done Access Control work (Richard at EY & APS at MY)
• 18:06-done Clean-up & ethernet cable install at EY & then EX (Dave)
• 19:59 SUSB123 reboot to address ITMx binary I/O (CDS)
  • Rebooting hardware (binary IO chassis) seems to have fixed this.
• 20:03-20:51 Slow Controls SDF down, cont from yesterday (Jonathan)
• 20:36-20:47 Fire dept MY to address non-working alarm bell (Ed)
• 20:36-21:00 FMCS work at EY air compressor room (apollo)
• 21:06-21:30 Access Control near PSL (Richard)
• 21:35 Access Control out to MX (APS)
• 22:00-23:02 Site Weekly