I am concluding that the scale factor in the original calibration (alog 16698) was underestimated by a factor of about 2.4 in 2 - 20 Hz frequency band (meaning, the DARM spectra we had collected were too good). This was due to my inaccurate estimation of the ESD actuation response.

For the frequency region above 20 Hz, it has been underestimated by a factor of 3.2 when the PSL power stayed at 2.8 W and the same DARM offset was used. This was due to the inaccuracy in the ESD propagating into the sensing factor and also inaccuracy in the UGF location. I did not try to track how the sensing calibration should have been compensated as a function of the PSL power or the DARM offset (alog 16726).

I have updated the CAL-CS online calibration coefficients accordingly in both the sensing and actuation paths.

Pcal_Y seems to still indicate that the DARM spectrum is consistently too good by 40-65 %.

(ETMX response agreed the sus model by 40 %)

The day before yesterday, I had a chance to repeat the calibration of the ESD response of ETMX by locking the X arm with the IR laser. Comparison with ITMX at 13 Hz gave me an ESD response of 6.32 x 10^-16 m/cnts in ETMX at 13 Hz. This is 1.4 times larger than the expected than the suspension model. Since I used alpha of 2.0 x10^-10 N/V² in the model, the measured response corresponds to a slightly larger alpha of 2.8x10^-10 N/V². With the right force coefficient of -124518.4 cnts applied on ETMX, I tested both the linearized actuation and non-linearized. They showed almost same strength in a frequency band of 10 - 59 Hz as expected but with the linearized version somewhat stronger by 3-ish % (see the attached) presumably due to the charge on the test mass.

Since the change between the linearized and non-linerized actuations is so small, I neglected this effect and kept using the transfer coefficient of the non-linarized version at 13 Hz.

(Estimation of the DARM optical gain)

Using the measured data taken by Alexa (alog 16805), I estimated the optical gain of the DC read out to be 9.09x10^-7 cnts/m. To get this number, I first extrapolated the ESD response to some frequencies at around 20 Hz. Since the loop shape is already known, fitting of the open loop gives me the optical gain. I did eye-fitting this time. The UGF was at around 23 Hz in this particular data.

Since I was able to lock the interferometer at 2.8 W with the DC read out tonight, I cross-checked the DARM open loop. Running a swept sine, I confirmed that it sill kept the same UGF (see the attached below). Good.

(Comparison with Pcal)

First of all, one thing I have to mention is that, in an alog (alog 16781) describing the comparison between LSC-DARM_IN1 and PCAL is not a fair comparison because we know that LSC_DARM_IN1 was not well-calibrated. I checked the CAL-DELTAL_EXTERNAL_DQ at this particular time, but unfortunately the spectrum did not look reasonable probably because I was in the middle of changing some parameters in the CAL-CS. Instead, I looked into a different lock stretch at Feb-02, 5:13:11 UTC with the same IMC incident power of 2.8 W. The Pcal reported greater displacement by a factor of approximately 4.6 (see the attached below).

If I applied the new accurate sensing calibration, the discrepancy would have been a factor of 1.45 or 45% with the Pcal higher than the DARM spectrum.

To double check it, I checked the Pcal again during one of today's lock stretches at Feb-21, 10:04:05 UTC. One thing we have to pay attention is that the Pcal excitation frequency is now shifted to 540.7 Hz (alog 16815). I used the Pcal calibration formula that Sudartian posted in alog 16718 to get the displacement. The ratio between the Pcal and DARM spectrum was about 1.65 or 65% with the Pcal greater than the DARM spectrum. Even though the ratio is slightly different from 8 days ago or so, it still indicates that the DARM calibration is too good by several 10%.

The other excitation at 36.7 Hz (alog 16815) did not have signal-to-noise ratio more than 2 in the DARM spectrum due to high noise in this frequency region and therefore I did not use it this time. Nevertheless, the Pcal at this frequency was also greater as well. So the relation between Pcal and DARM spectrum is qualitatively consistent.

Alexa, Sheila, Dan, Evan, Kiwamu

Tonight we have had good locking.  The take home message tonight was that our noise changes with aligment, and so we think that we need to spend some time getting some ASC going (or at least a reproducible alingment)  before we can make much progress on noise hunting.  (see alog 16839)

 We moved SR2, the difference between the noise spectrum before and after can probably be explained by the alignment depent noise rather than by reducing the rubbing (see alogs 16831 and 16811).  The new positions are shown in the attahed screen shot.  The SR3 OPLEV is not alinged any more.     If someone wants to use the OpLev over the weekend, you will have to go back to the old alingment of SR2+3. 

Turning on the OMC dither alingment improved the spectrum from 20-70 Hz in a way that is reproducble.  The main improvement in the noise tonight came from alinging IM4, which resulted in the best spectrum we have had so far around 100 Hz.  Note, the attached spectra are not calibrated!

Sheila, Alexa, Dan, Evan

Summary

Tonight on dc readout, we started to reduce the coupling of alignment fluctuations into DARM by closing some more ASC loops. We focused mainly on the input and power-recycling optics.

During this work, the lowest value of REFL_A_LF observed was 0.4 ct (compared with 21 ct on resonance), meaning the interferometer visibility is 98%. The highest arm power observed was 1150× single-arm buildup, meaning the interferometer recycling gain is 34 W/W.

Details

List of loops, and things tried:

• We were able to close REFLB9I → IM4 pitch with an OK bandwidth (> 0.1 Hz, based on step response). Here we have a 1/f loop shape everywhere (FM2+FM3 in INP1), and a gain of −1.0 ct/ct. We may want to use REFLA9I − REFLB9I instead (see below). Closing the loop had an immediate improvement on the mode seen on the REFL camera.
• For IM4 yaw, we noticed that the combination REFLA9I − REFLB9I gave a sensible error signal (as was the experience at Livingston [LLO#16254]). But the lock broke while trying to close the loop, and we did not pursue it further. The most egregeous alignment fluctuations in the corner appear to be in pitch anyway.
• At one point were able to close REFLA9I →PRM pitch, but it seems this error signal is only good intermittently. Possibly it requires the input pointing into the PRC to be good already (i.e., we may need to close it after the IM4 loops).
• We looked for a while for a good signal for the common ETM motion, but none of the responses in REFL9 or REFL45 seemed immediately good.
• The situation with AS36 → BS is still mysterious; neither ASA36Q nor ASB36Q seemed to give good error signals.
• The differential ETM loops ("DHARD", but not actually DHARD) seem to have more optical gain now that the SR2 position has been moved. Good filter module gains are 8 ct/ct for pitch and 80 ct/ct for yaw; these are possibly conservative for the 2.8 W lock. For the 8 W lock they may need to be reduced a bit further still. Otherwise they continue to work fine.

Alexa, Sheila, Evan, Dan

Peter had noted that our suspension compenstation for the LSC DARM filter was different than the one used at LLO. In his plot LHO#16728 he had actually missed a Lead filter at 200 Hz (FM9) that we turn on once we are on RF DARM. See new sus compenstation comparison plot. Even with this lead filer on, we still do not have as much phase as Livingston.

Today, I loaded LLO's suspension compenstation filter into FM1 of LSC DARM. We tried enaging this for ALS DIFF but immediately saturared L3. Our next plan in attempt to acquire more phase margin is to develop a filter which can be engaged along with the lead filter (FM9) once we are on RF DARM with our original sus compensation filter (FM8), and see if this causes saturation. TBD.

Before tuesday, we had been listening to IFO channels through the computer speakers using z audio.  It seems like z audio has disapeared. 

Since Betsy found out that SR2 is rubbing at its nominal alignment, (alog 16811), I've tried to investigate if we can move SR2 so that it is not rubbing without introducing clipping.  This was done by moving SR2 pitch, then adjusting SR3 to center on AS_C.  The attached plot shows the power on each of the PDs we have at the AS port, each PD is normalized to the mean powers at different alingments so they can be displayed on the same plot.  While we get some clipping on AS_C and AS_A when we are in the non rubbing zone, happily the best location for the OMC QPDs are in the middle of the SR2 alingments where betsy says there should not be clipping. 

Keita had previoulsy set the alingment of the SRC cavity and the pios to AS_C (alog 15145 ).

Dave O, Evan, Elli

This morning we prepared for a measurement of the SRC length we plan to take tomorrow.  We were working on IOT2R.  We realigned the Auxiliary laser beam going into HAM1 so that in follows the reflection of the carrier from the PRM onto IOT2R.  This realigned the Aux laser beam returning frm HAM1 onto the 1611 photodiode on IOT2R.  The beat note of the Aux laser and carrier is -34dBm, the same as what we saw in December.  We tried locking the beat note to the spectrum analyser but ran out of LVEA time, so this is a job for tomorrow the settings were the same as used in December.

While we had been playing with things, I kept the alarm levels a little sloppy but now that we'll likely leave this alone for a time, I've closed down the range of operating pressures.

The alarm handler will alarm (as it has for some time) at differential pressures outside of +-2PSI.  The servo should have no problems keeping the pressure within that range.  Further it will alarm MAJOR at +- 5 psi.  If the minor alarm goes off and stays out of major alarm, it is likely the servo has frozen or someone left it in manual mode.  Please address asap and feel free to seek realtime help from me.  There is an OPS wiki too.  If the alarm is ignored, an avoidable HEPI trip will likely be the result.

LVEA: Laser Hazard
Observation Bit: Commissioning  

07:15 Cris & Karen – Cleaning in the LVEA
07:15 Jodi – In the LVEA
07:52 Corey – Working in the Squeezer Bay
08:05 Elli & Dave – Working on IOT2R 
08:20 Jim – Running TFs on HAM4
10:00 Corey – Out of the Squeezer Bay
11:00 Kyle – Going to HAM5 area to get bolts for HAM1
11:14 Kyle – Out of the LVEA
11:17 Keita – Going into the LVEA to look for 3IFO parts
11:21 - Adjusted the ISS diffracted power from 5.2% to 8.1%
11:35 Keita – Out of the LVEA
12:13 Elli & Dave – Out of the LVEA
12:49 Ed – Retrieving totes from Mid-Y
13:21 John, Bubba, & Kyle – Going to Mid stations and end stations to check the weather stations
13:42 Dan & UM Students – Going to LVEA roof. 
13:54 Ed – Opening high-bay roll-up door to bring in totes. 
14:10 Ed – Going back to Mid-Y
14:30 Ed – Back from Mid-Y
15:05 John, Bubba, & Kyle – Back from mid and end stations

Looking for missing VE chamber door bolts! -> Also, noticed X-end turbo pump controller still energized from most recent pump down (fan has been running unnecessarily) -> Turned off controller and brushed up against OPLEV pier accidentally in the process

Finished bolting HAM1 East door -> Noticed West door also missing half of its bolts -> Will need to bolt West door Monday morning for anticipated pump of HAM1 on Tuesday

Several commissioners feel that our new seismic defenses leave H1 insensitive enough to truck traffic that our Hanford site contacts no longer need to email me weekly with reports of their levels of activity.  A quick glance at the 1-3Hz seismic trace in the control room will always settle the question of whether the trucks are hauling or not.    

We've built up a good bank of contacts related to site operations.  Feel free to email me any time if you have questions about the possibility of earth-shaking things occurring near LHO.  

Adjusted ISS diffracted power from ~ 5% to ~ 8%.

  Estimates are at least 10 working days needed to complete the 3IFO tasks before the end of March. To reach this goal, Tuesday’s and Thursday’s will be open access to LVEA and VEAs and noisy work (craning, forklifts, etc.) will be permitted between 08:00 and 16:00. During this time, the LVEA and VEAs can be transitioned to Laser Safe as needed. Always check in with the operator before starting a task.
  
The 08:00 to 10:00 noise windows are suspended while the extended Tuesday and Thursday noise hours are in effect.
 
Summary: No commissioning and noisy work on Tuesday and Thursday between 08:00 and 16:00. Commissioning during all other hours. These times can be altered due to special requirements, with agreement of the commissioners.
 
Fred brought up the need to review and refine the alarms, alarm handlers, and system monitoring. Fred asked that that the staff think about how these systems can be improved. This will be the subject of the next Science Team meeting.    

Tuesday 02/24 - GV5 and GV7 will be closed to support the pump down of HAM1.
Kyle – will be installing the remaining bolts on the HAM1 doors. 
Filiberto – Will be shutting down the Test Stand in the West Bay area to prep for rack removal.
Jim – running TFs on HAM4
    

model restarts logged for Thu 19/Feb/2015
2015_02_19 07:56 h1fw0
2015_02_19 16:34 h1nds1

Two unexpected restarts, nds1 most probably due to request overload. Conlog frequently changing channels report attached.

Dan, Sheila, Evan, Jeff, Alexa

Tonight locked many times (on RF) but didn't stay locked verry long.  We found two new lockloss causes that were relatively easy to solve:

• The ALS_DIFF guardian was going into the DOWN state (and setting the DARM gain to 0) even though it was stalled.  We have a temporary solution (which is awkward and can sometimes cause the DIFF guardian to get stuck in the DIFF_LOCKLOSS state) and Jamie is looking into why this happened.  
• The COMM (fast) Tidal was not happening.  The offset was off for END X, and the TIDAL_HACK guardian was also not running.  We updated the safe.snaps for h1alsex and h1alsey.
• By the time that we understood and fixed these two problems we got another large earthquake. 

During one of our short locks early in he evening ,  we made an attempt to align the green to the arm cavities after the DHARD WFS had come on. For the X arm the only thing we needed to do to get a good build up was move the TMS, we saw the spot move on the ITMX green camera and updated the spot positions for the green WFS (248.3 for PITCH, and 354.8 for YAW).  For the Y arm we saw that moving TMS was not good enough, we needed to also adjust QPD offsets.  We lost the lock in the middle of this process.  Note: the recycling gain tonight was low, around 25, but we think that having the green co-alinged even for this low build up would be better than our original situation.

During the earth quake we have spent some time on the new COMM IR search state that evan wrote.  We modified it, it is now 100% successful, but it can take a couple of minutes (generally under 5).  This is still faster on average than having a human do it, and we can think about something else while this is working now.