Due to an issue currently under investigation by Jamie, the Guardian nodes for BS, ITMX, ETMX, and ETMY were restarted at ~10:30am PST.  The SPM diff monitor was reporting various SWSTATs were being toggled quickly (a few times per second), but the SUS MEDM screens reported no such behavior.

Prep for HAM 6 vent ongoing

Jim W. working on filters for ISIs

HAM 6 SUS TFs have been taken in prep for vent (look good), SDF work ongoing

CDS installing dewpoint monitor cables in H2 output vicinity

Purge air being turned on

2nd cleaning on cleanroom complete

OpLev working on replacement lasers, PR3 needs recentering

PLL work today

Jeff B. moving dessicant cabinet into high bay for craning tomorrow

PCal work Tues. at EY, maybe EX

I worked on the output optics ASC characterization tonight. The measurement details will come later.

Here I want to note my activities for the other IFO users who might find my mess:

1. Initially I tried to use ITMY single bounce (PRM/SRM/ITMX/ETMX/ETMY misaligned). In reality, I had many difficulties having AS_C, AS_A_DC, AS_B_DC, OMC QPDA, and OMC QPDB in their linear regions at the same time. I jiggled SR2, OM1, OM2, OM3, and OMCS alignment biases. but no success. In the end, I gave up to use the single bounce.

2. I returned to the original values of the bias sliders. Decided to use DRMI which seemed reasonably aligned. I had to slightly tune the alignment of the BS, PRM, and SRM to acquire the lock.

3. Once lock is acquired, BS, PRM, and SRM were slightly aligned to maximize ASAIR_B_RF90 on the wall striptool. 

4. In deed, all the QPDs start to show somewhat linear signals. The SRC2 ASC servo was used to align the beam on AS_C. This servo output was eventually offloaded to SR2/SRM.

5. After spending some time on the OM1-3, OMCS alignment, the beams were mostly center of the five QPDs on HAM6. Only AS_B_DC Pitch had residual of -0.3~-0.4. I decided not to go further. During this process, ASC output matrix for DC3/DC4 were touched. (and returned to the original values).

6. OMC was locked on one of the sidebands. The transmission was ~20mW. This was comparable output power to the DC readout.

6. TF and PSD measurements between SRC2, OM1, OM2, OM3, OMCS to the five QPDs and the dither errors. During this measurement, SRC2P/Y FMs were touched.

7. OMC Dither ASC signal seemed to convey no ASC information. I tried several frequencies and retuend to the original freqs (1.68k-1.75k) with dither amplitude increased from 50-200 to 1000.
Dither demoduration phases were moved from (90, 90, 90, 90) to (75, 90, 90, 100).

8. Then moved on the OMC dither LSC characterization.

9. After some cleaning up, I returned to the single bounce. After all, the ITMY single bounce beam shows up all of the QPDs around the center. This is good. So I decided to leave this alignment. We want to recover this state during the HAM6 vent next week.

10. IFO is left with DRMI and LSC not engaged

Alignment sliders before and after:

PRM (P: -1369.8 Y:  506.37) -> (P: -1361.7 Y:  492.4 )
BS  (P:  149.03 Y: -297.35) -> (P:  148.98 Y: -298.04)
SR2 (P:  1935.2 Y:  776.7 ) -> (P:  1936.0 Y:  783.8 )
SRM (P: -688    Y:  907   ) -> (P: -695.2  Y:  915.0 )
OM1 (P: -533    Y: -524   ) -> (P: -643    Y: -484   )
OM2 (P:  879    Y:  736   ) -> (P:  899    Y:  656   )
OM3 (P: -423.3  Y:  625.9 ) -> (P: -423    Y:  644   )
OMC (P: -358.7  Y:  363.0 ) -> (P: 3641.3  Y: -637.0 )
 

Koji, Sheila

Koji and I searched around for the source of the periodic (every 4 second) glitch in DARM control when locked on ALS figure attached to 17684.  The problem seems to be the DIFF PLL board, we were able to see the glitches in the PLL control signal when it was locked to a marconi instead of the DIFF beatnote.  We locked the DIFF beatnote using the COMM PLL board, saw no glitches, and also swapped the ADC cables to make sure the DIFF ADC channels were fine.  I don't know where the spare is, so we are elaving the chassis in the rack for now, but the board needs to be swapped before we can get back to locking the full IFO reliably. 

Just too be clear, it seems likely these are a different class of glitches from those described in 17576 and linked alogs

model restarts logged for Thu 02/Apr/2015

no restarts reported

model restarts logged for Fri 03/Apr/2015
2015_04_03 10:11 h1iopseih23
2015_04_03 10:12 h1iopseih23
2015_04_03 10:13 h1hpiham2
2015_04_03 10:13 h1hpiham3
2015_04_03 10:13 h1isiham2
2015_04_03 10:13 h1isiham3
2015_04_03 10:46 h1hpiham2
2015_04_03 10:46 h1hpiham3
2015_04_03 10:46 h1iopseih23
2015_04_03 10:46 h1isiham2
2015_04_03 10:46 h1isiham3
2015_04_03 11:20 h1iopseih23
2015_04_03 11:21 h1iopseih23
2015_04_03 11:22 h1hpiham2
2015_04_03 11:22 h1hpiham3
2015_04_03 11:22 h1isiham2
2015_04_03 11:22 h1isiham3
2015_04_03 13:50 h1hpiham2
2015_04_03 13:50 h1hpiham3
2015_04_03 13:50 h1iopseih23
2015_04_03 13:50 h1isiham2
2015_04_03 13:50 h1isiham3
2015_04_03 18:42 h1fw0

one unexpected restart. Multiple restarts of h1seih23 for ADC and PCI issues.

This afternoon Elli, Kiwamu and I phased the AS A 36  in PRX, then again in DRMI.  We phased each quadrant to minimize the Q signal with the cavities locked, and the WFS centered, and then adjusted gain to get the same size signal on each quadrant ( the gain adjustments are no more than 40%).  This seemed to indicacte that the electronics for each qaudrant are working OK, so nothing needs to be done durring the HAM6 vent.  However, after this we tried exciting the angle of the SRM and saw that the signals are still highly coupled between pitch and Yaw

The glitches described in alog 17576 are here again tonight.  In addition to the kind of intermittent glitches described in that alog we have verry regular 4 second glitches in DARM control when locked on ALS.  This started around 22:38 local time (5:38 UTC on April 3rd).  These large glitches cause the half hertz motion of the ETMX suspension.  Dan and I are leaving the IFO locked on ALS to see if these go away on their own overnight as the ALS glitches have in the past.

ETMX is swinging in pitch at the half hertz resonance, this is rung up by the glitches.  Oplev damping is not an option because the ETMX optical lever laser is dying, as we have known for several weeks now.

Nairwita, Nutsinee

Attached below are the plots of EX CPS sensor vs. EX VEA temperature and EX roof temperature on March 27th and 28th. The more steady line seems to correlate with the roof temperature (out-door) somewhat while the more fluctuated line seems to correlate more with the VEA temperature. We weren't able to get the raw trend of the PEM so the resolution isn't too great. Judging from the data of March 27th CPS vs. VEA temperature, the temperature became steady around 06:00:00 while the bumbling line starting to settle around 08:00:00. Maybe this two-hour delay in response to the temperature can give us a clue of where the source of the bumbling line might be? 

Jim and Dave

we added a new frontend, x1seih23, to the DTS. I moved the HEPI and ISI models for ham2,3 from x1asc to the new FEC.

[Ed. Merilh, Jason Oberling, Doug Cook, Suresh D]

Doug replaced the diode laser at the HAM3 oplev this morning after it was fixed for reducing glitching (SL No. 197) in the optics lab 2.   We wanted to let it settle for a while and reach thermal equilitbrium before adjustting the power level.  We did that around 12:30PM and I checked the results around 4PM.  The laser is still settling down  as seen in the attached plots.  We plan to monitor it for another day. 

Scott L. Ed P. Chris S.

Yesterday the crew cleaned 52 meters of tube and 67 meters today to X-1-8 double doors. Results are posted here.

The extraordinary accomplishment of cleaning over 90 meters on 3-31 was very much appreciated, however I have asked the crew to consider a more reliable pace and not burn themselves out. I reminded them that we are only 20% complete with the overall task.

Monday will be spent relocating equipment, lights, and support vehicles. 

Measurements were carried out on the ETMX effective charge voltage over a period of 3.5 hours this morning. 

Firstly, some housekeeping, I svn'd up the charge scripts directory to obtain updates from LLO /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/Scripts/ and persevered local changes.

ETMX was selected since it does not currently have low-pass filters installed on each quadrant. It was not necessary to re-align the ETMX optic, since the OpLev was already well centred. Linearization was bypassed (turned off) for the duration of these measurements. The ESD_UL_LL_UR_LR_charge_07-H1.py script was run to drive the ESD at 4 Hz with an amplitude of 130k counts. The script attempts to write a bias to H1:SUS-ETMX_L3_LOCK_BIAS_OFFSET, however, this is nominally turned OFF at LHO. Therefore, it will need to be engaged, and the bias in DAC counts residing in H1:SUS-ETMX_L3_LOCK_INBIAS set to zero. Also, the ramp time should be reduced from 10s to 5s for the duration of the charge measurements.

Data was processed using the ESD_UL_LL_UR_LR_analysis_07_H1.m script, charging and charge deviations from today’s measurement can be seen below (all times in UTC).

A significant negative effective voltage is observed on the lower quadrants, which are quite variable. Upper quadrants exhibit less charge and are more stable (similar to what was seen for LLO ETMY, before it was discharged) n.b. there is also a large discrepancy between the effective charge reported by OpLev Pitch and Yaw.

Previous automated charge measurements carried-out on ETMX by Brett after the most recent vent did not show as larger effective charge (see LHO aLOG entry 16057). Follow-up measurements, may help determine how the charge is evolving. The infrastructure is in place to help determine if any future discharging is successful.

Processed results, and analysis scripts have been committed to the sus svn, raw data files have not.

Today has been a rough day for the input HAM chambers. This morning we found that a channel went dead in expansion chassis (see Richards alog for the resolution), and troubleshooting involved a lot of restarts of SEIH23. This afternoon, after that problem was sorted, Evan found that the SEI MEDM screens for HAM2&3 were frozen. Dave and JimB should be posting a log about the resolution of that issue.

It would be very good if Detchar could at do some comparisons of the H3 IPS  on HAM3 HEPI with other sensors to see if the failure that took out this chamber this morning (killing commissioning efforts until ~now) gave us any warning. I attach some dataviewer trends of the IPS blend ins, and I can kind of convince myself that the horizontal loops all look a little noisier 18 hrs ago versus now. Not necessarily true, I haven't looked in any detail and I'm just guessing based on the max/min being noisier 18 hours ago.

Last night, we again became unable to damp the roll modes (see previous experience in alog 17378) with the usual damping settings. After some random experiments, we became able to damp it with the usal damping settings for some reason. We have no idea why the mode occasionally behave in this way. Note that we use AS_WFS_A for damping them.

(The roll modes)

After the recycling gain study (alog 17645) and ASC study (alog 17646), we fully locked the interferometer with DC readout and 10 W. We immediately noticed that the DARM spectrum was extremely noisy which turned to be high roll modes saturating the OMC DC PDs at the ADC. Looking at the frequency of the peak in the DARM spectrum, we could idenfity the mode -- it was at 13.8 Hz which is the one from ITMX. The peak height was as high as 10^-12 m/sqrtHz in the DARM spectrum with 0.1 Hz BW. We went back to ASQ in order to address the issue. The PSL power remained at 10 W. Evan tried different phases (e.g. +-60 deg) and even the negative sign in the damping gain, but none of them seemed to work. This is exactly the same situation as the one previously reported (alog 17378).

(Damping experiments)

- ITMX

Since I knew that it was mostly from ITMX, I first disabled the damping on ETMY in order to make the experiment straightforward. Then I narrowed the pass band on ITMX, which is nominally 1 Hz wide with a center frequency of 13.9 Hz, to 100 mHz passband with a center frequency of 13.8 Hz. They are 4th order butterworth filters. According to foton, this change causes an extra phase rotation of 30 deg, which I did not try to correct as this seemed small enough. Engaging the narrower butterworth, I was able to damp the mode with the same positive gain. This brought the peak height in the DARM spectrum to as low as 10^-14 m/sqrtHz.

- ETMY

I then moved onto ETMY to propagate the same modification. ETMY also had a 1 Hz bandpass 4th order butterworth with a center frequency of 13.9 Hz. I tried a 100 mHz passband with a center frequency of 14 Hz. This again caused a 30 deg phase shift, but I neglected it. After engaging the narrower bandpass on both ITMX and ETMY, however the modes slowly started growing up. I tried different phases and negative damping gain on ETMY, but none of them helped. I also tried several configurations -- e.g. disabling ETMY and keeping ITMX, disabling ITMX and running ETMY, and etc. But I did not succeed in damping the modes. Moreover they kept growing on a time scale of a couple minutes.

- Ending up with the same old configuraion

After all, I switched the bandpss filters back to the 1 Hz passband ones to see if I can damp them. Yes, I was able to damp them. The decay time was approximately on a time scale of a couple minutes. No extra phases or sign flips were needed. Unsatisfactory (✖╭╮✖)

Summary: H1:SUS-ETMX_M0_DAMP_L_IN1_DQ looks to have been saturating during the long lock and making glitches in DARM at 9Hz. 

In Detchar we're looking at the 2015-04-02 lock from ~8-13 UTC, which had good sensitivity and some amount of undisturbed time. The hveto page for that day has several interesting glitch classes. The first round winner is a series of glitches centered at around 9Hz and associated with the SUS ETM* L1/M1 L channels. These glitches seem to only show up in this high sensitivity lock and not the low sensitivity locks around it (perhaps higher RMS on M0 in low-noise configuration?). Checking the raw data, it appears that H1:SUS-ETMX_M0_DAMP_L_IN1_DQ is saturating.

• Figure 1 shows a time-frequency map of all glitches (black circles) and the glitches associated with this mechanism (red pluses).
• Loads of omega scans showing how these glitches show up in DARM and in the SUS channels can be found here. 
• Figure 2 shows a spectrogram of the SUS channel lined up with its timeseries. I think the wavy cutoff at the top of the timeseries indicates saturation somewhere a little bit of filtering away from this channel.
• Figure 3 shows the spectrogram of the SUS channel lined up with the spectrogram of DARM. The broad SUS glitches up to 10Hz correlate with DARM glitches at around 8-9Hz. 

Note: CIS says this channel is calibrated in um. I don't know whether this is a digital saturation or some physical thing - will consult a SUS expert. 

One mystery, to me, is why the glitches occur at GPS times ending in .000, .250, .500, and .750. This might be due to time domain clustering in our glitch algorithm. At first I thought it indicated a digital origin for the glitches, which turns out to have been a red herring. 

Jim, Krishna,

After the troubles described in alog 17386, BRS was turned off to allow it to damp down naturally. This morning Jim and I restarted the BRS as attempted earlier in 17309. This time, the amplitude of the balance was low enough and we simply had to reposition the damper and start the software. Everything worked as designed. The attached plot shows the damping of the beam-balance.

After things had settled down I checked the spectra of the signals coming out of BRS and the tilt-subtracted super-sensor and everything looks normal. Wind speeds were at 0-10 mph and the subtraction looked good as seen in the attached pdf. The first plot shows the ground T240 X motion, the BRS_RY ( * w^2/g), ST1 T240 X and the super-sensor. The next plot shows coherences between these sensors.