H1 has been in Commissioning mode since just after the start of my shift. Since then, we have been locked and unlocked several times due to commissioning tasks. For the moment, we are in Observing for 1+ hour while the commissioners fuel their brains.
There are obvious signs of diode current increase from the Tues maintenance as described in Jason's aLog . Everything else looks correlated and normally proportional to this adjustment.
Concur with Ed, all normal here.
TITLE: 06/21 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 66Mpc
OUTGOING OPERATOR: Corey
CURRENT ENVIRONMENT:
Wind: 5mph Gusts, 3mph 5min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.10 μm/s
QUICK SUMMARY: Observing for the past ~7 hours. LLO has been down overnight due to an approaching tropical storm. At 15:13 UTC, Sheila began commissioning activities, so the Intent Bit and Observatory Mode have been set accordingly.
TITLE: 06/21 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: OBSERVING
INCOMING OPERATOR: Travis
SHIFT SUMMARY:
Decent shift with wind dying down for last 5hrs. Only a couple of glitches on H1 (one was a brief session of the new Pitch Instability & the other was due to inbound gravel trucks). L1 continues to be down due to heavy storm activity.
Pair of porcupines spotted by Peter King this morning.
LOG:
Spent a few hours addressing SUS modes for first part of shift. H1 has now been locked for 2.5hrs.
Rebooted alarm0 (the Verbal & Alarm Manager Computer) because it was running very slow.
Winds are now low/gone.
Damping Bounce & Roll
Since L1 was down, I took the opportunity to attempt to damp some modes (i.e. Roll, Bounce & Violin). I believe most of my efforts focused on ITMy Bounce Mode.
Feature: Wrong FULL Filter Bank File opened for ROLL filter banks on the Bounce/Roll medm screen (SUS_CUST_BOUNCE_ROLL_MONITORS.adl). For example for ROLL_ITMY, when I clicked on the FULL button, a BOUNCE_ITMY filter bank is opened up. (this was the same case for all Test Masses).
Regardless, after some time I was able to accelerate damping these guys down.
Damping Violin Modes
I then moved on to the Violin Modes. Main ~500Hz peak on the DARM spectra on the wall was around 1e-16. Here I didn't have as much luck. I worked on both ETMs.
ETMy: I was able to bring down the 506-513 MODE1 by ENABLING the +60dB filter (FM3) (I ACCEPTED this difference in SDF.). This phase change quickly minimized the OUTMON signal for MODE1, but on the VIOLIN OVERVIEW medm, this MODE didn't change much.
ETMx: Here I tried gain & phase changes for MODE 3 & MODE4. Unfortunately, I did not see any damping for any of the changes I did. This is when I gave up on violin modes.
A2L:
Ran one since H1 had been up for a few hours.
ALS SDF Diffs
There were some ALS QPD diffs (it was a channel related to Sheila's earlier alog), I went ahead and accepted these since the Diffs were on the order of 1e-17. (snapshot attached).
10:13 Back to OBSERVING
SUS_CUST_BOUNCE_ROLL_MONITORS.adl was edited to fix the "open full" issue.
TITLE: 06/21 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 68Mpc
OUTGOING OPERATOR: Jeff
CURRENT ENVIRONMENT:
Wind: 18mph Gusts, 16mph 5min avg
Primary useism: 0.06 μm/s
Secondary useism: 0.09 μm/s
The arc of wind seismic noise is coming down after the EVE windstorm.
QUICK SUMMARY:
Looking much better than yesterday. Jeff handed over a nice looking H1 lock with 65Mpc range & nice looking DARM spectra. Violin modes look like they could be reduced...perhaps something I can do later in the shift since L1 is down for the night (unless they come down on their own).
Just after I hit submit, H1 dropped out of lock! (No obvious issues)
Previous lock was 1hr 13min.
We haven't reset our green initial alignment reference is a while, so on the way back from maintainence I took some time to do this today. There are three useful scripts in userapps/als/h1/scripts
Procedure:
Attached is a screenshot of the SDF differences with the safe.snap, and the OBSERVE.snap
I have commented out the ALS CAMERA check from diag main, because we have to update them everytime we update the initial alignment references, and as far as I can tell all this check is doing is checking that the settings haven't changed, which is the purpose of SDF. I think that the problem which inspired this test was a bad safe.snap being restored.
Commissioning work for the first half of the shift. Winds are in the high 20s and 30Mph with several sustained gusts of well over 40mph. Trying to relock at this time, without much success. LLO is in DOWN due to high microseism from approaching tropical storm.
I repeated the CP fringe wrapping tests we have done a couple of times before.
For both CPs I used an excitation of 600 counts at 0.1 Hz into R0 DAMP L, which is similar to what was done in 30979 and 33521
have ended up with a position simliar to what Robert found based on the camera image by trying to minimize the fringe wrapping I see in DARM from the excitation. On the PRM camera there are clearly two beams from CPY, they are not completely gone in this alignment (I did't find an alignment where both beams are gone) The 2nd and 3rd attachments are before and after pictures of the PRM camera. I am having trouble opening the SRM camera.
Last night Jeff and Corey had difficulties with large pitch motion of the test masses.
This is described in a couple of alogs from Corey, and can easily be seen on the summary pages
Suggestion for the operators if you have this problem again:
1) If you see noise in the ITMY oplev laser sum again, try moving CPY around to see if you can get rid of it. (The ITMY laser is off for now, but you might still see noise on the SUM).
2)If you see that the circulating power is fluctuating at 0.4 Hz, try turning on the PSL 3rd loop.
The fringes seen on ITMY must be due to fringes of the OpLev laser with an OpLev ghost beam coming off CPY.
In the first attached screenshot I am driving CPY in L with 600 counts at 0.1 Hz in R0 DAMP L. You can see that the fringing got worse then better as I moved CPY to improve the camera image (36936), then I moved the CP to maximize the fringes. I went to the floor and unplugged the OpLev fiber, and the fringing went away, so this is not from IFO beams.
FOr a test, the ITMY optical lever laser was turned off. Because we want to return to observing before waiting a few hours for the laser to settle and stop glitching, we are going to leave it off for the night.
Turned back on, because LLO is down for the night anyway.
Daniel, Kiwamu,
This is a quick summary of our activity today. Some more details will be posted later.
We have looked into the WFS 72 MHz signals (beatnote of the 118 MHz and 45 MHz) that are derived from the AS port WFSs A and B. They look good in the sense that their alignment signals are not buried under some noises.
After our measurements were done, we reverted the setup so that we can get back to observing.
EDIT: The calculation of the modulation depth was corrected in response to Daniel's comment (shown below).
[Summary]
[Setup]
In the CER, we have two IFR units for this measurement (36354). One is configured for 118 MHz, providing the modulation, and the other is configured for 72 MHz, providing the demodulation RF source. We unplugged the RF source for the 90 MHz system in the ISC R3 rack (the one by HAM6) and plugged the 72 MHz source. This means that we use the 90 MHz demodulation system for demodulating the RF components at 72 MHz. This allows us for a minimum hardware modification at the cost of losing the ASAIRB_RF90 signals. Currently, ASAIRB_RF90 is used only once in the locking sequence where the ISC_DRMI guardian checks whether the DRMI is locked on a hopped mode or not. During this test, we have commented out this action from the ISC_DRMI guardian so that it doesn't stop at this point.
We cranked up the RF power of the 118 MHz unit from -10 dBm to 10 dBm. Note that the RF amplifier that is directly connected to this IFR unit has a input rate of +10 dBm. According to the previous measurement (36354), this should provide 30 dBm at the input of the EOM. The RF power of the 72 MHz unit was set to 13 dBm which gave reasonable RF powers in all the 90 MHz demodulator systems.
BTW, the Triplexer doesn't give appreciable loss at 72 MHz (see table.2 of E1600027).
[Measurement concept: frequency-offset demodulation]
Today we introduced an intentional frequency offset of 205 Hz to the 72 MHz unit. This results in the demod signals rotating in the I-Q phase space at the offset frequency. The main motivation for doing this frequency-offset technique is that it allows us for relatively accurate measurement of the relative RF phase between the two IFR units and the main RF source (Wentzel OCXO).
Looking at the raw RF signals with an oscilloscope, we confirmed that the RF phase of the IFR units with respect to the Wentzel OCXO slips at a rate of roughly 2 pi / 10 seconds even though the IFR units are synchronized to the 10 MHz source which is locked to the GPS 1 pps signal. Not surprisingly the relative phase between the two IFR units don't seem to slip by appreciable amount. In future, we will get an harmonic generator so that the 72 and 118 MHz RF signals are synchronized to the main OCXO.
Regardless of whether the RF phase slips or not, the idea is to have a look at the ASC-AS_WFS_A(B)_RF118 signals in frequency domain so that the peak height at the offset frequency gives us a measure of the modulation depth.
[Modulation depth]
We estimated the modulation depth of the 118 MHz RF sidebands to be 1 mrad 0.22 mrad, much smaller than the others (15661).
Our measurement is essentially comparison of the signal strength between the 36 and 72 MHz demodulated signals given that we know the modulation depth for 9 MHz. The below shows the derivation.
[Signal to noise ratio]
In the current freqeuncy-offset scheme, the ASC signals are upconverted to frequencies around 205 Hz. Looking at the spectrum of the demodulated signals when the interferometer was locked with a 2W PSL, we saw that the signal-to-noise ratio of the 72 MHz signals are worse than that of the 36 MHz by a factor of 10. See the attached dtt session.
After we reached a state equivalent to NOMINAL_LOW_NOISE, we took a look at the spectrum again to see how much the signal-to-noise ratio has improved. It seem to have improved by a factor of 5 or so even though the PSL power increased by a factor of 15 (2 W -> 30 W). See the second attachment. Some fraction can be explained by the 3 dB reduction of 45 MHz RF source power that takes place during the locking sequence.
It seems that we can sense the ASC signals up to 5 Hz before diving into some white noise.
[Future direction]
The difference between the transimpedance gains at 36 and 72 MHz is taken from LIGO-T1300488. Looking at Figs. 5 and 6 on page 3, we read the response as +2 dB at 36 MHz (Q3 trace in Fig. 5) against –22 dB at 72 MHz (Q3 trace in Fig. 6). The gain difference is then estimated to be 24 dB, or a factor of ~16.
The transmission ratio towards the antisymmetric port between the 9 and 118 MHz sidebands is around ~1/10, see Hang's presentation LIGO-T1700215.
The primary and redundant h(t) pipelines were restarted at GPS second 1182010698. This pipeline restart is not accompanied by any filter changes, but does pick up gstlal-calibration-1.1.7. For more information on this version of the code, please see its redmine page.
For more information about the filters currently being run, please see the following aLOG entries:
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=36864
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=36842
The corrected filter file needed for LHO Work Permit Number 7047 had already been staged on the DMT on June 14. Thus, this restart of the calibration code picked up the corrected filter file, and this completes LHO Work Permit Number 7047.
Correction to this alog: the pipeline restart does not affect the version of gstlal-calibration running, since version 1.1.7 was already running at Hanford. However it does pick up corrected filters, but the file pointing to those filters had the same name so no command line change was needed. I apologize for the confusion.
