A little late, but I've taken this week's charge measurement. The data live here: /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGL3/Data/ data_2016-06-03-16-09-42 data_2016-06-03-16-21-27 data_2016-06-03-16-33-11 data_2016-06-03-16-44-52 data_2016-06-03-16-56-34 /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/SAGL3/Data data_2016-06-03-16-11-05 data_2016-06-03-16-22-46 data_2016-06-03-16-34-27 data_2016-06-03-16-46-09 data_2016-06-03-16-57-51 I'll process later today or next week. A reminder: we should also (write a script to) flip the bias sign next week too, because we're near zero effective bias voltage, and we want to keep it there (see LHO aLOG 27255).
An additional ADC was added to the h1susauxb123 I/O chassis. The new card was added to the expansion board at bus 1-2, making it ADC1 in relation to the existing ADC cards. All ribbon cables between the ADC and interface cards were rearranged with the exception of ADC0 so that none of the cables to the AA chassis needed to be swapped and the h1susauxb123 model doesn't need to be modified.
It appears that the MySQL process on h1conlog1-master stopped at around 8:29 local time this morning. It is not yet clear why. /var/log/mysql/error.log: 160603 8:29:33 [Note] /usr/sbin/mysqld: Normal shutdown /var/log/syslog: Jun 3 08:29:43 h1conlog1-master conlog: ../conlog.cpp: 301: process_cac_messages: MySQL Exception: Error: Lost connection to MySQL server during query: Error code: 2013: SQLState: HY000: Exiting. Since I was going to stop it for the power outage this afternoon anyway, I will not try to restart it.
It appears that the MySQL process on h1conlog1-replica stopped at around the same time: /var/log/mysql/error.log 160603 8:28:54 [Note] /usr/sbin/mysqld: Normal shutdown
I have powered off both computers until after the power outage.
Activities:
Currently:
Work still planned for today:
Tours:
Moday timeline:
To be more clear regarding the HEPI task I will perform Monday morning, see WP 5910.
This is the Capacitive Accumulator Pressure checking which requires the HEPI Pumps off. This is done only every 3 to 6 months.
I took TFs on ETMX and ETMY this morning, driving L2 Test Pitch EXC and then L2 Test Yaw EXC and looking at the Oplev pitch and yaw signals.
Files are saved as:
PDFs of results are attached
PSL Crystal Chiller had a Low Water alarm. Added 200ml water to silence the alarm.
These are the temperature and RH data for the 3IFO desiccant cabinet in the LVEA and the two dry box storage cabinets in the VPW. No irregularities noted in the data.
Below I've attached screenshots of the running tmux session and both HWSX and HWSY spherical power. HWSY is constantly gone flat. This behavior started around 9:43 pm. I killed the code for tonight.
I was looking at time series of the op levs to see if one of the ETMs was moving around and it looks like there is something odd with the ETMY op lev. The Op lev says ETMY is moving ~ micron, but Sheila says if that were true we would be unlikely to lock ALS. Attached image shows StripTool traces of ETMX and ETMY. ETMX is blue and green, ETMY is red and aqua.
Tonight we are again having random, fast locklosses, in different configurations. We also are seeing some large glitches that don't knock us out of lock. Again they seem to correspond to times when there is something noisy in SR3 channels, while its not clear that the SR3 channels are seeing real optic motion, it is probably worth swapping some electronics as a test because these frequent locklosses are making commissioning very difficult.
See 27437 and Andy Lundgren's comments
The first attached plot shows that something about this channel changed on May 10th, and that there have been noisy periods since then. The next two are two more examples of sudden unexplained locklosses where something shows up in SR3.
KIwamu and I unplugged the cables from the Sat amp to the chamber for both M2 and M3, and the locklosses and glitches still happened. The good news is that Kiwamu seems to have found a good clue about the real culprit.
Our current theory is that locklosses are due to the ISS which shuts itself off for some reason at random times at a rate of once in 10 minutes or so. This causes a glitch in the laser intensity. Before a lockloss, there was a fast glitch (~milliseconds) in PRCL, SRCL and CARM error signals. That made us think that the laser field may be glitching. Indeed, we then found that the ISS had gone off automatically at the same time as the glitch and seemingly had caused the subsequent lockloss. We then tested the stability of ISS in a simpler configuration where only IMC is locked. We saw glitches of the same type in this configuration too.
In order to localize the issue, we are leaving the ISS open overnight to see if some anomaly is there without the ISS loop.
Conclusion: it was the ISS which had a too low diffraction power.
According to the overnight test last night, I did not find a glitchy behavior in the laser intensity (I looked at IMC-MC2_TRANS_SUM). This means that the ISS first loop is the culprit. Looking at trend of the recent diffraction power, the diffraction power kept decreasing in the past few days from 12-ish to almost 10% (see the attached). As Keita studied before (alog 27277), a diffraction power of 10% is about the value where the loop can go unstable (or hit too low diffraction value to shut off the auto-locked loop). I increased the diffraction power to about 12% so that the variation in the diffraction power looks small to my eyes.
Note that there are two reasons that the diffracted power changes, i.e. intentional change of the set point (left top) and the HPO power drift (right bottom). When the latter goes down, ISS doesn't have to diffract as much power, so the diffraction goes lower.
In the attached, at the red vertical line somebody lowered the diffraction for whatever reason, and immediately the ISS got somewhat unhappy (you can see it by the number of ISS "saturation" in right middle panel).
Later at the blue vertical line (that's the same date when PSL air conditioning was left on), the diffraction was reduced again, but the HPO power went up, and for a while it was OK-ish.
After the PSL was shut down and came back, however, the power slowly degraded, the diffraction went lower and lower, and the number of saturation events sky-rocketed.
Hi have set up the arm transmssion QPD monitor for storing the test mass resonant mode signals from 14.8-15.8kHz in 2kSa/sec channels:
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV1_DEMOD_I_OUT_DQ
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV2_DEMOD_I_OUT_DQ
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV3_DEMOD_I_OUT_DQ
H1:SUS-ETMX_PI_DOWNCONV_DOWNCONV4_DEMOD_I_OUT_DQ
represent ETMX QPD A segments 1-4 downconverted such the 0Hz represents 14.8kHz and 1kHz represents 15.8kHz.
Craig, Sheila, Rana, Terra, Jim, Evan
In light of 27483, we wanted to try to balance the test mass PUM common/differential and hard/soft actuation. As a start, we wanted to make better common/differential actuation for the ETMs and ITMs (next we will try to make better hard/soft actuation).
We drove the ETMs in common-mode (pitch and yaw) and looked at the AS 45 Q pitch/yaw signals. We then adjusted the L2 LOCK P/Y filter gains in order to minimize the AS 45 Q signals. Gain adjustments of a few percent were required. The biggest reduction in AS 45 Q was a factor of a few; the smallest was basically nil.
Along the way we noticed that there was essentially a 1:1 cross-coupling between cHard pitch and cHard yaw when driving ETMs (i.e., driving cHard pitch would produce equally sized signals in both cHard pitch and cHard yaw). This could be explained by the transmon roll orientation causing a rotation of pitch into yaw at the QPDs. However, removing the QPD blending (i.e., using REFL A/B 9I only) for cHard reduced the cross-coupling by a factor of a few.
So it seems that the transmon QPDs are not aligned with the ETMs pitch/yaw alignment. However, the REFL pitch/yaw seems rotated from ETM pitch/yaw by ~30 deg. The ITM drives do not produce this cross-coupling. We want to minimize this to reduce the Hard looop pit/yaw instability that we saw. Should we rotate the REFL WFS matrix to align with the ETMs or ITMs?
We lost lock twice trying to switch CARM to in-vac control, so that needs to be debugged tomorrow.
Craig is working on a WFS rotation matrix script so that we can easily software rotate the WFS into the correct up/down left right arrangement.
Today we also tried to balance the hard/soft actuation. Looking at the aLIGO T0900511 ASC design document, we see that the dHard signal is 10x bigger than dSoft in AS. So we adjust the output matrix elements for the ITMs until we minimized the 6 Hz soft excitation in AS45. The matrix elements before/after:
Before: ITM = 1, ETM = 0.87
After: ITM = 1.12, ETM = 0.87.
The previous numbers were set by using the RoC from the metrology and the arm length. I assume that this 10% correction is due to actuator strength and not RoC. Hopefully now that common/diff and hard/sfot are balanced the WFS loops will be more smooth. Tomorrow, we need to propagate these numbers into the ASC Output Matrix.
C. Cahillane The WFS rotation matrix script is done. This code is designed to rotate the WFS pitch and yaw signal quadrature together by the same angle over 5 seconds. It is located here:/ligo/home/craig.cahillane/Public/ASC_WFS_P_Y_Signal_Rotation.py
This code should be accessible for read write and execution by anyone. To run it, choose how much you want to rotate in degrees and then the WFS you would like to rotate. The first argument is rotation in degrees, and the second is the channel name. (You must separately rotate I and Q.) For example, I choose to rotate REFL_A_RF45_I by -10 degrees. To run this, type:python /ligo/home/craig.cahillane/Public/ASC_WFS_P_Y_Signal_Rotation.py -10 ASC-REFL_A_RF45_I
Once run, this code takes 5 seconds to spin the WFS signal orientation to the one you desire.
We spent today trying to damp the violin mode that had rung up last night (alog 27469). Two major updates:
Nutsinee, Kiwamu,
We cleaned up and rearranged the violin filters today. Unnecessary filters (e.g. 1000 Hz and higher order modes) are removed. As suggested by Evan, we are trying to assign one filter for each fundamental mode. For doing so, we also rearranged the filters so that they line up in ascending order. We did not try getting rid of any of the broadband filters yet; we can still use then when necessary. ISC_LOCK is edited accordingly although we have not gotten a change to test the code.
The attached screenshots show the old settings for ITMY and ETMY, as well as their gain settings. Nutsinee will post the setting information on ITMX and ETMX.
Attached screenshots show the old setting of ITMX (except MODE1 and 2) and ETMX (except MODE1). I splitted all the broadband filters but left those new filters turned off (gain=0) until we have a chance to test them. I only let the guardian turn on what was already turn on before this arrangement. ISC guardian doesn't touch ETMX violin filters so all gains should be 0 there.
I created another wikipage for the new violin mode table with updated filter information to live in. The old table can still be found here.
Rana, Evan
WE measured the SRM to SRCL TF today to find the frequency and Q of the internal mode. Our hypothesis is that the thermal noise from the PEEK screws used to clamp the mirror into the mirror holder might be significant contribution to DARM.
The attached Bode plot shows the TF. The resonance frequency is ~3340 and the Q ~150. Our paper and pencil estimate is that this may be within an order of magnitude of DARM, depending upon the shape of the thermal noise spectrum. If its steeper than structural damping it could be very close.
"But isn't this ruled out by the DARM offset / noise test ?", you might be thinking. No! Since the SRCL->DARM coupling is a superposition of radiation pressure (1/f^2) and the 'HOM' flat coupling, there is a broad notch in the SRCL->DARM TF at ~80 Hz. So, we need to redo this test at ~50 Hz to see if the changing SRCL coupling shows up there.
Also recall that the SRCLFF is not doing the right thing for SRM displacement noise; it is designed to subtract SRC sensing noise. Stay tuned for an updated noise budget with SRM thermal noise added.
** see https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=27455 for pictures of the SRM compsoite mass.
The peak is also visible in the DARM spectrum. In this plot the peak is at 3335 instead of 3340 Hz. Why is there a 1.5% frequency shift?
Here are projected SRM thermal noise curves for structural and viscous damping.
Given a typical SRC coupling into DARM of 1×10−4 m/m at 40 Hz, 20 W of PSL power, and 13 pm of DARM offset (25019), this would imply a noise in DARM of 1×10−20 m/Hz1/2 at 40 Hz if the damping is structural.
When I modelled the optics in https://dcc.ligo.org/LIGO-T1500376 and in particular the surrogate SRM I had assumed optic was bonded. After looking again earlier with Rana and Betsy realised it is held with 2 set screws (Peek?) on barrell at 12 o'clock and two line contacts at 4 and 8 o'clcok. See https://dcc.ligo.org/LIGO-D1200886.
The previous bonded model for the SRM surrogate (I believe) had a fisrt mode predicted around 8k Hz. However, from a quick model I ran today (with the set screws etc ... ) the first mode appears to be around 3400 Hz. The mode is associated with the optic held with the peek screws. (Now I was doing model using remote desktop so I will need to check it again when I get a better connection, so more to follow on this. I will also post updated model, once I get back to Caltech.)
The ~3340Hz peak is also clearly visible in the PDA/PDB x-correlation spectrum. See alog 26345.
A couple of comments on this topic:
Danny, Matt (Peter F remotely)
Due to the issues currently seen at LHO, we were asked how the LLO SRM surrogate was put together and if we could add to the alog for a record of the process. The easiest way is to do it via photos (which we have of the assembly process).
IMG_1462....There are only two setscrews that hold the optic in place. Can be seen putting these in place below in the "cup" that holds the optic (eventually). Im not sure of the material but Peter F's speculation is that "I think those set screws must be the carbon-loaded PEEK type. The only other option I can think of for a black set screw would be carbon-steel, and it surely isn’t that."
IMG_1455...Here you seen the three main parts. The optic, the “cup” that the optic goes into and then the main mass the cup goes in. Note in the “cup” you see the two raised parts at around 4 and 8 o’clock that the setscrews ‘push’ the optic onto. So its not 'really' a three point contact, its 2 points (set screws) and 2 lines (in the holder)
IMG_1466...Here is the optic going into the cup making sure the fiducial on the optic lines up with the arrow on the cup
IMG_1470.....Optic now in the cup and doing up the setscrews that hold it in place. I cant remember how much we torqued it up (we only did it by hand). But as Peter F again speculated that perhaps we just did the setscrews up tighter than LHO
IMG_1475....Flipping the cup (with the optic in it) over and placing in main mass
IMG_1478....Cup now sitting in Main mass (without screws holding cup into main mass)
IMG_5172......the SRM surrogate installed into the suspension
It looks like there might be a mode in the L1 SRM at 2400 Hz. See the attached plot of SRCL error signal from January, along with DARM and the coherence. There is also a broad peak (hump) around 3500 Hz in SRCL, with very low coherence (0.04 or so) with DARM. The SRCL data has been scaled by 5e-5 here so that it lines up with DARM at 2400 Hz.
Here are two noise budgets showing the expected DARM noise assuming (1) structural (1/f1/2) SRM damping and (2) a hyperstructural (1/f3/4) SRM damping. This hyperstructural damping could explain the DARM noise around 30 to 40 Hz, but not the noise at 50 Hz and above.
I also attach an updated plot of the SRCL/DARM coupling during O1, showing the effect of the feedforward on both the control noise and on the cavity displacement noise (e.g., thermal noise). Above 20 Hz, the feeforward is not really making the displacement noise coupling any worse (compared to having the feedforward off).
Note that the PEEK thermal noise spectrum along with the SRCL/DARM coupling is able to explain quite well the appearance of the peak in DARM.
I am attaching noise budget data for the structural case in 27625.
I'm assuming it is covered by ECR E1600064 though it is not clear if that ECR shows the additional ADC channels for the sus-aux system needed to support the PI-ESD install on the ITMs.