15:10 Lockloss due to EQ in Mariana Islands
16:05 Fil to CER to investigate cosmic ray detector noise
16:06 Fred down both arms with BBC crew
16:07 Peter to diode room to take pics
16:10 Peter out
16:21 JimW taking HAM1 HEPI down for filter install
16:27 Richard to CER
17:00 Kyle and Gerardo to Y-2-8 for ion pump work
17:07 Fil and Richard done
19:03 Kyle and Gerardo back
19:15 started initial alignment
19:35 Fil and Richard to MX PEM vault
19:54 locked low noise
20:05 Richard and Fil done
21:02 Kyle and Gerardo back to Y-2-8
Locking summary: Several short lock stretches today after an initial alignment post-earthquakes. Most of the locklosses can be attributed to local seismic activity. Others are being investigated by commissioners.
Craig, Jenne, Kiwamu,
We did a VCO calibration for the ALS diff vco in the last Friday when the interferometer was suffering from high wind. The new result suggests that the VCO calibration stays the same as the one for ER7 by 0.6%.
The new coefficient is 0.11847 +/- 9.3e-05 [cnts @ DIFF_PLL_CTRL_INMON / Hz @ DIFF VCO frequency read by the timing comparator ].
The attached below shows the fitting result:
The measurement method is the same as the previous one which is described in this alog (alog 18711). One difference is that we used the INMON as opposed to OUTPUT because we did not want to rely on the filter shape of the chain which contains the zpk([[40], [1.6]) which is supposed to cancel the low noise VCO circuit. The sweep was as slow as 255 [Hz/ sec]. The fitting uses a frequency region where the linearity was found to be good (as indicated in the plot as yellow shaded region).
The analysis code, data and figure are saved in SVN as follows:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/ALSDiff/vco_calibration_fitting.py
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/ALSDiff/2015-08-14_vco_sweep_v2.txt
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Results/ALSDiff/2015-08-14_VCO_calibration_v2.pdf
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Results/ALSDiff/2015-08-14_VCO_calibration_v2.png
I made another measurement which is an improved version of the last measurement.
The improvements are:
The fitted coefficient this time is lower that the last measurement by 0.4 %, presumably because of the improvements which should get rid of systematic biases.
Coefficient = 0.11802 +/- 4.92e-05 (0.042 %) in [cnts / Hz]
Here is a plot showing the data along with the fitting line:
Looking at the residuals, there seem to be two components -- majorities are on the wavy trend while there are scattered points which tend to have high values. I believe that the ones having high values are due to the impulse response of the VCO and comparator which deviated every time when I made a discrete steps. As shown, they tend to pull up the interception while they don't seem to affect the slop so much. Since the quantity we care is the slope of the fitting line, I think the data is good enough.
As usual, the data, script and figures are checked in to the SVN. They can be found at:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/ALSDiff/2015-08-18_vco_steps.dat
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/ALSDiff/2015-08-18_vco_calibration_fitting.py
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Results/ALSDiff/2015-08-18_VCO_calibration.pdf
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Results/ALSDiff/2015-08-18_VCO_calibration.png
Laser Status:
SysStat is good
Front End power is 33.48W (should be around 30 W)
Frontend Watch is GREEN
HPO Watch is RED
PMC:
It has been locked 6.0 days, 7.0 hr 35.0 minutes (should be days/weeks)
Reflected power is 3.071Watts and PowerSum = 26.12Watts.
FSS:
It has been locked for 0.0 days 0.0 h and 2.0 min (should be days/weeks)
TPD[V] = 1.472V (min 0.9V)
ISS:
The diffracted power is around 10.11% (should be 5-9%)
Last saturation event was 0.0 days 0.0 hours and 2.0 minutes ago (should be days/weeks)
Posted by Travis S.
One of the locklosses Travis has had this morning was due to an oscillation in DHARD. This lockloss was typical of ones we've been having in the last few weeks a few minutes after powering up. If we get a chance I will try to measure these loops at full power, especially pit where we added a resG.
We are acquiring 4 channels in the PSL which are not required in the science frames (see E1500349). They are
The BP, INT and ISO channels are not connected and only AMP is actually used. For the three unused channels the filter module output gains have been set to null, so that only zeroes are getting written (and compressed away). Since we are not going to restart the PSL, the AMP channel will be acquired until the next opportunity. The old gains were:
In the past few weeks we've made a few temporary changes to the guardians that we intended to revert when we start running. The first was commenting our the shuttering of the end station green, alog 20484.
The second was that we had a path to avoid closing the beam diverters in the corner on the way to nominal low noise. Both of these changes have been removed, so that now in nominal low noise the beam diverters and end station shutters will be closed.
We are aware of problems with the remote 2FA Yubikey login system, we are investigating. It has an opened ticket FRS3467.
Update: Jonathan's email explaining the situation:
There are problems remotely logging into LHO CDS via lhocds.ligo-wa.caltech.edu right now. It is being looked at, but a solution is not yet known.
It appears that a security update has changed how authentication can work in the ssh server and is no longer allowing multiple passes/layers of authentication. So your initial password (ie your LIGO.ORG) password is being checked by the LIGO.ORGauthentication infrastructure and then being passed onto the token system (without the chance of allowing a token to be prompted for). As your LIGO.ORG password is not the same as the output of your token (yubikey) the authentication fails.
However this only happens most of the time. Some of the time you do get prompted for both passwords (LIGO.ORG and OTP/token/yubikey) and it works.
Unfortunately we do not have a proper fix at this time. Until such a time as we do, please try again.
---
Jonathan Hanks
CDS Software Engineer
LIGO Hanford Observatory
Logins are now working.
10 day trends for LTS containers
Late last week we had one of the two compressors quit on the AAON unit at the staging building. See FRS 3455. This unit is designed to supplement the original 12 T Carrier chiller which also has one of the two condenser fan motors beginning to show signs of failure. See FRS 3451. The failed compressor has been disconnected and the AAON is operating at 50% capacity which should be enough to assist the main unit enough to keep the staging building cool especially during the somewhat cooler temperatures. The faulty parts have now been ordered and hopefully arrive before any additional triple digit temperatures.
LVEA: Laser Hazard IFO: UnLocked Observation Bit: Commissioning All Times in UTC 07:00 Take over from Ed M. 07:00 Commissioners working on IFO 09:11 Locked at Nominal_Low_Noise – Commissioning on going 11:09 Lock Loss – Commissioning activities 11:30 Dust counts at End-Y high 12:01 Locked at Nominal_Low_Noise – Commissioning on going 15:00 Turn over to Travis 15:04 Lockloss -
The attached pdf contains current Stage-1 and Stage-2 NB model performance of ITMY chamber for X,Y,Z and RZ dof. Fig 1- ST1 ITMY X Low frequency near microseism model performance is limited by the ground blend filter (HEPI L4C+IPS) 1-5Hz frequency band is limited by GND-STS passing through the sensor correction path 5Hz and above (upto 10Hz say) is limited by Stage-2 back reaction Below microseism model does not match with actual performance. (May be because of some tilt coupling?? But it looks like actual measurement is limited by the sensor noises (T240/CPS) via isolation filter. - Not sure about it) Fig 2- ST2 ITMY X Instead of T240 BLND OUT, I have used T240 BLND IN as the input (stage-1 displacement) to the ST-2 model. Though the model and measured GS13 are in agreement above blend frequency (250mHz), the shape between 1-3Hz are not same. The model output looks more like the input signal T240 BLND IN. May be a better input noise model will work better. Since the stage-2 model performance above ~1Hz is highly dependent on stage-1 displacement, we can san say that the Stage-2 back reaction on stage-1 can have effect on the final performance of the model. Fig 3 - ST1 ITMY Y Most of the features and model performance are same as X dof. Fig 4 - ST2 ITMY Y Though this one is same as ST2 ITMY X only thing I have noticed here is the actual IFO ST1 performance is better than ST2 between ~ 300-500 mHz. Fig 5- ST1 ITMY Z ST-1 model performance matches the actual measurement at almost all the frequency range of interest. The conclusions derived for ground model and Stage-2 back reaction hold here too. Fig 6- ST2 ITMY Z Unlike X and Y dof, the model performance between 60 to 250 mHz is quite good (I am still trying to figure out why this sort of discrepancy exists between these dofs ???) At the same time the mismatch between model and actual performance above 5Hz is noticeable. Model is over estimating the actual performance here (though the model has already included stage-2 back reaction in Stage-1) Fig 7- ST1 ITMY RZ Apart from the limitations of the model due to ground noise at low frequencies, the performance of this stage is mostly limited by CPS sensor noise via BLEND+ISO path. Fig 8- ST1 ITMY RZ Please DO NOT go through this figure. Still need to sort out the problems. Same sort of features can be seen in almost all the BSC chambers except BS where the stage-2 controllers are not in use.
T240 and GS13 sensor noise floors are added to the seismic noise budget plots.
Have been seeing high dust counts at End-Y during evening ops shift. The counts are not that far off the normal values for End-Y, but there is no apparent cause for the spikes. Will continue to monitor.
Darkhan, Jenne, Stefan, Evan
Upon revisiting the shape of the DARM loop, we found that we had 4 dB of gain peaking from 10 Hz to 50 Hz.
That seems a bit too strong for our taste, so we took a look at the DARM suscomp filter that we've been using for the past few months. Aside from the low-frequency (<2 Hz) suspension resonance compensation and the high-frequency (>900 Hz) inversion rolloff, there is a single pole at 200 Hz.
This serves us well when locking DIFF, but in full, low-noise lock it costs us phase (not least because we also have the effect of the 350 Hz RSE pole).
Anyway, there is now a filter installed in EY L3 lock with a zero at 200 Hz and a pole at 1000 Hz in order to push this pole up to higher frequency. This gives us a modest improvement in phase margin at the DARM ugf (34° to 46°). The DARM ugf is 40 Hz or so (more or less the same as before). The EY ESD has about 16000 ct rms, mostly accumulated around 1 kHz (magenta/orange in the attached spectra show the before/after).
[In the longer term, we should just roll p/z pair into the suscomp filter, so that it rises like f essentially from 1 Hz to 1 kHz. Then put a 200 Hz pole / 1000 Hz zero pair in EX L3 lock, so as not to disturb the DIFF loop shape. However, I've put what we have so far into the guardian and it works fine.]
Darkhan and I retuned the DARM OLTF template in order to not saturate with this new loop shape. The attachment shows the before (blue) and after (red), along with the closed-loop gain and loop suppression. There's still moderate gain peaking below 20 Hz.
Also attached is new pcal sweep measurement.
Attached is a screen snapshot of the ETMy L3 LOCK filter bank and the corresponding CAL-CS_DARM_FE_ETMY_L3 bank, now showing the new filter. There are still differences between the banks...
Evan, Stefan, Evan will make a more detailed log entry with actual measurements, but here are the highlights: - We beat the 45Mhz signal from the installed and the spare harmonic generators. - the first odd thing was that straight out of the harmonic generators, the 45Mhz signals were out of phase by about 170deg, even though the 9MHz inputs were nicely in phase... - We phased the two signals to be exactly in phase an stuck them into a mixer: 0.415V - We phased the. To be exactly 90deg apart: no DC signal, and ~ 220nV/rtHz of flat broadband noise. - this gives 5.3e-7 rad/rtHz between the two signals. - Assuming equal and non-coherent contributions, the phase noise of one box is thus: 3.75e-7 rad/rtHz - If we assume that the oscillator phase noise has the same coupling as the oscillator amplitude noise (9e-2mA/RIN), we would expect 3.4e-8mA/rtHz. Thats's pretty close to what we see on ODC_DCPD_SUM.
Data attached: two amplitude noise measurements, two phase noise measurements. One set taken sending equal drive levels into the mixer, and another set taken with the rf attenuated by 5 dB.
Sheila, Evan
Running the dc-coupled oplev servo on SR3 for long periods of time seems to be causing us grief (LHO#20519).
As an alternative, we are trying out a cage servo which feeds the witness sensor in pitch back to M2:
ezcaservo -r H1:SUS-SR3_M3_WIT_PMON -g -300 -s
The step response of this loop has a time constant of 30 s or so.
Jenne and I put this cage servo into a new guardian, called SR3_CAGE_SERVO. One hick up in this process was the fact that the gain setting that works for ezcaservo is opposite to the one that works for cdsutils.servo
This guardian is managed by the ISC_DRMI guardian, which doesn't turn it off but does make sure that it is turned on after DRMI locks. There are states to run the servo, turn it off, and to clear the history (clear offset). We've added this guardian to the list of guardians in IFO guardian. (That is the guardian who checks that the state of other guardians), and set the nominal state to CAGE_SERVO_RUNNING.
We've also added it to the ISC guardian overview screen.
If misaligning SR3, this servo needs to be off. The guardian will go to CAGE_SERVO_OFF if SR3 is misaligned.
Did you guys add this new node to the overview screen? Please let me know when you add new nodes. All nodes have to be tracked in the infrastructure, so we need to know all nodes that are running and are being depended upon by other nodes.
I alrady noticed yesterday that the DARM noise at the periscope peaks (200-400 Hz) was high at the beginning of the lock and then reduced over time.
The first attached plot shows a BLRMS of DARM around those peaks, starting right after reaching the low noise state. There is a clear reduction of the noise over time. The second plot shows that on a similar time scale, the OMC alignment output signal changed, mostly ANG_Y.
This seems to confirm the idea that input beam jitter at the periscope peaks is converted into intensity noise by an OMC misalignment, which changes over time.
To confirm this, I move the OMC angular loops during full lock, adding offsets of few tens of counts to the POS and ANG loops. The third plot shows the steps in the control signals. I was able to reduce the BLRMS by adding an offset of -40 to the ANG_Y loop. The fourth plot compares the DARM spectrum with (red) and without (blue) the ANG_Y offset. I should have increased the offset more. Unfortunately, I noticed that the output was hitting the limit of 300 and I stupidly increased it to 1000: but since the loop was integrating, I broke the lock since I suddenly increased the output from -300 to -1000.
However, the experiment confirms that the noise at the periscope peaks changes in amplitude with the OMC alignment, which is not optimal.
I am not 100% sure what value Gabriele meant to leave, but I have accepted in SDF (Sheila and I are in process of clearing a bunch of diffs in SDF) the value of -30 for ANG_Y for the OMC. I'll check with Gabriele about what value he meant to leave (his alog seems to indicate -40, but we found it at -30).
Since we're using the QPD loops to align the OMC, it's probably better to record any change in the alignment in the QPD offsets. I forget the channel names at the moment, but these are the offsets in the OMC QPD channels (not the same channels in the ASC models). If the offsets are stored in the ANG and POS loops, they will have to be turned off if/when we switch to the dither alignment. If they are recorded in the QPD filter banks it is one less thing to think about.
To summarize the OMC alignment: the QPD offsets have been tuned so the OMC is well-aligned in the low power state. In this state, the dither error signals should be zero. We know that as the power is increased, the QPD offsets are no longer a good alignment, especially in pitch -- this is according to the dither error signals. We suspect the misalignment is due to some junk light that shifts the nominal alignment position on the QPDs. Unfortunately, the misalignment is large enough that engaging the dither loops in the high power state saturates the drive to the OMC SUS. This is why we have stuck with the QPD alignment for now...we should find a solution before O1 that allows us to use the dither loops. The last time the alignment scheme had any attention was in late May.
Needless to say, do remember to check the drives to the OMC SUS OSEMs when changing the alignment settings, they may saturate!
The offsets I left (-30) is better than 0, but not the optimal one yet. It's better to check the OMC alignment again
After the PSL temperature adventure on monday afternoon, it seems as though the PMC alignment shifted. We now get less transmitted power, although the sum of refl and trans has not changed much.
In looking at the data around the period of the temperature excursion, all the power monitoring photodiodes indicate a change in power monitored. The ones located before the pre-modecleaner return to their previous values. The ISS photodiodes after the pre-modecleaner return to their previous values however the transmission and reflection signals are lower than before. The pre-modecleaner reflected spot doesn't look substantially different, however the pre-modecleaner heater output did not return to its previous level. It has remained at an elevated level since the temperature excursion. The coefficient of thermal expansion for aluminium is approximately 22 microns per degK. The attached plot suggests the body of the pre-modecleaner changed by 0.5 degK and stayed at the higher temperature. It should be noted that the pre-modecleaner heater did its job and relieved the PZT high voltage. In doing so the length of the spacer is different and this may be the cause of any mis-alignment. The plot also shows the Laser Room temperature. It might be worth trying reducing (presumably reducing, might also be increasing) the heater offset to bring the pre-modecleaner temperature back down to 304.5 degK from its current value of 305.0 degK to see if this peaks the power transmitted by the pre-modecleaner.
Attached is the output of the quadrant photodiode in the ISS photodiode box with the corresponding temperature measurement. Clearly a change in the beam position is indicated, with the vertical not returning to its previous value. The horizontal seems to track the room temperature.