Evan and Rick reported that the Test1 and Test2 On/Off switches were always on, no matter
what the MEDM switch setting was.

The corresponding output of the AI filter checked out okay at the end of the lilac coloured
cables, for both Test1 and Test2.

The output was checked at the end of the DB37 cable going into the TTFSS.  Although a change
in voltage was observed when both switches were toggled, the change for Test2 was not high enough
to trigger the MAX333 switch inside the TTFSS.  This was traced to a problem with the HCPL2231
optocoupler on the TTFSS fieldbox (D1100367).

Since we do not currently have any HCPL2231s, part N1 and N2 were swapped since part B of N2
was not used.  This has fixed the problem for now.



Jeff B, Evan, Peter

Two tip-tilts have been assembled for 40m.  They are sitting on the optics bench in the Optics lab.

These have thinner wire (43 microns in diameter) to avoid the hysterises seen in the thicker 125 micron wire.  Therefore these have to be handled more carefully.  The wires are quite unforgiving of any kinks or handling errors.

As agreed, these do not contain BOSEMs.  Type-B (one stage before the production line)  bosems will eventually be used in these.

The tip-tilts are ready for shipment to 40m.  They have been wrapped in Al-foil.  For long term storage, these have to be stored in a dry atmosphere to avoid rusting of the "piano wire" fibers.  The mirror holders are locked into place for shipment using the eddy current dampers on either side of the mirror mounts. 

The Sl nos are 007 and 038 (Bottom Plate).  Images of the assembled tip-tilts and their various reference numbers are attached. 

The SUM counts on ETMX oplev laser were around 16000 counts.  I changed the Binary switch settings to increase the gain on the Whitening Chassis to bring the counts to 40k.

The new switch state of the binary switches is recorded here in the attached image.

[Dan, Koji]

Last week, the OMC cavity was scanned with the fully locked IFO at 5.22W. In addition to the usual cavity scan analysis (let's say "DC scan"),
the technique called "beacon scan" was tried in order to check the signal content in each carrier higher-order mode.
Here are some preliimnary results.

Motivation

- Dan took OMC scans in a full lock with and without the DARM offset a while ago (LHO ALOG 16747).
- When the DARM offset is zero, basically there is no (or almost no) carrier TEM00.
- No matter how the offset is, there are carrier higher-order modes.
- This means that we are actually not sure how much of the carrier higher-order mode is coming from the arm.
- Aren't we under-estimating the signal mode matching because of the carrier that has no signal?
- We want to characterize the signal mode matching.
- We can use the DARM signal to distinguish the signal carrier and the others

Measurement conditions

- The DRFPMI was locked at 5.22W MC input.
- DARM was locked with RF with an offset. (~10mA for TEM00)
- The OMC HV PZT (PZT2) was swept from 30V to 90V with the ramp speed of 0.6V/sec (i.e. 100s per ramp).
- During the scan, the whitening filters of the DCPDs were turned off in order to prevent from their saturation.

Signal processing (Attachment 1)

- DCPD_SUM and PZT2 Readback were sampled at 16k. All the signal processing have been done offline with MATLAB.
- DCPD_SUM was preconditioned for demodulation by a bandpass with the passband of fmod +/- 20Hz, where fmod is the demodulation frequency.
- The preconditioned signal and sin or cos signals at fmod were multipled.

- The DC and demodulated signals were decimated to 512Hz (the decimation ratio=32).
- The decimation filter is the MATLAB default one. (i.e. fc=0.8*fsample, 0.05dB ripple 8th Cheby LPF)
- The decimated demodulation signals were further LPFed for noise reduction. (f_LPF = 5Hz)
- The RMS of the demodulated signals are calculated to obtain the beacon amplitude.
- The noise reduction filter imposes the phase delay in the pass band. This was approximated as a time delay.
  i.e. Negative time delay (or sample shift) of 60 samples were applied. (Dan suggested me to use "filtfilt" function
  in order to suppress this kind of phase delay. I'll use it in the future scan.)

Result (Attachment 2)

- The demodulation frequency of 1009.4Hz was used for the beacon scan.
  There was a big peak in DARM spectrum due to undamped ITM violin mode.

- As seen in the figure, a big response found at the carrier TEM00 mode. (Success!)
  (In fact, the response was too weak at the demod frequency of the calibration lines. That's the reason why the violin peak is used.)

- Not all the carrier amplitudes in the DC scan were explained by the beacon scan result.
  This indicates that each higher order modes consists of a signal carrier from the arm and a non-signal carrier.
  Note that the peaks in the DC scan and beacon scan are matched up by multiplying the factor of 5800 to the beacon result.

- As the background data, the demod frequency of 700Hz was used. There was no visible peak in the DARM spectrum at 700Hz.
  Most of the carrier peaks are above the background level. So this is not an artifact of the noise power in a peak.

Discussion

- The table below is showing the peak heights that were read from the plot. (Note this is not a peak fit result.)
  The ratios were estimated from the sum up to 8th order.

Mode       DC_scan         Beacon_scan
  #      [mA]   [ratio]      [ratio]
---------------------------------------
  0    9.18      0.589        0.928
  1    0.539     0.035        0.010
  2    0.675     0.043        0.020
  3    1.327     0.085        0.024
  4    0.564     0.036        0.004
  5    0.821     0.053        0.005
  6    1.355     0.087        0.006
  7    0.568     0.036        0.001
  8    0.559     0.036        0.001
---------------------------------------

- The table indicates that the signal mode matching was 92.8% and was way better than the DC matching.
- The 3rd and 6th order modes (both in DC and beacon) are larger than the others. Is there any reason?

How can we improve?

For better result:

- Slower scan: The cut off of the noise reduction filter is determined by the scan speed. Slower scan will improve the SNR of the measurement.
- Beacon at ETMs: The current beacon isone of the ITM violin mode. I suspect that is the reason why some of the sidebands shows some signal
above the background level. We should use pure DARM signal.
- Better alignment: The alignment of the beam to the OMC was not perfect. We can definitely improve it.

For better understanding of the result:

- Mode healing/harming: What does the SRC do for the peak heights? Are any particular modes enhanced/suppressed by the SRC?

SRM & SR2 Phase 3b Acceptance TFs were presented in LHO aLOG entries 17633 and 17634, however, there was an issue affecting the scaling of the plots of the lower suspension stages.

The discrepancy in the scaling was as a consequence of the recent modifications to the Triple Coil Driver actuation strength carried out only at H1 (ECR E1400369) not being taken account of in the Matlab calibration script. Therefore, I've updated the Matlab (calib_hsts.m) script to support different calibrations factors for suspensions at both sites.

The aforementioned TFs have been re-processed using the updated Matlab scripts. Measurements for each stage have been compared with similar L1 and H1 Suspensions at Phase 3b (in-vacuum), as follows:-

- SRM & SR2 M1-M1 undamped & damped results (allhstss_2015-04-09_Phase3b_H1HSTSs_M1_D*_ALL_ZOOMED_TFs.pdf)
- SRM & SR2 M2-M2 undamped & damped results (allhstss_2015-04-09_Phase3b_H1HSTSs_M2_D*_ALL_ZOOMED_TFs.pdf)
- SRM & SR2 M3-M3 undamped & damped results (allhstss_2015-04-09_Phase3b_H1HSTSs_M3_D*_ALL_ZOOMED_TFs.pdf)

Summary:

M1-M1, undamped TFs are consistent with model and similar suspensions. Very minor shift of H1 SRM pitch modes above 3 Hz. Damped TFs demonstrate variation in damping between sites. However, just to note that H1 SRM vertical DOF peaks still remain relatively high Q.

M2-M2, both undamped and damped TFs taken are consistent with model and simialr suspensions. However, H1 SR2 can be seen to be weaker due to failed UL actuator (Integration Issue #930).

M3-M3, despite suffering poor coherence below 0.5 Hz, both undamped and damped TFs taken are very consistent with model and similar suspensions.

Therefore, these TFs raise no concerns for SRM & SR2 suspensions, other than the failed SR2 M2 stage actuator noted above.

All data, scripts and plots have been committed to the sus svn as of this entry.

I've been working on trying to improve BSC performance by adding elliptical filters to the CPS part of different blend filters, see logs 17702 and 17488. At ETMX I was getting good improvements in Z (first plot, black(sts) and grey (gs13) is 2 nights ago with the "old" blends, green(sts) and red(gs13) are for my new blends) so I was trying to clean up the extra filters I had (which prevent the seismic blend switching scripts from working nicely) and start exporting what I had to other chambers. This involved cutting some elements out of some existing blends and a lot of copy/paste. For example, on St1, the 90 mhz Z blend, I cut out a couple of pole and zero pairs that were very close to each other (almost cancelling each other out) and adding my ellipse. The result is shown in the second plot, blue is the stock, red is the modded version. There's a third, barely visible green trace, which is what I cut the original blend down to before adding my elliptical. I also modified a version of the 01_28 blend  from the HAMs, (third plot, blue is stock, red modded) to use in Z but ETMY keeps ringing up with this blend, so maybe I've compromised the complementarity too much. I've tried my modified blends on ETMX and ITMY and it works there. I'll get all of the chambers in a consistent configuration by tomorrow afternoon, but as of now ETMX and ITMY are in slightly different configurations from ETMY and ITMX.

Last week during a low-noise lock the COMM tidal signals were hitting their software limits.  This is a somewhat insidious problem: right now we don't have a good monitor for these limits, and there are some channels (like the tidal drives) that can hit these limits without causing the IFO to lose lock.

I've written a python script that will scan the frame files for any channels that have their LIMIT enabled, and check whether that limit was reached over a span of GPS times.  The script is not elegant, and I'm hoping someone from DetChar can modify it and make it faster.  For now it provides some important information: which channels to look at, which channels to ignore, and how to figure out if the LIMIT is enabled from the SWSTAT setting.  (Turns out it's the 13th bit.)  Note that the integrator filter module that is used in the tidal drives and the ALS WFS has a different channel to indicate whether the limit is enabled.  Gotcha!

The script is on the LHO cluster here, the current version only runs on the LDAS clusters on archived data (~10min old or more), I will write a version that can run in the control room using cdsutils.  It's not fast, mostly because of the frame-reading.

For H1, there are currently 107 channels with their LIMIT enabled during low-noise, a list of these channels with their LIMIT value is attached.  (Some of these aren't important, like the ITM oplev outputs.)  For the lock on Apr 2 there were three channels that hit their software limit: the two ETM common tidal drives (really, the same signal), and the ETMX BRS output, which wasn't being used.

J. Kissel, J. Betzwieser, M. Wade, C. Cahillane

After finally getting the LHO GST-LAL, GDS, Low-Latency pipeline up and running, we noticed that the reconstruction of DARM_ERR and DARM_CTRL that is shipped over to CAL-CS and stored in the frames was corrupted by numerical precision errors. We had been using the same whitening filter that's used for the DELTA L RESIDUAL, CTRL, and EXTERNAL channels, i.e.
    zpk([1;1;1;1;1],[100;100;100;100;100],1,"n")
but that *over* whitens DARM CTRL and DARM ERR. As such, I've changed the filters to what LLO has installed, a less aggressive,
    DARM_ERR = zpk([10;10],[100;1000],1,"n")
    DARM_CTRL = zpk([5;5],[500;500],1,"n")
I attach two sets of plots:
(1) Bode plots of the new filters, and
(2&3) Courtesy of Joe, Comparison between the raw ASDs of DARM control for a recent lock stretch, and that which is whitened with the above mentioned filters.

We wanted to install the proper parking beam dump on HAM2 before we go high power, and the arm gate valves are closed right now so it seemed like a perfect opportunity. We tried, and failed.

1. Assy in question

https://dcc.ligo.org/LIGO-d1201430

It doesn't show the viewport, so it's not clear how it is supposed to be mounted, except that three hooks grab the outer edge of the flange.

2. The problem

The beam comes out of HAM2 at a steep angle (this picture was taken when we installed the non-final version back in Jan. 2014).

The new beam dump assy seems to be mounted on top of the viewport protector assy. The problem is that the protector is too high, which is kind of obvious from the above picture. For the non-final version, we had to cut the protector ring so the beam comes out of the ring, and a beam dump outside received the beam. We cannot do that with the final beam dump, and as far as the dump sits on top of the protector assy, the beam will hit the protector assy.

As of now, there is a large space between the bottom of the lexan plate and the viewport. There seems to be two versions of the protector assy, one higher than the other, and we're using the higher version. However, even if we use the lower version, it seems likely to me that the beam still does not come to the steering mirror inside the beam dump assy. It should be possible to modify the viewport protector assy such that the lexan plate sits almost flush to the viewport while the beam dump optic table sits almost fluch to the top of the lexan plate. It seems as if this works, but I'm not 100% sure without CAD.

Or maybe it is designed to be used without viewport protector assy. I couldn't find drawing that shows how it's mounted, so I'm asking around.

I told Kyle to hold off to open the gate valve in a hope that somebody offers me an easy solution by tomorrow morning.

Dan, Fil

Today we swapped R23 on the AS_C transimpedance board (D1001974) to increase the gain on the single-ended sum output that is used for the triggering of the HAM6 shutter functions (the fast shutter, and OMC PZT shutter).  The old resistors were 424 ohms, the new ones are 26.7k.  The increase of 63x compensates for the reduced transmission of the OM1 mirror (was 5%, now is 800ppm - half of which goes to AS_C).  The new resistor value allows us to keep the same threshold setting for the shutter logic: 1W into the chamber results in 400uW on AS_C, with a 1k transimpedance resistor and 80% quantum efficiency the threshold should be (400e-6 * 0.8 * 1000 * 26.7e3/4.99e3) = 1.7 volts.  The maximum threshold we can set via Beckhoff is 2V, so this is a good fit.

As Rich pointed out the last time we made this swap, it would be better to account for changes in the gain at the input to the shutter controller, so that the max output of the AS_C sum channel (10V) matches the full range of the PD (10mA).  Unfortunately the Beckhoff readbacks of the PD input to the shutter controller are picked off before the input gain stage, so if we adjusted the gain on that board, the shutter threshold setting in EPICS would not longer agree with the PD input channel.  This feels like a bigger source of confusion than the signal loss we suffer from changing the gain on the output from the transimpedance box, so we've stuck with the old kludge for now.

Also since the timing of the Beckhoff readbacks violates causality in strange ways, it would be good to have a 16k RCG readback of this single-ended sum output from AS_C.  There's a spare channel in the PD interface box on ISCT6.

I have updated the E-traveler for this board (S1301506).

With this change the HAM6 shutter should be functional with the new OM1, we will test it tomorrow to be sure.

Kyle, Gerardo 

Finished bolting HAM6 East door -> Helium leak tested door outer O-ring -> Began pump down of HAM6 -> Pumping HAM5/6 annulus with pump cart at each pump port

On the DTS I was able to reproduce LSC receive errors for RFM IPC channels sent by ISC-EX when changing the run time of the ASC model.

The set-up is: The DTS has a full set of nodes on the X-ARM RFM loop (LSC - SUSEX - ISCEX - OAF - ASC - LSC). I’m running H1’s h1iscex model on x1iscex, it has two RFM sender channels. I’m running H1’s h1asc model on x1asc0. I’ve modified your h1fe3tim16 model on x1lsc0 to receive the two h1iscex channels. So a 16kHz sender, a 16kHz receiver with a 2kHz system in between.

The h1asc model has 8 sending channels. I can vary the usrTime on h1asc by either running with no filters defined, or with the full set of H1 filters defined or with something in between. When transitioning between the two extremes, it takes the ASC about 50 seconds to do so due to the large number of filters and the usrTime varies linearly between 87uS (no filters) and 133uS (all filters). When the usrTime is in the range 105-120uS, the LSC receive errors shoot up into the thousands per second.

I then customized the H1ASC.txt to the number of filters needed to keep h1asc usrTime at 113uS (in the middle of the bad range) and the LSC gets 2046 errors per second, close to the ASC processing rate.

So it looks like the ASC IPC writes are colliding with the ISC writes. This is not quite the same as the H1 fix I put in yesterday, were I reduced the ASC RFM payload size from 16 channels to 8 channels and zeroed the LSC errors, but the mechanism could be the same.

08:18 Jeff B. to LVEA, check desiccant cabinet, recover contamination control supplies
08:46 Joe to LVEA, check forklift battery, eyewash stations
08:46 Filiberto to LVEA, work on LTS dewpoint sensors by H2 enclosure
08:55 Jeff B. done
09:11 Richard to LVEA to check on Filiberto
Richard back
09:40 Corey to LVEA to pick up supplies from HAM6 work
09:41 Peter K., Jeff B. to H1 PSL enclosure to work on FSS servo
09:44 Delivery from Platt electric
09:45 Corey to H1 PSL enclosure with Peter K. and Jeff B.
09:50 Doug to LVEA to take picture of optical lever installation
John and Bubba craning platform in LVEA
09:58 Elli and Nutsinee to end X, HWS work
10:06 Betsy and Andres to LVEA to pick up equipment in east and west bay
10:07 Doug back
10:10 Richard looking at H1 PSL air shower
10:16 Richard done
10:27 Joe done
10:34 Corey done
10:51 Bubba, John drilling holes for platform posts in LVEA
11:12 Gerardo and Kyle starting pumpdown of HAM6
11:13 Travis and Sudarshan to end X, PCAL
11:56 Betsy running undamped transfer functions on PR3 M3, undamped spectra on SRM, SR2, SR3
12:11 Hugh deisolating HAM1 HEPI
12:28 Elli and Nutsinee back
12:40 Vending machine truck through gate
12:54 Tours in CR
13:38 Peter K. out of H1 PSL enclosure
13:58 Corey to squeezer bay, checking for equipment to install beam dump on HAM2
14:43 Jason and Ed to take voltage reading from field box near H1 PSL
14:53 Jason and Ed done
14:56 Bubba back to LVEA to continue drilling holes for platform posts
15:12 Corey and Keita climbing on HAM2 to test fit of beam dump
15:35 Peter K. to H1 PSL enclosure
15:43 Suresh to end X to set whitening filters on optical lever laser
16:30 Corey and Keita done

I took away the state selection and some other stuff that wasn't needed and added a total of 4 message boxes. If there are ever more than 4 messages, a small, black, blinking box will appear around the ALL button to aleart you to click, ALL.

I found damped TFs which Kissel took last Dec when he imported the LLO HLTS filters and applied them to the LHO HLTSes 15730.  Today, I ran the undamped set.  Attached are results and comparisons with other HLTSes.  I think this closes the PR3 acceptance measurement dedt.

Ed, Jason, PK

Eearlier this afternoon the ISS AOM Diffracted power was up to ~39%. Reason, still unknown except for folks were in the enclosure working on FSS. Peter King set the refsignal to -2.5V and brought the diff power to ~8.5%. It's seems stable for now. We'll see.

Nutsinee, Elli

We have aligned EX HWS to within ~+/-5cm from the ETMX image plane.  This is as good as we can get with the current level of motion in the HWS images.  To locate the image plane more acurately, the next step is to understand why there is this variation in the HWS images.

The distances on the HWS path are now:

L1-L2: 610mm (unchanged)

L2-L3: 877mm

L3-HWS:  1593mm

To do this we applied a 0.05mHz, 2microrad yaw excitation to the M0 optic align filter bank, and looked at the motion of the x centroid in the HWS images.  We moved L3 51mm towards L2, the HWS 57mm away from L3, and mirrors M7 and M8 each 80mm to the right to the lengthen L3 to HWS path.  We also adjusted the pitch of ALS-BS 1 to lower the beam on HWS-M1, which was clipping slightly.

Attached are the Phase 3b damped and undamped TFs of SR3 taken over the last few months.

The damped TFs of M1 are pretty squashed, but this is because there is some pretty heavy damping filtering engaged for commissioning.

Attached are the Phase 3b damped and undamped TFs of SR2 taken over the last few months.

Note, there is only the damped M2 stage TF due to the fact that there is a broken coil o magne at that stage and I was leary of driving too hard or too much.