The conlog process on h1conlog1-master failed at 12:25PDT Saturday 8th August. The error is shown in the FRS report linked below. I restarted the process this afternoon. Conlog is reporting 412 disconnected channels which relate to the guardian and h1calcs work which was done last week, we will need to regenerate the conlog channel list tomorrow.

Fault Report 3433

After pulling the latest ASC_MASTER.mdl and talking to Adam at LLO, I added the following channels in ASC_MASTER to the science frame in addition to what Adam did:

ASC-DC1_P_OUT_DQ , (also Y, also DC2, DC3, DC4 and DC5): 512Hz

ASC-OMC_A_PIT_OUT_DQ (also YAW and SUM, also B): 2kHz

I then changed H1ASC.mdl to use the new ASC_MASTER. Dave compiled the model without an error. We'll install it tomorrow.

Some details:

0: Pzt outputs for new POPX thing is terminated at LHO.

At LLO this is connected to DAC, but here I simply terminated the output.

1: Initial Alignment system (obsolete, not used these days) are purged from h1 model.

This was purged from the latest ASC_MASTER. To accomodate this,  access to ALS_X_REFL_B_LF_RFM, and ALS_X_REFL_B_LF_RFM_IPC_ERR, and their Y-arm counterparts, were all deleted from the top level.

2: DARM_CTRL and IM4_TRANS_PIT and YAW input for the common block are terminated in h1 model

This is a part of LLO dither scheme, but I just terminated these input in h1 model.

3: Unused PZT[12][XY]_[PY] and QPD[12][XY]_[PY] are gone from ASC_MASTER.

These were already obsoleted by green WFS at LHO and were terminated at the top level at LHO. Now these signals are gone.

4: New dither outputs are connected to some masses in h1 model.

New ASC_MASTER has dither outputs to BS, ITMs and ETMs in addition to PRM, PR2 and PR3.

In the old h1 model, RFM sender to corresponding optics already existed but was sending 1 or 2 (constant). In the new h1 model these things are connected to the dither output even though we do not use dither these days.

There are unused RFM sender to SRM, SR2 and SR3, these are kept there.

5: Deleted some obolete text labels and an unused orphaned RFM receiver in h1 model.

JeffreyK, Darkhan

Overview

We found that some of the calculations in the recently implemented CAL_CS front-end model (see LHO alog #20360) do not produce expected results. We found this problem in the division block that takes input of significantly smaller number for denominator vs. number in the nominator.

Since this calculation is done on quantities that should change only as a result of manual input we've decided to calculate these quantities in Matlab and then export final results to EPICS. Tomorrow we will add these EPICS inputs into CAL_CS front-end model.

Details

In this section we show how this bug was identified.

Following EPICS input channels exist in the CAL_CS front-end model: REF_A_TST_REAL and REF_A_TST_IMAG. They form a complex quantity A_tst = Re{ A_tst } + i * Im{ A_tst } = REF_A_TST_REAL + i * REF_A_TST_IMAG.

We wanted to calculate Re{ -1/A_tst } and Im{ -1/A_tst } as

| A_tst |² = Re{ A_tst }² + Im{ A_tst }²

Re{ -1/A_tst } = - Re{ A_tst } / | A_tst |²

Im{ -1/A_tst } = Im{ A_tst } / | A_tst |²

When we provided both inputs (real and imaginary) with quantities their values, the quantity | A_tst |² came out to be about right, but the final values Re{ -1/A_tst } and Im{ -1/A_tst } were off by several orders of magnitude.

The finals values should have been

Re{ -1/A_tst } = 1.39199e+16

Re{ -1/A_tst } = -1.14388e+16

We don't know for sure, but it might be possible to avoid this bug by trying rearrange signals in simulink design (e.g. replace division by multiplication by inverse of the quantity or maybe some other way).

For this case we decided to calculate these final quantities in Matlab and into EPICS only final results.

Leonid.Prokhorov, Jeffrey.Kissel
Charge measurements was done on both ETMs.
Results are in attachments. For most quadrants we have follow trend: 

From June, 24 to July, 21 (from discharging to changing the bias sign) data are consistent with positive charging for ETMY and negative charging for ETMX.
ETMX Bias: +9.5V, Mean charging rate: -10 V/month (st. dev. +/- 3 V/mon)
ETMY Bias: -9.5V, Mean charging rate: +7 V/month (st. dev. +/- 3 V/mon)

From July, 22 to Aug, 10 (from changing the bias sign to today's measurements) data for most of quadrants are consistent with the changed sign of charging - negative for ETMY and positive for ETMX.
ETMX Bias: -9.5V, Mean charging rate: +17 V/month (st. dev. +/- 9 V/mon)
ETMY Bias: +9.5V, Mean charging rate: -20 V/month (st. dev. +/- 14 V/mon)
Note, because the standard deviation is less that the mean, it shows that the rate is roughly the same for each quadrant. However, there are outliers (see, e.g. Right quadrants of ETMY).

Now the effective bias voltage is about few volts for ETMX, and about 10 volts for most quadrants of ETMY, but ETMY UR shows as much as 15-20 Volts. 
Probably, it's a good time to reverse the bias sign at ETMY.


There are two sets of plots, each which show the same data in a different way:
(1) ETMX_Mean.png & ETMY_Mean.png shows both the mean and standard deviation, and weighted mean and sqrt(weighted variance) of the charge measurements for a given day (which can be from ~4 to ~15 of these 12 minute measurements per mean point). We believe this better shows the long-term trend of the charge.
(2) ETMX.png & ETMY.png show the "raw" data, where the result of each estimate of the effective bias voltage shown *since* the discharging. Each single data point is an estimate of the effective bias voltage, i.e. the charge, as determined by driving the test mass while varying the requested bias voltage and measuring the response with the optic's optical lever.

Related alogs: 19848, 19821

High created an alarm for the PSL north & south A/C temperatures. These will alarm if the PSL temperature goes above 74F. 

The anti-aliasing filters deploy AD8622 OpAmp buffers at the input of each signal line. This is before any filtering. So, these OpAmps need to be able to handle the full signal bandwidth. Unfortunately, the slew rate limit of the AD8622 is only 0.28V/µs. This is an order of magnitude lower than the ubiquitous OP27. In other words, the largest signal amplitudes at 1MHz, 100kHz and 10kHz are 45mV, 450mV and 4.5V, respectively. The readbacks of the EOM driver have a signal BW of about 300kHz and a signal amplitude of ~0.5V. This was too much and produced excess in-band noise—more than a magnitude above the digitization noise. We swapped the OpAmps in this path with AD8672 which have a slew rate of 4V/µs.

Plot 1. Green trace is readback with AD8672, amber curve is AD8622, and red trace as inication of digitization noise level.

Scott L. Ed P. Rodney H.

The crew hung lights and cleaned 74.3 meters of tube and bellows ending 13.7 meters east of HSW-2-015. Test results for previous tube sections cleaned are posted here.

This morning, with an hour long 60mpc lock behind us, Evan and I cleared SDF from the weekend commissioning efforts.  We:

- accepted most of the re-phasing of the ASC/LSC PDs that was done (we reverted a few of his changes which he did not like). 

- set the SDF to ignore the LOCKIN channels that had been used over the weekend.

- zeroed out a few ASC loop offsets (MICH, DHARD, etc.) that were put in over the weekend during testing, but were then turned off.

- accepted Dan's change of the 4 OMC dither path gains from 0.1 to 1.0 on Wed Aug 6th (H1:OMC-ASC_P1_CLOCK_GAIN, ...)

J. Kissel, S. Dwyer

Sheila put together a new MEDM screen for the updates I made to the violin mode monitoring system (see LHO aLOG 20177). see attached. These have been used profusely during the ETMY 508.29 [Hz] violin mode saga (see LHO aLOG 20316).

Attached are plots of the NPRO output power, the output power of the NPRO pump diodes, and the output of the front end laser for the past 4 years.  Whilst there's not much wiggle room left on the NPRO pump diodes, there's room left on the power amplifier pump diodes.  The laser output should be good through to the end of O1.

The IFO was not locking for hours so I took the SEI to READY at EndX and restarted the Pump Servo.  This required a trip to the end station.  The controller started without issue and while the platforms were down, I captured safe.snaps for the ISI and HPI.  It has been a long time since we've had a pump controller hang like this, maybe I can pull this from the log.

The ISI did trip on the T240s but I don't know exactly what the platform was up to at the time.  I isolated fully second attempt no problem.

I injected particulate by tapping on the beam tube at various locations with a scissors, imitating the taps that the cleaners make by accident. The acceleration measured on the beam tube for similar taps was around 0.1 g with a frequency peak at about 1000 Hz (Link). At each location I made the first tap at the top of the minute and made a tap at every multiple of 5 seconds for 1 or 2 minutes. My tapping uncertainty was about 1 second.

To observe the glitches in DARM I filtered the time series of H1:CAL-DELTA_RESIDUAL_DQ to be dominated by the 120-1000 Hz band, with violin modes notched. The table shows the time and the fraction of taps that made glitches. The distribution of glitch sizes is shown in the Figure. There were roughly the same number of glitches in each size decade.

In summary:

1) Glitches were produced from most regions of the beam tube.

2) Only about 20% of taps produced glitches

3) 9/252 taps produced multiple glitches 

4) Only 1 glitch of size comparable to the particulate glitches was observed more than 1s from a tap time in the entire 2 hour lock (DetChar may want to double check this). Thus the data suggest that there is not a reservoir of particles that are freed by the taps but fall later at an exponentially decreasing rate (so it is very unlikely that midnight glitches are particles freed by cleaning and cleaning is unlikely to have increased the background rate).

5) The figure shows that the number of glitches in each size decade was about the same, not increasing with smaller size. 

I can't find the posts now, but several months ago, an intermittent issue with ETMX was spotted that was narrowed down to the CPS's, possibly specfically the corner 2 cpses (?). This problem then somehow "fixed" itself and was quiet for months. As of the night of the 4th, it seems to be back, intermittently (first attached image, spectr should be pretty smooth around 1 hz, it's decidedly toothy). Looking at the Detchar pages, it shows up about 8 UTC and disappears sometime later. I took spectra from last night (second image) and everything was normal again.

Still don't know what this is. Anybody turn anything on Monday afternoon at EX that shouldn't be?

Based on measurements of the DARM OLTF and the EY PUM/test crossover that Jeff and I took last week, we can estimate the current value of the EY ESD actuation coefficient. It is 1.45×10⁻¹⁰ N/V², with a 20 % uncertainty. This is an 80 % increase compared to the previous value (0.8×10⁻¹⁰ N/V²) which was measured at the end of May.

This number mostly relies on the crossover measurement, since above 10 Hz, the effect in the OLTF of changing the actuation coefficient is largely the same as changing the optical gain. Additionally, this number requires us to assume a number for the PUM actuation coefficient. Here I assume that it has not changed since the May calibration (i.e., I use 7.0×10⁻¹³ m/ct at dc).

Note that the modeled crossover doesn't really agree well with the measurement above 80 Hz. More investigation is required, particularly since during ER7 we already knew there was an issue with the DARM model around 10 Hz. (This discrepancy is why I say the uncertainty in the coefficient is no better than 20 %.)

To generate this number, I took Jeff's ER7 calibration script and made a version (H1DARMXO.m) that models the crossover. Both scripts (and the parameters file for the July 25 measurement) live in the CalSVN under Runs/PreER8/H1/Scripts/DARMOLGTFs. All parameters were left the same as their ER7 values except for the optical gain (I use 1.0×10⁶ ct/m), the DARM pole (I use 330 Hz), and the EY L3 drive strength (I use 11×10⁻¹⁵ m/ct at dc). By tuning the L3 drive strength to match the measured crossover, we can extract the ESD actuation coefficient, assuming the rest of the L3 signal chain has been well-characterized. This is how I get the number quoted above.

The 80 % increase is sort of consistent with the 70 % increase that we saw when retuning the L3 digital gain post-vent. Strictly speaking, that was a measurement of the relative strengths of EX and EY. However, the DARM OLTF (with the retuned EY L3 gain) stayed roughly the constant before and after the vent, indicating that this 70% increase really is a change in EY.