noise in IM4 Trans yaw = 0.007

2.5urad change in IM3 yaw as seen on IM4 Trans yaw = 0.007

2.5urad change in IM3 yaw as seen on ISS2 yaw (-p) = 0.030, which is 4.3 times larger than the change on IM4 Trans yaw, and 6 times larger than the noise on ISS2 yaw (-p).

IM4 Trans yaw is a marginal signal for tracking changes in IM3 yaw alignment.

attached: noise chart, IM changes on im4t and iss2, plots of im4t and iss2

I have generated a new FIR filter bank for Hanford and tested it by running gstlal_compute_strain in partial calibration mode over 1024 seconds of data during a recent lock stretch, starting at 2016-09-27 at noon UTC (GPS second 1158926417). Kappas and strain spectra look reasonably sane compared to CAL-DELTAL_EXTERNAL_DQ. N.B., the EPICs values recorded in this new filters file are not correct, so kappas ought to be computed based on what is in the raw frames. There also appears to be an error with relative timing of the residual and control chains which is not yet resolved at either site; see the CALCS vs. GDS residual plot below and notice the large downward spike near 38 Hz. Aaron also noted this problem at LLO; see https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=28277.

The new filters file can be found in the calibration SVN:
aligocalibration/trunk/Runs/PreER10/GDSFilters/H1GDS_ 1158989379.npz

These filters were made using revision #3358 of the calibration SVN. 

Several plots are attached below:
(1) The h(t) spectrum as calibrated in partial mode using the new filter bank, and as read out of the front-end CALCS model and de-whitened;
(2) The ASD residual of CALCS vs. GDS (data calibrated using the new filter bank are of frame type TEST); and
(3) Plots of the new control and residual correction filters.

For plots (1) and (2), I had to highpass filter above a corner frequency of 8 Hz and use a 32-second FFT (with 16 second overlap) to get rid of some nasty spectral leakage. I filtered both channels identically (except for an extra de-whitening filter applied to CAL-DELTAL_EXTERNAL_DQ) and used a Kaiser window to overcome dynamic range issues. Plots of the new filters were made using the matlab code in the calibration SVN.

J. Oberling, J. Bartlett, R. Schofield

We went in to the PSL today and swapped the old cable crossover that was overflowing with a larger one, see attached picture.  The installation is not complete, the 2nd section was too long so we need to cut it.  If anyone goes into the PSL, if you need to walk across the crossover, please do not walk over the exposed cables.

While in there, we took a look at the known slow leak in the PSL cooling manifold.  Unfortunately there's nothing we can do about it in-situ; a fix will mean pulling the manifold out, which has caused us problems in the past.  Since the leak is very slow and we are working on a new manifold design, we will leave it as is for the time being.

Since we have also been seeing air bubbles in the system (seen in the fill port of the crystal chiller, most recently reported by Sheila here) we bled the system at the filter canister under the PSL table.  This initially tripped the laser (bled too much, chiller got low and shut off), so we then recruited Cheryl to fill the chiller in the chiller room as Jeff bled the system in the enclosure.  A good bit of air was let out of the system; Robert will do some analysis to see if this has improved things.

When bringing the laser back up, the PMC was having a hard time locking.  This turned out to be due to a small shift in the beam alignment into the PMC.  Best guess at this point as to why the alignment shifted is that we were in the PSL long enough for the AC to lower the ambient temperature enough to cause this shift.  I did a small tweak to the beam alignment into the PMC and everything locked up again without issue.

Calibration measurements for End Y Pcal are consistent with previous measurements.  Optical efficiency for both beams is 99.2%.  See attachment for the full report.

In alog 29940 I measured the change in alignment slider counts vs optic alignment change (on OSEMs) for all IO IMs.

I calculated and proposed new gains for the IM alignment sliders, however, today I noticed that the ratio of the current gains yaw/pitch is alomost exactly equal to my proposed gain ratio of pitch/yaw.

This is evidence that the current gains are reversed from what was intended.

Below I show that swapping the current pitch and yaw gains gives a more consistant value for urad / slider count of about 0.045, instead of the current situation where the urad / slider count in yaw is 3x pitch.  I also correct the gains to make the urad / slider count consistant and 0.050.

current alignment slider gains and urad / slider count

current alignment slider gains - swapped

alignment slider gains corrected to give 0.050 urad / slider count

Meant to make a note of this earlier, but the Maintenance deluge took over.  

H1 was locked this morning.  Apparently it had been down, but went back to Nominal Low Noise (NLN) on its own!  

While in NLN, received a Verbal Alarm at 8:14am (15:14utc) about the PI of Mode #25 was ringing up.  I took the gain from +100 to -100, and this seemed to turn it around, BUT we did drop out of lock 5min later.  Mentioned the alarm and addressing of the PI to Terra.

 
Installed and tested the scroll backing pump for the Vertex Turbo (part of a site-wide modification to main turbo pumps which allows selecting either QDP80 or scroll pump to back Turbo).  Confirmed that the Turbo's fore-line isolation valve (aka "Safety" valve) closed at the loss of scroll pump control cable connection or AC at its motor winding, i.e. that the backing pump interlock functionality remained as originally designed.  

Also - Ran both Corner Station QDP80 pumps for ~2 hours and energized all four Turbo Pump controllers (done weekly to charge levitation batteries)  

Leaving Vertex Turbo controller energized until after lunch to allow rotor to slow down after braking.

This information is based on the cumulative spectrum of recent lock stretches (9/18-9/26, computed from Fscan SFTs with spec_avg_long), plus Fscan magnetometer data.

0.997698 Hz

• Worst comb at present
• Previously noted in ER9
• Higher in DARM 9/24-9/26 than 9/18, 9/23
• Appears in CS mags and is fairly steady there (based on available Fscan data since April).

1.0 Hz

• Present in CS, EX, EY magnetometers

0.5 Hz odd harmonics (AKA 1 Hz with 0.5 Hz offset)

• Looking better! Weaker than ER9 by a factor of ~5-10 (varies across spectrum). Improvement presumably due to timing system LED reprogramming.
• Hoping for more improvements as IO chassis timing slaves are put back on alternate power supplies.

1.0 Hz with 0.998889 offset (new)

• Very close to 1 Hz comb, but distinct peaks are visible

0.987987 Hz (new)

• Present in EX magnetometers
• Increases on 9/11/16 in magnetometers

Attached plots:

• 1: LSC-DARM_OUT_DQ cumulative spectrum with the noted combs highlighted
• 2-4: Representative (SUSRACK) magnetometer channels at CS, EX, EY with combs highlighted
• 5-6: Plots showing 0.5 Hz odd harmonics improvement between ER9 and present

Saturations Cleared this morning per FAMIS #7073.  The counts seen are listed below:

• HAM1:  3 counts
• HAM2:  391
• HAM6:  1271

Fil Marc Keita Daniel

We looked at the "broken" channel 5 today, but no problem was found. After reconnecting the ISS chassis and reshuffling some of the cables under HAM2, everything was working fine again.

We took the opportunity to measure dark noise with the PSL shut off. The attached plot shows the dark noise with no light on the photodetectors and calibrated in relative intensity noise for 50 W input. Also, shown is the shot noise for 30 mA of photocurrent at the 3 x 10^–9 level.

There is an AC coupling in the RIN_INNER and RIN_OUTER channels which explains the discrepancies below 0.3 Hz. ADC noise explains the difference between these channels and the RIN_ERR1 and RIN_ERR2 at frequencies of 300 Hz and above.

We are not sure why there is a difference between PDA and PDB. The PDB readout seems to be ADC noise limited through the entire freqyuency band.

I removed the drivers S1600266 and 267, added capacitor 4.7pF in the C25 position and returned the drivers to service. HV was turned back on and confirmed. See Patrick's aLog entry.

High voltage supplies at CS, EX and EY are back on. (Filiberto EX, Patrick EY, Ed CS)

WP 6184

Added EPICS alarm levels to the Inficon BPG402 gauges. I didn't realize I didn't need to do h0vacly until after I did (no BPG402 gauges there).

I burtrestored to 8am this morning.

Sheila, Keita

The 3rd whitening filter does not switch for AS_C segment 3.  The readbacks look OK. 

Summary:
Repeating the Pcal timing signals measurements made at LHO (aLOG 28942) and LLO (aLOG 27207) with more test point channels in the 65k IOP model, we now have a more complete picture of the Pcal timing signals and where there are time delays.

Bottom line: 61 usec delay from user model (16 kHz) to IOP model (65 kHz); no delay from IOP model to user model; 7.5 usec zero-order-hold delay in the DAC; and 61 usec delay in the DAC or the ADC or a combination of the two. Unfortunately, we cannot determine from these measurements on which of the ADC or DAC has the delay.

Details:
I turned off the nominal high frequency Pcal x-arm excitation and the CW injections for the duration of this measurement. I injected a 960 Hz sine wave, 5000 counts amplitude in H1:CAL-PCALX_SWEPT_SINE_EXC. Then I made transfer function measurements from H1:IOP-ISC_EX_ADC_DT_OUT to H1:CAL-PCALX_DAC_FILT_DTONE_IN1, H1:IOP-ISC_EX_MADC0_TP_CH30 to H1:CAL-PCALX_DAC_NONFILT_DTONE_IN1, and H1:CAL-PCALX_SWEPT_SINE_OUT to H1:CAL-PCALX_TX_PD_VOLTS_IN1, as well as points in between (see attached diagram, and plots)

The measurements match the expectation, except there is one confusing point: the transfer function H1:IOP-ISC_EX_MADC0_TP_CH30 to H1:CAL-PCALX_DAC_NONFILT_DTONE_IN1 does not see the 7.5 usec zero-order-hold DAC delay. Why?

There is a 61 usec delay from just after the digital AI and just before the digital AA (after accounting for the known phase loss by the DAC zero-order-hold, and the analog AI and AA filters). From these measurements, we cannot determine if the delay is in the ADC or DAC or a combination of both. For now, we have timing documentation such as LIGO-G-1501195 to suggest that there are 3 IOP clock cycles delay in the DAC and 1 IOP clock cycle delay at the ADC.

It is important to note that there is no delay in the channels measured in the user model acquired by the ADC. In addition, the measurements show that there is a 61 usec delay when going from the user model to the IOP model.

All this being said, I'm still a little confused from various other timing measurements. See, for example, LLO aLOG 22227 and LHO aLOG 22117. I'll need a little time to digest this and try to reconcile the different results.