I got the LLO test mass charge measuring script running here at LHO. There was an NDS error initially that Dave Barker magically made go away. Otherwise, the script required no modification other than some missing commas in the bias voltage definition. There is a timing error that seems to pop up at pseudo random times. In these cases, the excitation appears shifted from the oplev response by 9 sec. See UR_timing_err.pdf.  Of all the ESD quadrants it most often occurs on the UR, though I saw it once on upper left. Not sure if it has something to do with the settings of the script. The way it is now, the timing error has appeared in 3 to 5 out of 20 measurements in each run. I have run the script in the current configuration 7 times.

In any case, I was able to get a 2 hour trend of the ESD charge. See ETMY_Charge_Trend_9Jan2015.pdf. The charge wanders a bit, but has some consistency.

The charge measuring script is:

.../SusSVN/sus/trunk/QUAD/Common/Scripts/ESD_UL_LL_UR_LR_charge_07-H1.py

The analysis script, which I am still updating for LHO is:

...SusSVN/sus/trunk/QUAD/Common/Scripts/ESD_UL_LL_UR_LR_analysis07_BrettTest.m

A lot of work has been done on HAM3-ISI for the past month. I'm trying to summarize here what we know and which path we should follow.

Situation before the SEI meeting

. We see a high Q peak around ~0.65Hz in all the local sensors (GS13+CPS) and all the DOFs, except RZ.

. This peak is present only when the Z sensor correction is ON. It doesn't matter if the Z sensor correction is coming from HEPI or the ISI, the peak is present when one of them is ON (see here and here). It doesn't seem to have any link with the X,Y sensor correction.

. The peak seems non-stationary. First of all, the peak is not the same if the sensor correction is done with the ISI or HEPI (see first attachment). Second of all, the amplitude and frequency of the peak vary with time (see second attachment and here).

Progress made

. The problem doesn't come from the ground STS. We checked the electronic chain (swapping distribution chassis) and tried another ground instrument (see here). The problem is independant (see here).

. This is not mechanical/rubbing issue. We did a driven transfer function around this frequency with a perfect coherence/no sharp peak.

. The problem doesn't come from HEPI. We turned OFF the HEPI loops with no improvement (see here)

. We don't think it comes from a specific sensor. Everything looks fine wihtout sensor correction, plus the problem shows up in all the sensors (if it was , let's say, a CPS issue, it wouldn't appear in the GS13).

. It might come from the blend: by switching to a 750mHz blend, the peak seems to disappear. However, we know that the 750mHz blend is obsolete, so I wouldn't draw solid conclusions from that...

. It might come from the drive (see here)

New situation after the SEI meeting

Now it seems that the peak appears even when the sensor correction is OFF (see third attachment)! I don't know if it's a good or bad thing, but that's the first time we've seen that. The only thing I did this afternoon is switching blend filters on all DOFs and turning the Z sensor correction ON and OFF... The ground motion doesn't seem any different than usual.

Action item for Sunday

. Keep investigate to see if the sensor correction is the cause of this peak

. Implementation of a slighty different blend in Z to see if it makes a difference.

. PR2 and MC2 have a mode at 0.67Hz. Could it be a weird coupling between the sensor correction and suspension? We'll try to turn the damping loops ON and OFF to see if it makes a difference

. The ISI model has been restarted before, but we haven't tried to restart the actual computer

Since we rolled out the sensor chains from our investigation (I'll do a summary alog about that in a minute), I've looked at the actuation chain.

I took the transfer function between the actual ouput of the actuators (counts) and the related voltage read by the coil driver readback channels. This is the same information in different units, so except some color coming from the electronics, we shouldn't see any sharp peak in the transfer function. I did this exercise on HAM3 (HEPI Z sensor correction ON and OFF) and HAM2 (Sensor correction OFF) for the comparison.

The results are interesting. First I'm not sure I understand why we don't have a perfect coherence (noise?), but I don't think that's linked to our issue. More interesting, we can see a small peak around 0.66Hz on HAM3 when the sensor correction is OFF (which is not the case on HAM2).

This might be an indication that the problem is coming from the actuators.

With Kiwamu's blessing, I modifed the following LSC common files to ground all unused inputs of filter module with control parts

lsc/common/models/lscpsl.mdl

lsc/common/models/lscimc.mdl

These are common parts, so I have not committed the changes to SVN as this may break l1lsc. There appears to be a mismatch between the sites for these files which I'll let the ISC team resolve.

h1lsc0 now compiles with RCG2.9

The BSC-ISI sensor correction screens were updated based on Jeff's request (SEI aLOG #666). A screenshot of the new screens is attached. A link to the old screens is still available on the bottom right of the new ones. Jeff already gave his approval. I will wait for feedback from the other commissioners before commiting to the SVN.

Work was performed under WP #4998 which remains open so the same changes can be applied to the HAM-ISI and HEPI.

I wrote a script which compares a target's autoBurt.req file against its safe.snap file. This is a channel list check, verifying that the safe.snap has no more and no less channels compared to autoBurt.req. I am not checking channel values or channel read-only-status.

I ran the script on all the H1 models (100 of them). For models I manage (IOP and PEM) I fixed any mismatches.  For any system which was missing a safe.snap, I created one by snapshotting the system.

The end result is that all safe.snaps are concurrent with the exception of:

certain SUS safe.snaps still retain the GUARD channels which were removed this Tuesday, Jeff K is going to resnap these this weekend

h1pslfss.snap is missing some DINCO channels, I'l work with PSL to resolve this

LVEA: Laser Hazard
Observation Bit: Commissioning  

08:00 Jodi & Rodica – In LVEA looking for IO parts
08:13 Manny – Removing test stand cables from LVEA west bay
08:30 Jodi – Out of LVEA
09:00 Jodi – In LVEA working with Rodica on IO
09:12 Hugh – In LVEA working on 3IFO HAM storage retrofits 
09:18 Elli – Working on IOT2R table
09:20 Mitch – Going to LVEA for HAM 3IFO storage work
09:25 Filiberto – Going into LVEA to help Manny with removing cables from the west bay
09:29 Jodi – Out of the LVEA
10:30 Kyle – At End-X to start vent
10:31 Peter & Rick – Going to End-Y to work on PCal camera focus
10:31 Hugh & Mitch – Out of the LVEA
10:34 Travis – Going into the cleaning area to get tools for End-X vent
11:24 Doug – Checking TCS chiller alarm
11:49 Filiberto – Out of LVEA
11:49 Filiberto – Going to End-Y and End-X to check on TCS equipment
12:00 Electrical inspector on site to inspect work at VPW
12:00 Manny – Out of the LVEA
12:05 Doug – Out of the LVEA
12:08 Jodi & Rodica – Out of the LVEA
12:35 Jodi & Rodica – Going to Mid-Y to check on 3IFO IO parts 
13:17 Filiberto – Back from end stations
13:20 Jodi & Rodica – Back from Mid-Y
13:36 Sudarshan – Working on PCal cameras at End-Y
13:45 Kyle & Gerardo – At End-X working on BSC9 vent
14:05 Corey – Going to squeezer bay
14:40 Kyle & Gerardo – Back from End-X
14:56 Dale – Taking tour into LVEA 
14:57 Bubba & Kyle – Going to End-X to remove BSC9 door
14:57 Travis & Betsy – Gathering tools and heading to End-X for EQ stop work
15:17 Elli – Going to IOTC2R to check on fan noise
15:35 Corey – Out of the squeezer bay
15:43 Betsy – Going to End-X for Quad EQ stop work

Schedule for BSC09 "Abbreviated Vent & Closure"- II: Earth Quake Stop Adjustment of EX PUM Stage, January 9, 2015

Approved work to be done:

1.  Assessment of earth quake stops gaps for the test mass and pum stage
2.  Set lower  EQ stops gaps to ~1.5 mm of test mass and pum stages

Friday, Jan. 9

AM

• Turnoff EX BRS (Seismic Beam Balance)
• Cleaning of BSC9
• Verify or transition to “Laser Safe”
• Move Clean Room (CR) into position for BSC9, check rooftop of Clean Room and attach sock, verify fans are working
• Turn on purge air for BSC9
• Verify supplies: Green Lantern, Flashlights, ion gun, etc. and make sure CR supplies are in place (gowns, change room, ...)
• Dust Monitors - verify operation and take readings for before and after entry
• Verify safe.snap files to save settings
• Follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown", Turn off high voltage
• Review and follow E1201035, "aLIGO Chamber Entry & Exit Procedures" checklist as annotated by Calum and Dennis for abbreviated entry
• Review and follow M1100068-v1, "Hanford Checklist - BSC Door Removal", Review door removal procedure with crew
• Start vent on BSC9

PM

• Remove door
• Document entrance
• Enter, assess quality of HR surface of ETMX with green flashlight
• Inspect EQ stops of test mass and pum stage
• Adjust EQ stops gaps.
• Verify optic, its suspension, and the reaction chain are free
• Assuming all goes well, obtain approval and signatures for volume closure, LHO (e.g., E1400474-v1).
• Obtain signoff signatures for chamber closure
• Notify door crew to hang door
• Verify readiness to pump down, follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown". Confirm all high voltages are off.
• Notify Vacuum crew of readiness to start pumps

The last step is at the time and discretion of the Vacuum crew.

Conlog searches unavailable for duration.

Schedule for BSC09 "Abbreviated Vent & Closure": Earth Quake Stop Adjustment of EX Test Mass, January 7-8, 2015

Approved work to be done:

1.  Assessment of earth quake stops gaps for the test mass
2.  Set lower  EQ stops gaps to ~1.5 mm

Wednesday, Jan. 7

• Turnoff EX BRS (Seismic Beam Balance)
• Cleaning of BSC9
• Verify or transition to “Laser Safe”
• Move Clean Room (CR) into position for BSC9, check rooftop of Clean Room and attach sock, verify fans are working
• Turn on purge air for BSC9
• Verify supplies: Green Lantern, Flashlights, ion gun, etc. and make sure CR supplies are in place (gowns, change room, ...)
• Dust Monitors - verify operation and take readings for before and after entry
• Verify safe.snap files to save settings
• Follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown", Turn off high voltage
• Review and follow E1201035, "aLIGO Chamber Entry & Exit Procedures" checklist as annotated by Calum and Dennis for abbreviated entry
• Review and follow M1100068-v1, "Hanford Checklist - BSC Door Removal", Review door removal procedure with crew
• Start vent on BSC9

Thursday, Jan. 8

• Remove door
• Document entrance
• Enter , assess quality of HR surface of ETMX with green flashlight
• Adjust EQ stops gaps.
• Verify optic, its suspension, and the reaction chain are free
• Assuming all goes well, obtain approval and signatures for volume closure, LHO (E1400474-v1).
• Obtain signoff signatures for chamber closure
• Notify door crew to hang door
• Verify readiness to pump down, follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown". Confirm all high voltages are off.
• Notify Vacuum crew of readiness to start pumps

The last step is at the time and discretion of the Vacuum crew.

Alexa, Thomas, Evan

Over the past 24 hours, the alignment slider values of MC1, MC2, and MC3 have been changed. (Perhaps the WFS offloading script was run?) However, these new alignments weren't saved.

This morning, we changed the IMC guardian from LOCKED to DOWN to do a scattering test with the Y arm. When we brought the IMC guardian back to LOCKED, we found that the WFSs would cause MC2 trans to ramp continually in a saw-tooth fashion, from about 100 % nominal transmission to less than 50 % transmission.

Eventually Alexa figured out it was because the guardian had restored the old, previously saved alignments for MC1, MC2, and MC3, and this had caused the beam to fall off WFS A and WFS B. Dialing in the new slider values for MC1, MC2, and MC3 (and then saving them on the IFO ALIGN screen) made the WFS loops work again.

The TFs I took this morning show that the rubbing is back on the ETMx main chain now that we are back down to 7 Torr in pressure.  The rubbing TF looks exactly like the rubbing TF we had before I opened up the gap of the EQ stops around the test mass.  While we knew that the rubbing could have been possibly due to the barrel stops around the test mass OR the PUM mass above the test mass, we assumed it was specifically the stops around the test mass since those were the only ones adjusted during the Dec vent.  I did not check the PUM stops (or any other stops further up the chain) yesterday.  Darn it, I should have!  The temp+buoyancy effect is the same on the PUM as it is on the Test mass, so the gap of the EQ stops should be bigger around the barrel there too.

So, we are re-venting today to now:

- Inspect other EQ stops, look for outliers in gap settings further up the main chain

- Open up the gap around the barrel of the PUM to the 1mm (top stops) and 1.5, (bottom stops)

We'll employ the same stripped down version of the entry/exit checklist as yesterday, namely to inspect and DI Nitrogen blow the HR face of the ETMx on the way out.

The reaction chain TFs continue to look healthy, so no problems there.

Keita, Elli

Continuing with Evan's and my attempts to lock the auxiliary laser or IOT2 to the PSL with a frequency offset in order to continue the PRC measurements started by Paul Fulda...

Today Keita and I got the auxiliary laser locked for periods of ~20s.  Then PLL servo control signal would reach its maximum of 5V and the lock would drop.  The beat note between the aux laser and the PSL was continually drifting in one direction- this may have been due to temperature instability on the table (the fan was off to start with and then I turned it on for a while when adjusting the Aux laser temperature.)  I am watching

The PLL is controlled by an SR560 servo controller with 10Hz low-pass filter cutoff and 500 gain. A 7dBPm signal is demodulated with the beat signal between the PSL and the auxiliary laser for the error signal.

The sensor correction is installed and ON on all the chambers, but with a nominal matching gain of 1.

I made a small script to calculate the correct matching gain for X, Y, Z. The script works only for the HAM-ISIs for now, but it will be pretty easy to adapt. What it does:

- Grab the ground seismometer and GS13 data in X, Y, Z.

- Calculate the ASDs and calibrate them in m/rt(Hz).

- Calculate the GS13 over Ground ratio.

- Take the mean of the ratio for a [0.1Hz 0.4Hz] bandwidth.

Before running this process, the ISI needs to be in High blend mode (750mHz) on all DOFs with sensor correction OFF.

I've done this exercise for HAM4-ISI. The numbers seem a little small (Gain for X: 0.8784, gain for Y: 0.8702, gain for Z: 0.8574) but brings some improvement (see plot attached).

This has been done during the day, we might want to do it overnight for better tuning.

I'll do the other chambers ASAP. The script that I made is for now commited in the HAM4 folder of the svn:

/ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM4/Misc/gain_matching_calculation.m

Sheila, Jeff, Thomas

We changed the H1:SUS-$(OPTIC)_ODC_CHANNEL_BITMASK from 1 to 0 for all the LOCK States for the following optics:

• - BS
• - ITMs
• - ETMs
• - PRs
• - MCs
• - OMC

J. Kissel, R. McCarthy

At my request, after seeing that the EY BSC 10 vacuum pressure has dropped below 1e-5 [Torr] (see attached trend), Richard has turned on the H1 SUS ETMY ESD at ~2pm PST. I'm continuing to commission the chain, and will post functionality results shortly. 

Also -- 

I've found the ESD linearization force coefficient (H1:SUS-ETMX_L3_ESDOUTF_LIN_FORCE_COEFF) to be -180000 [ct]. I don't understand from where this number came, and I couldn't find any aLOGs explaining it. I've logged into to LLO, their coefficient is -512000 [ct]. There's no aLOG describing their number either, but I know from conversations with Joe Betz in early December 2014 that he installed this number when the LLO linearization was switched from before the EUL2ESD matrix to after. When before the EUL2ESD matrix the coefficient was -128000 = - 512000/4 so we was accounting for the factor of 0.25 in EUL2ESD matrix. I suspect that -128000 [ct] came from the following simple model of longitudinal force, F_{tot} on the optic as a result of the quadrant's signal voltage, V_{S} and the bias voltage V_{B}, (which we know is incomplete now -- see LLO aLOG 14853):
     F_{tot} = a ( V_{s} - V_{B} )^2
     F_{tot} = a ( V_{s}^2 - 2 V_{s} V_{B} + V_{B}^2)
     F_{lin} = 2 a V_{s} V_{B}
where F_{lin} is the linear term in the force model, and a< is the force coefficient that turns whatever units V_{S} and V_{B} are in ([ct^2] or [V_{DAC}^2] or [V_{ESD}^2]) into longitudinal force on the test mass in [N]. I *think* the quantity (2 a V_{B}) was mistakenly treated as simply (V_{B}) which has always been held at 128000 [ct] (or the equivalent of 390 [V] on the ESD bias pattern) and the scale factor (2 a) was ignored. Or something. But I don't know.

So I try to make sense of these numbers below.

Looking at what was intended (see T1400321) and what was eventually analytically shown (see T1400490), we want the quantity 
       F_{ctrl}
       -------
      2 k V_{B}^2
to be dimensionless, where F_{ctrl} is the force on the optic caused by the ESD. Note that comparing John / Matt / Den's notation against Brett / Joe / my notation, k = a. As written in T1400321, F_{ctrl} was assumed to have units of [N], and V_{B} to have units of [V_{esd}], such that k has units of [ N / (V_{esd}^2) ], and it's the number we all know from John's thesis, k = a = 4.2e-10 [N/V^2]. We now know the number is smaller than that because of the effects of (we think) charge (see, e.g. LHO aLOG 12220, and again LLO aLOG 14853).

In the way that the "force coefficient" has been implemented in the front end code -- as an epics variable that comes into the linearization blockas "Gain_Constant_In,"  (see attached) -- I think the number magically works out to be ... close. As implemented, the linearized quadrant's signal voltage is as shown in Eq. 13 of T1400490, except that the EPICs record, we'll call it G, is actually multiplied in
     V_{S} = V_{C} + V_{B}(1 - sqrt{ 2 [ (F_{ctrl} / V_{B}^2) * G  + 1 + (V_{C}/V_{B}) + (V_{C}/V_{B})^{2} * 1/4 ] )}
Note, that we currently have all of the effective charge voltages set to 0 [ct], so the equation just boils down to the expected
     V_{S} = V_{B}(1 - sqrt{ 2 [ (F_{ctrl} / V_{B}^2) * G  + 1] )}
which means that 
     G == 1 / (2 k) or k = 1 / (2 G)
and has fundamental dimensions of [V_{esd}^2 / N]. So let's take this "force coefficient," G = -512000 [ct], and turn into fundamental units:      
     G = 512000 [ct]             {{LLO}}
         * (20 / 2^18)     [V_{dac} / ct] 
         * 40              [V_{esd} / V_{dac}] 
         * 1 / (V_{B} * a) [(1 / V_{esd}) . (V_{esd}^{2} / N)]
     G = 9.5391e9 [V_{ESD}^2 / N]
   ==>
     k = 5.37e-11 [N/V_{ESD}^2]  {{LLO}}
where I've used V_{B} = 400 [V_{esd}] and the canonical a = 4.2e-10 [N/V_{esd}^2] originally from pg 7 of G0900956. That makes LLO's coefficient  assume the actuation strength is a factor of 8 lower from the canonical number. For the LHO number, 
     G = 180000 [ct]             {{LHO}}
         * (20 / 2^18)     [V_{dac} / ct] 
         * 40              [V_{esd} / V_{dac}] 
         * 1 / (V_{B} * a) [(1 / V_{esd}) . (V_{esd}^{2} / N)]
     G = 3.2697e9 [V_{ESD}^2 / N]
   ==>
     k = 1.53e-10 [N/V_{ESD}^2]  {{LHO}}
Which is within a factor of 3 lower, and if the ESD's as weak as we've measured it to be it may be dead on. So maybe whomever stuck in 180000 is much smarter than I.

For now I leave in 180000 [ct], which corresponds to a force coefficient of a = 1.53e-10 [N/V_{ESD}^2].