Secretary notes from BSC9 today:

• The chamber door was pulled by Gerardo/Kyle/Bubba.
• ~20 mins later, with the billowing C3 door cover on, I reached in and took particle counter counts of 30 - 0.3um, 20 - 0.5um, 10 - 0.7um.  A pretty clean sample.
• I reached in an wiped ~2/3 of the floor.
• Jim locked the HEPI.
• Jim locked the ISI.
• Travis, Jason and I went into the chamber.
• We attached the locking bracket to the ACB and let it swing back to it's natural hanging position, giving us a bit of room to work, yet not occulting the pcal camera view.
• We removed the vertical witness plate that was hanging from the bottom of QUAD structure.
• We inspected the ETMx-HR - We saw no dead-ringer particle that was a more obvious "scatterer" than any other particles on the surface of the mirror.  We also did not see any large bits of left over FirstContact or other debris.  We put the green lantern onto the suspension structure and counted ~5-10 particles per sq. inch roughly everywhere in the central 8" circle area of the mirror - higher than what we counted on the ETMy.  We spent a few minutes blowing with the deionizing N2 Top Gun blower - not much moved.
• We decided we should FC clean the surface given that the particle count level was higher than the ETMy level, even though we did not find the one we were looking for.  We also noticed that more particulate was floating around in the flashlight beams than we noticed at ETMy.  See my particle count data below, though.
• Rick took quite a few pictures of the surface in an attempt to capture the particulate condition - pictures will be available tomorrow when we post final results.
• We clamped the optic with the TFE rail tooling.
• We applied brush-on FC in the same manner as yesterday (thick short dabs/strokes, 3 coats) and put the PETG cap on.
• WE wiped more of the floor.
• We removed all of the extra tooling/blow gun/lights from the chamber and exited for the day.

We will pull the FC sheet ~9:30 am tomorrow and hopefully get the door back on by lunch.

The Ops Overview screen that shows the graphic representation of the IFO (OPS_OVERVIEW_CUSTOM.adl) had been previously unable to report individual suspension stage watchdog trips. According to the models, the discreet watchdog stages are "ANDED" into an EPICS channel called $(IFO):SUS-$(LOC)_DACKILL_TRIG_STATE which was the only conditional channel included for the Visibility Calculation in MEDM. This channel will never show it's alarm state unless all upstream watchdogs have been tripped therefore making said "trips" invisible in this overview, which has become a popular one with operators and others as well (imo). Discreet watchdog channels have been added and tested for BS and all Quad suspensions. This overview screen can now be relied on  for accurate reporting on the status of any suspension watchdog trips.

[Alexa, Mackenzie, Paul]

This morning with some free time on the IMC, we were going to re-run the alignment offset calibration procedure in preparation for a beam jitter measurement (a la aLOG 9870 and aLOG 10016). However, I found that the script failed when looking for the channel H1:IMC-WFS_SWTCH. The IMC_WFS_MASTER medm screen still has a button that should be controlling this switch.

Alexa dug around in the IMC_WFS_MASTER.adl file to find out what that switch was linked to and found that it actually calls the scripts "/opt/rtcds/userapps/release/ioo/h1/scripts/imc/mcwfson" and "wfsoff". 

Looking into the mcwfson script, we saw that the script sets the WFS gain to 0.25 (writing to H1:IMC-WFS_GAIN), and attempts to switch the missing channel H1:IMC-WFS_SWTCH to 1. 

Running the script from the terminal gives the error: channel H1:IMC-WFS_SWTCH not accessible. A quick caget gives the same result. 

Does anyone know where this channel went? 

K. Venkateswara

Due to the preparation for the vent at EX, the clean-room fans and lights are on which have increased the temperature in the VEA by ~1.5 deg C. Also, the cranes and sundry equipment has been moved around which has also changed the gravity gradients around BRS. Both of these changes have signficiantly changed the DC position of the beam-balance and it is almost out of range as seen in the attached graph. The Driftmon signal can be interpreted as the DC position of BRS.

I've temporarily turned the system OFF for the vent. Jim or I will turn it back on once conditions return to normal at EX.

Richard transitioned End-X to laser safe. 

model restarts logged for Wed 17/Dec/2014
2014_12_17 04:41 h1fw0

one unexpected restart. Conlog frequently changing channels report attached.

[Mackenzie, Paul]

We took some initial sweeps of the PRC with the aux laser this afternoon with the PRMI locked on sidebands. We'll save most of the analysis for later, but just as a quick update, I've attached data from sweeps around two FSRs which are 20 FSRs apart, as well as a full FSR sweep. Just estimating the peak frequencies of these sweeps gives a rough FSR estimate of 2.6005MHz, or 57.6413m for the PRC length. We'll increase the frequency resolution on subsequent scans, and take more data from FSRs over a greater frequency range for the Schnupp measurement. In the end we'll do some fitting rather than just guessing peak frequencies too. More to come later.

Dan, Fil, Thomas

We made a quick modification to the ASC-AS_C transimpedance board today, so that the HAM6 fast shutter threshold can be set for 1W of light into the chamber.  The modification was a swap of R23, from 1.24k ohm to 422 ohm.  This changes the gain on the SUM_OUT channel on the back of the chassis, that's used for the fast shutter logic.

ASC-AS_C gets 2.5% of the light into HAM6, so we'd like to set the threshold at 25mW.  The input to the shutter controller rails at 2V.  The QPD transimpedance is 1000 ohms, the quantum efficiency is probably about 80%, and the new resistor changes the final gain stage to 422/4.99k = 0.0845.  So, the correct shutter threshold is 0.025*1000*0.8*0.0845 = 1.7 volts.

This modification only affects the signal path to the shutter controller; it doesn't change the signal path that is acquired by the ASC front end.  So the ASC-AS_C sum that you see on the MEDM screen hasn't changed.  (The input to the HAM6 shutter controller is recorded by the channel H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_VOLTS.)

Stefan, ThomasV, Kiwamu,

Tonight we continued working on the BS high bandwidth loops (see previous alog 15662). We successfully engaged both pitch and yaw loops with unconditionally stable 1/f open loop shapes.

We also worked on PR3 loop a bit as well.

(BS high bandwidth loops)

Even though we had success yesterday on the BS loop, we were not satisfied with the loop shape as there was multiple UGFs. Today we tried inverting the BS M2 stage plant so that we can nicely have a 1/f open-loop shape. We studied the plant inversion using the oplev damping paths at the beginning and PRMI. Later on we applied the resultant inversion plant in the actual DRMI ASC loops. Here are the inversion filters we used as a starting point:

• BS M2 P to P = zpk([ 0.013 + i * 0.485; c.c.; 0.0183333 + i * 1.112; c.c.], [], 1)
• BS M2 Y to Y = zpk([ 0.2 + i* 0.45; c.c.; 0.022 + i * 2.19; c.c. ] [], 1)

Note that the lower resonance in Y-to-Y has a mismatch both frequency and Q. With these inversion plant filters in, we then modified the location of the resonances as well as their Qs of the inversion filters as we observed instability in the loops. In particular, we tended to slightly lower the resonant frequencies and Qs such that the phase of the open-loops go up in order to prevent them from small phase margin. The actual resultant inversion filters are written in the foton files.

We did a simple in PRMI where we ramped up the overall gain of two loops from 0 to the nominal in a minute to see if there is unstable region. As expected, we did not see instability at all. So the loop is unconditionally stable with opelv damping loops off. Then we applied the new inversion fitter in DRMI with the new AS_Q input matrix. This went pretty smooth. The attached is the nominal open loop transfer functions for both pitch and yaw. They are currently set to 7 Hz. The whole setup is coded in guardian. ISC_DRMI.

(PR3 ASC loops)

We briefly closed the PR3 ASC loops using REFL_B9_I. There was large coherence between the power build-up and PR3 angular motion. For now we made a low bandwidth loop, but tomorrow we should commission a high bandwidth loop as there was fast residual angular motion.

(Pointing DOF)

We also quickly checked if the POP QPDs are sensitive to a pointing DOF. We moved IM4 and let PRM and PR3 follow the IM4 pointing to see if we can see it on the POP QPDs. And we confirmed that_POP_B QPD was sensitive to the pointing DOF.

  (Some guardian update for SRC2 loops)

The setup for the SRC1 and SRC2 loops are now coded in the guardian as well. This is something reported in alog 15638,

I launched an overnight measurement for Alexa at 8:21:33 UTC (or 0:21:33 local)

J. Kissel

After Betsy and Travis successfully finished in-chamber close out (after LHO aLOG 15677), and Kyle, Gerardo, and Bubba have put the door back on (LHO aLOG 15696), I've taken H1 SUS ETMY Top2Top transfer functions on both main and reaction chains to confirm that the suspension is free and clear of rubbing. The transfer functions look spectacular. I'd call it ... wait for it ... a clean exit.

I think the only other thing we should confirm before pump-down is that the ESD drive is functional by turning on the high-voltage driver, driving at ~5 [Hz] in angle, and checking optical lever for the signal, as has been done for the charging measurements. This would clear the work done by Filiberto and Richard also during this vent 

The new templates for this data set live here:
2014-12-18_0143_H1SUSETMY_M0_Mono_L_WhiteNoise.xml
2014-12-18_0143_H1SUSETMY_M0_Mono_P_WhiteNoise.xml
2014-12-18_0143_H1SUSETMY_M0_Mono_R_WhiteNoise.xml
2014-12-18_0143_H1SUSETMY_M0_Mono_T_WhiteNoise.xml
2014-12-18_0143_H1SUSETMY_M0_Mono_V_WhiteNoise.xml
2014-12-18_0143_H1SUSETMY_M0_Mono_Y_WhiteNoise.xml

2014-12-18_0203_H1SUSETMY_R0_L_WhiteNoise.xml
2014-12-18_0203_H1SUSETMY_R0_P_WhiteNoise.xml
2014-12-18_0203_H1SUSETMY_R0_R_WhiteNoise.xml
2014-12-18_0203_H1SUSETMY_R0_T_WhiteNoise.xml
2014-12-18_0203_H1SUSETMY_R0_V_WhiteNoise.xml
2014-12-18_0203_H1SUSETMY_R0_Y_WhiteNoise.xml

Krishna, Sheila, Hugh, Fabrice:

We have been chasing  large amplifications at low frequencies (in the range of 10mHz to 30mHz) caused by the Z zensor correction of HEPI, which is necessary to reduce the Z to RZ coupling on Stage 1. It looks like the Z HEPI inertial isolation is causing rotations (RX, RY), that are causing tilt signal in the Stage 1 horizontal seismometers, that couple to X and Y as we blend at 45 mHZ, and then shows up into the cavity signal.

The problem was mostly  visible on the BS unit.  We convinced ourself that Z to tilt  was the problem by moving Stage 1 in high blend, which very significantly reduced the Mich amplification around 20 mHz (which exist only when the Z sensor correction is ON)

It seems that the excessive Z to tilt coupling in the BS was caused by off centered  vertical position sensors (up to 24000counts). We recentered them by applying  a HEPI vertical force. The Z to Mich coupling is now much lower. So I guess that the gain of the sensors was affected by the large offsets and thus creating excessive Z to RX and RY couplings.

Comparison with high blend configurations show that there is probably room to further reduce this coupling. We need the measure the Z to RX and RY coupling and apply corrections.

(Doug C and Suresh D.)

    This afternoon we replaced the glitchy diode laser  (Sl. No. 193) in the BS optical lever with a repaired and thermally stabilised laser (Sl. No. 130-1) which was under observation in HAM3 oplev.     The attached plots show the improved performance due to the repairs and stabilisation.

Things to note:

1) Broadband noise injection into pitch has disappeared after swapping the lasers

2) Constant glitching and consequent broadband injection of noise into yaw signals has disappeared after swapping.

3) The RIN has dropped by an order of magnitude at all frequencies

4) The spectrum is stable and does not oscillate between stable and unstable regimes as the temperature in the LVEA changes due to the airconditioners.

Please note that the laser is still approaching a stable operating condition and is under observation for a futher 24 hrs.  However its performance over the past six hours is satisfactory.

Evan, Alexa

Following the preparation described in alog 15524, we made a ringdown measurement of both the x- and y-arm. For each arm, we locked the IR beam and ran the wfs to ensure maximum build up. We then turned the wfs off, and switched the input polarity of the MC common mode board to unlock the MC quickly (based on LLO's alog 11727 the MC has about a 15usec ringdown time). We used the relfected signal at the AS port to capture the ringdown. We repeated this measurement 10 times to have ample data for our uncertainities. We also measured the "off-resonance" ringdown, by unlocking the arm and misaligning the respective ETM. All the data can be found in /ligo/home/alexan.staley/Public/Ringdown/EX(Y)data (these folders are then split into locked and unlocked times).  From this data we calculated the total loss:

X arm: 14310(100) ppm

Y arm: 15000(100) ppm

Based on the galaxy ITMY transmissivity (1.42%) this amounts to 800ppm of loss in the y-arm. Meanwhile, for the x-arm, the ITMX transmissivity is 1.39 % corresponding to a 410ppm loss in the arm. We are in the process of calculating the transmissivity of the ITMs based on our ringdown fit. Our code can be found in /ligo/home/alexan.staley/Public/Ringdown/proccess.py. The y-arm losses seems consitent with our scan measurements; however the x arm does not. These numbers are very sensitive to the transmissivity we use; so before we make an conclusion with this we should inprove our confidence in the transmissivity values.