Kyle, Gerardo, Bubba -> ~0930 hrs. local -> Removed BSC9 West door Kyle -> ~1350 hrs. local -> Started pumping BSC10 annulus Kyle -> ~1500 hrs. local -> Decoupled pump cart from HAM1/HAM2 annulus (Climbed on and around HAM1 and HAM2)
LVEA: Laser Hazard Observation Bit: Commissioning 07:15 Karen & Cris – Second cleaning at End-X 08:15 Jim – Testing BSC10 08:25 Cris & Karen – Back from End-X 08:33 Krishna – Going to End-X to shutdown BRS ahead of door removal 08:57 Kyle, Gerardo, & Bubba – End-X door removal 09:00 Gerardo – Installing viewport protectors at BSC10 08:58 Richard – End-X to verify Laser Safe and to test interlock 09:03 Mitch – In LVEA west bay 09:15 Richard – Transition End-X to laser safe 09:18 Cris & Karen – In LVEA for cleaning 09:45 Betsy & Travis – Going to End-X 09:49 Filiberto – End-Y taking pictures ESD in-air cables 10:08 Rick & Jason – Going to End-X 10:15 Filiberto – Going to End-X to drop off power supply 11:00 Gerardo – LVEA HAM1 & 6 to check vacuum comp 11:00 Doug – Working on HAM4 OpLev alignment 11:20 Gerardo – Out of LVEA 11:31 Vending machine delivery 11:37 Kyle – Back from End-X 13:15 Kyle – Pumping the BSC10 annulus at End-Y 13:30 Power cycle Video4 monitor 14:05 Kyle – Start pumping BSC10 chamber at End-X 14:15 Dave & Rick – Going to End-Y to work on cameras 14:43 Kiwamu – Cleaning up tools at HAM1 14:49 Kyle – Disconnecting pump cart from HAM1 15:02 Kyle – Out of LVEA 15:30 Dave & Rick – Back from End-Y
F. Matichard, K. Venkateswara
On Tuesday (12/16/2014), Fabrice and I got an opportunity to test the ETMX ISI in different configurations. The wind speed was in the 7-12 mph range at EX. The configurations I tested were:
A) ISI Damped
B) ISI isolated with High (T750) blends. Inertial isolation happens only at frequencies above ~750 mHz.
C) Nominal LLO blend configuration. Inertial isolation happens above ~45 mHz.
D) (C) + sensor correction using LLO filter.
E) (C) + sensor correction using Rich's Z sensor correction filter and the tilt-subtracted super-sensor.
The first page of the first pdf shows the ground seismometer (RED) and the tilt-subtracted super-sensor output (BLUE) in displacement units. It shows factors of ~5 subtraction below ~50 mHz. The second page shows the T240 on Stage 1 under the different configurations. The following page shows the CPS and the final page shows the T240 RY.
Looking at Page 2, Configuration E appears to improve over D, roughly by factors of 2-4 below 0.5 Hz, while showing no excess amplification at low frequencies, as measured by the CPS. This is in agreement with modeling predictions described here. Unfortunately, I couldn't make a measurement in (E) but with BRS off for comparison, because someone walked into EX VEA and drove up the BRS amplitude.
Measuring this improvement interferometrically has not been possible using the ALS (green laser system). It is likely that ALS is noise limited in this frequency range as described here. Measuring it using the IR laser needs much more dedicated time which is not easy to come by.
So far, we have not tried using different blends for the inertial sensors. Some improvement may be possible by blending higher in X on Stage 1. But so far, it looks like BRS can improve ISI performance by factors of 2-5 in the 50-500 mHz range. Improving performance at the microseism might significantly improve detector robustness as seen during ER6 at LLO.
The other two attachments show the coherence between various sensors when the ISI was damped and when ISI was in the (E) state.
Secretary notes from BSC9 today:
We will pull the FC sheet ~9:30 am tomorrow and hopefully get the door back on by lunch.
Note, there were apparently no witness plate or witness optics placed on the floor of BSC9 when it was closed last time, so we did not pick them up today.
Also, I forgot to mention that when we inspected the ETMx-HR, we saw some mottling and haze across the surface but we did NOT see the "ring" feature that the FC left on the ETMy-HR.
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.
TMSs and everything down the output arm has been added to his list, also.
All suspensions have been covered at this point. Please let me know if anyone experiences false reporting of status of suspensions in this view.
[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?
This switch was removed in favour of another trigger switch at LLO. I believe the related alog to this change is this LLO alog 10933 by David F
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.)
Something seems odd here. The QPD amp single ended sum output (D1001974) is designed to accommodate the full design dynamic range of the QPD (10mA per quadrant)by use of the R3 = 1.24k and to produce 10V at the sum output during this full scale optical input. The shutter controller (D1102312) photodiode input is a unity gain receiver, although for some bizarre reason, this design only operates on +5V for all the opamps. The correct way to fix this dynamic range problem should have been by lowering R13 from 10k to 2k thus preserving best SNR on the QPD sum output. Also, I see no mention of serial numbers here. Hopefully the eTraveler's are being updated as this is the only way to track such changes at the board and chassis level.
I launched an overnight measurement for Alexa at 8:21:33 UTC (or 0:21:33 local)
I had to restart this because I had forgotten to enable the modulation on the IFR -- second try started at 08:32, or GPS = 1102926745.
And then had to start it again, after I realized the REFL9_Q output was turned off...
1102928116
8:55:00 UTC
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
Travis, Betsy, Jason, Rick, Jim
After the noon SYS/COC/SUS telecon the chamber closeout went like this:
- Took particle counts in chamber - 20 - 0.5um size, 10 - 0.3u size, rest 0.
- Retidied the ESD cable loop after yesterdays fix which needed slack to pull out of the port.
- Blew all 4 of the large optical surfaces for 5-9 mins of N2 deionizing flow in an attempt to reduce charge.
- We attached the green lantern to the ETMy SUS and made a final count of particulate of ~2 particles per square inch.
- Took a few more pcal camera pix to compare with pix from before we attempted cleaning of the ETMy-HR.
- Released the ACB locking bracket and swung it back into place.
- Suspended the CP and the ERM, removing extra teflon payload.
- Reattached the QUAD witness plate holder now loaded with a new witness plate.
- Attached the new 1" vertical witness optic to its place on the side of the suspension frame.
- Removed all tool pans, optic covers, blowers, foil, etc. from the chamber.
- Asked Jim to unlock the ISI.
- Placed the new horizontal floor witness place and 1" vertical witness optic.
- Verified damping loops could enable on the ETMy.
- Took quick P and V TFs of the main and reaction chains.
- Called Bubba/Kyle/Gerardo to proceed with the door attachment.
Reminder the test of the ESD can be done after we have pumped down. 10-5 torr or lower.
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.
The plot attached shows the Mich Out signal:
- in the first box, HEPI Z sensor correction is ON, Stage 1 X abd Y are in low blend, the IPS are off centered. The low frequency amplication is huge.
- in the second box, HEPI Z sensor correction is ON, Stage 1 X abd Y are in high blend, the IPS are still off centered. The low frequency amplication is gone.
- in the third box, HEPI Z sensor correction is ON, Stage 1 X abd Y are in low blend, the IPS are re-centered. Our current understanding/aseumption is that the Z to RX and RY coupling on HEPI has been well reduced.
The latest configuration is likely the best compromize:
- good micro-seism atenuation thanks to the low blend on X and Y
- low vertical to pitch coupling thanks to the Z feedback
- little RZ amplification at the micro-seism thanks to the Z sensor correction to HEPI (that offloads Stage 1 Z drive at the micro-seism)
- amplification acceptable at very low frequency, now that the IPS have been re-centered. We'll try to further improve it.
An ASD plot of the MICH_OUT channel is attached under different configurations. The first (RED) is with no sensor correction on BS, ITMX and ITMY. The second (BLUE) is with X, Y sensor correction signals to all three BSCs. The third (GREEN) is with Z sensor correction to HEPI for the BS chamber, showing the large low frequency amplification. The fourth (BROWN) shows the MICH_OUT with the IPS recentered and same configuration as the third. Tilt-decoupling on HEPI ought to reduce the amplification further.
Z sensor correction has been turned OFF on BS and ITMY. X and Y sensor corrections seem to be working fine and can be left ON.
Could be that I'm missing something but it sounds to me like at least one of the IPS is not working properly (ie broken). They are supposed to be linear to within 0.1% over the full range (+/- 0.05 inches)
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.
I’ve attached the code, the data, and the plots in a zip file.
Also attached are a few representative plots with the arms locked and unlocked.
Also, Dave wants me to note that the inferred loss of 410 ppm in the X arm is probably wrong; we’ve just pulled the ITMX transmissivity from the galaxy website instead of extracting it from our data. This is in progress.
The time constant of the ringdown is half of the cavity storage time, and the cavity storage time is related to the arm reflectivities by an equation in Isogai (sec 4.3):
We've assumed that we know RE = 1 − 5×10−6.
Here are the values for the ITM transmissivities, as inferred from the ringdown data.
In summary, to within experimental error there is no anomalous loss in the X arm. In the Y arm, the anomalous loss is 1330(370) ppm.
An updated version of the code is attached, along with a document giving the expression for TITM in terms of the measured quantities.
Here I've assumed RETM = 1, as was done in the paper by Isogai et al.
[Edit: Alexa has pointed out that we need to use m1 = RITM(P0+P1), rather than the original Isogai formula m1 = P0+P1, since we are using a PD in reflection. I've updated the table and the attachments accordingly. The ITM transmissivities change slightly and the extra losses go up a bit, but the conclusions remain the same.]
| X arm | Y arm | |
|---|---|---|
| m1 | 201(5) mV | 153(5) mV |
| m2 | 70(13) mV | 467(30) mV |
| m3 | 203(16) mV | 114(12) mV |
| m4 | 1.863(13) ms | 1.778(12) ms |
| ITM transmission, TITM | 1.419(35) % | 1.366(36) % |
| Total loss, L | 14 310(100) ppm | 14 990(100) ppm |
| L − TITM | 120(360) ppm | 1330(370) ppm |
For posterity, the old, incorrect values for the ITM transmissions were 1.425(35) % for X and 1.37(4) % for Y. The incorrect values for the extra losses were 60(360) ppm for X and 1290(410) ppm for Y.
Check the assumption on ETM transmission? Our measurement is 3.6 ppm with a tolerance of 0.2 ppm for both LHO ETMs. https://dcc.ligo.org/LIGO-E1300313
