Alexa, Kiwamu

We performed another ring down measurement using the REFL port. The data still did not make sense.

We probably should switch the approach to something else e.g. a cavity pole measurement (see alog 5429).

The setup:

Since we had the PRM reflection on ISCT1, we used this light instead of the one in IOT2L (see alog 13280). First of all, wiggling PRM and looking at the REFL analog camera, we confirmed that there was no clipping in the REFL path. In fact, the beam already looked quite centered on the REFL camera from the beginning because of our alignment effort (see Alexa's previous alog 13317). We intentionally misaligned PR2 to avoid any interference from the main interferometer.

We moved a PDA55, which had been on ISCT1 for triggering the REFL shutter, to a point right in front of the 3-f broadband PD. In the process of aligning the beam, we touched a steering mirror that was in front of the broadband PD. We then made sure that the gain setting is at its minimum of 0 dB. Since at this point the light was too bright for the PDA55, we placed a ND1 filter to cut down the laser power. This resulted in a DC voltage of about 440 mV when the IMC is in lock -- therefore the dark offset of the PD was negligible this time.

The results:

We repeated the same measurement as the previous one, but with the PRM reflection. We flipped the polarity of the fast path in the IMC common mode board to rapidly unlock it. Every measurement, we obtained a 1/e time of roughly 20 usec. This was coarsely measured with the cursor in a digital oscilloscope. Obviously, the results don't make sense. The attached is a photo of the oscilloscope display.

In Y-end from 1735-1745 hrs. local, X-end 1755-1800, LVEA 1805-1810

Alexa, Kiwamu, Borja, Stefan

With the IMC locking reliably, and the input beam hitting the BS, we
- Found the good alignment for PRM and got the REFL beam centered on ISCT1.
- tweaked the PR2 alignment to get fringes in PRX (ITMY misaligned)
- locked PRX on the carrier and tweaked down the REFL power with PR2 and PRM.
- installed a camera looking down to HAM5 from HAM4. We could clearly find the beam on the Faraday cage.
- Using SR2 we steered the beam through the Faraday, and verified that it arrives in HAM6.

Attached is an alignment snapshot.

Remarks:
- while the input beam through IM3,IM4 and PR2 might still be going a bit up and down, after PR3 it should be pretty good (we didn't change the PR3, BS, ITMX and SR3 aligment (compared to alog 12816 )
- we didn't try to tweak the SRM yet.

Greg, Dan, Dave

h1fw0 is back up and running. 

The problem was with disk9 in the raid raid-dcs-h1a. Its status led was flashing yellow instead of steady green. But it appears to have only partially failed, and the raid continued to try to use it. The result was an unstable file system which cannot keep up with the frame writing.

Step 1 was to run the Oracle 'guds' command to provide diagnostics.

The second step was to stop reading this file system and only have h1fw0 write it, still unstable.

The third step was to power cycle the solaris box h1ldasgw0, remount to h1fw0 and restart frame writer, still unstable.

The fourth and most drastic step, was to walk to the LDAS server room and physically remove the offending disk #9 from the raid (hot removal). This forced the raid to stop trying to use disk9 and to start using the hot-swap spare.

At the time of writing h1fw0 has been running for 20 mins, which is longer that it has since 4am this morning.

Came on site to resolve this issue. Console for h1sush2b shows many errors and is frozen. First recovery attempt is a power cycle of the front end computer.

First removed h1sush2b from the Dolphin IPC network using h1susb123 as a remote disabler, this worked.

Power cycled the computer, let the models start themselves. As I suspected, h1sush2b was actively corrupting the DAQ data streams to the concentractor. As soon as h1sush2b was powered down all front ends DAQ data became good again.

IOP model started with large IRIG timing error, daq status 0x4000. Stopped h1susim and restarted h1iopsush2b, still get IRIG-B errors. Checked IRIG-B is OK, suspect problem is at the IO Chassis end.

Step 2 was a full power down of both computer and IO Chassis. Stopped all models, and removed h1sush2b from Dolphin using itself to do this. Powered down h1sush2b. In CER, turned front panel switch to OFF, this did nothing. Disconnected the 24V-DC power cable at the power strip, noting that this was the only thing plugged into this strip (the two other IO Chassis use a different strip) maybe a hint. Powered IO Chassis backup, switch to ON, waited for timing slave to sync. In MSR power up h1sush2b, both models start with no errors.

So not sure why h1sush2b died, but suspect a glitch in CER at 00:08 this morning.

Two unrelated problems with the DAQ ongoing:

1. disk9 of the DCS raid system for h1fw0 failed at 10pm Friday night. h1fw0 lost its file system at 1:50am this morning and has not been running since then.

2. h1susim front end has failed and has caused a DAQ error for the following frontends: h1susb123, h1sush2a, h1sush34, h1sush56, h1susauxh2, h1susauxh34, h1susauxh56, h1sieb1, h1sieb2, h1seib3, h1seih16, h1seih23, h1seih45, h1psl.

both end stations have good DAQ data.

I've emailed LDAS regarding the disk failure in the LDAS server room.

For problem 2, I'm going to try restarting the DAQ data stream from those frontends.

model restarts logged for Fri 08/Aug/2014
2014_08_08 00:32 h1fw1
2014_08_08 04:32 h1fw1

unexpected restarts of h1fw1

(Stefan, Kiwamu, Koji, Alexa)

We repeated the ringdown measurement with the low gain setting (0dB compared to the nominal 30dB) and the ND0.6 filter removed (we still need to eventually revert to the nominal configuration). This time we found that the ringdown time was approximately 25µs, which is still larger than what we expected. We want to repeat this measurement with REFL from ISCT1, however, we could not find the beam for a while and then got distracted with other things...This is still to be done.

We adjusted the gains, phase rotation, I-Matrix and IMC WFS matrix. We can now engage the WFS; this increased the trans PD to ~1200 and was stable. I have attached a screenshot of the current configuration.

We increased the PSL power to 1.9W.

The beam is too high on MC3 by 1.5mm and horizotanlly off by 2.138mm in the direction away from IOT2L. This result is almost the same as the previous measurement in alog 8943, so we are fine with this off-centering.

(Richard, Cyrus, Alexa. Kiwamu)

GigE camera 08 of PR2 was first rebooted and then had to be adjusted because the image was clipped. 

Keita, Stefan

In the hope to go back to a previously established alignment we tried to restore IM1, IM2, IM3 and IM3 to two previous sets of values:
- one of the last in-vacuum days back in may (we picked May 25)
- The time of a good in-air alignment (7/17/2014 22:00 UTC)
- Interestingly, for both setting we didn't get IM4 trans out of HAM2, even after the IMC was aligned well. Thus we decided to go back to the settings we had in the morning. Here we get IM4 trans out, and can center it with IM3.

- We then decided to ignore the PRM for now, and start pointing down the PRC.

(Borja and Rai)

We followed the procedure of switching on the turbo-pump safely at the ETMY. The turbo-pump was switched on more or less about 7pm and the pressure very quickly went down to 10^-5 torr at which point we turned on the discharge gauge (about 7:40pm). We did wait until the presure was below 10^-6 torr before we powered up the power supply to the ESD HV amplifier (at about 8:30 pm). I verified, looking at the analogue readouts of the ESD HV outputs, that they were not railing as reported being a known issue in the past. This will allow me to take new charging measurements tomorrow when the ETMY pressure is safe at or below 10^-7 torr (more about this in another entry).

J. Kissel, J. Warner, G. Grabeel

Given that there is no obvious cause for the locking mechanism failure on the recently rescued GS13 s/n 574, I've elected to replace the stock delta rods (some of which had already buckled) with the much-more-robust aLIGO flexures (D0901318 and D0901319). The fragile delta rods are the primary reason the instrument needs a locking mechanism, so with the next flexures and the already-present, high-resistance pre-amp (D050358, s/n "Larry") the instrument should now be portable again with much less fear of irreparable damage. Thanks to Jim for grabbing me flexures, and thanks to Greg (already an expert in the modification procedure) for actually performing the replacement. Pictures attached.

For now, the instrument remains in my office.

New tally:
S/N     Config      Current Location
568        V        EX, in change-room, by bench
574        V        CS, In my office
578        ??       EY, on change-room racks
584        ??       EY, on change-room racks

J. Kissel, K. Venkateswara, E. Shaw

We've processed the 1 [mHz] excitation data taken over night, and it confirms our preliminary results from yesterday that the center of mass of the beam is d = 20 [um] above the suspension point. Indeed, because we shielded most of the open end of the thermal box with Ameri-stat (as shown in yesterday's pictures), the insturment's noise floor was much better. 

Note, we've also switched from Krishna's sine-wave fitting code to just grabbing the excitation amplitude from the ASD, and obtaining a transfer function value from there,
peak amplitude [rad_{pk}] = ASD [rad_{rms}/rtHz] * sqrt(binWidth) [rtHz] * sqrt(2) [pk / rms].
Since we know the response to ground tilt should tend to unity at high frequency, as any inertial sensor, and we've not changed the excitation amplitude, the collection of peak amplitudes are normalized by the highest-frequency amplitude to obtain the (beam / ground) [rad/rad] tilt transfer function. We lose a quantitative estimate of the uncertainty with this method, but we gain simplicity/clarity and it's reasonable to say from the SNR that the estimates are good to at least 20%, if not better. See attachment. 

The adjustment masses are a distance D = ~3 [in] above the C.o.M., so the change in (d = C.o.M. w.r.t the Susp. Point) per gram of adjustment weight, dm, is

dC.o.M.    D     3.0 [in]   76.2e-3 [m]
------  = --- =  -------- = ----------- = 18.1 [um/g]
  dm       M     4.2 [kg]     4.2  [kg]

As such to achieve a minimal separation, Krishna and Eric spent the rest of the morning/early afternoon removing 1.1+/- 0.05 [g]  of mass (equal to a 19.91 [um] shift in C.o.M. down toward the Susp. Point). A separation of ~1 [um] means the rejection of horizontal acceleration is

d * M_{bar}    1e-6 [m] * 4.2 [kg]        
----------  =  -------------------- = 7e-6 [rad/m]
  I_{bar}          0.59 kg.m^2

... pretty awesome! After rebalancing, they sealed the vacuum chamber (tool tight), confirmed that the new resonant frequency is 8.8 [mHz] as expected, and headed home for Seattle. 

When Krishna returns on Monday, we'll start pulling vacuum on the tank which should take about a day. From there we tweak the balance of the beam to remain within range of the autocollimator, re-measure the C.o.M.-Sus.Point separation to confirm the awesome acceleration rejection, and begin the process of connecting the system to the aLIGO DAQ.

I checked the difference in position of the Imx mirrors before and after the chamber was pumped.

I used the vacuum pressure sensor channel (HVE-LY:Y1_120BTORR) to find the times were the pumped was performed.
Then, to check the difference in position I used the times:
Before: 	2014/08/05 09:00:00 UTC
After: 	2014/08/07 10:00:00 UTC

The table shows the count difference (before and after the pump):

Difference			
        L (counts)	P (counts)	Y (counts)
IM1	10	                7.42	         -7.76
IM2	-5	               -10.6	           38.8
IM3	-27	              -21.2	           9.7
IM4	4	                31.8	           38.8

The DAC is 18 bit , which gives us a maximum of +- 131072 counts (2^18 /2 = 262144/2) in OSEMS basis (UL, LL, UR, LR).
Right now, the maximum number of used counts is 116600 (H1:FEC-104_DAC_OUTPUT_0_5), which give us a free range of 14472 more.

	UL	        LL	         UR	        LR
IM1	133.0	5.4	         -0.4	        -128.0
IM2	-425.8	-243.6	241.1	423.3
IM3	-272.3	92.1	        -105.6	258.8
IM4	-59.2	-605.7	607.7	61.2

To recover the position had it before the pump, we need a maximum of 425.8 counts.
The next table shows, in counts, how much is needed to recover the original position.
 
I am attaching the spreadsheet used for the calculations and the times series plots.

[Alexa, Kiwamu, Koji]

We found that IMC WFS B had quite small error signals. We tracked down this to be too small LO.
What we found was the LO cable had bad connection at the SMA connector. This is the same problem as Kiwamu reported before.

After recrimping the IMC WFS B cable, the all of the cables on ISC-R2 rack was reviewed.
All of the cables had the same crimping issue. Also, most of the SMA were not secured.

All of the SMA cables were recrimped and 4~5 SMAs have been replaced.

Here is the list of the LO powers in the monitor. WFS REFL45 has CH1 and CH2 with +13dBm LO power
while CH3/4 indicates very low numbers. In fact these nubers (and the corresponding RF power mons)
are not changing at all. So this could be a DAQ related problem.

=== Rack ISC-R1 U07 ===
H1:IMC-WFS_A_DEMOD_LOMONCHANNEL_1 = 16.0804
H1:IMC-WFS_A_DEMOD_LOMONCHANNEL_2 = 15.9532
H1:IMC-WFS_A_DEMOD_LOMONCHANNEL_3 = 15.999
H1:IMC-WFS_A_DEMOD_LOMONCHANNEL_4 = 16.5534
=== Rack ISC-R1 U05 ===
H1:IMC-WFS_B_DEMOD_LOMONCHANNEL_1 = 16.1007
H1:IMC-WFS_B_DEMOD_LOMONCHANNEL_2 = 16.1821
H1:IMC-WFS_B_DEMOD_LOMONCHANNEL_3 = 16.1618
H1:IMC-WFS_B_DEMOD_LOMONCHANNEL_4 = 16.3296
=== Rack ISC-R2 U38 ===
H1:ISC-RF_C_REFLAMP45M_OUTPUTMON = 17.5009
=== Rack ISC-R2 U37 ===
H1:ISC-RF_C_REFLAMP9M1_OUTPUTMON = 20.2811
=== Rack ISC-R2 U34 ===
H1:LSC-REFLAIR_A_RF9_DEMOD_LOMON = 20.6277
H1:LSC-REFL_A_RF9_DEMOD_LOMON = 20.9278
=== Rack ISC-R2 U30 ===
H1:LSC-POPAIR_A_RF9_DEMOD_LOMON = 23.059
H1:LSC-POPAIR_A_RF45_DEMOD_LOMON = 19.8342
H1:LSC-REFLAIR_A_RF9_DEMOD_LOMON = 20.6073
H1:LSC-REFLAIR_A_RF45_DEMOD_LOMON = 19.8494
=== Rack ISC-R2 U28 ===
H1:LSC-POPAIR_B_RF18_DEMOD_LOMON = 22.5656
H1:LSC-POPAIR_B_RF90_DEMOD_LOMON = 20.1851
H1:LSC-REFLAIR_B_RF27_DEMOD_LOMON = 23.0234
H1:LSC-REFLAIR_B_RF135_DEMOD_LOMON = 18.0488
=== Rack ISC-R2 U24 ===
H1:LSC-POP_A_RF9_DEMOD_LOMON = 23.3642
H1:LSC-POP_A_RF45_DEMOD_LOMON = 19.8494
H1:LSC-REFL_A_RF9_DEMOD_LOMON = 20.9328
H1:LSC-REFL_A_RF45_DEMOD_LOMON = 20.119
=== Rack ISC-R2 U18 ===
H1:ASC-REFL_A_RF9_DEMOD_LOMONCHANNEL_1 = 17.174
H1:ASC-REFL_A_RF9_DEMOD_LOMONCHANNEL_2 = 17.0824
H1:ASC-REFL_A_RF9_DEMOD_LOMONCHANNEL_3 = 16.94
H1:ASC-REFL_A_RF9_DEMOD_LOMONCHANNEL_4 = 17.3011
=== Rack ISC-R2 U16 ===
H1:ASC-REFL_A_RF45_DEMOD_LOMONCHANNEL_1 = 13.3693
H1:ASC-REFL_A_RF45_DEMOD_LOMONCHANNEL_2 = 13.471
H1:ASC-REFL_A_RF45_DEMOD_LOMONCHANNEL_3 = -75.0432
H1:ASC-REFL_A_RF45_DEMOD_LOMONCHANNEL_4 = -74.9568
=== Rack ISC-R2 U10 ===
H1:ASC-REFL_B_RF9_DEMOD_LOMONCHANNEL_1 = 17.3215
H1:ASC-REFL_B_RF9_DEMOD_LOMONCHANNEL_2 = 17.2604
H1:ASC-REFL_B_RF9_DEMOD_LOMONCHANNEL_3 = 17.2096
H1:ASC-REFL_B_RF9_DEMOD_LOMONCHANNEL_4 = 17.3011
=== Rack ISC-R2 U08 ===
H1:ASC-REFL_B_RF45_DEMOD_LOMONCHANNEL_1 = 13.5117
H1:ASC-REFL_B_RF45_DEMOD_LOMONCHANNEL_2 = 13.1913
H1:ASC-REFL_B_RF45_DEMOD_LOMONCHANNEL_3 = 13.3642
H1:ASC-REFL_B_RF45_DEMOD_LOMONCHANNEL_4 = 13.4558
 

(Borja)

Several issues has not allowed me to drive the ETMY ESD until late afternoon today. At this point I was able for the first time to test, with real data, the automation code for the ESD charge measurements develped at Livingston. I did have previously adapted it for Hanford's slightly different configuration but this was the first time I was able to test its results. Unfortunately the automation on the injection, data request and analysis is not robust, not allowing for the whole process to finish several times. Also the code does not take into consideration conversion factors on the V BIAS from Voltage to counts and viceversa. I assume this is taken care in Livingston outside of the code but certainly that solution does not make it universal.

Looking at the procedure with Rai I realized that we have to be careful on the level of the driving signal amplitude to be below the minimum V BIAS used in the analysis otherwise linear approximation assumptions in the methodology are no longer valid.

Rai is leaving on Saturday and we need to apply his discharging technique before then (optimally tomorrow). Before this takes place we need to have some ESD charge measurement data so that we can compare with data taken after the discharge and see the effects observed. This time constrains has made me decide to do the measurements manually tonight. I may be able to run the automation code afterwards and compare it tomorrow with the manual measurements but this may not be possible. See manual measurements in the attached document.