EX PLL measurements

(Alexa, Daniel, Sheila)

PLL Beatnote:

• Beatnote height of -11.6dBm (or -24dBm before the preamplifier which has a gain of 12dB)
• BBPD reads 5.2mW
• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, rest OFF ---- under this configuration we found the lock was unstable with the input 1 gain at 6dB
• Turning Boost 1: ON, the lock was then unstable with the input 1 gain at 4dB
• We decided the best stable configuration was with the input 1 gain set to 0dB (gives a factor of 2 gain margin)

PLL Open Loop Transfer Function:

• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, rest OFF
  • EX_PLL_OpenLoopTFmag_BoostOff EX_PLL_OpenLoopTFphase_BoostOff  (collected with SR785)
  • EX_PLL_OpenLoopTF_High_BoostOff/AAAA2.TXT (collected with RF spectrum analyzer for high freq)
  • UGF at 22kHz, phase margin of 50 deg
• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, Boost 1: ON rest OFF
  •  EX_PLL_OpenLoopTFphase_BoostOn (collected with SR785, need to recollect mag data)
  • EX_PLL_OpenLoopTF_High_BoostOn/AAAA3.TXT (collected with RF spectrum analyzer for high freq)
  • UGF at 26kHz, phase margin of 20 deg

PLL Noise Spectrum -- via IMON of PFD (S1000758)

• PFD test report indicates the board has a noise of ~500nV/SqrtHz from IMON
• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, rest OFF
  • EX_PLL_Noise_PFD_BoostOff (collected with SR785)
  • EX_PLL_Noise_PFD_High_BoostOff/AAAA4.TXT (collected with RF spectrum analyzer for high freq)
• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, Boost 1: ON, rest OFF
  • EX_PLL_Noise_PFD_BoostOn (collected with SR785)

PLL Servo Board Transfer Function:

 

• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, rest OFF
  • EX_PLL_ServoBoard_TFmag_BoostOff, EX_PLL_ServoBoard_TFphase_BoostOff (collected with SR785)
• Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, Boost 1: ON, rest OFF
  • EX_PLL_ServoBoard_TFmag_BoostOn, EX_PLL_ServoBoard_TFphase_BoostOn (collected with SR785)
• Note: DC gain of -30dB nominal

Shot Noise of PLL BBPD:

• Measured noise from laser to be -95dB at 100Hz BW
• Noise of RF spectrum was -100dBm at 10Hz BW

HEPI EX offset relieved by giving TMS offset as much as we can

It was not advertised well but the HEPI isolation loop actually caused the alignment jump of [+25, -8] urad according to IPS in HEPI when it was turned on Friday evening (attached). We've never had a good alignment after that but this might be a coincidence. This is not a huge deal but annoying nevertheless.

When I started to restore the known good alignment of HEPI by giving new setpoints to HEPI it tripped the watchdog repeatedly because IPS completely railed, and later I was told that that was the reason why SEI gave up on restoring the original alignment.

Anyway, I was sufficiently annoyed and relieved the HEPI offset by pushing TMSX as far as we can in a hope that this is the last time I'm annoyed by the difference between offset-only and isolated (because we'll always isolate from here on).

1. Get back to offset-only for HEPI. This didn't exactly give me the old no-isolation alignment because the output filters (FM1 in H1:HPI-ETMX_OUTF) were changed, but was close enough.
2. Turn ISI isolation on.
3. Adjust TMS bias to hit one of PDs on ITM baffle and confirm that the offset is not that much different from before.
4. Put more TMS PIT bias and reduce the HEPI offset to get the beam back on the baffle PD. I reduced the offset such that, in the end, TMSX has 20urad headroom when the beam is on PD4. This means that even if there's a  PIT drift of +20urad we can still perform full initial alignment.
5. Read the IPS location monitors for PIT and YAW (H1:HPI-ETMX_IPS_RY_LOCATIONMON and RZ, these are calibrated by nrad). These were (-610000, 107900) before I made adjustment, and (-369800, 111650) after.
6. Disable the offset, turn on the HEPI isolation.
7. Put the new setpoints (H1:HPI-ETMX_IPS_RY_SETPOINT_NOW, RZ)=(-369800, 111650).
8. Fine adjust the HEPI setpoints until we fully recover the beam on PD.

In a retrospect I didn't have to go back to offset-only, I could have just changed the setpoints, but that's what I did due to various reasons. Anyway, In the end, I obtained this: (H1:HPI-ETMX_IPS_RY_SETPOINT_NOW, RZ)=(-389800, 111650).

I also copied these numbers and put them in H1:HPI-ETMX_IPS_RY_TARGET and RZ.

IPS are still yellow (about 20000 cts on V1 and V2) but not railing.

Work at EX complete

Alexa, Daniel, Sheila....we have safely returned from EX and completed our work there for the evening

X arm alignment today (Alexa, Sheila, Keita)

	TMSX (PIT, YAW) w/ PD Voltage	ITMX (PIT,YAW) w/ V	ETMX (PIT, YAW) w/ V
PD1	(205. -206) w/ ~2.5, 0dB	(84.5, -45) w/ 6.5, 0dB	(242.0, 95.5) w/ .36V, 0dB
PD4	(274.5, -268) w/ ~2.5,  0dB	(52.5,-78) w/ 6.7, 0dB	(265.5,65.5) w/ .4V, 0dB
aligned	(239.75, -237)	(68.5,-61.5)	(253.75, 80.5)
slider cal [urad/urad]	(1.04, 1.16)	(1.17, 1.14)	(1.53, 1.20)

After HEPI offset was relieved by moving TMS PIT, initial alignment was attempted again, and we got the above. The power level is consistent with the original alignment (alog 9064).

However, strange thing is that the ETMX slider calibration seems to have changed by a factor of two-ish for both P and Y (Ref: alog 9126 and alog 9087).  Because of this, I cannot totally kill the possibility that we're fooled by multiple bounces though it's very unlikely because the power levels are the same as before. (But the question is, did somebody mess with SUS?) Tomorrow we need to start with the "aligned" numbers above and see what happens.

	TMSX slider cal (P, Y) [urad/urad]	ITMX	ETMX
Dec 24 2013	(1.04, 1.14)	(1.2, 1.1)	(0.8, 0.6)
Jan 06 2014	(1.04, 1.14)	(1.17, 1.14)	(0.90, 0.51)
Jan 13 2014	(1.04, 1.16)	(1.17, 1.14)	(1.53, 1.20)

Keita and Alexa writing as Sheila.

ETMy welding complete

We have successfully completed the rewelding of the ETMy monolithic.  We decided to leave EY in laser hazard mostly as a double safety measure to keep excess personnel out of the area until it has proper protection.  Tomorrow we will continue with violin mode, pitch mode, bounce mode, and roll mode measurements.

Investigation of LED errors on ITMY Hardware Watchdog

Jim and Dave

Over the weekend the HWWD unit attached to ITMY has been giving LED error status roughly once an hour but randomized. Each error is only a few seconds in duration. The sister unit in the DTS has shown no errors (we installed a long 37pin cable on friday). This afternoon at 12:50 we replaced the ITMY unit (S1301699) with the DTS unit (S1301706). The only issue with the swap is that the 706 unit did not boot up automatically on application of power, we had to press the reset button. On the other hand the 699 unit when powered up in the DTS booted first time every time.

About an hour later we saw an LED error condition on ITMY (now the 706 unit) so the problem seems to be with the ITMY osem/sat-amp/cabling and not the HWWD (the 699 unit now in the DTS has shown no errors). Jim and I went out to the CER and LVEA to verify the monitor cables look ok at 15:18. We noticed that the ITMY M0/R0 sat amp is a replaced unit, the original unit is stored on the BS shelf. Filiburto remembers there was a possible low frequency issue with this sat amp, hence the swap out.

We trended the photodiode signals of the ITMY top osems to verify that nothing is actually physically happening with the LEDs or their light output. No correlation was seen.

Next step is to look at the LED current monitor signals coming from ITMY to see if the signal is dropping out at this very low rate of one second every hour or so.

HAM4 SEI Install Progress

HughR, MitchR, JimW

Today, we finished our inital payloading of the HAM4 ISI, removed the shipping braces, locked the ISI, took a look at the level, and started working on cabling. Not many issues, but  a few. Currently, HAM4 ISI corner 3 CPSes read out on the corner 1 of HAM5 ISI. Hugo is looking at the model, Filiberto is looking at the IO chassis cabling. The level of the ISI is a little out, but I think good enough for now. We may address the level of the ISI with HEPI tomorrow, after we look at the numbers more. Hugh also powered on and verified that the HEPI pier pods seemed to be working. Tomorrow we will look at cabling more, and start balancing the ISI.

Ops

Monday 13 JAN 2014

-Windy conditions all day, 20-30mph

-X-Arm impassable due to tumbleweeds. Y-arm passable with caution. Bailing crews at work on both arms.

 

-920-940 Apollo using sawzall at BSC1

-919 AndresR looking for parts in around HAM4/5

-950 EY transitioned to laser HAZARD for welding operations

-957 LVEA transitioned to laser SAFE

-1000 Koji/DickG/DanielS working on electronic racks at H1PSL; unk completion time (1200?)

-1009 Bubba opening LVEA outside exit door at NE corner

-1019 TravisS, BetsyW, Giles and JasonO begin welding ops at EY

-1026 -1200 Hugh/JimW/Mitch working at HAM4

-1030-1600 Filiberto working on documentation at HAM6

-1244 DaveB and JimB swapping out hardware watchdog in the CER

-1330-1600 Mitch, JimW, HughR continuing SEI work at HAM 4

-1358-1445 JohnW, Sheila going via offroad route to EX

-1459 Sheila, Alexa, DanielS to EX (on the road to MX, then offroad)

-1512-1545 JimB and DaveB returning to CER to work on HWWD

ENDX Ion Pump

I noticed that LLO was running their main ion pump at 7kv in the end station. Ours was set to 5kv.

Today at 22:30 UTC I set the voltage to 7kv. The immediate response has been a small increase in pressure at PT510. We'll watch for a few days and see where it goes.

 

Fixed minute trend readback from NDS on DTS

Fixed an error which specified a non-existent file for minute trends on the x1nds1 server.  Minute trends can now be read by dataviewer and other clients.  Note that minute trends have been written properly, but could not be read back using nds.

ITM03 Test Mass processing incident

On Friday, Gerardo and I encountered an issue while processing the optic as per the ear bonding procedure.  During the processing, the optic suffered a 3mmx 3mm crack at the bevel on the HR side of the optic and some scratches out near the edge of the HR face.  We're working to understand whether or not it can be used in BSC3, but our expectation is that it can, owing to the small nature of the crack.  We are also working with COC/SUS/SYS so this damage does not occur during future processing.

PRX locking stably

Kiwamu, Stefan

We did some tweaking of the PRCL servo in order to get stable locking of the low finesse half-PRC for further actuator commissioning.

- We are feeding back to PR2 and PRM.
- We removed any low-pass filter from the PRCL control filter, but left a CPL300 in the M3 locking filters of PRM and PR2. Currently only M3 and M2 are feeding back - the filter modules snapshots are below.
- This gives a PRCL UGF of about 18Hz (see OLG measurement, as well as the signal levels in counts below). 
- With that, fine-tweaking the alignment showed that PR3 was moving too much in pitch. We increased its L and P damping gain, and engaged corresponding boost filters. (snapshot below)

2f demodulator installed

[Dick, Daniel, Koji]

The POP 2f demodulator unit previously installed on row 28 of the ISC R2 rack (c.f. this entry ) was replaced with the 2f demod unit.
This unit has a 24MHz LPF and a 80MHz HPF on CH1 and CH2, respectively, forming a diplexer configulation for 18MHz (2xf1) and 90MHz (2xf2) signals.
Therefore, the temporary power splitter for the POP 2f path was removed.

Because of this action, we expect that the demod phase for the POPAIR18 and POPAIR90 were changed.

The 3f demods (CH3/4) still have the power splitter. This will be removed when the 3f diplexer unit is installed on row 27.

We also cleaned up some of the RF cables:

- The REFLAIR9 cable plugged on row 34 is now routed through the patch panel on row 27.
This means that the demod phase of the REFLAIR_A_RF9 was changed.

- The cable for REFL9 was made and connected to the demodulator on row 34.

- Unnecessary connectors/cables were removed from the patch panel on row 29.

TFs for H1-SR2

   After making several adjustments to the Coil Holder, the BOSEMs, flag alignments, and adding the third Coil Holder Mounting Bracket on H1-SR2, a new set of transfer functions were taken Friday evening. (See aLOG #9211). The plots for this latest set of transfer functions are posted below. All scripts and data files have been committed to the SVN repository. 

Note: The 4th Coil Holder Mounting Bracket has been modified and is being run through C&B this week. It will be installed on the suspension as soon as it comes out of clean and Bake.    

Sawzall work at BSC1

Apollo doing some cutting 920-940

X arm alignment and slider calibration, part 2

References:

• https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=9064
• https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=9087

This is an update of the above alog entries. After turning off the isolation loop for EX ISI, I started the initial alignment of the TMS, ITMX and ETMX again.

This was done by pointing TMS to ITM arm cavity baffle diodes PD1 and PD4 (note that for ITM baffle PD4 is connected to PD3, so the actual channel I looked at was H1:AOS-ETMX_BAFFLEPD_3_POWER), take note of the TMSX alignment slider values, set the TMS slider to the mean of PD1 and PD4, then align ITMX to point the beam to ETMX baffle diodes etc.

The bias sliders are calibrated using 4000m arm length and the vertical/horizontal distance between the PDs.

In the table below, (P, Y) refers to the alignment slider values for each optic,  "Aligned" is the mean of PD1 and PD4

optic	TMSX	ITMX	ETMX
PD1 (P, Y)	(109, -203)	(67, -80)	(322, -1)
PD4 (P, Y)	(178, -266)	(99, -47)	(362, -71)
Aligned (P, Y)	(143.5, -234.5)	(83, -63.5)	(342, -36)
Slider calibration (P, Y) [urad/urad]	(1.04, 1.07)	(1.17, 1.14)	(0.90, 0.51)

Note that HEPI still has 12000 counts RY offset to relieve TMSX PIT which is due to 300urad systematic in ETMX.

OSEM calibration of TMSX, ETMX and ITMX

References: D1201036 (BSC9 ACB assy) and D1200314 (BSC3)

Gerardo read the distances between the baffle diodes off of CAD drawings for me (see the attached cartoon). 

ITM baffle PD1-PD4 separation is 11.3" over 4km (72 urad) both horizontally and vertically. For ETM the number is 11.8", so it's 75 urad.

Don't know why the patterns are different for ETM and ITM, but using these we can calibrate TMSX, ITMX and ETMX bias sliders. Note the factor of 2 between TMS and mirrors, this is because TMS moves with the beam but mirrors don't.

	TMSX P	TMSX Y	ITMX P	ITMX Y	ETMX P	ETMX Y
PD4-PD1 [urad in slider offset]	187-118 = 69	-253+190 = -63	99-66.6 = 32.4	-38+72.9 = 34.9	355-310 = 45	-34-26.5 = -60.5
Slider Calibration [urad/urad]	72/69 = 1.04	72/63 =1.07	75/32.4/2 = 1.2	75/34.9/2 = 1.1	72/45/2 =0.8	72/60.5/2 = 0.6
Slider sign	positive=down	positive=out of L	positive=down	positive= inside of L	positive=down	positive=out of L

 

Calibration of ETMX is somewhat suspect (at 10urad level) because of the fact that the position loop of EX ISI got accidentally off before I did ETMX adjustment.