(Chris, Kiwamu, Stefan)

We roughly calibrated the IR transmitted light (still ASC Quad sum, since Sheila wasn't quite able to finish due to a short earthquake).

Method:

- We sit on the side of the fringe (peak/2) of the IR cavity fringe, which has a pole frequency of 82Hz, i.e. power is proportional to P0/( 1+( f/82Hz )^2 ) .

- This gives a slope  of dP/df = Po/(2*82Hz), i.e. the DC calibration (with P0=250cts) is 0.656Hz/ct (at DC)

- The cavity pole is now complex (since the two freq-mod side bands see different transfer function), but we were too lazy to do this math right, and just stuck in a real zero at 82Hz to compensate the cavity pole. This is good within a factor of 2 above the cavity pole.

The attached plot shows

- Green: Transmitted IR at peak/2, calibrated in Hz/rtHz

- Dashed-Green: RMS of previous one.

- Blue: MC_F, calibrated in Hz. above the x-over (~100Hz) this measures the laser frequency drive

- Mustard: Ey PLL noise, calibrated in Hz (free running Laser noise)

- Gold: EY PDH control signal (actually wong - should be ~10 times higher, due to the changed PDH control scheme - see previous elog for correct calibration)

Conclusion: we supress real motion down to ~40Hz, above that we are imprinting ALS sensing noise (probably from the corner setup) onto the IR light. The obvious strategy to lower the 34Hz RMS noise is to lower the UGH (turn the AO path off) and add some significant boost filters at low frequency. Our initial attempt for doing this ran into DAC saturation issues on MC2.

(Kiwamu, Alexa, Matt, Stefan, from yesterday)

As part of the ALS noise hunting, we revisited the PLL and PDH loops at EY.

- First we realigned the PDH diode that was intentionally misaligned the night before. We verified the the DC oscillations observed on that diode's read-back are not present in analog, so there must be some issue with the acquisition of that signal.
- Next, we looked at the PLL loop. With a UGF around maybe 20kHz it produced a lot of gain peaking around 30kHz. We turned the BOOST stage 1 on the PLL Sigg board off. That helped, but the loop was happiest at another 10dB lower gain.
- This suggested the idea of an "additive offset" like path, bypassing the PLL loop all together. We rigged this control scheme by using one additional BNC cable:
  - We moved the cable that runs to the VCO tune input from the PDH Sigg board fast output to the PDH Sigg board EXC B monitoring point (either 1 or 2 - they have opposite sign). We would like to use the slow path for this option, but it had additional undesired low-pass filtering.
  - We added a cable from the PDH Sigg board fast output to the PLL Sigg board EXC A input. This keeps a high-frequency roll-off as well as some PZT notches in the path.
  - The PDH Sigg board fast gain was lowered from 0dB to -22dB to set the AO gain. The PDH Sigg board input 1 gain was set to -4dB.
  - With this setting we got a nice, roughly 1/f total loop shape, and a UGF of 20kHz.


Our hope was that this configuration will change the noise seen at the end corner, but we had no luck - the corner noise was unchanged.

PS: Attached is a plot of the calibrated frequency noise in Hz/rtHz seen by 3 sensors:
 - Blue: PLL control signal: dominated by free-running laser noise
 - Purple: PDH control signal: above 2kHz this shows coherence with blue (not in figure), indication laser noise. But below 2kHz we seem to be limited by some other PLL sensing noise (electronics dark noise ?) Note that this noise was taken in the old control loop topology, because the control signal calibration was simpler.
 - Red: ALS in-loop common mode error signal from the corner beat node. Note that it is NOT coherent with any of the noise we see at the end.


PPS: We also noted that we are able to grab an arm lock with the PLL input disabled (i.e. without relying on the fiber for per-stabilization). However we would need some more low frequency gain to keep the lock in this configuration.

 

h1lsc and h1iscey front ends were updated yesterday as follows.

LSC:

• Add/change sample rates of DAQ channels.
• Restore in-air IMC TRANS PD's IPC from h1ascimc.  (This is a local mod: at LLO the in-air PD is not installed, and the in-vac MC2 TRANS QPD sum was used instead.  Yet the in-air sensor still exists in the table layout and the ADC/DAC channel allocation.  Also, we won't have an IPC for the MC2 TRANS QPD available until we rebuild h1ascimc.)

ISCEY:

• Add/change sample rates of DAQ channels.
• Hook up the communication link to the Beckhoff/Ethercat slow controls.  The front end uses two bits received from the Beckhoff system to toggle the first two filters in H1:ALS-Y_ARM.  It sends one bit to tell the Beckhoff whether the input beam pointing is good or not.  The Beckhoff PDH autolocker still has to be updated to take advantage of its newly acquired knowledge and powers.

Attachments: (1) ISCEY top level; (2) ALS subsystem showing state/control logic.

For both systems, safe.snap files have been updated and committed to SVN.

Closing WP 4005.

(Betsy W, Gerardo M, Gerardo A. M)
Prism was removed today, finally. It took about 7 days of the common process of soaking the prism joint in acetone, then working on the joint by hand with a razor blade along with some acetone as a lubricant.
2 photos attached, one is where the prism used to be, second photo is the removed specimen.

Turbo valved-in for 8 hrs -> End value 4.1 x 10-7 torr*L/sec

I cleaned up and extended the rudimentary support for SUS AUX that Dave Barker recently added to the SITEMAP:

* I tweaked the screen linked from the AUXEY menu item, /opt/rtcds/userapps/trunk/sus/common/medm/SUS_AUX_EY_OVERVIEW.adl, and the args supplied to it, fixing errors and changing all the H2-specific stuff to be generic.

* I adapted SUS_AUX_EY_OVERVIEW.adl to create SUS_AUX_HAM2_OVERVIEW.adl, SUS_AUX_HAM34_OVERVIEW.adl, SUS_AUX_HAM56_OVERVIEW.adl and SUS_AUX_EX_OVERVIEW.adl.

* I changed the names of the existing  HAM2 and HAM34 buttons to AUXHAM2 and AUXHAM34 to match AUXEY and linked the HAM2 and HAM34 screens to them. However none of the X-arm section of the SITEMAP is populated as yet so I didn't attempt to link to the HAM56 or EX screens.

All the new stuff was committed to the userapps SVN.

BSC2 NE Vert HEPI Actuator back in RUN mode (Hugh)

Operate HAM3 East Door RGA (John)

More work on TMTS (Transmon Telescope SUS) model by Mark B starts around 10:45am (requiring DAQ restart by Dave afterward)

PCal Work starting in H2 PSL Room (Pablo, Colin, Craig, Michael R.)

CDS Alarm:  several h1iscey IOP State Word alarms several times a day

Jim B shutting down framewriter0 (10:35am)

changing compressor at MX; gave instrument air alarm, and also Vacuum alarm for CP6 since we use Instrument Air for the valve. (Ski)

Crew here for taking water samples at 11:40am

MitchR, JimW

We started taking the eLIGO HAM6 ISI apart today, so that we can replace its sensors and cabling with aLIGO parts. Walls covering GS-13's were removed, then we started on the seismometers themselves, with 4 out of 6 removed. Horizontal CPS's are mostly out, we just didn't have cutters for some zipties. Tomorrow, we will finish up the pods, and strip the remaining cabling. We did find one bolt that galled as soon as we put a wrench on it (maybe before?), which ended up breaking instead of cooperating, and one bolt that threatened to gall, but it behaved after plying it with alcohol.

The following new RCG library parts have been added to the repository for use with the ISCEY/ALS model.

• Communication link with Beckhoff (in .../isc/common/models/STATECOMM.mdl, plus C source code in .../isc/common/src/RtCommunication.c)
  This part interacts with the RtCommunication.lib library in the Ethercat slow controls system (documented in E1300442), allowing it to exchange state bits with the realtime front ends via ADC and DAC channels.
  (see attachment 1 for detail)
• Schmitt trigger with HI and LO outputs (in .../cds/common/models/SCHMITTTRIGGER.mdl)
  This was added alongside the already existing Schmitt trigger module, which only provides a HI output.  (Since this is a hysteretic trigger, LO is not the same as NOT HI.)
  (see attachment 2 for detail)
• RMS trigger (in .../isc/common/models/LSC_TRIGGER.mdl)
  Added alongside the LSC trigger part, this part provides the complementary behavior (activating a trigger when the input signal goes LO).  This is useful when the input signal is an RMS.
  (see attachment 3 for detail)

Found instrument air was valved-out in the chiller yard -> something Ski was doing earlier -> Opened valve -OK

Per a request of Jeff K, I made an additional update to the TMTS_MASTER.mdl, to add DAQ requests for the 6 ...M1_DAMP_*_IN2 channels. I then rebuilt and restarted h1sustmsy.mdl.

In the process I noticed that there were error messages being generated from the following lines in the safe.snap (these may have been there yesterday, see alog 6883, but I don't recall), so I manually edited the file and removed the second half of each line.

H1:SUS-TMSY_M1_DAMP_P_STATE_GOOD 1 H1:SUS-TMSY_M1_DAMP_P_STATE_GOOD 0
H1:SUS-TMSY_M1_DAMP_R_STATE_GOOD 1 H1:SUS-TMSY_M1_DAMP_R_STATE_GOOD 0
H1:SUS-TMSY_M1_DAMP_T_STATE_GOOD 1 H1:SUS-TMSY_M1_DAMP_T_STATE_GOOD 0
H1:SUS-TMSY_M1_DAMP_V_STATE_GOOD 1 H1:SUS-TMSY_M1_DAMP_V_STATE_GOOD 0
H1:SUS-TMSY_M1_DAMP_Y_STATE_GOOD 1 H1:SUS-TMSY_M1_DAMP_Y_STATE_GOOD 0

Chris Wipf then reported that sometime in the last few days, the setting for the alignment offset gains in the safe.snap had been reset to 1 (whereas they are supposed to be magic numbers that convert mrad of desired offset to counts of actuation). So I transplanted the following lines from an hourly backup from 6/20/13:

H1:SUS-TMSY_M1_OPTICALIGN_P_OFFSET 1 -8.950000000000000e+01
H1:SUS-TMSY_M1_OPTICALIGN_P_GAIN 1 1.583586000000000e+02
H1:SUS-TMSY_M1_OPTICALIGN_Y_OFFSET 1 1.899000000000000e+02
H1:SUS-TMSY_M1_OPTICALIGN_Y_GAIN 1 5.171050000000000e+01

The updated master model and safe.snap have been committed.

The assembly of the TMS ISC table is essentially done.
As far as I know, the only missing things to be installed are:

- everything related with cabling - pico cables, cable brackets, cable posts and cable ties
- one leg of the high beam dump 
- the optic (HR532HR1064, E1000425) for the bottom mirror of the periscope is ready to be installed, it is packed and labeled in one of the plastic bins under the ISC optics table at EX. 
- lens tags for the 1" lenses of the green sled (f = -56mm, I gave them to Corey)

Yesterday we finished doing the "coarse" alignment of the 532 nm and 1064 nm paths (a picture of the set-up will follow).
We also tested the QPDs.
To align the path from the beam diverter to the high power beam dump we used the green laser beam at full power.
The "fine" alignment will be done once the ISC table is mated to the transmon telescope.

Entry by Kyle,

Start  4.5 x 10-7 torr*L/sec

End 3.8 x 10-7 torr*L/sec

(Dick, Daniel)
The readback of the  IMC/PSL VCO was flaky. Today, we concluded that the 3rd and 4th channel on the timing comparator/frequency counter do not work very well above 40 MHz. We put the PSL on the 5th channel and it now is reliable. We were also missing about 20 dB of signal. This turned out to be the splitter mounted to the patch panel in the LVEA which was operated in the wrong direction. Fixing this gave us a signal of about 3 Vpp.

A new medm screen with name ALS_CUST_FREQUENCIES.adl has been created which list all the VCO frequencies as well as linear combinations describing the various beat notes.

Activites From Today

Aaron/Dominick running accelerometer cabling from H1 Elec Room -> H1 PSL Room

9:00 Hugh/Greg replacing BSC2 NE HEPI Vert Actuator Valve (will be invasive)

~11:30 Mark B will do model/channel work on EY TMS (this later required a DAQ restart by Barker)

Rogers Contractor here for Mechanical Room work (for Kyle)

Rodruck replacing Dust Monitor in Diode Room

Jim/Cyrus taking down FrameWriter0 (9:36am)

Robert with SURF student at EY

HIFO Investigations 1:20pm (Dick)

Chris W worked on lsc & isc models in the afternoon

h2 isi storage dewar filling (Greg)

Sheila is working at EY in the afternoon

Maintenance: 

• Paradise Water
• Liquid Nitrogen to MY (CP3)
• Pallet Pick Up around 3:30pm

 RGA data from HAM 3:

Attached plots are:

HAM3 RGA only - RGA prior to opening any valves to the system - this is "as found" after starting the 2l/s ion pump on the RGA tree after moving from ENDY to the LVEA.

HAM3 RGA + T - Kyle and I installed a T fitting beween the RGA and the 10inch gate valve so that we could evacuate the "dead space" prior to opening to HAM3. This required opening the all metal 1.5 inch valve on the RGA tree.

HAM3 RGAall - this is with the RGa open to HAM3  - ie the 10inch gate valve was opened. The total pressure at HAM3 is estimated at  3 e-8 torr.

From the plot HAM3 RGAall the relative ion currents and partial pressures for some amus are:

amu 2 - 1 e-9 amps   ~5e-9 torr

amu 18 - 3e-10         ~9e-9 torr

amu 28 - 2e-10         ~ 6e-9 torr

amu 41 - 1.8e-12       ~ 5e-11 torr     corrected these values x10^-1

amu 51 - 1e-12          ~3e-11 torr

amu 69 - 5e-13          ~1.5e-11 torr

Assume that the total pressure = 0.5x amu2 + amu18 + amu28 you get a calibration of 1 amp = 30 torr.

For all these measurements the small 2l/s ion pump registered 3.8 mvolts or 0.038 milliamps ion current.

I am uncertain of the SEM voltage in these scans as the software appears to let me change the voltage and yet the plots look identical.

Note that the calibration gas of the RGA tree appears to be open to the system but it is not - the Nupro valve has been damaged and no longer seals completely.

This is a 2 hours trend when the end PDH signal was offloaded to the BSC6 HEPI yesterday (see alog 6862).

This worked good so far --- the end laser stayed locked for more than an hour without an obvious sign of misalginment.

Although we do see drift in the ETMY oplev signal as the amount of the offload increases. Since the alignment of the arm stayed good, this could be a longitudinal to angle coupling of the oplev itself.

The TMTS_MASTER.mdl has long had an error whereby the slow channel giving the text label for BIT4 of the ODC word was called H1:SUS-TMSY_ODC_BIT6 or the like. This caused the text field opposite BIT4 in the SUS_CUST_TMTS_ODC.adl screen to show white.

I fixed the master model and rebuilt and restarted h1sustmsy. I also manually edited the safe.snap file, changing _BIT6 to _BIT4, and confirmed that the old BIT6 value was being correctly applied to BIT4 on a BURT restore.

I committed the new master model and the new safe.snap file. Although the change didn't involve any channels being written to disk, David Barker restarted the DAQ as a precaution.

LLO should also apply this fix. Any scripts that initialize the ODC bit labels should be rewritten to no longer work around the error.

This is the current setup for our PLL-based frequency sensor and this reads out the beatnote of the green light at the vertex serving as a CARM sensor currently.

Here is a measured open loop transfer function of the PLL :

Some parameters and notes:

• UGF is at 60 kHz
• VCO DC response was measured to be 285220 Hz/V by a measurement with the IFR signal generator
• PFD coefficient was found to be 45 deg/V according to my eyeball fitting
• The was a phase lag which can be modeled by a delay of ~ 1.5 usec.
• The in-loop SR560 has
  • gain = 5, pole 300 kHz and another pole at 300 kHz
• The out-of-loop SR560 has
  • gain =10, pole at 100 Hz

These model parameters were used for calibrating  the analog CARM signal described in the previous alog (see alog 6878).The raw data is also attached.

Giles report from yesterday's work:

(Travis, Mark, Jason, Doug, Giles)

After leaving the PUM hanging overnight there was no further development of the crack. We then proceeded to re-lock the PUM and hang the ETM to perform modal measurements. Using the autocollimator we measured the longitudinal, pitch and yaw modes. We then setup and optical lever to measure the transverse, bounce and roll modes. Finally we measured the 4 fundamental violin modes. The modal data gathered was:         

Longitudinal    0.656 Hz

Pitch  1.09 Hz

Yaw  1.09 Hz

Transverse 0.656 Hz

Bounce 6.75 Hz (this will be sqrt(2) higher when the PUM is free)

Roll 9.6 Hz (this will be sqrt(2) higher when the PUM is free)

FR  505 Hz

FL  506.5 Hz

BR  506.5 Hz

BL  505 Hz

We finally installed the fibre guards and covered the entire lower stage.