HAM6 alignment - VICTORIOUS!

Alexa Dan Fil Keita Koji

This afternoon we brought the second of Koji's three OMC children under control.

After working in the morning to understand the quadrant layout of the OMC QPDs, we were able to close simple diagonalized versions of the OMC QPD alignment loops to stabilize the beam in the chamber.  With Fil's help we enabled the high voltage to the PZT driver (in the process finding a cable that was plugged into the wrong slot on the AI chassis).  Before fiddling with the high voltage we checked that the HV readbacks were working as advertised.  We were able to drive the high-voltage PZT in a triangle wave across its entire range (0 -> 100V) and see flashes in the OMC.  We tried to improve the alignment by watching the flashes and searching for a clear 00 mode, but this turned out to be fruitless, probably because the beam is moving too much.

We proceeded to align the rest of the beam paths on the HAM6 table: OMC REFL QPDs, AS WFS, and the OMC REFL beam through the viewport.  For a while we were confused by a mirror on a too-short pedestal; Keita showed up at a lucky moment and fixed it.  The beam has been aligned onto all of the QPDs in the vacuum.

We should be able to lock the OMC tomorrow and study the alignment (and, possibly, take a first stab at the mode matching).  At the moment, the beam is moving a lot in pitch; this motion is due to something upstream of HAM6.  We suspect SR3 and the ISI table in HAM5, but it could be something else.  This motion really needs to be fixed before any robust OMC locking can happen, either by stabilizing the source or constructing a more robust OMC QPD servo.  While we flashed the OMC Koji was able to visualize the modes inside the cavity, and the 00 mode was there.

Before leaving the chamber we relieved the yaw and pitch bias on the OM tip-tilts and centered the OSEMs, and then clamped the tip-tilts to the table.  The TTs are in good shape.  One of the OM3 OSEM cables can potentially slip and block the beam to the AS WFS, we should find a way to clamp this cable in a safe place.

Tomorrow we need to install the kapton washers on the pico drivers.  We still need to align the OMC TRANS path, but we probably have to lock the OMC on a fairly strong 00 mode in order to see the beam.  In principle OMC TRANS can be aligned after the north door is installed.

Now that we have a beam we can do RF balancing of the AS WFS, if that's necessary.

We'd like to try to put the north door on HAM6 by the end of the day tomorrow.  Two other things need to happen before we can attach the door: cable dressing and table balancing by the SEI crew, and a check for ground loops.  (These steps may need some iteration if the ground loop situation is bad.)

For now the purge air has been turned off to give the mirrors a rest.

end X FMCS readbacks invalid

It appears that the end X FMCS EPICS readbacks went invalid at around 08/19/2014 23:35 UTC (from a trend of H0:FMC-EX_VEA_202A_DEGF). I checked the FMCS Windows computer and they appear to be down there as well. I'm not sure how to fix this, so I will email John.

J. Kissel, J. Worden

John called and suggested we reboot the FMCS machine in the back of the control room. After 20 minutes of windows updates, I was able to log back in, but the status of the X-end did not change. We're both unsure if there's any program to be restarted, but John thinks not. The in-vacuum components (SEI / SUS), nor to the ground instruments (T240 / BRS / PEM) and other PEM instruments show no sign of bad news, and the vacuum pressure looks reasonable, so we assume this is just a failure of the readback system. John will look into the problem when he's back in on Friday.

This is a known issue with the network hubs that are used in the mechanical room to connect the FMCS controller to the network (along with a couple other systems); they are flaky after power outages, and just in general.  In this case, I changed out the hardware since it's been flaky over the past few days and the usual power on/power off thing didn't clear it up today.  The long term fix is to pull more cable so that these things can be directly connected to a real switch.

P.S.  Only the vacuum system shares any common infrastructure with FMCS - the operation (or non-operation) of any 'fast' front end EPICS system is not a useful indicator for problems limited to either of these (vacuum/FMCS).

Reverted to Turbo Pump at Y-End

I closed the gate valve for the ion pump @ 4:40 pm today. Turbo pump gate valve was opened a few minutes later.

Test mass charging measurements

Borja, Sheila, Gerardo

As per original plan, and after taking another set of charge measurements in X and Y, today at about UTC 2014-08-20 23:00:00 we turned on the green laser light with a measured power of 57.5mW going into the periscope that injects the beam into the ETMX chamber. In parallel Gerardo turned on the turbo pumps in ETMY and closed the gate valve of the ion pump.

CDS model and DAQ restart report, Tuesday 20th August 2014

model restarts logged for Tue 19/Aug/2014
2014_08_19 08:56 h1isietmx
2014_08_19 12:00 h1susetmy
2014_08_19 12:00 h1sustmsy
2014_08_19 16:33 h1hpibs
2014_08_19 16:33 h1iopseib2
2014_08_19 16:33 h1isibs
2014_08_19 16:35 h1hpiham4
2014_08_19 16:35 h1hpiham5
2014_08_19 16:35 h1iopseih45
2014_08_19 16:35 h1isiham4
2014_08_19 16:35 h1isiham5
2014_08_19 21:37 h1dc0
2014_08_19 21:38 h1dc0
2014_08_19 21:42 h1dc0
2014_08_19 21:43 h1broadcast0
2014_08_19 21:43 h1fw0
2014_08_19 21:43 h1fw1
2014_08_19 21:43 h1nds0
2014_08_19 21:43 h1nds1
2014_08_19 21:46 h1dc0
2014_08_19 21:47 h1dc0
2014_08_19 21:48 h1broadcast0
2014_08_19 21:48 h1fw0
2014_08_19 21:48 h1fw1
2014_08_19 21:48 h1nds0
2014_08_19 21:48 h1nds1

maintenance work on ISI ETMX and SUS ETMY. Unexpected restarts of SEI B2 and H45. Restart of DAQ following maintenance.

green laser on at end X

Borja, Sheila

We turned on the laser at end X, so that Borja can do a charging measurement after having green light on for 1 day.  To do this Rai would like 50mW of 532nm light on the optic.  When we turned on the laser the setttings were 1.843 Amps 31.8 C  and for the SHG crystal 33.83 C (set value 33.81C). We measured 54 mW of green out of the laser and 34 mW going into the chamber.

Borja adjusted the doubling crystal temperature to 33.53C actual value (33.51C set value) and the power going into the chamber increased to 38.5mW. 

Borja then turned the laser current up to 1.912Amps and the power going into the chamber stabilized at 57.5mW.

We plan to reset the current to the old value after the charging measurement is done, but leave the doubling crystal temperature at this setting.

IMC cavity pole: comparison of the IMC locking open-loop TFs

In order to figure out what is going on with the IMC cavity pole, I made a comparison between a recent and past IMC open-loop transfer functions.

If the cavity pole really dropped to 7.7 kHz from 8.8 kHz, this would cause a measurable change in the open-loop transfer function. According to the comparison, I did not see a large change. This result supports the hypothesis that the IMC cavity pole stayed (almost) the same.

---

The plot below shows the IMC open-loop transfer functions: one is taken yesterday shown in in blue, and the other was measured on February 7th with the same servo board configuration but with a higher laser power.

As shown in the plot, they look similar to each other except for the gains. The difference in the gains must be due a combination of the different laser power and non-carefully adjusted gain on the IMC servo board. In addition, there is a large discrepancy at high frequencies above 80 kHz, but this is pretty much out of our interested frequency band. So we don't care about it.

* * * *

If the cavity pole really dropped from 8.8 to 7.7 kHz, this would decrease the response above 7.7 kHz by about 12 % in amplitude and also give an extra retardation in the phase by 3-4 degrees at around 8 kHz. In order to check if there is such change between the two transfer functions, I took a ratio of the two TFs -- the plot below shows a transfer function of (recent TF) / (past TF).

Even though the data does not look super smooth, we can already see that there is no 12% drop above 8 kHz in the amplitude or no 3-4 degrees retardation in its phase at around 8 kHz. It rather looks as if the IMC stayed almost the same since February. Also I am attaching a matalb fig file of the same plot in case somebody wants to play with it.

Ops shift summary

08:33 Tim to EY for B&K cleanup

09:05 Sheila unlocking PMC momentarily

09:45 HAM6 crew to work

09:59 Krishna to EX to check pressure

10:04 Jason to LVEA for SR3 OpLev work

10:19 Gerardo to EX to swap power supply for ion pump

10:50 Andres to LVEA on parts hunt

10:56 Tim to LVEA to check for parts

11:20 Jordan, Paul, and Sudarshan to EX high bay

12:35 Krishna to EX CER

13:51 Jordan, Paul, and Sudarshan to EY high bay

14:30 Jason starting work on HAM3 OpLev

15:05 Dave restarting DAQ

15:06 Borja to EX to turn on green laser

15:57 Jason out of LVEA

DAQ restart , EDCU is now green

I restarted the DAQ to fix a duplicated IOP ini file entry in the master and reinstalled the H1EDCU_GRDLITE.ini file (minus duplicated channels which I accidentally added yesterday). The EDCU is now GREEN, and if it goes PURPLE we should investigate the cause.

IMC visibility and MC2 trans seem fine

Since we have been struggling to understand our measurements of the IMC cavity pole, I had a look at the power in different ports of the IMC.  

The IMC visibility is 96%.  

MC2 transmitts 1.3mW, where 1.4mW are expected

Paul calibrated the MC2 trans QPD in uW ( alog 9716), there is a 90% splitter between the QPD and MC2, so with the QPD sum at 127.7uW-1.4uW dark offset we have MC2trans=1.26mW.  With 1.622Watts input power (measured by PSL periscope PD) we expect 1.622Watts *166( expected IMC build up)*5.1e-6 (MC2 transmission)=1.4mW

The cavity pole measurement (alog 13381 ) would indicate that the IMC build up should be 178, (instead of the expected 168)  which would require the transmission of MC2 to have decreased to 4.2ppm. 

The IMC throughput is also OK, based on Kiwamu's IM4 trans measurement yesterday (alog 13495 )and assuming the input Faraday has 3% losses, we have an IMC throughput of 90%.  If the cavity pole measurement were correct this would require MC3 transmission to have dropped from 0.58% to 0.48%.  

The simplest explanation here seems to be that the cavity pole measurement is wrong, and that the IMC hasn't changed.  

 

moved IM4 trans pico for centering

I centerred the IM4 trans QPD in HAM2 using a picomotor. I moved it from (X,Y) = (0, 0) to (500, 19000). Before I centered it, the beam was not hitting the segment 1 and 2.

Also, I plugged the IO_CAB_243 (see D1200666-v11) to the first input of the picomotor controller box #5. This cable had been disconnected for some reason.

HAM6 alignment - morning report, some progress

Alexa, Dan, Koji

Using a laser pointer we were able to verify that the four quandrants on each OMC QPD were behaving correctly.  We found that the diodes were rotated 90deg from the expected orientation.  Koji says this should not be possible given the pinout structure of the diodes, maybe there's something in the cabling between the diode and the ADC.

With confidence in the diodes, we used OM2 and OM3 to walk the beam through the OMC.  We observed that the flashes we saw on QPDA yesterday were due to some terrible clipping of the main beam inside the OMC, and using a card and IR viewer we were able to bring the correct beam into the QPD path and center the beam on the OMC QPDs.  Success!  The sliders on OM2 and OM3 are in the hundreds of counts, which is not terrible but needs to be offloaded eventually.

Right now the beam to the OMC cavity is off in yaw, and the OMC REFL beam is too high in pitch, enough that we can't compensate with the mirrors on the table.  We may need to adjust the fixed steering mirror (in a lens holder).

We are close to using the OMC PZT, so we'll need the high voltage to be enabled.

mDV function called

J. Kissel

Krishna tried using Brian's 
/ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/asd2.m
function, which requires a prior version of the function,
/ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/asd.m
however, using the controls account, he ran into problems with a shadowed function in the mDV directory:
/ligo/apps/linux-x86_64/mDV/extra/asd.m
which is also in the control matlab path (because we need that directory for other useful mDV tools).

As such, I've moved the mDV function,
/ligo/apps/linux-x86_64/mDV/extra/asd.m
to the same location, but with a different name,
/ligo/apps/linux-x86_64/mDV/extra/asd_mDV.m
It's unclear whether anyone uses this function, but to those people, I'm sorry ahead of time. This directory is not under any sort of repository or version control, so this only changes LHO's local copy of this function. More apologies. 

This merely reiterates a point recently made that someone needs to maintain and support a library of semi-basic Matlab functions used regularly by commissioners, like asd2, get_data, tfe2, coh2, get_schroeder_tf, autoquack, specexplain, sos2freqresp, readFilterFile, vectfit, etc.

One suggestion had been to import all the 40m stuff under mDV in their CVS.  However, this included several MATLAB functions that had identical names to ones in the standard MATLAB libraries. This was why we did not include these at LLO. So we need a repository (likely scrubbed by CDS sys-admins) to hold these (and of course a standard directory for links, as we have for scripts, Perl, etc.)

H1 EX BRS Installation, Day 13: More plots

J. Kissel, K. Venkateswara

The ion pump current this morning was 0.25 mA, which should correspond to a pressure of ~ 5E-7 torr. Looks normal so far and the low pressure should ensure a long lifetime for the pump (~ 5 years).

The data from Tuesday night looks quite good. Unfortunately, we forgot to reset the filters FM1 and FM2 (described in alog 13448 ) for the transfer function correction. This is why the BRS/tiltmeter resonance is visible in Tuesday nights data.

The first plot of the first file shows the ASD of the reference mirror, BRS, STS and the PEM Guralp seismometer. The plot below it shows the coherence between BRS and STS. The wind speeds were about ~ 10 mph.

The second file shows a comparison of the ASD's from Monday and Tuesday nights for the BRS and the STS. There is a clear elevation of the noise floor between few mHz to ~ 0.6 Hz on Tuesday compared to Monday.

3rd IFO AA/AI Filter Board Updating & Voltage Regulator Modification

All known AA/AI & Whitening chassis that are currently stored in the "H2" building have been opened up and inspected for version6 filter boards. Those with less than version6 that can be updated have been removed and stored in bins in the EE Lab until further action can be taken. A number of filter boards that are marked version5 and then removed to find version6 mods have been done already, have remained removed and a great deal of these boards are being shipped to LLO. Approximately 306 boards have been removed in total for update. It is my understanding that there are some much earlier revisions that may not undergo this modification. There are currently approximately 223 boards in 64 chassis that remain intact for India. All AA/AI & Whitening chassis, regardless of filter board status have received new insulation for the Negative side of the +/- 5V regulator modules.