Filiberto, Kiwamu (WP4816)

We have installed three analog cameras that are going to monitor the signal-recycling mirrors (i.e. SR2, SR3 and SRM) on HAM4 and HAM5. We put a good TV lens on each of them and adjusted the aperture and focus.

The detailed location of the cameras are described in the viewport final design document (page 54 and 55 in DCC-T1000746-v7) and we followed it.

no restarts reported.

Maintenance: Reset HEPI overflow counters for HAM2, HAM3, HAM4, HAM5, ITMX, and ITMY 

 Attendees: Gerardo, Filiberto, Keita, Koji, Kiwamu, Jim, Jeff B, Ed, Peter, Justin, Aaron, etc …

Today's Tasks:

•	Viewports installation on HAM6 – Gerardo
•	Running power cables for illuminators and analog cameras in LVEA – Filiberto
•	SR3 Optical Lever work continues in LVEA - Jason
•	Cameras installation on SR2, SR3, and SRM (LVEA) - Filiberto
•	Dust monitor work in LVEA – Jeff B
•	ISC table to be moved (LVEA) – Keita
•	Cable pulling all around the LVEA – Aaron
•	Moving 3IFO (Quad#8) to its proper location in LVEA – Jeff B

The performance of the intensity stabilisation servo (ISS) will not be measured this week due to some problems with the servo.  I am not sure what the cause of the problems are but the servo has
problems locking.  The diffracted power as indicated in the MEDM screen, switches between two states, regardless of whether the servo is attempts to lock in either automatic or manual mode.

The relative power noise measurement is close to the reference measurement.  It is slightly better below 10 Hz and slightly better above ~5 kHz.  Both are well within the requirement for the laser.

Both the control and error signals in the frequency noise measurement are better than the reference measurement.  The error signal looks strange below about 60 Hz with a number of steps present.

The beam pointing measurement is not as good as the last one performed on August 12th, with the 1x and 1y error signals being a factor of 3 higher.  The control signal in both cases is about the
same as the previous measurement.  The power incident on the reflection photodiode is about the same.

The mode scan does not look all that different from the previous two scan measurements.  The relative peak heights look the same to the eye.  The higher mode content has increased by 2%, with the
higher order mode power increasing by 0.2%.  The cavity finesse is the same within the errors.

I checked the Crystal Chiller this morning. The water level was fine.

Borja

Yesterday's results in ETMX although positive from aLIGO operation point of view (no charging mechanism was observed based on green light and ion pump) however it was discouraging from the point of view of providing answers to the big charge changes that were observed in ETMY. If the ion pump was not charging the mass then what was doing it? Is this unexplained behaviour in ETMY charge changes casting a shadow over the charge measurements methodology? Fortunately a new set of measurements in ETMY that were taken during the experiments at ETMX confirms that the measurement method is reliable and it also tells us what is charging ETMY. For a period of 62 hours 6 charge measurements were taken on ETMY, for all these measurements the ion pump gate valve was closed. The results are remarkable in their consistency and stationarity of the charge values for all quadrants and for both orientations (pitch and yaw) within no more than 20Volts (less depending on the quadrant and orientation). The charge values agree with the last measurement taken just before closing the ion pump gate valve.

The amount of measurements make it impractical to show a summary table like in my previous aLog so this time I go for a more friendly graphical display. As always attached are the measurement documents and the standard VBIAS vs normalised deflection plots comparing each measurement with the ion pump gate valve closed with the first one, and the first one with the one previous to closing the valve.

So what is different between X and Y regarding the charging effect of the ion pump? mainly 3 differences:

1) The Earth magnetic field

2) The pressure being different by an order of magnitude. The pressure in end-X is 2.7e-7 torr while in end-Y is 4.8e-8 torr. A higher preasure will reduce movement of the ions, but at the same time the higher the pressure the more charge is emitted by the ion pump (see attached document "charged_particle_emiss_ion_pumps.pdf").

3) Both ion pumps were costume made to the same specifications. They are made of 50 smaller ion pumps so maybe the way these were configured is different for each final ion pump.

Next I show the summary plots of all measurements taken so far both for ETMX and ETMY. Each mass has 2 set of plots; Veff and slope of normalised deflection vs VBIAS. Each set of plot is divided in 2 subplots, one per deflection orientation (pitch and yaw).

ETMX:

ETMY:

The numbers in the plots represent the major changes that took place at the time of the measurements. These are summarised next:

1) 1st ionizer discharge.

2) 2nd ionizer discharge.

3) Wire swap to right configuration: BIAS going through the ESD LP filter box.

4) Wire swap to wrong configuration: LL quadrant driver going through the ESD LP filter box.

5) Wire swap to right configuration and Final: BIAS going through the ESD LP filter box.

I saw the measurement status indicator blinking in the SRM screen, but no excitations. According to trend, this has been on all the time in the past three or four days. So I assumed that this is something Arnaud forgot to turn off and therefore I switched it off.

I have spent some time today trying to get decent interferometer alignment.

The goal today was to get good PRMI alignment while maintaning the POP beam at ISCT1. I could obtain good alignment only in pitch. The yaw alignment still needs to be touched up. 

(background)

Even though we managed to get the POP beam extracted at ISCT1 (see alog 13547), this resulted in bad alignment in the PRMI.  We basically could not flash the PRMI without loosing the POP beam if we touch a single optic to align the PRMI. So a combination of some optics needed to be touched up.

(What I did)

Since the Michelson had been already (kind of) aligned, I assumed that ITMX is well-aligned. Also, I assumed PRM and IM4 to be already aligned (this may not be true -- I should have carefully checked IM4 and perhaps other IMs). Under these assumptions, I tried to aligning PRX. Note that I misaligned ITMY and BS during the process. I touched PR3 and PR2 in pitch to find an optimum alignment. Doing some iteration, I got a good alignment. The attached is the resultant alignment. This alignment maintains all the signal ports including REFL, POP and AS. However, since only pitch is optimized, this configuration does not allow the PRMI to flash yet. In order to flash the PRMI, one needs to steer yaw of some optics. For example, one can change yaw of PR2 from 3640 urad to 2179 urad to flash the PRMI. No pitch adjustment is required.

Also, I tried the same iteration process in yaw. But this did not seem successful for some reason. As I aligned the combination of PR2 and PR3, it seemed that the beam started hitting the right hand side of the PR3 cage. And indeed the amplitude of the demodulated signals decreased at REFL. The work continues.

~1610 hrs. local -> Began pumping HAM5/6 annulus 

model restarts logged for Sun 24/Aug/2014
2014_08_24 06:26 h1fw1

unexpected restart of h1fw1

I locked and unlocked the ISI to confirm it's position shift remains in spec, it does.  While locked, I unbolted three of the 10kg masses and set them on three 1/2x1/2x1/8" viton.  The position on these damped masses is on the as-built redline I have added to the D1201388 DCC record.

0845 - HAM6 close-out work. Hugh, Kiwamu and Keita verifying all cables properly grounded and doing final survey for class B tools and parts

900 - LVEA transitioned to laser SAFE by Keita/Kiwamu for door hanging and crane work.

1000 - Kyle, Gerardo prepping for hanging N, S doors on HAM 6.  Removing viewport emulator.

1011 - Jason working on SR3 oplev

1030 - Besty working in West Bay LVEA

1038 - Christina/Sudarshan working at EX

1225 - Patrtick working on Conlog...system offline

1250 - Conlog recovered

1310 - Doors going on HAM 6

The upgrade of Conlog from 2.0 to 2.1 is done. This completes work permit 4810.

This required an approximately 35 minute gap in the recorded data from around 12:21 to 12:56 PDT.

The data recorded prior to the upgrade was backed up in /ligo/lho/data/conlog/h1/backups/h1conlog_dump_25aug2014.sql.tgz.

Keita and Kiwamu

In order to investigate the large cross coupling issue in OMs (alog 13575 by Dan), we checked the OM driver electronics.

We found that the OM1 and OM2 coil driver Vmon are not properly functioning. However, this does not explain the cross coupling that Koji and Dan experienced.

Anyway, these two coil driver chassis (S1200614 and S1200612) need to be swapped at some point.

(some details)

When we started looking at the OM screens, we immediately noticed the LL voltage monitor of OM1 and OM2 displaying anomalously high voltage while the zero DAC voltage were requested. OM1_LL showed approximately 23000 cnts and OM2_LL showed approximately -23300 cnts. Even so, these channels were still sensitive to the bias we sent through the DAC -- we could change the readout values by changing the biases. But they did not go to the other sign in the readout voltages.

We then went to the electronics room to check out the analog circuits. Looking at DB9s' signals for the Vmons by inserting a 9-pin breakout board, indeed we saw LLs exhibiting a funny voltage. LL of both OM1 and OM2 were at -14 V when the zero DAC voltage were requested. Then we went to the AS port rack to check if this is also the case for the actual drive signals. However the drive signals looked healthy on both OM1 and OM2. We checked this by looking at the signals at the input of the satellite amplifiers. All the signals could swing from -22 to 22 V as we changed the DAC voltages.

We are concluding that the Vmon part is not properly functioning in the OM1 and OM2 coil drivers. But, since the actual drives are healthy, this issue is independent of the cross coupling issue.

By the way, the OM3 coild driver looked healthy and its Vmon looked fine. So we did not check them.

Borja

It has taken me quite a long time to process all the data I had on the several experiments that were run at ETMX as suggested on my previous Log. It is late already and I still have to think about how to plot all the data in a more friendly way (probably tomorrow). But here goes a quick update.

As a reminder, ETMX charge measurements showed relatively small effective BIAS voltages which translates into relatively low charge. This charge probably were left overs from the process of removal of the "first contact" 1 month ago when End X was vented. Several charge measurements taken over a period of 4.5 days showed consistent charge values (within 25Volts or so) in all quadrants in pitch and yaw as shown in the next table:

ETMX was an ideal test bed because I saw no issues with the wiring (all quadrants could be driven) and there were no illuminators On, the ion pump had the gate valve closed and the only known charger that was active (for a long time) was the cold cathode at the top of the ETMX chamber. Although the consistency of values above may discard it as an effective charger for the test masses. Two main charge experiments took place with mass in the last few days:

1) Green light charge effect: Between UTC 2014-08-20 23:00:00 and UTC 2014-08-22 20:45:00 the green laser was turned on at ETMX at a maximum power of 57.5mW going into the periscope which translated to 46mW actually hitting the test mass. This is a factor of 4.5 below the expected resonant power during future normal operation of aLog (about 35mW from laser into ETM and with a finesse of 12 it means a power build up of 6) but it is the maximum I could get from the laser. Here is the summary of the measurments that took place for an interval of 46 hours. It is clear that no charging trend is observed and the change in effective voltage of less than 20V is within the normal deviations of the measurement method accuracy. The fact that green light does not seem to charge the mass is certainly good news.

2) Ion pump charging effect: After the green light was turned off in End-X, we opened the gate valve of the ion pump to see its charging effect, the gate valve was opened at about UTC 2014-08-22 20:40:00 and again we measured three times for an interval of 37 hours. The summary table is given next:

In this case also the effective voltage variation is within the 20Volt resolution with the exception of two quadrants (LL and LR) we observed in the middle measurement (in blue) a considerable votage difference with the measurements that took place before and after although only obvious for one of the deflection orientations (Pitch for LR and Yaw for LL). The fact that the increase in effective voltage took place in the middle measuremnt and then went back down may indicate that the charge change is not real or that a complex mechanism of charge dissipation or cancellation took place after the charge. I will run another charge measurement tomorrow to see if there is actually a charging trend but why would only be isolated to those quadrants?

yesterday we noticed that ITMX has been tripping, it seems to happen within a minute or so of becoming fully isolated.  HEPI seems to have position loops running, there is no feedback from ISC to the suspension or HEPI.  The last few trips have been just stage 2, actuator trips.  It looks like something is ringing up.

The stage 2 blends were on Tbetter expect RZ, which was on Tcrappy for the two trips plotted in the first screenshot attached.  I've tried setting stage 2 blends to start, this also caused a trip which is the second attached screenshot.

Now I have set the guardian to isolated_damped, so that stage 1 is isolated and stage 2 is damped.  So far its not tripped.