RPN: 35W- no change

        200W- no change    

FRQ: 35W- no change from 10Hz to 1K. Control signal is better than last week from 1-10Hz. Error signal higher at HF.

        200W- no change

PNT: 35W- no change

         200W- no changes to speak of. High peaks at 100Hz, 1K and HF noise.

MSC: 35W-  no change. TEM₁₀ looks a bit high. HOM power and cts are down marginally from last week

        200W- no significant change. Plot actually looks slightly better than last week despite no adjustments. Errors during measurement can be seen in the .pdf below.

Gerardo, Marc

We tested the HV Ion Pump cable at the Y end station with a DMM and the Fieldfox this morning.  After pulling the cable out of the conduit we found damage on the cable about 17m from the connector.  The damage is electrical in nature and is about where the Fieldfox predicted, see image. 

We did find another scorpion, this time on the toolbox inside of the Y end station VEA.  Watch where you put your hands, Gerardo almost grabbed it looking for a screwdriver.  Gerardo thinks it got in through the ceiling light fixture.

~1115 hrs. local 

Opened exhaust check-valve bypass-valve, opened LLCV bypass-valve 1/2 turn -> LN2 at exhaust in 2 minutes 2 seconds -> Restored valves to as-found configuration.  

Next CP3 overfill to be Friday, Aug. 5th.  

(Betsy, Corey, Keita, Koji & also some photos by Richard M)

Following up on alogs from Keita & Koji, photos from yesterday's work has been uploaded to resourcespace and can be found here:

https://ligoimages.mit.edu/?c=1696

(There's 91 photos.  I did not upload blurry photos.)

I'm attaching highlight photos to this alog & they are roughly numbered in the order taken:

1. M14 (was removed to blow particle off)
2. Fingerprints on NW corner of shroud
3. V-beam Dump (on/near QPD sled on northern part of table) with major damage on both pieces of glass
4. Burn hole at entrance aperature on the shroud glass for OMC
5. Photos of damage on V-Beam Dump after pulled out and on inspection table.
6. Photos of damage on V-Beam Dump after pulled out and on inspection table.
7. Photos of damage on V-Beam Dump after pulled out and on inspection table.
8. Action shots of Betsy/Koji & OMC removal
9. Action shots of Betsy/Koji & OMC removal
10. Action shots of Betsy/Koji & OMC removal
11. OMC PZT mirror with burn mark
12. OMC PZT mirror with burn mark
13. Particle contaminants on OMC Breadboard
14. Delaminated epoxy on one of the "tomb stones"

Note pressure spikes in HAM 6 chamber leading up to OMC failure reported on July 27th. Attached are two trends: 1) pressure between two vents April - Aug; 2) zoomed in with dates annotated.

   Posted are the particle count data from the door removal during the HAM6 vent. No serious contamination issues were encountered during the door removal. It appears the north side of the HAM6 area is dustier than the south side. This could be caused by a variety of factors (such as the ITO table on the north side makes it more difficult for the cleaning crew to access this area.)

   Trend data from the permanent dust monitor at HAM6 over the past 48 hours shows no reasons for concern. 

   In general, the area in and around HAM6, as far as contamination control, is in good shape. Kudos to Christina and Karen for all their hard work and dedication to keeping LIGO's contamination sensitive areas very clean.           

Jason, Nutsinee

Yesterday we replaced the RF driver with a spare hoping it would fix CO2Y power dropped issue (alog28506). CO2Y laser is now a Schrodinger's cat -- we won't know if the new RF driver fixes the problem until we get to lase the laser again after HAM6 work is done.

Procedure

First we shut off the chiller and TCSY power supply. Then we unplugged the power cable, BNC cables, cables from splitter box, and chiller hoses. Since none of the cables were labled, the cables from the splitter box weren't necessary plugged back in to where they used to be (all the output should be the same) but the BNCs cables were plugged back in the same way. Particulates were seen inside the chiller hoses and later got flushed into the system when we restarted the chiller.

Posted below are the past 10 day trends. I don't see anything of interest apart from the DB3 current for the HPO showing 100A (incorrect/known issue).

As usual, for more in depth analysis refer to Jason O or Petet K. For chiller specifics, Jeff B is the man.

Relevant HAM6 vent alogs:

alog28825

alog28823

alog28820

alog28811

SEI - HAM5 having some issues, investigating

CDS - Continuing cabling.

    Mystery solved (see alog28826) from after the timing chasis upgrade. Procedure to come. If needed to power up/down an IO chasis, definitely need a WP and make it clear what you will be doing.

    Digital video displays are currently broken, work is in progress.

PSL - Tweaked FSS yesterday, diffracted power for ISS was off previously but is now fixed (this should be around 3% now).

Vac - Ion pump on Y28 is currently down.

Facilities - No safety meeting today.

    Laser enclosure in North Bay of LVEA is being broken down.

Michael, Krishna

Summary: Compact-BRS is deployed in the 'bier-garten' area, next to ITMX, photos attached. The instrument survived the drive unharmed and the electronics appear to be working correctly.

Details: Compact-BRS consists of a cross-shaped, 30-cm-long beam-balance whose angle is measured by two fiber-optic interferometers. The instrument is housed in a glass, vacuum-bell-jar, which has been gold-coated to reduce stray forces from charges. The vacuum pressure has not been low enough to run on the Ion pump for long periods, so we will test it's sensitivity without vacuum. We expect that it's sensitivity at high frequencies will not be affected despite not being in a vacuum.

With Jim's help, we cleaned the instrument and moved it in to the LVEA yesterday. Today, we opened the bell-jar, unclamped the beam-balance and lowered it on the flexures. It needed some minor mass adjustments but was soon balanced and working normally, with a ~19 second period.

After Fil and Mark made us the power cables, we powered up the electronics and the laser (10 mW, 1310-nm, DFB diode-laser) and connected the fiber-optics to the instrument. The PD output looked normal indicating the optical cavities were still well aligned. Tomorrow, after the input/output cables to CDS are pulled, we will start developing control/damping filters.

New PI code

Kiwamu, Dave:

Kiwamu installed new h1omcpi and h1susprocpi code. DAQ was restarted

New NGN code for CBRS

Krishna, Chris, Jenne, Jim, Dave:

Jenne added a CBRS component (Compact BRS) to h1ngn. We discovered a conflict with DAC channel allocation, so for now the new code is not driving DACs. Tomorrow we will swap DAC channels between h1pemcs and h1ngn. DAQ was restarted.

Timing FPGA upgrade at EX

Daniel, Ansel, Jim, Dave:

Daniel installed the latest FPGA code on the fanout at EX. This required a power cycle of the front end computers. We did not power cycle irig-b, comparator or RF amps.

Investigation into strange signal behaviour seen during timing upgrades

Daniel, Hugh, Jim W, Ansel, Patrick, Jim, Dave:

A reminder, during the timing system upgrades on 19th May 2015 and 19th July 2016 we saw surprising behaviour of HEPI fluid pressures (they appeared to quickly increase) and the vacuum cold cathode gauges (they saw a slight increase over a long time base of several hours).

To investigate this further, we powered down the EY front ends and went through the same power sequence as we followed during the 19 July upgrade. We quickly found that when the IO Chassis for h1seiey was powered up (with the h1seiey computer powered down) the hepi pump controller reported an increase of the hydraulic fluid pressure from 80 to 107 (as was seen May 2015 and July 2016). We powered down the IOC chassis and all AA and AI chassis. We powered up the IO Chassis and then, one at a time, each AA and AI chassis. When we powered up the AI chassis for the first DAC, the problem reappeared. This DAC is used by h1hpietmy model to drive the HEPI Valve Controller chassis. At this point it was looking more like a real fluid pressure increase. This was confirmed at EX during the timing upgrade by viewing the mechanical fluid pressure gauge attached to the pump station, it reported the increase in pressure from 80 to 115.

The sequence is (from a fully powered down state): the IO Chassis is powered up, the fluid pressure increases over several seconds from 80 to 105. When the h1seie[y,x] computer is powered up, the pressure drops immediately at the time the power button is pressed (before the OS is loaded and any models are started). Specifically, when the One-Stop expansion card in the IO Chassis is activated the fluid pressure drops.

To prevent any run-away issues, the hepi pump controller at both end stations were set into manual mode during these tests and returned to auto PID control later.

On the test stand, we found that a 16bit DAC card, when the IO Chassis is powered up, outputs 9.97V. It stays at this voltage until the front end computer is powered up, at which time its output voltage drops to -0.1V.  Hugh thinks that this large voltage drive to the valve controller could be causing a back pressure to the pump station. One way to prevent this would be to power down the AI Chassis prior to the frontend/IO-Chassis power cycle, and only power the AI back on when all the code is running and the DAC channels are being fully controlled.

We saw evidence of different power up behaviour with 18bit DAC cards, and some variation depending upon which PCI slot they are in. Investigation is continuing.

We suspect the cold cathode signal change is associated with chamber cooling when the ISI and SUS drives are deactivated for a long period of time (many hours). We see daily variations of CC signals which match the room temperature's daily variation.

Bottom line, these signals appear to be real and not caused by software or electrical issues linking dissimilar systems in unknown ways. There is no connection to the reprogramming of the timing system, this activity just provided the power sequence which allowed these issues to emerge.

1605 hrs local -> Dew point measured at HAM6 check valve exhaust <-31C. 

1630 hrs. local -> Kobelco running colder than normal (also noticeably quieter?) 

As found "LOADED" temps (manual coolant valve at the exit of the 2nd stage was 1/4 turn open)

1st STAGE DISCHARGE TEMPERATURE 276F 
2ND AIR SUCTION 79F 
2ND AIR DISCHARGE 257F 
LUBE OIL 91F  

10 minutes after closing closing manual coolant valve 1/8 turn "LOADED" temps

1st STAGE DISCHARGE TEMPERATURE 288F 
2ND AIR SUCTION 81F 
2ND AIR DISCHARGE 280F 
LUBE OIL 108F 

Corner Station chilled water set point @ 44F (as per Bubba - normal is 48F) 

Compressor UNLOAD-LOAD cycle time = 1 minute 17 seconds 

Drying Tower switching cycle time = 4 minutes 56 seconds

Summary:

High power beam path in HAM6 was carefully inspected using flashlights and so-called green lanterns. Some of the OMC shroud panels were removed and the OMC was pulled out of the chamber.

Some damages and contaminations were found.

1. One of the OMC cavity mirrors on PZT was found to have a large defect very close the center. From the picture it seems as if the defect is a ring or a disk, the size of which is comparable to that of the beam. Hopefully this is the main cause of our problem.
2. OMC TRANS steering mirror had a big particulate at around the center. This might have made the OMC trans video look worse.
3. A big crater in one of the black glass panels for the V-shaped beam dump receiving the beam diverter reflection of the OMC REFL. The other panel had the evaporated glass "coated" all over.
4. Much smaller, but obvious, damage on another V-shaped beam dump that receives the reflection of 90:10 BS downstream of the beam diverter.
5. A crater above the entrance beam hole for the OMC shroud. It seems as if some large power came out of SRM when OMs were totally misaligned in PIT.

HAM6 didn't look particularly clean, there were some particulates on OM mirrors for example but they were all far from the center.

Note that all of the above except 2. could have been prevented if the fast shutter was working.

No other problem was identified.

Corey will post some of the pictures.

Fixing things:

We will proceed to replace the OMC as planned.

OMC TRANS steering mirror was removed from the Siskiyou mirror holder, particulate was removed on the table using Top Gun, and First Contact was applied. Later the mirror will be installed back in the mirror holder. This way we don't need to worry about the alignment.

V-dump glasses were replaced on the spot.

We might replace the damaged shroud panel if we have a new one and if the cleaning can be done fast, otherwise we might just leave it there.

Other things to note:

We also visually inspected low-power beam path and found nothing suspicious.

AS for the OMC mirror damage, speculation of me and Koji is that we had a particulate contamination of some kind when the large power hit the OMC as the fast shutter was not working.

WP 6022

I have updated the PI models (28462) in order to accommodate four excitation paths for test mass' drum head modes. The h1omcpi and h1susprocpi models will be restarted tomorrow. The modification will be used

1. as a part of the OMC beacon (or deacon) dither alignment control, and
2. as a part of study on the mobility of test mass's mechanical modes.

This update actually involves not only h1omcpi and h1susprocpi models but also h1omc. However, in light of the upcoming in-vac activity with the OMC, we will hold off the update on h1omc so that we can recover the interferometer with least confusion. The update on h1omc will go in some time later once we recover the interferometer.

[eLIGO amplitude locked loop]

Here is a screenshot of the digital amplitude locked loop of a drum head mode that had been used in eLIGO.

This algorithm is imported to the current PI models. One update we might additionally implement in some future is a clock recovery with iWave instead of the clipping-based clock recovery.

[Modification on h1omcpi]

h1omcpi has one update i.e., normalization of the OMC DC signals.

I modified one of the down conversion channels, chan 8, to have a normalization using the OMC DCPD SUM. It is show in the orange-shaded region. This signal is sent to the susprocpi model and processed to generate feedback signals for the test masses.

[Modification on h1susprocpi]

Here is a screenshot of the top level of h1susprocpi in which a parallel excitation block for the drum head modes (a pruple block at the bottom) are shown.

This block contains four identical amplitude locked loop for generating excitation signals. The feedback outputs (shown as yellow tags) are summed on the right hand side of the output matrix so that they are sent to the test mases to excite the drum head modes. Also the rms information of a selected mode will be sent back to h1omc through an PCIe communication so that it can be used as a beacon alignment error signal. The contents of the purple block look like this:

As seen in the upper right, one can select which mode to use for the OMC alignment. The red blocks on the left hand side contain the function blocks as seen in the following screenshot.

The amplitude error signal is generated by a combination of an Abs block and lowpass filter. Then it is fed back to the output of the clock generator (which is based on the clipping technique as was done in eLIGO). The bandpass filter on the left allows one for selecting a mode out of the four modes. In addition, we placed an iWave block so that we can read out the frequency directly. A future expasion would be to use the output of the iWave block to generate the clock or sinusoidal excitation signal instead of the clipping-based one.