The two new BRS status Guardian nodes have been added to the Guardian Overview. The purpose of these nodes is to give the condition of the BRS in the node's state (ie. READY, DAMPER_ON, FAULT). The nodes seemed to have ran well over night so I added them and we'll see what they do over the weekend.

I attached a screenshot of the important code for BRS X. I would still like to make a way to check if the software has crashed since this was a big issue previously, but there are plans to change the computer soon anyway.

The code is simpler for the BRS Y, and the node only really looks at the DAMPCTRLMON channel. If this channel is above 8000 then it is in good shape, if around 3000 then the damper is on, and if less then it is in some type of fault.

1/2 open LLCV bypass valve, and the exhaust bypass valve fully open.

Flow was noted after 1 minute and 11 seconds, closed LLCV valve, and 2 minutes later the exhaust bypass valve was closed.

I isolated the aux pump cart yesterday afternoon to let the HAM6 annulus ion pump run on its own.

Today at 21:30 utc the aux pump cart and accesories were shut down.  All hardware is decoupled from the chamber.

Extended, routed and terminated CDS signal cable for HAM5 annulus ion pump controller.

With the need for heat in the LVEA low we took Heater 5 offline to convert it over to the variac system.  To protect the components we have limited the unit to 440V AC.
Must have a bad heater on C phase as the current draw was too low.  I have to talk to the vendor about adjusting the span on the controller.  We now max out at 14ma instead of 20ma.

4ma off <.5A
6ma 2.41 A 90V
8ma 8.6 A 175V
10ma 19.1A 265V
12ma 33.5A 355V
14ma 50.1 A 439V

No issues unlocking and no issues reisolating the platforms.  I'll run range of motion & linearity tests; possibly transfer function too, just because.

Late entry from yesterday. We discovered that h1pemcs's channel H1:PEM-CS_ADC_4_26_16K_OUT_DQ was railed at +20V. It was determined that this channel in the AA chassis was bad. I demoted this channel in the model back to 2048Hz and promoted H1:PEM-CS_ADC_4_28_16K_OUT_DQ to 16384Hz so Robert continues to have two 16kHz channels for his microphone work.

SEI - HAM6-5 still locked - to be unlocked. Hugh doing PEM inventory

PSL - touching base on beam availability at lunch time

Attached are plots of the power fluctuations from the HPO and its PZT.  The fluctuations in the HPO
power seem to coincide with the variations in the PZT voltage.  Both have a period of about 70 minutes.
We may have to reduce the injection locking servo gain.

    Also attached is a plot of the free running power fluctuations transmitted by the pre-modecleaner
and the output of the HPO.

In trying to engage the power stabilisation servo, we found that its behaviour was
somewhat erratic.  The servo would lock for brief periods of time before a low frequency
change would cause the servo to go out of lock.  Engaging the integrator, when possible,
did not prevent the low frequency fluctuation from knocking the servo out of lock.
Coincidentally the free running power fluctuations through the pre-modecleaner exhibited
large (~2-5%) fluctuations too.

    Thinking that these fluctuations were perhaps caused by diffraction effects associated
with the corona aperture within the laser, a number coronia apertures were tried and their
effects on the beam were examined with a CCD camera.  Whilst looking at the beam profile of
both the oscillator and the front end, it was observed that the profile of the front end
laser was terrible.  Whilst the beam profile from the oscillator was good, it would change
at random intervals.  The front end (seed) beam was re-aligned and the overlap between the
seed beam and the oscillator output improved.

    Without re-doing the mode matching to the pre-modecleaner, the pre-modecleaner was locked.
Its transmitted power appeared more stable.  The power noise spectrum after the pre-modecleaner
appeared more stable too.  The power stabilisation servo was engaged and could be locked.
Its behaviour was noticeably better than previously.

    We could not engage the frequency stabilisation, for reasons unknown at the moment.  But
we will pursue this later this morning.





Jason, Peter

All time in PT.

~17:30 Jason and Peter came out after spent all day in the PSL. No laser. No commissioners. I guess my shift ends early...

I also noticed some bright-than-usual scattered light on the PSL enclosure camera besides the laptop screen. It's probably nothing but just want to make note of it.

Added 150ml to chrystal chliller.

Close FAMIS #4146

Michael, Krishna

In this post, I'll try to summarize the work accomplished on the BRS-Y (2) and BRS-X (1) over the last few weeks.

1) BRS-Y:

The instrument including the box in the VEA and the Beckhoff computer/modules were installed (26242, 26265, 26276) . The tilt transfer function was measured and we then adjusted the center of mass to minmize 'd'. We then remeasured the transfer function to confirm that d was indeed small. This isn't particularly necessary for the goal of tilt-subtraction but does allow us to study the tilt from surface waves during an earthquake.

Tilt-subtraction for the ground seismometer has been shown to be very effective under 20-30 mph winds at both EY and EX in the 10 mHz to 1 Hz band. We have shown some modest improvements to ISI motion using sensor correction in the 'along-the-beam' direction in the 0.1-1 Hz band (as seen be ST1 T240)  without any increase to the total rms motion (as measured by the CPS). Both of these are local sensors and it would be interesting to test these configurations with the interferometer. There are also likely other ways to use the BRS signals which may prove more beneficial.

The C# and the Beckhoff PLC code for BRS-Y have been uploaded to svn under slowcontrols. This system is more robust than the one at EX and allows for greater CDS integration and control. Several of the BRS parameters (such as damping on/off, damping thresholds) can be controlled through EPICS commands. For example, typing " caput H1:ISI-GND_BRS_ETMY_USER 0" disables damping and " caput H1:ISI-GND_BRS_ETMY_USER 1" enables it.

We just discovered today that one of the two capacitive actuators was shorted internally and cannot be used. The damping is thus asymmetric and less strong. There are also other minor issues with it but it still meets its main goal of keeping the amplitude small.

The vcauum system is working well. The ion pump current is ~25 microamps, corresponding to a pressure of ~1.5 X 10^(-7) torr. The corresponding current for BRS-X is 14 microamps after ~two years.

The DC position of the beam-balance has been slowly settling with a very long time constant (~10 days). The attached plot shows the DRIFTMON channel over the last 16 days. The two main spikes followed by DC shifts were caused by us changing the DC position using a small moveable rod on the beam-balance. Based on the trend we expect it to drift down and then approach an equlirbrium value within the range of the autocollimator (+/-16k counts on the Y-axis).

2) BRS-X:

BRS-X was restarted from hibernation and works well for the most part.

The startup procedure for the code has been simplified. There are now two shortcuts on the BRS-X laptop's desktop screen - the one labelled "Damping ON" runs the software with damping enabled (DC subtraction is automated) and the other one runs with damping diabled and 2.5 V for the DAMP_CTRL channel, which can be used to reset the damper, if needed. A recurring problem with it is the damper turn-table vibrations causing the beam-balance to ring up. A new Beckhoff computer/modules and a GigE camera have been/will be ordered for it and we will develop a new smoother turn-table which will address these problems.

1/2 open LLCV bypass valve, and the exhaust bypass valve fully open.

Flow was noted after 1 minute and 37 seconds, closed LLCV valve, and 3 minutes later the exhaust bypass valve was closed.