I appear to be alone at the moment.  I need to gather a few more items from the outbuildings for Monday's activities.  Afterwards, I should be in the old Vacuum Prep and Bake Oven labs testing the to-be-installed vacuum gauge heads (forgot to do this last week).  

I'll make a comment to this entry when I leave the site.

Krishna

BRS-2, the ground-rotation sensor for installation at EndY, will be delivered by us on March 23rd. The installation and commissioning is expected to take ~2-3 weeks. The aim is to reduce the impact of wind on the ISI and consequently DARM. This post is to describe the components and the current plan.

Refer to T1500596 for the wiring diagram. Refer to the following SWG logs for more info on BRS-2: 11355, 11362. Here is a check-list of major components:

1. BRS-2 Instrument including the autocollimator, platform and foam box. Also includes the 30-meter optical fiber and light source. 

 2. An Ion pump and pump controller.

 3. The Satellite controller box is done (pic attached) - this is the same as in the diagram except for the AI filters and preamp which are not needed. There is no pressure gauge on the vacuum can, but there is a 2-3/4" CF port to which one can be added. The RTDs are included.

 4. The ISI interface chasis (not yet built). We will bring the EP4374 and EP4174 but we need help building the chasis. Specifically, the AI filter, the SE to Diff Amplifier, the Front Panel adapter board and associated wiring. 

 5. The Beckhoff computer and the C# and PLC code. The C# code reads the camera at 2 kHz and can send data out at ~200 Hz to the PLC, which is currently running at 250 Hz and writing out the following signals: Tilt, Drift and Ref signals and the Status bits.

 6. We will bring the Piezo stacks and Piezo amplifiers to measure the tilt-transfer function.

 7. Spare flexures, and additional hardware for the assembly process.

Rob, Stefan,

THe pictures are in /ligo/home/controls/sballmer/20160312/LIGO

Logged in remotely to check that indeed all vioin modes damped down to the normal range.

Tried once to go to 20W, but failed. more tomorrow.

State of H1: locked at Increase Power at 5.2W

Work tonight on:

• power increase
• ASC
• violin modes

Before locking tomorrow:

• Load ISC_LOCK Guardian - for a test power in Increase Power was set to 5W, and the code is reverted, but needs to be loaded

Stefan has H1

We are daming them overnight, sitting at 5W. Also wrote the adjustDamperGain script below. It measures the peak count output of a fliter module, and scales the gain to set a target peak level. (Or the maximal allowable gain.)

We left the guardian script calling this function for the modes that were problematic toinight:

ISC_LOCK.py, line 2362

        # the following violins were saturating on March 11 2016 with above gains - turn them down
        time.sleep(10)
        adjustDamperGain('SUS-ETMY_L2_DAMP_MODE5',-100,1.5e5)
        adjustDamperGain('SUS-ETMX_L2_DAMP_MODE6',100,1.5e5)
        adjustDamperGain('SUS-ITMY_L2_DAMP_MODE3',100,1.5e5)
 

def adjustDamperGain(FM,maxgain,targetCounts):
    """read the FM output and scale the gain to match targetCOunts"""
    dmax=numpy.max(numpy.abs(cdsutils.getdata(FM+'_OUTPUT',1).data))
    oldgain=ezca[FM+'_GAIN']
    newgain=oldgain*targetCounts/dmax
    if (abs(newgain/maxgain)<1.0):
        ezca[FM+'_GAIN'] = newgain
    else:
        ezca[FM+'_GAIN'] = maxgain
    
 

We have put a few new settings into the ISC guardian, and one should now be able to use it to go to DC Readout.  As of this writing, we have not yet tried to increase the power with the new ASC settings beyond 5W input (bad violin mode situation, see other elog later).

The SRC1 and SRC2 loops are now opened along with the PRC1, PRC2 and INP1 loops, for the duration of the CARM offset reduction sequence.  Yesterday we were able to get past the SWITCH_TO_QPDS with the SRC loops closed, but today both our daytime operator (Ed) and our evening operator (Cheryl) were struggling.    The SRC loops are re-closed during the main Engage ASC set.

We also temporarily increase the test masses' offloading gain to M0 while the SOFT loops get up and running.  This is to prevent saturation of the L2 actuators when we start off with large SOFT offsets.  Since these can cause slow oscillations, I have them turning off again after 90 seconds at the end of ASC_PART3.  To further prevent saturations, we are resurrecting an old decorator by Stefan that checks the size of the output of the SOFT loops, and if they're getting too big, will turn the loops off so that the offloading can catch up, and then turn the loops on again.  This decorator is included in every state between ASC_PART3 and DC_TRANSITION, which is the state that waits for SOFT loop convergence. 

After some OMC investigation and fixing by Rob and Sheila, we are able to transition to DC readout, and have increased the power to 5W.  The ASC loops are all still stable.  Once Stefan has the violin modes damped a little more, we'll try going to higher power.

Evan, Rob

During a low noise lock last week we took some spectra to look for test mass mode frequencies. The test mass drumhead modes are clearly visible in the cross-power spectrum of the IOP channels of the DCPDs. The frequencies are at 8158.07, 8160.41, 8160.92, and 8162.68 Hz. These differ from the (modeled) values in the table in entry 20513 by ~0.5%.  We haven't yet worked out which frequency corresponds to which test mass.

The xml filename is in the screenshot.  

This is a small idea of measuring SRC gouy phase, following the recent ASC discussion (25999). 

The basic idea is that the propagation phase of an upper sideband HOM and a lower one moves in opposite direction, whereas the gouy phase goes in the same way. This will naturally lead to an unbalanced pair of sideband HOMs, whose ratio will be a function of gouy phase. By inverting this function, we can have a measure of gouy phase based on the ratio of sb. HOMs (which is independent of any absolute calibration).

We thus built a numerical simulation of DRMI only, with BS intentially misaligned. We computed the ratio of |E_usb|/|E_lsb| at the AS port as a function of SRC gouy phase, assuming a good prior knowledge of PRC gouy phase, cavity length, etc. The result was attched. It seemed that the |E_{+9M_10}| / |E_{-9M_10}| could be a good probe of gouy phase. 

We might want to do an OMC scan when the IFO was available, with DRMI locked. We could intentionally misalign BS (or the two ITMs) which would pump some +-9MHz 10 modes into the SRC cavity. With some clever stablization (e.g. using AS 18 as an error signal?), we could deduce the ratio of |E_{+9M_10}| / |E_{-9M_10}| from the OMC scan result. Comparing it with simulation, we could find out srcl gouy phase.

P.S. From the simulation we saw that the +-45M HOMs were pretty well balanced. However, this did not contradict with the observation of 25999, because the error signal for DC is <+45_10| +45_00> + <-45_10| -45_00>, and the error signal for 90 is <+45_10| -45_00> + <-45_10 | +45_00>.  Thus for the 90 MHz and DC seeing a different error signal, we only need the +/- 45 MHz 10 modes to have different phases relative to the +/- 45 MHz 00 modes. 

I've created a new filter for the RH substrate lens in TCS SIM. I'm testing it in H1:TCS-SIM_ETMY_SUB_DEFOCUS_RH. The filter bank is called "realRH". 

The poles and zeros are derived from a fit of a series of exponentials to HWS data for the measured RH spherical power at LLO. 

The (normalized) behaviour of the HWS measurement can be reproduced with the following sum:

defocus = -1 + sum(a_i * exp(-t/tau_i) )

Each exponential acts as a low-pass filter with a pole frequency of 1/(2*pi*tau), so the transfer function is the sum of each of these LPFs weighted by the coefficients a_i. Math then can convert that into a ZPK filter with 4 zeros and 5 poles and the desired response should ensue. That's what I'm testing at the moment: see H1:TCS-SIM_ETMY_SUB_DEFOCUS_RH_OUTPUT from 1141778267.

I think I've put the wrong sign in the filter bank ...

I moved the seismometer to a new hole, 20 m +Y of the EY station. I did this because I made an estimate that suggested that the wind was causing ground tilt through Bernoulli forces at the level of the tilt signal we were seeing from the buried seismometer (as judged by comparing Z, which is insensitive to tilt, to X and Y). I thought that these forces would be lower if the seismometer was up-wind of the building instead of beside the building where there was building induced turbulence. This 20m +Y location seems better than the 20m location +X of the building, and is generally a factor of 2 or more below the building seismometer in the tilt band below 0.1 Hz. All plots are a comparison of the buried seismometer to the SEI GND seismometer in the building. The red traces are the inside seismometer. The first plot is for an average of 14 MPH, the second for an average of 23 MPH. We havent had higher winds yet since I buried the seismometer. I believe that Jim is trying out the new blend filters on this buried seismometer.

Averaging Mass Centering channels for 10 [sec] ...

All STSs prrof masses that within healthy range (< 2.0 [V]). Great!

Details:
STS A DOF X/U = -0.054 [V]
STS A DOF Y/V = 0.494 [V]
STS A DOF Z/W = -0.385 [V]
STS B DOF X/U = 0.875 [V]
STS B DOF Y/V = 0.593 [V]
STS B DOF Z/W = 0.539 [V]
STS C DOF X/U = -0.198 [V]
STS C DOF Y/V = -0.642 [V]
STS C DOF Z/W = -0.98 [V]
STS EX DOF X/U = 0.5 [V]
STS EX DOF Y/V = -1.072 [V]
STS EX DOF Z/W = 0.4 [V]
STS EY DOF X/U = 0.521 [V]
STS EY DOF Y/V = 0.689 [V]
STS EY DOF Z/W = -0.26 [V]

Assessment complete.
 

Friday: ASC work and noise hunting

Saturday: LIGO discovery celebration

Next week:

• Grouting work on HEPI piers
• Manifold vent to install viewports for green camera
• Pump diagonal
• Cancelled: PSL high power work

Weeks 3/14 and 3/21: TCS optimization, ASC work and noise hunting

Week 4/4:

• PSL high power work
• HAM6 vent to install high QE DCPDs
• Install HAM6 GS13 and spring blade dampers

TITLE: 03/11 day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Cheryl
SHIFT SUMMARY:'
LOG:
17:00 Kiwamu has the IFO addressing OMC issues.
17:16 Jim and Robert to EX
17:50 Jim, Robert and Kyle back from EX
20:44 Fil to EX to check on/retrieve a cable
21:00 Fil leaving EX.
21:15 set IFO to sinle bounce mode for Sheila to troubleshoot OMC trouble
22:15 begin locking
00:02 Sheila called from LVEA to inform me that they'ere trying to get the OMC locked

Jenne, Hang, Robert Ward, Stefan, Matt, Lisa

Today we spent some more time on ASC

1) We realized that ASB36 has the DC centering and SRM both orthogonal to the BS signal, so this is a better signal to be using for BS than 36A. We swithced to this, and also switched SRM to ASB36 I, since we saw that the error point was good for SRM in full lock when we have MICH controlled with ASB36 Q.  This loop is not insensitive to the centering (it is basically parallel), but we seem to be OK.  

2) 25999

3) We have the CHARD at high bandwidth in the guardian, although this is quite rough and we need to think about how to engage it more smoothly.  

4) We have measured several sensing matrices, Hang will post them.

5)We are able to engage the soft loops even when they all have ofsets of about 0.1, and they converge very slowly without bringing our buildups down, with all the rest of the ASC on.  We think this means that we don't (at least not any longer) have a problem with error points changing, but we might still have a problem with loops are cross coupled.  We have done this 3 times now. 

We are now having trouble with the OMC locking, it seems to be locking on the side of the fringe, even though the dither line is supressed.  We tried a bust restore (the computer was restarted today.) but that hasn't solved the problem.  We will come back to this tomorow.