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Reports until 11:20, Wednesday 10 June 2015
H1 SUS (DetChar, ISC, SUS, SYS)
betsy.weaver@LIGO.ORG - posted 11:20, Wednesday 10 June 2015 - last comment - 16:10, Wednesday 10 June 2015(19049)
ESD/charge measurements have ~commenced - status report on IFO

We attempted to set up the IFO for some end station ESD measurements around 10am.  During some of the switch settings, the IFO lost lock.  Relocking is ongoing with help from commiss.  A suite of ESD/charge measurements have become increasingly more important, hence time has been allotted today.

Comments related to this report
kiwamu.izumi@LIGO.ORG - 12:45, Wednesday 10 June 2015 (19050)

I was asked by Keita to update the ETMX actuator calibration path for their charge measurement in full lock. I updated the foton filter of CAL-CS and a few settings associated with the simulated ETMX actuators in CAL-CS. The SDF is updated accordingly. We are now temporarily using the simulated ETMX in CAL-CS by switching the output matrix as of around 2015-06-10 19:00 UTC. We did not touch the ETMY actuator path at all.

 

* * * * * *

The changes I made are:

  • H1:CAL-CS_DARM_ANALOG_ETMX_L3_GAIN
    • 1.42 -> 1.0
  • H1:CAL-CS_DARM_ANALOG_ETMX_L1_GAIN
    • -1.0 -> 1.0 (this must be a typo)
  • H1:CAL-CS_DARM_FE_ETMX_L1_LOCK_OUTSW_L
    • OFF -> ON
  • H1:CAL-CS_DARM_FE_ETMX_L3_LOCK_OUTSW_L
    • OFF -> ON
  • Changed the DC gain of FM1 in H1:CAL-CS_DARM_ANALOG_ETMX_L3
    • DC gain is set to 3.3491e-13 [m/cnts] (alog 18756

 

betsy.weaver@LIGO.ORG - 13:18, Wednesday 10 June 2015 (19051)

With Keita's guidance, we calibrated the TR QPDs to the ETM OPLEVs to get a calibration constant which will be needed to interpret the charge data being taken.  We found the calibration by driving at the L2 stage at 6Hz and watching the QPDs and OPLEVs.  Note, the Y-arm QPD TR B was not as well centered as the X-arm TR A and B and X-arm TR A.

Here are the calibration numbers:

 

    OPLEV QPD A QPD B OL/QPD  
    uRad/ct ct/ct ct/ct Calib Const  
          uRad/ct  
ETMX  PIT AMP 3.26654e-8 2.30053e-8 2.31317e-8 1.419907587  
  PHASE -12 169 169    
             
ETMX YAW AMP 4.1988e-8 3.08716e-8 2.88229e-8 1.360084997  
  PHASE -12 169 169    
             
ETMY PIT AMP 3.40891e-8 2.30263e-8 5.51346e-9 1.480441929  
  PHASE -31 167 165    
             
ETMY YAW AMP 4.07971e-8 3.26463e-8 1.5472e-8 1.249669947  
  PHASE -31 169 169    
             
betsy.weaver@LIGO.ORG - 16:10, Wednesday 10 June 2015 (19053)

Keita has completed the ESD/RH charge measurements for ETMx and ETMy, however he is still chewing on the numbers.  He expects to post something later today.

H1 General
nutsinee.kijbunchoo@LIGO.ORG - posted 10:44, Wednesday 10 June 2015 (19045)
Owl Shift Summary

00:00 IFO not locked. Jim said it lost lock twice at BOUNCE_VIOLIN_MODE_DAMPING. And lost lock again at ANALOG_CARM when I came.

          Knowing that it fails to grab lock repeatedly, I approach all the Guardian state with caution (wait until the spectrum becomes settle before requesting the next state)

01:13 Lock lost at REFL_TRANS. I brought everything down, readjust SR2, PR2, PR3, BS, and IM4. Ended up took me a while because I messed up the alignment.

         Couldn't get ASC-C_COMM_A_DEMOD_RFMON to reach 5 counts. I touched PR3 all I could. Any other optics I could touch to improve this?

2:18 4.7 Earthquake in Japan - no WD tripped.

4:00 Lock loss at LOCK_DRMI_1F

4:10 Trouble locking ALS-X

5:00 Kristina to the wood shop.

        The ifo still tries to lock DRMI.

5:10 Kristina back.

6:16 Still not grabing DRMI lock. Evan suggested bad BS alignment as AS air momentary locked at 10 mode. I couldn't get it to lock just by adjusting the BS so I redid the initial alignment. The earthquake earlier might have thrown the optics off.

6:50 Lock loss at REFL_TRANS.

7:19 Lock loss at REFL_TRANS AGAIN. I waited until AS90 and POP18 became stable before requesting the state.

7:31 Stopping at DRMI_LOCK. Waiting for the 6.0 earthquake in Chile to pass (it didn't affect us - no WD tripped at least).

8:06 Hugh came to find ITMY Optlev damping has been turned off. This could have been the cause of repeated lock losses through out the night. Next time I'll be sure to check SDF before even touching the interferometer....

       Evan touched PRM to bring up POP18 (and AS90) before requesting RESONANCE. Maybe helped with the lock loss at REFL_TRANS?

       The ifo is now locking. Handling the ifo off to Jeff B.

H1 PSL
jeffrey.bartlett@LIGO.ORG - posted 09:32, Wednesday 10 June 2015 (19048)
Add Water to PSL Chiller
Add 150ml water to the PSL Crystal chiller. 
H1 General
jeffrey.bartlett@LIGO.ORG - posted 09:28, Wednesday 10 June 2015 (19047)
08:30 Meeting Minutes
Operators and commissioners were reminded to check the SDF file for changes. There were problems with locking last night due in part to the ITMY OpLev. This error was apparent when looking at the SDF overview.

All were reminded to aLOG, aLOG, and aLOG. The aLOG is a valuable repository for documenting the many things that happen during a day. When in doubt aLOG it.
 
The kitchen sink has been fixed. The Facilities folks asked that food scraps not be put into the sink, as they cause plugged pipes. Food scraps should be put into the compost bins or at the least put in the garbage, but not down the sink drain.

Repairs to the RO system are complete. There is no potable water in the staging building due to a water leak. 

Beam tube cleaning continues.

No safety meeting for today.

Charge measurements will be taken today at both end stations.  
H1 AOS
edmond.merilh@LIGO.ORG - posted 09:19, Wednesday 10 June 2015 (19046)
PSL Weekly Report - Past 10 day Trends
Images attached to this report
H1 SYS
betsy.weaver@LIGO.ORG - posted 08:46, Wednesday 10 June 2015 (19044)
SDF apon arrival

Apon arrival, I see that the IFO is back up but there are 2 red SDF channels:

One is a somewhat benign LIMIT on the BS OPLEV YAW bank.  The other is 2 new filters that are enabled on ITMY_M0_DARM_DAMP_R.  I *thought* I saw these being switched a bit via commissioners yesterday during the locking attempts that were taking a while yesterday.  There are no alogs about these being turned on.  This needs to be addressed by ops/commiss today.

 

OPERATORS:  The SDF and GUARDIAN overview screens are very useful at determining what is out of configuration when attempting to lock.  If the GRD overview screen is litup like a "holiday" tree on the SUS and SEI banks, things are wrong and likely inhibiting lock.  Likewise on the SDF overview screen.  If there are red indications of channel diffs, it might help locking to work through the diffs.  Yesterday we had numerous indications on both of these screens that things were not in good states to lock.

Images attached to this report
H1 AOS
david.barker@LIGO.ORG - posted 08:08, Wednesday 10 June 2015 (19043)
CDS model and DAQ restart report, Tuesday 9th June 2015

model restarts logged for Tue 09/Jun/2015
2015_06_09 10:26 h1iopsush2a
2015_06_09 10:26 h1susmc1
2015_06_09 10:26 h1susmc3
2015_06_09 10:28 h1suspr3
2015_06_09 10:28 h1susprm
2015_06_09 10:32 h1iopsush2b
2015_06_09 10:32 h1susim
2015_06_09 10:37 h1iopsush34
2015_06_09 10:37 h1susmc2
2015_06_09 10:37 h1suspr2
2015_06_09 10:37 h1sussr2
2015_06_09 10:48 h1broadcast0
2015_06_09 11:47 h1iopsusb123
2015_06_09 11:47 h1susbs
2015_06_09 11:47 h1susitmx
2015_06_09 11:47 h1susitmy
2015_06_09 17:25 h1fw1*
2015_06_09 19:16 h1fw1*
2015_06_09 21:03 h1fw1*

* = unexpected restart

Maintenance day. Restart of SUS IOP models for 18bit DAC recalibration. Reboot DMT broadcaster.

H1 General
nutsinee.kijbunchoo@LIGO.ORG - posted 07:39, Wednesday 10 June 2015 (19042)
Lock lost on REFL_TRANS third time tonight

The last time it lost lock I tried my best to approach this state slowly. I have attached the screenshots of the spectrum and PRMI StripTool when it was at CARM_5PM. I waited until POP18 and AS90 became relatively stable before moved on and requested REFL_TRANS.  Didn't help...

Images attached to this report
H1 INJ (INJ)
eric.thrane@LIGO.ORG - posted 06:59, Wednesday 10 June 2015 (19041)
transient injections restarted with new lock check + intent check
I restarted transient injections at LHO and LLO at (06:43, 08:51) local time respectively. The injection code was not running when I logged on at each site. I've started a new log file tinj.err to try to ascertain why. Before restarting, I implemented a new check so that tinj should only attempt an injection if the detector is locked and if the intent bit is on. At LHO, I restarted tinj using the new user=hinj account.
H1 General
jim.warner@LIGO.ORG - posted 00:19, Wednesday 10 June 2015 (19036)
Shift Summary

17:13 IFO Locked, Intent bit set,

20:08 LLO has gone down, I start a DARM OLG measurement, done at 20:19

21:49 Lock loss

23:00 I start initial alignment again, start trying to lock at 23:45

H1 AOS
darkhan.tuyenbayev@LIGO.ORG - posted 20:57, Tuesday 09 June 2015 - last comment - 08:41, Monday 22 June 2015(19031)
Cavity pole fluctuations calculated from Pcal line at 540.7 Hz

Sudarshan, Kiwamu, Darkhan,

Abstract

According to the PCALY line at 540.7 Hz, the DARM cavity pole frequency dropped by roughly 7 Hz from the 17 W configuration to the 23 W (alog 18923). The frequency remained constant after the power increment to 23 W. This certainly impacts on the GDS and CAL-CS calibration by 2 % or so above 350 Hz.

Method

Today we've extracted CAL-DELTAL data from ER7 (June 3 - June 8) to track cavity pole frequency shift in this period. The portion of data that can be used are only then DARM had stable lock, so for our calculation we've used a filtered data taking only data at GPS_TIME when guardian flag was > 501.

From an FFT at a single frequency it is possible to obtain DARM gain and the cavity pole frequency from the phase of the DARM line at a particular frequency at which the drive phase is known or not changing. Since the phase of the resultant FFT does not depend on the optical gain but the cavity pole, looking at the phase essentially gives us information about the cavity pole (see for example alog 18436). However we do not know the phase offset due to time-delay and perhaps for some uncompensated filter. We've decided to focus on cavity pole frequency fluctuations (Delta f_p), rather than trying to find actual cavity pole. In our calculations we have assumed that the change in phase come entirely from cavity pole frequency fluctuations.

The phase of the DARM optical plant can be written as

phi = arctan(- f / f_p),

where          f is the Pcal line frequency;

                     f_p - the cavity pole frequency.

Since this equation does not include any dependence on optical gain, the technique we use, according to our knowledge, the measured value of phi does not get disturbed by the change of the optical gain. Introducing a first order perturbation in f_p, one can linearize the above equation to the following:

               f_p^2 + f^2
(Delta f_p) = ------------- (Delta phi)
                    f

An advantage of using this linearized form is that we don't have to do an absolute calibation of the cavity pole frequency since it focues on fluctuations rather than the absolute values.

Results

Using f_p = 355 Hz, the frequency of the cavity pole measured at the particular time (see alog 18420), and f = 540.7 Hz (Pcal EY line freq.), we can write Delta f_p as

Delta f_p = 773.78 * (Delta phi)

Delta f_p trend based on ER7 data is given in the attached plot: "Delta phi" (in degrees) in the upper subplot and "Delta f_p" (in Hz) in the lower subplot.

Judging by overall trend in Delta f_p we can say that the cavity pole frequency dropped to about 7 Hz after June 6, 3:00 UTC, this correspond to a time when PSL power was changed from 17 W to 23 W (see lho alog 18923, [WP] 5252)

Delta phi also show fast fluctuations of about +/-3 degrees, and right now we do not know the reason that causes this "fuzzyness" of the measured phase.

Filtered channel data was saved into:

aligocalibration/trunk/Runs/ER7/H1/Measurements/PCAL_TRENDS/H1-calib_1117324816-1117670416_501above.txt (@ r737)

Scripts and results were saved into:

aligocalibration/trunk/Runs/ER7/H1/Scripts/PCAL_TRENDS (@ r736)
Images attached to this report
Comments related to this report
darkhan.tuyenbayev@LIGO.ORG - 13:36, Thursday 11 June 2015 (19078)

Clarifications

Notice that this method does not give an absolute value of the cavity pole frequency. The equation

Delta f_p = 773.78 * (Deta phi)

gives a first order approximation of change in cav. pole frequency with respect to change in phase of Pcal EY line in CAL-DELTAL at 540.7 Hz (with the assumptions given in the original message).

Notice that (Delta phi) in this equation is in "radians", i.e. (Delta f_p) [Hz] = 773.78 [Hz/rad] (Delta phi) [rad].

shivaraj.kandhasamy@LIGO.ORG - 08:41, Monday 22 June 2015 (19266)

Darkhan, Did you also look at the low frequency (~30 Hz), both amplitude and phase? If these variations come from just cavity pole, then there shouldn't be any changes in either amplitude or phase at low frequencies (below cavity pole). If there is change only in gain, then it is optical gain. Any changes in the phase would indicate more complex change in the response of the detector.

H1 General
jim.warner@LIGO.ORG - posted 20:08, Tuesday 09 June 2015 - last comment - 20:19, Tuesday 09 June 2015(19039)
Intent bit turned off, DARM OLG measurement starting

LLO just went down and Jeff asked for a DARM OLG measurement, should be 20 minutes or so. Will revert intent bit when done.

Comments related to this report
jim.warner@LIGO.ORG - 20:19, Tuesday 09 June 2015 (19040)

Measurement done.

H1 General
vernon.sandberg@LIGO.ORG - posted 18:57, Tuesday 09 June 2015 (19037)
ER7 Policy on Handling GRB and SNEWS Alarms in the Control Room

from Michael Landry

This is a policy announcement about how to handle GRB and SNEWS alarms in the control room. (GRB = gamma ray burst and SNEWS = SuperNova Early Warning System.)

In the event of a GRB/SNEWS alarm during ER7, a 1hour stand-down time (no hardware injections, no calibrations, transfer functions or elective interventions such as mini-commissioning studies or IFO tuning) is in effect.  The DMT-ANALYSIS_READY (and thus the intent bit) should remain high for this time on a best-effort basis.

H1 CAL (AOS)
sudarshan.karki@LIGO.ORG - posted 17:45, Tuesday 09 June 2015 (19025)
Calibration Study during the first week of ER7

Calibration Team

Summary:

We did some Pcal trend study from the data taken during the first week of ER7 (03 June to 08 June).  Different comparisons were made between PCAL amplitude and DARM amplitude at these calibration frequencies.  We also used the data to estimate the Actuation stregth of ETMY ESD.

Details:

We use Spectral Line Monitoring Tool (SLMT) to  retrieve the data from the LIGO data frames and calculate the amplitude and phase by performing 60 seconds FFT on the time series. After that  we slected only the lock-stretch data (Guardian state vector greater than 500).  We use CAL-DELTAL_EXTERNAL_DQ channel for DARM readout and and respective PD channels for PCAL readout .

Plot 1-4:

We then plotted DARM/PCAL (Amplitude Ratio) at each calibration frequency.  The DARM/PCAL ratio varies at an average of about 10-20%  at higher frequency calibration lines(~500 Hz)  and slighlty more at lower frequencies (~30 Hz).  The first subplot is the DARM/PCAL Ratio. We also looked at the PCAL RxPD and TxPD reading along with DARM Amplitude and Phase.

PLot 5-6:

We also calculated the actuation strength of ETMY ESD using the PCAL calibration lines. Knowing the calibration coefficient of Pcal in [N/V] we use the DARM as an intermediary to calculate the ESD Actuation strength in [N/cts] of ESD excitation using the following equation:

[N]/ESD_EXC[cts] = PCAL_CALIBRATION_FACTOR[N]/[V]*(PCAL_PD[V]/PCAL_DARM[m])*(ESD_DARM[m]/ESD_EXC[cts])

Ideally this coefficient should be same at all frequencies but we see almost an order of magnitude different between the high frequency calculation and low frequency calculation. Don't know why.

PCAL Channel Higher Freq Low Freq
534.7 Hz 540.7 Hz 33.1 Hz 36.7 Hz
RX 3.44E-10 N/cts 3.72E-10 N/cts 3.64E-11 N/Cts 2.92E-11 N/cts
TX 3.50E-10 N/cts 3.66E-10 N/cts 3.71E-11 N/cts 2.87E-11 N/cts

P.S. Kiwamu pointed out CAL-DELTAL_EXTERNAL_DQ may not be an ideal chnanel to conside for this comparison because of multiple loop involved between injection and read out. I will followup by comparing this calculation using LSC-DARM_IN_DQ channel.

Images attached to this report
H1 SUS (CAL, DetChar, ISC)
jeffrey.kissel@LIGO.ORG - posted 16:31, Tuesday 09 June 2015 - last comment - 13:49, Tuesday 16 June 2015(19018)
Dynamical Model of the QUAD Tagged Before Update for Future Reference
J. Kissel

In preparation for updating LHO's local copy of the QUAD model to receive all of Brett's new goodness (see LHO aLOGs 18987 and 18809), I've tagged the current SUS model that has been used for recent calibration studies for ER7. The tagged model lives here:
/ligo/svncommon/SusSVN/sus/trunk/Common/SusModelTags/Matlab/quadmodelproduction-rev7508_ssmake4pv2eMB5f_fiber-rev3601_fiber-rev7392_released-2015-06-09.mat.

Details:
--------
The tag was created using the following script:
/ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/tagsusdynamicalmodel.m  rev7650

The parameter set used,
/ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/quadopt_fiber.m  rev3602
are the parameters that have been originally fit to match H1 SUS ETMY's M0-to-M0 (TOP to TOP) transfer functions, but used generically for all quads. It does *not* however include the "correct" frequencies of the violin modes as measured from H1 SUS ETMY (this is half the reason for the update).

The filters for local damping loops wrapped around the dynamical model were grabbed directly from the following foton filter file
/opt/rtcds/lho/h1/chans/filter_archive/h1susetmy/H1SUSETMY_1116978122.txt,
HOWEVER, *which* filter module was used and the damping loop *gains* (i.e. the EPICs settings) were hard-coded to a value that Brett captured a few months ago:
loading M0_DAMP_L with module #s: 1   2   3   5  10. 
loading M0_DAMP_T with module #s: 1   2   5  10. 
loading M0_DAMP_V with module #s: 1   2   5  10. 
loading M0_DAMP_R with module #s: 1   2   5  10. 
loading M0_DAMP_P with module #s: 1   3   5   6  10.
loading M0_DAMP_Y with module #s: 1   2   3   5   6  10. 
with a gain of -1.17. This is different from the current typical gain of -1.0 (except for pitch which is -3.0), so all DOFs are slightly over damped, except pitch which is under damped.

Comments related to this report
brett.shapiro@LIGO.ORG - 16:50, Tuesday 09 June 2015 (19035)

Jeff, you should also tag

makequad_with_modal_fibers.m (same directory)

This is the function that the generate script calls to add violin modes. It has also changed (a couple of times in the past couple weeks).

Just to clarify, because I don't think I said in any other log, the quadopt_fiber.m parameter file is unchanged in all these updqates. Any custom changes for particular suspensions are meant to be applied to new parameter files now on the SVN:

h1etmy.m, h1etmx.m, h1itmy.m, h1itmx.m, l1etmy.m, etc.

Currently all these custom quad parameter files are direct copies from quadopt_fiber.m. They are intended to be updated with measurements at some point. h1etmy.m differs only in that the measured violin modes from H1ETMY are included (first 8 modes).

Incidentally, quadopt_fiber.m was created by fitting it to H1ETMY data (as a representative case). Not just M0 to M0 TF data, but the single, double, and triple hang resonances were used too. Also, the measured mass values of the 4 stages are included. Therefore, h1etmy.m may be considered 'complete' in that it is already customized for H1ETMY, simply because quadopt_fiber.m was. The other files are just place holders for the other suspensions currently.

Previously, in log 18809 the violin modes for H1ETMY were hardcoded in the generate scripts. Now that we have customized parameter files, the violin modes have been moved into those.
So, unless you call the generate script with a custom parameter file, you will simply get the modeled modes.

jeffrey.kissel@LIGO.ORG - 13:49, Tuesday 16 June 2015 (19172)CAL
This purpose of these tags is to document the QUAD model that was used in the DARM calibration models circa ER7 (see LHO aLOG 18769). I have *not* yet updated the local copy of the repository to absorb all of Brett's recent work on improving the model (in fact, I really *want* to start using those improvements, which is why I need to make sure the calibration model for ER7 does not depend on the new-ness, and uses these tagged versions). So, yes, eventually, after I svn up the local LHO copy of the quad model directory, I will make new, additional, tagged version of the model, but for now the focus is preserving what we had *before* these upgrades that Brett mentions in his comment.

This being said, the ability to add violin modes to the model (albiet with in-accurate frequencies), has been around for a while. As such, I did use the first 25 violin modes modeled with viscous damping in the DARM calibration model. HOWEVER, the above mentioned tagging function did not include the violin modes (i.e. it didn't give generate_QUAD_Model_Production enough inputs) because that script pre-dates the addition of violin modes, and I forgot.

So in the same place as described in my above aLOG, I've
(1) changed the name of the above mentioned 2015-06-09 tag to reflect that it is with NO violin mode damping (which may still be useful to people):
/ligo/svncommon/SusSVN/sus/trunk/Common/SusModelTags/Matlab/
quadmodelproduction-rev7508_ssmake4pv2eMB5f_fiber-rev3601_fiber-rev7392_NOviolinmodes_released-2015-06-09.mat, 
and
(2) tagged a new version of the model WITH violin modes:
/ligo/svncommon/SusSVN/sus/trunk/Common/SusModelTags/Matlab/
quadmodelproduction-rev7508_ssmake4pv2eMB5f_fiber-rev3601_fiber-rev7392_WITHviolinmodes_released-2015-06-16.mat

Again -- BOTH OF THESE TAGS STILL HAVE INCORRECT LOCAL DAMPING LOOP GAINS, as mentioned above.
H1 CDS (SUS)
david.barker@LIGO.ORG - posted 14:28, Tuesday 09 June 2015 - last comment - 15:41, Wednesday 10 June 2015(19030)
status of 18bit DAC calibrations

We are seeing two issues with the autocal of the 18bit DAC cards (used almost exclusively by suspension models). The first is a failure of the autocal; the second is the autocal succeeding but taking longer than normal.

There are three calibration completion times: ~5.1S for unmodified DAC, ~5.3S for modified DAC, ~6.5S for modified long-running DAC

h1sus2b, h1sush34, h1susex, h1susey all have no DAC issues

h1sush2a: the third DAC is taking 6.5S to complete. This DAC is shared between PRM and PR3 models. First two channels are PRM M1 Right and Side. Last six channels are PR3 M1 T1,T2,T3,Left,Right,Side.

h1sush56: this has unmodified cards. 4th DAC is failing autocal

h1susb123: This one is strange:

On first autocal run after a computer reboot: 7th DAC failed autocal

On first restart of all models: 1st DAC failed autocal, 7th DAC succeeded

On second restart of all models: 1st DAC failed autocal, all others good (consistent restart behavior)

In all cases, 5th DAC card is running long for autocal (6.57S).

In the current situation with the 7th card now succeeding and the 1st DAC failing, the 1st DAC is driving ITMY M0 (F1,F2,F3,LF,RT,SD) and M0 (LF,RT)

Comments related to this report
jeffrey.kissel@LIGO.ORG - 15:41, Wednesday 10 June 2015 (19052)CDS, DetChar, ISC, SUS
I've been asked to translate / expand on the above entry, and I figure my reply was worth just commenting on the aLOG itself. If one person asks, many more are just as confused.

---------
We know that DetChar have seen Major Carry Transition or "DAC" [digital-to-analog converter (DAC)] glitches in some of the detectors interferometric signals, that have been pin-pointed to be from a few select stages of a few select suspensions (see e.g. LHO aLOGs 18983, 18938, or 18739).

To combat the issue, yesterday, we restarted all the front-end processes (including the Input Output Processor [IOP] process) on the four corner station SUS computers:
h1sush2a (controlling MC1, MC3, PRM and PR3 all in HAM2)
h1sush2b (controlling IMs 1 through 4)
h1sush34 (controlling MC2 and PR2 in HAM3 and SR2 in HAM4)
h1susb123 (controlling ITMY, BS, and ITMX in BSCs 1, 2 and 3 respectively)

Restarting the IOP process for any front-end who is coupled with an I/O chassis that runs 18-bit DAC cards performs the auto-calibration (autocal) routine on those 18-bit DACs, recalibrating the voltage bias between the (2-bit + 16-bit cards) of the 18-bit DAC to reduce Major Carry transition glitching. When the front-end computer is rebooted or power-cycled, the IOP process is started first, and therefore runs the auto-calibration routine as well. After autocalibration is complete, the user models for each suspension are started. 

Note that the other 3 SUS "control" computers,
h1sush56 (controlling SRM and SR3 in HAM5 and the OMC in HAM6 )
h1susex (controlling ETMX and TMSX)
h1susey (controlling ETMY and TMSY)
were NOT restarted yesterday, but have been restarted several times over recent history.

Each of these front-end or I/O chassis contains many DAC cards, because it (typically) controls many suspensions (as described above), hence the distinction between the card numbers in each front-end. Said differently, each DAC card has 8 channels -- because of initial attempts to save money and conserve space, the above mentioned corner station computers / IO chassis have some DAC cards that control OSEMs of two different suspensions. There's a map of which DAC card which controls which OSEM in the wiring diagrams; there is a diagram for each of the above mentioned computers / I/O chassis; each diagram, named after the chambers the I/O chassis controls can be found from the suspension electronics drawing tree, E1100337.

Recall that we have recently swapped out *most* of the suspensions' 18-bit DAC cards for a "new" 18-bit DAC card with upgraded EPROMs (see LHO aLOGs 18557 and 18503, ECR E1500217, and Integration Issue 945). This is what Dave means when he references "modified" vs. "unmodified" DAC cards. All DAC cards in h1sush56 remain unmodifed, where as the other corner-station DAC cards in all other SUS I/O chassis have all been upgraded.

Dave also describes that 18-bit DACs are used "almost exclusively by suspension models." The PCAL and PEM DACs are also 18-bit DACs. Every other fast DAC (used by TCS, SEI, PSL, ISC, etc.) is a 16-bit DAC which have not been found to have any issues with major carry transition glitching. Note that because the tip-tilt suspensions (the OMs and RMs, collectively abbreviated as the HTTS for HAM Tip-Tilt Suspensions) were purchased under ISC dollars, who made the decision to do this (as with many other things) differently -- they have 16-bit DACs. 

After we've restarted the IOP front-end process, we track its start-up log file to ensure that the auto-calibration was successfully completed. We've found that there are two "failure" modes to this auto-calibration process that get reported in these log files. 
(1) The IOP process log reports that the auto-calibration process has failed.
(2) The IOP process log reports that the auto-calibration process took longer than is typical. 
We don't know the practical result of either of these two failure modes means. This was brought up on the CDS hardware call today, but no one had any idea. I've pushed on the action item for Rolf&Co to follow up with the vendor to try to figure out what this means.

As for (2), 
- the typical time for an IOP process to complete the auto-calibration of one unmodified DAC card is 5.1 [sec]. 
- the typical time for a modified DAC card with the new EEPROM is 5.3 [sec].
- the atypical "errant" time appears to be 6.5 [sec]. 
But, again, since we have no idea what "running long" means, our only reason to call this a "failure mode" is that it is atypical.

So re-writing Dave's above status (which is a combined status that is the results of yesterday's IOP model restarts and other previous IOP model restarts) with the jargon explained a little differently and in more detail:
- h1sus2b, h1sush34, h1susex, h1susey all have no DAC auto-calibration issues. All DAC cards in these front ends / I/O chassis report a successful auto-calibration routine.
- h1sush2a: of the all the DAC cards in this I/O chassis, only the 3rd DAC (which is s controls the some of the TOP, M1 mass OSEMs of PRM and some of the TOP, M1 OSEMs of PR3) is suffering from failure mode (2).
- h1sush56: the 4th DAC is suffering from failure mode (1).
- h1susb123: this computer's IOP process was restarted several times. 
	- Upon the first autocal, which was performed as a result of rebooting the computer, 
		- the 1st and 7th DAC card suffered from failure mode (1), 
		- the 5th DAC card suffered from failure mode (2),
		- all other DAC cards reported success.
	- Upon the second autocal, which was performed as a result of restarting the IOP process, 
		- the 1st DAC card suffered from failure mode (1), 
		- the 5th DAC card suffered from failure mode (2),
		- all other DAC cards reported success.
	- Upon the thir autocal, which was performed as a result of restarting the IOP process again, 
		- the 1st DAC card suffered from failure mode (1), 
		- the 5th DAC card suffered from failure mode (2),
		- all other DAC cards reported success.
	The first DAC card is shared between the two TOP, M0 and R0 masses of ITMY. (note Dave's typo in the initial statement)

For previous assessments, check out LHO aLOG 18584.
H1 General
jim.warner@LIGO.ORG - posted 00:00, Tuesday 09 June 2015 - last comment - 19:32, Tuesday 09 June 2015(19001)
Shift Summary

Mostly quiet shift

16:00 Took over initial alignement from Cheryl, trying to lock

18:30 Finally locked

19:00 Robert to  EY to bang on beam tube, lots of glitching -> particulate?

20:00 Evan breaks lock with a small change to Guardian

22:00 Lock reacquired, LLO is up too.

23:26 HFD is on site, out the gate at 23:55

Comments related to this report
robert.schofield@LIGO.ORG - 19:32, Tuesday 09 June 2015 (19038)

I went out to watch the cleaning earlier in the day and returned after work had finished to reproduce some of the cleaning activities. I was on the phone with the operator who monitored DARM for glitches. I found that tapping the beam tube with metal like the water/vacuum nozzles produced large glitches, but brushing with the brushes did not. I found that the softer the instrument, the harder it was to make glitches. I was never able to make glitches with my fist, but there was nearly a one-to-one coincidence with metal taps. All glitches, according to Jim, the operator, were broad band and a couple of orders of magnitude above background. I had to wait quite a time for the spectrum to settle down before tapping again. The glitches were like delta functions, not like scattering shelves. There did not seem to be a difference between locations at a baffle and half way between baffles.

I suggested to Bubba and John that we might make fewer glitches if there was a polymer guard on the nozzles.

I guess that the important quantities for freeing metal oxide particles are either acceleration or change in curvature of the beam tube. The difference between soft and hard "hammers" is consistent with both of these hypotheses. I think that it is important to estimate the inter-site coincidence rate and propose that I mount an accelerometer and a shaker on the tube to study glitching as a function of frequency and amplitude. I suspect that there is a soft threshold in curvature change or acceleration, and that this will be fairly constant with time since the oxide layers should no longer be growing. 

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