Kiwamu, Sudarshan

ISS Outer Loop Servo Board (S1400214) was modified to include a zero at 100 Hz to obtain a better phase margin. This was done by replacing a resistor R74 from 0 Ohm to 154 Ohm (D1300439) and has been documneted in the E-traveler. 

Initial test has been done after the modification and the board will be installed today during the maintenanace period. Further performance test will be done after the installation and with loop closed.

J. Kissel, E. Merilh, J. Warner

Found the IFO held in the INCREASE POWER state (that's why we're only at 30 Mpc, bcause the global DARM control hadn't switched to ETMY's LVLN driver, so we're limited by ETMX's HV Driver's DAC noise), though the requested state is DC READOUT. It's been locked for the past 4 hours.

Checked SDF for any new differences since last night:
- Accepted a few changes on the ITMs and ETMs for Violin Mode Damping (described in LHO aLOG 19594)
- Looks like we've been messing with DRIVEALIGN P2L and Y2L gains for the ETMX as well. (No associated aLOG, but I've accepted them anyway, since we're locked) I've not accepted these changes (and therefore will be lost with the front-end maintenance today), but if they're needed:
                                      In the safe.snap     Currently
H1:SUS-ETMX_L2_DRIVEALIGN_P2L_GAIN      1.1                   1.0
H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_GAIN      1.37                  1.3

- Brough the ISC_LOCK to DOWN (this didn't break the lock)
- Brought IMC to offline (this broke the IFO lock)

- Brought HAMs 1-6 to OFFLINE (technically just "ready" for HAM1 HEPI)
- Brought BSCs 1-5 to OFFLINE
- Brought ETMs and TMSs to SAFE

We're ready to begin the scheduled tasks  -- see LHO aLOG 19600

Sheila, Jenne, Matt, Stefan, Evan

List of things done today:

• EY L2 now has a rolloff filter (FM7+FM8 in the L2L drivealign) to remove the unwanted L2/L3 crossovers around the violin resonances.
• We switched the BS M2 coil drivers to the low-noise state.
• We spent some time investigating in-vac REFL9 as a CARM sensor:
  • We drove a line into MCL at 48 Hz and then tuned the analog delay line to minimize the apperance of the line in REFL9Q. We found that the best extinction we could get was REFL9Q/REFl9I ≈ 1/5, which seems abysmal.
  • We switched the CARM sensor to REFL9I (settings attached for 23 W operation), but the high frequency DARM noise is worse than with REFLAIR9I.
• We were able to switch control of the common dofs of the test mass ASC into the hard/soft actuation basis (not measured, but calculated from the cavity geometry).
  • This new acutation scheme works fine when engaging the ASC and when powering up (at least to 10 W).
  • The gains of cHard pitch and yaw were adjusted (to -10 and -20 ct/ct, respectively) so that the loops have bandwidths of something like 300­–500 mHz (measured by step response). A bandwidth of 500 mHz will allow us to set reasonable bandwidths for the cSoft loops (perhaps 100 mHz or so?) while still maintaining the appropriate gain hierarchy between the loops. (According to simulation, the hard mode must be suppressed before the transmission QPDs become good error signals for the soft mode.)
• We also looked at the DARM spectrum as a function of DARM offset. Evidently, at lower offsets, the low end of the spectrum improves while the high end gets worse.

Jenne, Sheila, Evan

We locked at 10Watts with low noise, and redid the OMC excitations that Koji and I did in alog 17919.  We plotted the OMC L excitation against a model with a peak to peak motion of 36 um, and the result seems consistent with a reflectivity of 160e-7 that we measured on Friday by exciting the ISI.  This is slightly worse than what we measured in April.  

We made these excitations with the same amplitudes and frequencies that we used in April, but some of the velocities seem to be smaller.  Jenne is working on doing a more thourough comparision, but it seems that the scatter is better when we are exciting Yaw and Transverse, if a little worse for longitudnal.  

We used a frequency of 0.2 Hz for all excitations.  

[Matt, Jenne, Evan, Sheila]

There is an enormous peak in the DARM spectrum at 4735 Hz.  Shown in the DTT printout below is the IOP channel for the OMC DC PD (H1:IOP-LSC0_MADC0_TP_CH12), from 1 kHz to 25 kHz, and this 4.7 kHz peak is dominating by about 2 orders of magnitude.  

We wonder if this is perhaps an acoustic internal mode of one of the test masses, although we are having trouble finding a listing of such modes.  

Does anyone know where we can find a listing of test mass acoustic modes?  Or, alternatively, does anyone have any thoughts on what this mode might be?

Sheila, Matt, Elli

Today, like yesterday, we used AS A 45Q YAW to damp the roll modes.  The ITMY settings were different today compared to yesterday; the sign and the phase has changed.  Currently the roll mode damping is working with settings

The filter settings are in the guardian, however the H1:ASC-OUTMATRIX element; H1:ASC-OUTMATRIX_TESTMASS_DAMP_1_3, does not get set from 0 to 1 in the guardian, so these filters do not currently turn on automatically.

Matt, Sheila, Eli

At some point today the bounce mode on EX got excited enough that we could see it in the PUM OSEMs as pitch motion.  The RMS of the observed "pitch" was about 3 nrad, and the line in DARM was about 1e-13 m.  Assuming that OSEM misalignent is providing the roll to observed pitch motion, and that this misalignment is of order 1 degree, the estimated roll motion was about 3e-7 rad.

This gives an order of magnitude estimate of the Roll to DARM coupling of 3e-7 m / rad.

Assuming a 10cm lever arm, this give a dimentionless coupling of 3e-6.  Compared to the bounce to DARM coupling, which is order 1e-3, the roll coupling is tiny, which means that the roll motion is HUGE (since they both look about the same in DARM).

Today I saw, via my monitor programs, a freeze up of EPICS data from LSC and ASC between the times 20:27:25 and 20:27:40 UTC, a duration of 15 seconds. My strip tool showed flat-line for this time. I was able to get the load-average on a variety of corner station front ends around this time, they were all elevated. Looking at the Guardian ISC_DRMI node logs and checking writes against the DAQ data I see that systems other than LSC, ASC appear to be frozen. For example ISC_DRMI attempted to change the H1:SUS-IM4_M1_LOCK_P_GAIN during this period. The modifications which were attempted during the freeze time did not show up in the DAQ data.

To see if IPC was playing a role in this, I started a third monitor on h1susauxb123 (no IPC). At 17:23 as I was writing this alog we got another event, which was seen by all three ASC, LSC and SUSAUXB123.

Investigation continues.

A Guardian top node as been added to H1: IFO:

(The node should now be visible in the GUARD_OVERVIEW MEDM screen.)

ifo: H1
name: IFO
CA prefix:
module:
  /opt/rtcds/userapps/release/sys/common/guardian/IFO.py
usercode:
  /opt/rtcds/userapps/release/sys/h1/guardian/IFO_NODE_LIST.py
nominal state: ALL_NODES_OK
initial request: ALL_NODES_OK
states (*=requestable):
  50 * ALL_NODES_OK
  20   WAITING_FOR_NODES_OK
  10   NODE_FAULT
   0   INIT

The node is monitor only; it only monitors the status of all other nodes in the system.  This is based on the system previously deployed at L1.

The sole purpose of this node is to report on the full status of the guardian system.  This is done via the node OK channel, and is defined similarly to L1:

• H1:GRD_IFO_OK == 1 ('True' ) - interferometer is observation-ready
• H1:GRD_IFO_OK == 1 ('True' ) - interferometer is NOT observation-ready
• record missing: IFO top node is not running

The check is essentially that all nodes in the system are themselves reporting OK == True, e.g.:

self['OK'] = self['OP'] == 'EXEC' 
             and 
             self['MODE'] in ['AUTO', 'MANAGED'] 
             and 
             self['REQUEST'] == self['NOMINAL'] 
             and 
             self['STATE'] == self['NOMINAL'] 
             and 
             self['STATUS'] == 'DONE' 
             and 
             not self['ERROR'] 
             and 
             self['CONNECT'] == 'OK'

In other words, all nodes are running as expected, are not in error, and their STATE and REQUEST are equal to the NOMINAL state.

The list of nodes being monitored is currently stored at:

/opt/rtcds/userapps/release/sys/h1/guardian/IFO_NODE_LIST.py

The list currently includes:

• ISC_LOCK
• ISC_DRMI    <----  NO NOMINAL STATE DEFINED
• ALIGN_IFO   <----- NO NOMINAL STATE DEFINED
• OMC_LOCK
• ALS_*
• SUS_*
• SEI_*
• HPI_*
• ISI_*

NOTE: the nodes without NOMINAL states defined will prevent the IFO node from ever becoming OK.  We need to either define NOMINAL states for these nodes, or temporarily remove them from the list of monitored nodes.

[Stefan, Jenne]

Earlier in the day, we were struggling to get through the INCREASE_POWER state in the ISC guardian, which happens after the transition of DARM to DC readout.  

After much tracking and searching, we discovered that the problem was that the setpoint for the OMC transmitted power was done as an ezcaread after the PSL rotation stage had already started moving.  Stefan had seen in the past that this kind of system will often have some lag (you're not reading the current OMC DC PD value infinitely fast, so you're constantly changing your setpoint) which causes the system to run away.  

We have changed this to a hard-coded value (defined as lscparams.omc_dcpd_sum_target), so that the DARM offset is changed while the power is increased to keep the OMC DC PD at this value (currently 20 mW).

This seems to now work exactly as we expect, and we're easily able to get past this state.

J. Kissel, E. Merilh, J. Warner, B. Weaver

As we begin to figure out what it means to be on the relocking team, we've made our best attempt at organizing / coordinating all planned maintenance day activities such that we understand their impact on the IFO and can recover from them as quickly as possible. See below. Have patience while we figure this "new" "system" out with you!

All tasks have been arranged and coordinated so as to not conflict with one another. All tasks and estimated times for completion will be added to the reservation system when they are scheduled, and after the task manager has checked in with the operator. PLEASE PAY ATTENTION TO THE RESERVATION SYSTEM (to help, we're going to put it on the big projector during maintanence). As always, please keep the operators informed of your activities as accurately as possible / reasonable throughout this maintenance day so the reservation list can be adjusted accurately. We appreciate your cooperation!

Maintenance Day Timeline:

• SDF system for affected front end computers cleared out (Operators on Shift, Re-Locking Team)
• EX/EY SEI/SUS systems brought to OFFLINE / SAFE via gaurdian (Operators on Shift, Re-Locking Team)
• IMC brought to OFFLINE via guardian (though check to see if bringing HAM2/HAM3 SEI to damped does it for you!) (Operators on Shift, Re-Locking Team)
• CS SEI systems brought to OFFLINE via guardian (Operators on Shift, Re-Locking Team)

• PSL - Periscope Alignment (to be done immediately following PMC/FSS Re-alignment. ET ~4hrs (R. Schofield)
• PEM CAL - This will be going on in multiple places in VEAs. Sensor correction will be turned off during these activities -  ET ~2hrs (V. Roma, J. Palamos)

I ran my brute force coherence script on last night lock. The results are available here:

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1120811417/

I'll post as summary soon.

I have been working on putting together a power dudget for Hanford IFO. I have calulcated the power on the beamsplitter using abolute power on vaious photodiodes, and put this into a shot noise curve model.  I have compared this to shot curve is measured using DCPD null readout.The shot noise curve is taken from the GWinc model.  The parameter file I am using is attached.  These files are available in /ligo/home/eleanor.king/PowerBudget. 

I calculated the power on the beamsplitter using the TR QPDS  (TR_X/Y_QPD_A/B) to determine the power in the arms,  and using the POP sensors(POP_A_QPD, POP_B_QPD POP_A_LF).  The resuts are summarized in the table below.  There is a matlab script with my actual calculations in /ligo/home/eleanor.king/PowerBudget/PowerOnBS.  The recycling gain for the TR is larger than that measured with the POP_PDs.  If calibrate the POP_A PDs to a single shot, same result. I am assuming the TR QPDs are correct.  The resylsing gain calculated by the absolute powers on these PDs agrees with the recycling gain calculated by the relative power change before and after locking using both TR and POP photodiodes.

I have taken an average value of all of the TR QPDs, which is 41(+/-15%).  I have also included lines showing +/- 1 standard deviation in the plot of the shot noise curve.  The photodecetctor quantum effieciency is 85%, and the losses in the arms are 120ppm, measured alog 16579.  Next I plan get a better understanding of the mode matching numbers used for generating the shot noise curve.  (Mode matching into arms and mode matching into SRC, which is currently assume dto be perfect.)

-------

Additional Comments:

Propagation of arm power to recycling gain:

Assume losses in arms 0f 120ppm, alog 16579.

Recycling gain from power on the beamsplitter:

Pinput=IMC_input_power*0.88*Tprm.  (It is power on the beamsplitter that I am calculateing from the photodiodes and putting into the GWINC noise model.  But I find it easier to convert from this to recycling gain, and think in terms of recycling gain.

Some comments on the current photodiode calibrations:

POP LSC Photodiodes were calibrated by Kiwamu in alog 13905, based on the transimpedence of this photdiode.  [cnts/W] = 0.76 [A/W] x 200 [Ohm] x 2¹⁶ / 40 [cnts/V]

TR_QPDs and  POP_QPD calibrated using Dan's calibration alog 15432.  Note the whitening gain changes on these during full lock, so it is important to keep track of the multiple dewhitining filter banks.

Nic, Sheila

We put an excitation into the HAM6 ISI ISO Y filter bank, (30000 counts at 0.3 Hz) from about 3:17-3:19 UTC July 11.  We then did a by eye fit  (on a log log scale)for a fringe wrapping model.  We expected the excitation to result in 30 um motion of the OMC, but we had to use 36 um to get the fringe speed right. We get an amplitude reflectivity of 1.6e-7 for the single pass shelf. (compare to 1e-5 measured in 17919)  We see no evidence of a second shelf or a shelf in the null stream.  

We plan to make measurements in exactly the same was as 17919, if we get a chance again tonight.

Stefan, Sheila, Nic, Evan

We remeasured the relative strength of the EX and EY ESDs in full lock. EX was driven with the high-range driver (40 V/V dc), and EY was driven with the low-noise driver (2 V/V dc). All other things being equal, we expect a relative strength of 20 V/V between the two actuation chains.

We found that the relative strength is instead 30 V/V (see attachment, which includes a digital gain of 30 ct/ct in the EY path). When we first did this measurement (back in May, pre-discharging), the relative strength was more like 50 V/V. So we are closer to the nominal value.

We successfully transitioned control of DARM from EX to EY with this new digital gain. We also took a quick DARM OLTF, both before an after the transition. The attachment shows an old, pre-vent OLTF (blue), today's OLTF with EX (green), and today's OLTF with EY (red).

List of commissioning tasks

The list below is for the time between now and O1. Since the sensitivity has reached the nominal goal set for O1, we plan to prioritize reliability and operations issues to maximize the up-time.

Reliability and Operations

1. MICH freeze/feed forward
2. Move to 90mHz blends everywhere
   Beam splitter and in transverse direction on test masses.
3. Better automation of bounce/roll damping based on monitors
4. Investigate alignment drift of SR3 (heating)
5. Alignment stability at high power
6. Thermal tuning of ITMs (stability, check contrast defect, sensitivity, ASC matrix)
7. Make a permanent PI monitors (down-convert 15kHz and record)
8. Optimize PI mitigation
9. Duty cycle improvements in locking procedure
10. Damp violin mode harmonics (needs more filters in SUS model)

Sensitivity

11. Monitor discharging, charge noise and ring heater coupling
12. Angle to length decoupling; try to make it permanent.
13. Intensity noise coupling and mitigation
    Are the IMC ASC offsets stable without auto-centering?
    Minimize acoustic noise coupling (new PSL periscope mount ready?)
14. Move to in-vac refl sensor (or figure out why we can't)
15. Frequency noise investigation; why is it so high?
16. Oscillator noise couplings
17. New OCXO and EOM drivers
18. Re-engage low pass on ETMY ESD
19. Investigate/find low frequency noise
20. Investigate beam tube dust glitches (histogram, distribution, quiescent rate)
21. HAM6 scattering measurements after the shroud installation and beam diverter move
22. SRC/PRC alignment effect on sensitivity
23. Check noise on all coil outputs(?)
24. Check/explain shot noise number (null stream)
25. Find best beam spots on ETM/ITMs (maybe wait for ER8)

Others

26. Finish SRC length/Gouy phase measurements
27. Final OMC alignment scheme
28. OMC alignment scheme that doesn't rely on the OMC SUS
29. HWS to investigate thermal loading
30. Timing studies