Sudarshan, Kiwamu,

As planned, we disabled the two pcal lines at around 550 Hz this evening (i.e. 534.7 and 540.7 Hz, see alog 19272) which brought some saturation issue the other day (alog 19891). From now on, we will have to use the 325.1 and 331.9 Hz lines (alog 19823) for calibration for the  high frequency part.

Also, we moved the suspension line from 538.1 Hz (alog 19926) to 329.9 Hz so that it is close to the new Pcal lines at around 330 Hz. We chose this frequency based on a prime number, 3299. This frequency should be also good in terms of the continueous wave search according to Jeff's alog 14836.

We tested the new suspension line in full lock, with DARM actuating on ETMY with a low pass ESD filter engaged. As we kind of expected, the suspension line used up a good fraction of the total rms in ESD DAC counts. We decreased the line amplitude by more than a factor of two, which resulted in 1x10⁴ counts in the ESD DAC as of now. This is sort of OK, but commissioners can feel free to disable it if necessary. The attached shows a spectrum of the ESD DAC when it was fully locked with the low pass engaged on ETMY and with the new suspension line injected. As seen in the spectrum, the suspension line is a dominant rms source when the low-pass is engaged. Also a screenshot of the new setting for the suspension line is attached.

Joe, Matt, Sheila, Dave:

We have used Joe B's latest PI_MASTER file to build h1susetmxpi and h1susetmypi. The master puts the DEMOD I,Q channels into the commissioning frame at 2kHz. If we try to run this model, we get the "DAQ too small" error. Rolf says that channels must be added to the DAQ at the native rate (64kHz) to remove this error. We put in two fast channels on the top level (we tried with one, but it looks like there must be at least two). To reduce these channels impact on the commissioning frame, I made these testpoint parts with an input of ZERO, which should be effectively removed by compression.

Matt and Sheila requested that the data rate for the DEMOD be increased from 2kHz to 4kHz, this was done.

After the models were restarted, the DAQ was restarted. h1dc0 did not autostart its daqd process, we had to do this by hand.

Per ECR E1500322, I've added the Wiener filter sensor correction path to the BSC and HAM ISI master models. Pretty simple change (even if it took ~3 hours to do), as there were already terminated STS paths on both models that just needed connection to a bus and a few filter blocks needed to be added to the Senscor paths. I've commit the changes to the SVN and checked to that HAM2 and ITMX would "make" on the new models. We should be able to install and use on all chambers tomorrow, the MEDMs should be pretty easy, too.

Attached is the whiteboard list of tomorrow's scheduled tuesday maintenance activites.  We'll start with RCG upgrade and work through various other invasive around-site tasks. 

Here are the list of tomorrow's maintenance day tasks organized as we intend to execute them chronologically, and prioritized such that the tasks with the most global impact on the IFO are done first (such that we have the most time to recover from them). As with last Tuesday (LHO aLOG 19600), all tasks, associated estimated times for completion, and responsible persons (or "task manager") will be added to the reservation system when they are *actually happening*, and removed after the task manager has checked in with the operator and confirmed completion. PLEASE PAY ATTENTION TO THE RESERVATION SYSTEM (to help, we're going to put it on the big projector during maintenance). 

As always, please keep the operators informed of your activities as accurately as possible / reasonable throughout the maintenance day so the reservation list can be adjusted accordingly and remain accurate. We appreciate your cooperation!

1st Round:

RCG 2.9.6 upgrade and associated restarts of all FEs

2nd Round

ETMX LVLN Driver

Ongoing VE work at EX/EY (NEG pump regeneration)

3rd Round (start relocking things):

Continue ETMX LVLN Driver work

Ongoing VE work at EX/EY (NEG pump regeneration)

EY Magnetometer calibration

PR3 OPLEV work

Potentially revert EY SUS to slow FE

4th Round:

Turn on HEPI Actuator pump flushing stand - look for noise (doubted)

We continue the charge measurements on ETMs.

About a week ago the bias sign was changed of both ETMs. Before this week data are consistent with positive charging for ETMY and negative charging for ETMX. Charging speed is about 10-20[V] per month. 
This week's data seems to be consistent with a changed sign of charging - negative for ETMY and positive for ETMX. 
Plots are in attachment. 

The SPM diffs on both ISI stages of the corner station BSCs are generated from incorrect setpoint references.  The channels are configured correctly and the notifications are incorrect.  Possibly taking the chamber down (down to INIT maybe?) will correct this and we'll endeavor to do this Tuesday if allowed.  It seems this started on Thursday when the models were restarted.  However, the guardian machine was restarted last week as well and that too may be related.  FR 3382.

Hang, Kiwamu

As a prep work for tomorrow's ASCIMC model update, we went ahead and made the update on the h1ascimc model. We confirmed that the model compiled without an issue. We did not do a make-install or restart of the model. We are ready for tomorrow's update.

We svn-updated the common ASCIMC model which JoeB checked in a week ago. As Joe told us, this gave two more outputs which are IM4_TRANS_PIT and IM4_TRANS_YAW. Following his instruction, we placed two new shmem sender blocks at the top level for these two new outputs. They weill be received in the h1asc model which we did not make change today. So the shemem signals are going nowhere as of now. We updated the associated screens as well. Since we did not install or restart the model yet, the new parts are shown as blanks in the screens (see the attached screenshot). So, don't be surprised. The new h1ascimc model is cheched in the svn.

• IFO had been unlocked since the Alasakan earthquake activity. 
• Guardian had been set to lock the ALS and it was locked and looking good.
• SUSDIAG notifications reporting high AOM diffracted power in ISS. Found 14% diffracted power. Adjusted down to 7%
• Initiated first attempt at DRMI lock at 08:04. Alignment looked pretty bad so initial alignment checks began.
• Even with ISC_LOCK in 'DOWN' state, Guardian seemed to still be wanting to take over which made intial alignment rather tedious. After the tug of war, I got things aligned better and was able to achieve DRMI lock on 1F. The transfer to 3F ws unsuccessful.
• IFO turned over to commissioners for measurements

• REMINDER:  Code Freeze of 8/10!!
• SEI:  Nothing invasive planned (Hugh)
• SUS:  Nothing to report
• CDS:  PEM stuff remains before O1, Low noise/voltage cabling at EX
• PSL:  power budget/calibration for PDs, Round 2 FSS box, PR3 oplev work
• PCAL:  EX work (Wed?)
• VAC:  one or both end stations to regenerate (heating it) pumps (a few hours work tomorrow)
• Spare desks outside of Staging:  You can claim for your office!!
• Beam Tube cleaning400m from EY on way to LVEA
• DetChar FtF Thurs/Fri

The frame writers are now stable after this weekend's configuration changes. Attached is a plot of the frame writer restarts for the past 7 days. The first blue line is when h1fw0 stopped writing commissioning frames, the second blue line is when h1fw1 stopped writing commissioning frames.

In this configuration we have redundency in the science frame channels as they are written to the commissioning frame along with the commissioning channels.

I happened to witness the lock loss after 16h. We had several PRM saturations spread over ~8 minutes, before one of them took down the interferometer.

J. Kissel

Investigating the DAC saturations I've been hearing this morning from H1 SUS ETMY, I've taken a live ASD of the requested DAC outputs (which are not yet in the frames -- see E1500323) to see if / where we're close to saturating. If looks like the only place where we're "in danger" of saturation is the PUM around the microseism (~0.05 - 0.5 [Hz]). I put "in danger" in quotes because the RMS is still at ~8000 [ct_RMS] or ~11000 [ct_Pk], which is only 8% of the 2^17 = 131072 [ct_Pk] range of the DAC, but this still doesn't seem to be enough.

 
We've recently put lot of good effort has been put into rolling off the PUM faster (LHO aLOG 19859), and I think as such we've been focused on the ~above 1 [Hz] RMS levels (since the (L2/PUM) - (L3/TST) "crossover" is at "30 [Hz]").

Since there's *plenty* of range left in the UIM, I suggest we roll-off the low frequency end of the PUM drive better.

It's surprising really, because Brett put together a paper on a more sophisticated metric for determining the probability of saturations in a given time period (see P1000101), which suggests that the probably of saturation in one sample is

p_{i} = 1 - erfc( 1 / (sqrt(2)*dacMargin) )

and the probably over a given time period T is

p_{T} = 1 - p_{i}^(T / Ts)

where dacMargin is the ratio of ( measured RMS / DAC limit [in RMS] ), the DAC limit (in RMS) is (2^17 [ct_Pk]) / sqrt(2) =  92681.9 [ct_RMS], Ts is the sample time = 1/16384 = 61 [us], and erfc is the complementary error function (see Wikipedia and more importantly Matlab's definitions). (Note -- there's a bug in Brett's Eq. (4) of the paper I cite -- the "scale factor" of 10 was intended to represent the DAC range in aLIGO, but 10 is the peak voltage limit; the RMS voltage limit is 7.07 [V_RMS]. I've accounted for this bug in my (re)definition of dacMargin and in the calculations below.)

I've calculated this for the RMS at each stage for the probability of saturating in 1 hour,
                           L1/UIM      L2/PUM       L3/TST
dacOutput_rms [ct_RMS] =  1618.2       7658.3       4623.7
dacMargin              =  0.01746      0.08263     0.049888
probSat_oneTs          =  0            1.09e-33    2.23e-89
probSat_1hour          =  0            0           0
i.e. matlab ran out of numerical precision to give us an estimate of the probability since its so small.

Summary

Attached is the dark noise of REFL9Q, along with an estimate of the shot noise and a conversion of these noises into equivalent frequency noise in CARM.

The dark noise appears to be slightly below the shot noise level.

Details

I took the TNC that goes directly into the common-mode board and put it into an SR785. Also attached is the noise with the input of the SR785 terminated.

I also have tried to estimate how this compares to the shot noise on the diode. In full lock at 24 W, we see 3.6 mW of dc light on the PD (according to the calibrated REFL_A_LF channel). Off resonance and at 2.0 W, we have 13.6 mW of dc light. So the CARM visibility is about 98%.

The shot noise ASD (in W/rtHz) and the CARM optical plant (in W/Hz) are both given in Sigg's frequency response document. With a modulation index of 0.22 rad and an incident power of 24 W, the shot noise is 9.4×10⁻¹⁰ W/rtHz, the CARM optical gain is 11 W/Hz, and the CARM pole is 0.36 Hz. [Edit: I was missing some HAM1 attentuation when first calculating the shot noise level. Out of lock, the amount of power on REFL A should be 24 W × 0.1 × 0.5 × 0.5 × 0.5 = 300 mW. That gives a predicted shot noise level of 7.7×10⁻¹¹ W/rtHz, assuming a sideband amplitude reflectivity of 0.44. On the other hand, from the measured in-lock power we can calulate 2(hνP)^1/2 = 5.2×10⁻¹¹ W/rtHz for P = 3.6 mW. This includes the factor of sqrt(2) from the frequency folding but does not include the slight cyclostationary enhancement in the noise from the sidebands (although this latter effect is not enough to explain the discrepancy).] Additionally, I use Kiwamu's measurement of overall REFL9 response (4.7×10⁶ ct/W) in order to get the conversion from optical rf beat note power into demodulated voltage (2900 V/W). These numbers are enough to convert the demodulated dark noise of REFL9Q (and the shot noise) into an equivalent frequency noise. At 1 kHz, the shot noise is about 10 nHz/rtHz; as a phase noise this is 10 prad/rtHz (which is smaller than Stefan's estimate of 80 prad/rtHz). The dark noise, meanwhile, is about 5 nHz/rtHz.

Stefan, Evan

Summary

We temporarily switched back to the IFR as a sideband generation source, and then used it to drive the sidebands in frequency and amplitude. Then we looked at the coupling in OMC DCPD sum.

Details

We ran the spare LSC DAC channel (LSC-EXTRA_AO_2) into ISC patch cable R1 #11-4, which goes to ISC C4 #2-4. Then we sent this into the IFR's external modulation input.

First, we did the amplitude measurement. The IFR was set to dc-coupled AM with a nominal deviation of 10%. We drove 25 mV out of the DAC and watched the response in the OMC DCPD sum. The observed AM coupling is roughly flat from 300 Hz to 5 kHz, with a level of about 0.01 mA/RIN.

Next, we did the phase measurement. The IFR was set to dc-coupled FM with a nominal deviation of 1 Hz. We drove 100 mV out of the DAC and watched the response in the OMC DCPD sum. The observed FM coupling is roughly flat from from 300 Hz to 5 kHz, with a level of about 2×10⁻⁵ mA/Hz.

[An aside about the IFR actuation calibration: The IFR is designed so that in order to get 10% peak RIN, you must supply 1 V rms at the modulation port, which 1.41 V peak. Stupid stupid stupid. Anyway, I verified with an oscilloscope that the actuation coefficient was 0.068 RIN/V, which is close enough to the expected 0.071 RIN/V.

The same nuttiness applies to the frequency calibration: to get 10 Hz peak deviation, you must supply 1.41 V peak. However, Stefan and I measured this coefficient and found that it is really 3 Hz/V rather than 7.1 Hz/V. Measurement as follows:

• We beat the IFR and the OXCO against each other and looked at the mixed, low-passed output on a scope
• We adjusted the IFR frequency to match the OXCO as best we could.
• We applied 5 V dc from the DAC channel to the external input of the IFR, and measured the beat frequency (it was 14.8 Hz). This gives the acutation coefficient as 3.0 Hz/V.]

We observed broadband coherence of OMC_DC_SUM with ASC_AS_C_LF_SUM and ASC_A_RF36_PIT. We made some numbers and plots, using the 64kHz version of the channels.

First the measurements we made on OCXO oscillator:
- ASC_AS_C sees a RIN of about 5e-7/rtHz above 100Hz (either from H1:ASC-AS_C_SUM_OUT_DQ or from H1:IOP-ASC0_MADC6_TP_CH11). The same is true for its segment 1.
- The calculated shot noise RIN at 20mA (quantum efficiency 0.87) detected is 4.0e-9/rtHz.
- The 4.0e-9/rtHz agrees with DCPD_NULL_OUT_DQ's prediction (8.0e-8 mA/rtHz/20mA).
- DCPD_SUM_OUT_DQ sees a slightly elevated RIN of 4.6e-9/rtHz (9.2e-8 mA/rtHz/20mA).

- The RIN in DCPDA (H1:IOP-LSC0_MADC0_TP_CH12, corrected for the whitening) is about 5.9e-8 mA/rtHz, or RIN = 5.9e-9/rtHz at 20mA/2diodes (~15pm DARM offset)...
- ...or about 3.3e-8 mA/rtHz or 1.2e-8/rtHz at 5.7mA/2diodes (~8pm DARM offset).

- ASC-AS_C_SEG1 (H1:IOP-ASC0_MADC6_TP_CH11) and OMC-DCPD_A (H1:IOP-LSC0_MADC0_TP_CH12) shows a coherence of 0.053 at 20mA, suggesting a white noise floor a factor of 0.23 below shot noise.
- At 5.7mA the same coherence is about 0.13, i.e. the white noise floor is a factor of 0.39 below shot noise.
- These two measurements are in plot 1.

- Taking the last two statements together, we predict a coherent noise of
  - 5.9e-8 mA/rtHz *0.23 = 1.4e-8 mA/rtHz at 20mA/2diodes (~15pm DARM offset)  (RIN of coherent noise = 1.4e-9/rtHz) - The pure shot noise part is thus 5.7e-8 mA/rtHz
  - 3.3e-8 mA/rtHz *0.39 = 1.3e-8 mA/rtHz at 5.7mA/2diodes (~8pm DARM offset)  (RIN of coherent noise = 4.5e-9/rtHz) - The pure shot noise part is thus 3.0e-8 mA/rtHz.

- AS_C calibration:
 - 200V/W (see alog 15431)
 - quantum efficiency 0.8 (see alog 15431)
 - 0.25% of the HAM 6 light (see alog 15431)
 - We have 39200cts in the AS_C_SUM. Thus we have
   - 39200cts / (1638.4cts/V) * 10^(-36/40) (whitening) / (200V/W) = 1.89mW and AS_C. (shot noi
   - 1.89mW/0.025 = 76mW entering HAM6. I.e. we have slightly more sideband power than carrier power (Carrier: 27mW in OMC transmission).
   - Shot noise level on AS_C_SUM is at 2.0e-8 mA/rtHz, corresponding to a RIN of 1.6e-8/rtHz. I.e. the coherent noise seen at 5e-7/rtHz is high above the shot noise. Dark noise TBD.
   - The light entering HAM 6 has a white noise of 5e-7/rtHz*76mW = 3.8e-5 mW/rtHz 
    

Bottom line:
 -We have ~1.4e-8mA/rtHz, or 1.9e-8mW/rtHz of coherent white noise on each DCPD.
 -It corresponds to 3.8e-5mW/rtHz before the OMC, i.e. the the OMC seems to attenuate this component by 2000.
 -This noise stays at the same level (in mW/rtHz) for different DCPD offsets.


Next, we switched back to the IFR for testing. plot 2 shows the same coherences (all at 5.7mA / 8pm DARM offset), but on the IFR. Interestingly now AS_C and AS_A_RF36 start seeing different noise below 2kHz. We convinced our selfs that the higher excess noise seen in AS_A_RF36 is indeed oscillator phase noise from the IFR - so that is clearly out of the picture once of the OCXO. (Evan will shortly log the oscillator phase noise predictions.)


64k Channel list:
H1:IOP-LSC0_MADC0_TP_CH12:     OMC-DCPD_A  (used in plot)
H1:IOP-LSC0_MADC0_TP_CH13:     OMC-DCPD_B
H1:IOP-LSC0_MADC1_TP_CH20:     REFLAIR_A_RF9_Q
H1:IOP-LSC0_MADC1_TP_CH21:     REFLAIR_A_RF9_I
H1:IOP-LSC0_MADC1_TP_CH22:     REFLAIR_A_RF45_Q
H1:IOP-LSC0_MADC1_TP_CH23:     REFLAIR_A_RF45_I
H1:IOP-LSC0_MADC1_TP_CH28:     REFL_A_RF9_Q
H1:IOP-LSC0_MADC1_TP_CH29:     REFL_A_RF9_I
H1:IOP-LSC0_MADC1_TP_CH30:     REFL_A_RF45_Q
H1:IOP-LSC0_MADC1_TP_CH31:     REFL_A_RF45_I


H1:IOP-ASC0_MADC4_TP_CH8:      ASC-AS_A_RF36_I1
H1:IOP-ASC0_MADC4_TP_CH9:      ASC-AS_A_RF36_Q1
H1:IOP-ASC0_MADC4_TP_CH10:     ASC-AS_A_RF36_I2
H1:IOP-ASC0_MADC4_TP_CH11:     ASC-AS_A_RF36_Q2
H1:IOP-ASC0_MADC4_TP_CH12:     ASC-AS_A_RF36_I3
H1:IOP-ASC0_MADC4_TP_CH13:     ASC-AS_A_RF36_Q3   (used in plot)
H1:IOP-ASC0_MADC4_TP_CH14:     ASC-AS_A_RF36_I4
H1:IOP-ASC0_MADC4_TP_CH15:     ASC-AS_A_RF36_Q4

H1:IOP-ASC0_MADC6_TP_CH11:     ASC-AS_C_SEG1  (used in plot)
H1:IOP-ASC0_MADC6_TP_CH10:     ASC-AS_C_SEG2
H1:IOP-ASC0_MADC6_TP_CH9:      ASC-AS_C_SEG3
H1:IOP-ASC0_MADC6_TP_CH8:      ASC-AS_C_SEG4

We have been sending the PRCL length to PRM M3 and M2.  Even with the modified driver we are using for M2, there is no frequency where we can get more actuation with M2 than either M1 or M3 has.  There have been a few problems related to this not great offlaoding.  Locklosses due to using up the M2 range, glitches when the drives were near 2^16 (alog 18983 ) and locklosses where a 20 second oscillation used up the M3 drive (alog 19464 ).  

We are now sending PRCL to both M3 and M1.  A screen shot of the measured crossover (currently around 0.5 Hz) is attached.  We are roughly compensating the suspension resonances at 1.4 and 2.8 Hz, just to prevent mulitple crossovers.  We are curently using a pole at 0.01 Hz, a susComp filter that compensates for the suspension resonances, 27 and 60Hz notches and an elliptic lowpass at 70 Hz.  It is probably possible to push the crossover up above the suspension resonances, as my original suspension compensation was designed to do, this didn't work, it might be that I accidentally used an undamped suspension model to design it.  

This is implemented in the ISC_DRMI guardian now, and is fine.  It works for PRX, but the gaurdian has not been updated yet so the old offloading will come on until that is done.  We can do the same for SRM soon.  

Summary

A lower-estimate of absorption in the end test masses was measured using the end-station HWS cameras.  This can be used to get a lower estimate of absorption in the test masses.  I only got 30mins of data with the interferometer locked at 3W, we should repeat this measurement for a longer lock stretch to get a better idea of the absorption in the end test masses.  The current measurement gives an absorption of 230ppb in ETMY and 130ppb in ETMX.  Becasue we only measured for a 35min lock stretch, this will be an underestimate of the true test mass absorption.  Also, the ETMY HWS measurement looks untrustworthy, so it would be worth checking the PZT off sets.

Details

The EMT HWS cameras use the green als beam to measure the curvature change of the ETMs.  We want a single reflection of the green beam off of the ETM, we cannot take this measurement when the green beam is resonant in the arm cavity.  The green beam is usually shuttered and not present in the interferometer once the interferometer has reache DC_READOUT.  To take a measurement with the HWS, once the interferometer is at DC_READOUT and the green beam is shuttered and no longer used,  we re-open the ALS shutters and mislalign the green PZTs enough that the HWS sees no return beam from the ITM, only seeing a single bounce off of the ETM.  I choose the PZT misalignment offsets as stated in alog 17860.  Pictures of the HWS camera images are attached.  Both cameras measure 22 centroids.  The X-end image does not show a nice round beam, I may have to adjust the PZT alignment offset settings for this arm.

HWS reference centroids were taken before any locking started, with green PZTs in same misaligned state as we use when taking a measurement.

The ALS X/Y PZT2 are misaligned with type 'fixed', and with misalignment offsets:

H1:ALS-X_PZT2_PIT_MISALIGN_BIAS=15500

H1:ALS-X_PZT2_YAW_MISALIGN_BIAS=8300

H1:ALS-Y_PZT2_PIT_MISALIGN_BIAS=16100

H1:ALS-Y_PZT2_YAW_MISALIGN_BIAS=12000

The change in the spherical power of ETMY was 30udopters and ETMX was 11udiopters over a 35 minute lock stretch at 25.3W input power.  For a change in spherical power of 1udiopter, 1.06mW of power is absorbed, according to Aidan's model of the test mass absorption (LLO alog 14634).  The input power was 1.7W into the IMC, assuming 0.88 IMC-Faraday throughput efficency, 45 recycling gain, 280 arm cavity gain, 50:50 splitting ratio at BS, then 25.3*0.88*45*.50*280=140.3kW stored in the arms.  Absorbed power/stored arm power = optical absorption.  (Arm cavity gain is calculated using G_arm=(t_ITM/(1-r_ITM*r_ETM)).^2, where r_ETM=sqrt(1-TETM-L) and L=120ppm=loss in the arm. )  The arm power can also be caclulated using the four ASC_TR QPDs, which agree with the calulation using IMC input power, the variation between the four QPDs puts the uncertainty of the arm power at 15%.

Attached is a dataviewer plot of the HWS spherical power output during a 30min lock at 25W.  The shutters are opened when the shutter value=0.  I have calculated an absorption value for both test masses, but the spherical power inn the ETMY is growing in the wrong direction.  Either there is a sign error in a model or script somewhere, or this HWS is not set up correctly currently.  I will investigate this.

This measurement assumes the test masses have had enough time to reach thermal equilibrum, which actually takes longer than 30 mins.  This means that the absorption measurement is an underestimate.  It would be desirable to get a measurement of a lock stretch of >1hr.  The HWS measurement itself is quite noisy.