SR2 Top Satellite Box OSEM Photodiode Oscilloscope Traces

The oscilloscope traces attached show a comparison of the time domain signals between SR2 Top OSEM Photodiode A and SR2 OSEM Photodiode B, as seen from connector J2 "Analog Rack". (We use the satellite box signal and connector naming conventions as shown on D1400098-v1.)  OSEM Photodiode A was from the SR2 Top OSEM, the suspect channel.  In the images, the upper trace, labeled "1", is from OSEM Photodiode B, satellite box connector J2 pin 2.  The lower trace, labeled "2", is from OSEM Photodiode A, satellite box connector J2 pin 1, the noisey channel under investigation.

Two x10 probes were used.  The vertical scale factors for images 1 and 2 are 0.200 V/div.  The vertical scale factor for image 3 is 0.050 V/div.

Image 1 shows the satellite box as found, all cables connected. Photodiode A shows significantly more noise.

Image 2 shows the photodiode signals with the "Vacuum Tank" cable, connector J1, disconnected. All quiet.

Image 3 shows the photodiode signals with the "Vacuum Tank" cable reconnected to J1.  Both photodiode signals now have the same amplitudes. (Note the more sensitive scale factor for image 3.)

An intermitant? A poorly seated connector? Pickup from the SEI CPS 25kHz?  Betsy reported that the noise spectrum did not change!

(Richard M, Fil C, Ed M, Daniel S)

ECR E1600192.

Split Whitening Chassis S/N S1101627:

• On the interface chassis remove R7, R8, R9 and R10, R17 and R18 (disconnects in-vac cables and Z-switch).
• On the interface chassis jumper 220 pF capacitors on J3 between pins 1-3, 9-11, 2-4 and 10-12 (adds one pole of high pass at 7.2 kHz).
• On the 2nd whitening board remove C37, C38 and C39 (removes both poles of low pass).

AA Chassis S/N S1102788 & S1202201:

• On channels 15 and 16 remove C1, C6 and C9 (two poles of 10 kHz low pass).
• On channels 15 and 16 remove C7 (one pole of 10 kHz low pass).
• The twin-T notch was left in. It is fairly wide and attenuates ~17 dB at 50 kHz.

The attached plots show the transfer functions of

1. whitening chassis: OMC DCPD_A: same as before
2. whitening chassis: OMC PI DCPD_A: modified
3. whitening chassis: OMC DCPD_B: same as before
4. whitening chassis: OMC PI DCPD_B: modified
5. AA chassis: channel 15
6. AA chassis: channel 16

The OMC DCPDs have proven to be useful for monitoring the test mass acoustic modes around 15 kHz, but there is a lot of low-pass filtering in the readout chain that render them less useful for monitoring higher frequency acoustic modes. This is now being changed with modifications to the electronics that will provide separate, faster channels for PI monitoring:

• In-vacuum pre-amp: this has 2 poles at 16 kHz (these will remain, since in HAM6)
• Whitening board: 1 pole at 14 kHz; 1 pole at 18 kHz. These will be eliminated in the new chain.
• Anti-alias filter: 3rd order Butterworth low-pass at 10 kHz. These will be eliminated in the new chain.

The attached plot shows the magnitude response of the low-pass filtering in the previous case, and with the poles removed from the whitening and AA channels. It is no wonder that no PI modes have been seen above the 15-16 kHz grouping, as there is 40 dB of relative attenuation already at 25 kHz.

I also attach a 1kHz - 10 MHz transfer function of the in-vacuum DCPD readout that Koji measured at Caltech:

https://nodus.ligo.caltech.edu:8081/OMC_Lab/235

The infrasound mics have already been upgraded at LLO but today I removed the sensors at LHO.  I removed the sensors from the microphones in the CS, at EX, and at EY.  This meant unscrewing the bottom of the instrument box and pulling out some of the equipment.  As far as I could tell everything went as planned and the equipment will now be sent away for upgrades.

WP 5954

All of the 18bit DAC cards in h1susb123 and h1sush2a now successfully pass the autocal on both power up and restart of the IOP models.  Results shown below:

h1susb123 - power up
[   61.694760] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   67.057232] h1iopsusb123: DAC AUTOCAL SUCCESS in 5340 milliseconds
[   72.850938] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   78.213461] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds
[   85.247010] h1iopsusb123: DAC AUTOCAL SUCCESS in 6571 milliseconds
[   90.610149] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   95.973497] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds
[  101.336018] h1iopsusb123: DAC AUTOCAL SUCCESS in 5340 milliseconds
h1susb123 - IOP model restart
[  911.921930] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds
[  917.282286] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds
[  923.070351] h1iopsusb123: DAC AUTOCAL SUCCESS in 5341 milliseconds
[  928.430617] h1iopsusb123: DAC AUTOCAL SUCCESS in 5344 milliseconds
[  935.453979] h1iopsusb123: DAC AUTOCAL SUCCESS in 6576 milliseconds
[  940.814416] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds
[  946.174750] h1iopsusb123: DAC AUTOCAL SUCCESS in 5345 milliseconds
[  951.535191] h1iopsusb123: DAC AUTOCAL SUCCESS in 5341 milliseconds

h1sush2a - power up
[   48.086815] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   53.450158] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds
[   60.479701] h1iopsush2a: DAC AUTOCAL SUCCESS in 6576 milliseconds
[   65.843077] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   71.640028] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds
[   77.001396] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[   82.364713] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds
h1sush2a - IOP model restart
[ 1252.909059] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[ 1258.269410] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[ 1265.292831] h1iopsush2a: DAC AUTOCAL SUCCESS in 6572 milliseconds
[ 1270.653176] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[ 1276.441059] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[ 1281.801414] h1iopsush2a: DAC AUTOCAL SUCCESS in 5344 milliseconds
[ 1287.161817] h1iopsush2a: DAC AUTOCAL SUCCESS in 5345 milliseconds

Last week, Rana was inquiring about how locklosses affect oplev sums. 

Took a random sample of locklosses from O1 and came up with fairly consistent results for after a lockloss, so here's the nitty gritty:

• HAM oplevs sums don't change
• ETM sums drop ~3%
• ITM sums drop ~1%  (which is small compared to overall DC drift of the sum value)

Attached is an example of a lockloss from Nov.

We adjusted the pressure on the pwrmtr water circuit from its nominal 5 bar to 4.5 bar.  The flow rate to the
laser heads decreased somewhat.  Put the pressure back to ~5 bar to set the flow rate in the circuit to be
over 1.25 l/min.

    In doing so, the other flow rates seemed to behave as expected.  We will monitoring the flow rates and
pressures over the the next few days to see if anything settles out/down.






Jeff, Peter

Measured ~18 mV, 20 ohms between the table surface and the chassis of the ISS AOM.  Installed DC block.
Measured the same afterwards, so I removed the DC block.

This clearly does not work as well as the one on the FSS AOM (for whatever reason).

I have set the level setpoint to 90% to exercise the new PID control.

Found that the PI output for CP5 was 0% even though the pump level is at 83% -> I switched CP5 to manual control with LLCV %open of 90% -> The other vacuum group members have been experimenting with CP5 of late so I'll "stay out of the kitchen" and let them continue/investigate.

Jenne, Carl, Sheila, TJ, Stefan, Lisa

We have a quite reliable locking sequence to 40W at this point (recycling gain ~28.5, same SOFT offset strategy as over the week-end with one set of offsets engaged before power up, one at 40W; SRM alignment done by end), so tonight we started going back to low noise while doing PI testing.

Here is the list of things we successfully did; we still need to modify the ISC LOCK code to be compatible with some of those (note that we are still on POPX, so the POP beam diverter is open):

  
Coil driver switched to low noise 
  
ASC cut-offs: JLP35 for DHARD (P/Y) and CHARD (P) 
  
Modified CHARD-Y 35 Hz cut-off (the new one is called "modcut"), because the current one had gain peaking between 20 and 30 Hz that was preventing us from switching ESD Y to low noise; CHARD-Y gain also lowered by 40% (from -0.7 to -0.4)
  
ESD Y switched to low noise 
  
ISS3 loop off, ISS 2 ON (instructions from Kiwamu; Jenny had to reduce the actuation delay from 0.2 to 0.1 to engage the second loop) 
  
OMC whitening on 
  
MICH feed-forward: the -15.9 nominal gain seemed ok 
  
Nominal SRCL tuning: LP 80, gain reduced by a factor of 2, feed-forward engaged with nominal gain -1 
  
REFL and AS beam diverters closed (POP open as we are still on POPX)  
  
ESD X in state 2 (tested bias off -- no impact on the noise) 
  
ITMY ESD state switched to 2 
  
Jenne realized that the OMC ASC output had railed --we switched to QPDs and stayed on QPDs for the rest of the lock, but awe were already transitioned back to high noise at that point.. 


The best spectrum we have achieved was at June 28, 6:00 - 6:10 UTC (with the OMC alignment railed) . 

Below 60 Hz we still have a lot of ASC noise, and that was expected, but there was a clear excess of noise also at 100 Hz that we didn't expect to be there. For the records, sensMon claimed 40 Mpc.

We run out of time because of the 15542.6 ETMY PI, accidentally driven up while trying to damp the 15542. We lost lock at June 28, 6:35 UTC, after about 2 hours at 40W. 


Some notes:

 * we systematically lose recycling gain when we increase the power, we go from 35 at 2 W to 29 at 40W. Attempts to improve the recycling gain by changing the alignment offsets of most loops failed;

 * because of the lower recycling gain, the shot noise improvement at high frequency that we expect is ~30%

Daniel, Ross, Carl, Kiwamu,

WP#: 5957

We made two modifications on the h1omspi, h1susetmxpi and h1susetmypi models as follows.

• We added all the I and Q down sampled channels to science frame at 2 kHz.
• We added two new OMC DCPD signals which don't get attenuated by two 10 kHz poles of the whitening circuits.

We are ready for tomorrow's model restart during the maintenance period.

[I and Q signals to science frame]

Since all the I and Q down sampled signals have been already recorded in commissioning frame, we just added a star symbol to each channel name in the DQ text field in the simulink models. In total, 24 channels (8 channels from each model) will newly go to science frame at 2 kHz.

[New DCPD signals]

We decided to do a quick hack on the OMC whitening board so that we don't suffer from the two 10 kHz poles (technically, 14 and 18 kHz from the differential receiver stage, see alog 21131) to obtain a better signal to noise ratio. Some more details of this quick hack will be reported by Daniel and Stefan later. In the mean time, we have edited the h1omcpi model so that it is capable of handling these two signals. In the first attachment it shows the two new ADC inputs (adc_0_14 and adc_0_15) which then go to a subblock called PI_DCPD. One can choose whether the normal DCPD is used for the PI error signal or the new signals by the two choice blocks that are behind the PI_DCPD block.

Once we become able to damp the PI modes using the new DCPD signals, we should get rid of the old DCPD signals. But for commissioning purpose, we are leaving the normal DCPDs available for now.

Also, we added these two new signals to commissioning frame at the full sampling rate at 64 kHz. So, in total, we now have four 64 kHz DQ channels, which should be reduced to 2 or 1 channels as we complete the commissioning at some point in future. The new DQ channels have the names as PI_DCPD_64KHZ_A(B)HF. Note that in order to save the test points for the normal DCPD signals, we pulled them out of a subblock and placed them at the top level as seen in the first attachment.

In the PI_DCPD subblock, we have placed controlled-IIR-fitlers so that they can be synchronized with the analog board settings as have been done in the LSC and ASC models. See the second attachment.

All the changes are checked into the SVN repo. We made sure that they compiled without errrors.