Koji, Sheila, Dan, Evan

Summary

Noise coupling measurements for MICH, SRCL, PRCL, intensity, and frequency have been taken.

We also tried a few small noise-hunting activities.

Details

Coupling measurements

For PRCL, MICH, and SRCL, we excited each dof with a swept sine and then recorded the transfer function from the error signal (IN1) to the DARM channel. MICH was already done previously.

For intensity, we did the same as described earlier.

For frequency, we used the same DAC channel (LSC-EXTRA_AO_2) to drive the common-mode board excitation point with a few millivolts of swept sine. Then we recorded the transfer function from REFL_A_9I (which is out of loop) to the DARM channel.

The dtt files are attached. More analysis to follow.

Other

Koji and I saw that ASC-MICH_P had significant cohrence with the DARM spectrum between 20 and 40 Hz. We took an OLTF and found that the UGF was 2 Hz with 60° of phase. We installed an elliptic LPF at 20 Hz, which removed most of this coherence (see attached). Correspondingly, the DARM spectrum dropped by a factor of 1.5 or so around 30 Hz.

We then tried to tune the bias of the EX ESD to see if we could improve the DARM spectrum. We could not find a sharp optimum; rather, anything from −190 V to 0 V seemed to be OK.

Koji then suggested trying to excite a scattering shelf in DARM by driving the OMC suspension. We drove the suspension longitudinally, transversely, and then vertically by a few microns at 0.15 Hz, but we found we could not make anything appear in the DARM spectrum.

Twice today the high voltage for the OMC PZT tripped, requriring the power supply to be reset by hand. The voltage is set at 100 V and the current limit is 2 mA. The quiescent draw is 0.8 mA.

Here are results from an SR785 spectrum of the output of the DCPD whitening field amp for OMC DCPD 1. I have included the ASD plot as a PDF and listed the major frequencies below. Below Nyquist the frequencies are consistent with H1:IOP-LSC0_MADC0_TP_CH12, so I have used these instead of the frequencies derived from the SR785 data. The amplitudes are from the SR785 data throughout. Those amplitudes differ from H1:IOP-LSC0_MADC0_TP_CH12 as they are measured before the whitening filter / antiwhitening DSP.

Index. Frequency (Hz) ; Amplitude (uVrms/rtHz)
1. 8160 Hz ; 595 uV
2. 9880 Hz ; 177 uV
3. 10426 Hz ; 206 uV
4. 13000 Hz ; 135 uV
5. 13857 Hz ; 145 uV  (wideband cluster in H1:IOP-LSC0_MADC0_TP_CH12 - looks narrower in SR785 data)
6. 15072 Hz, 15218Hz ; 136uV (double narrow peak in H1:IOP-LSC0_MADC0_TP_CH1 - unresolved in SR785 data)
7. 19554 Hz ; 52 uV
8. 21128 Hz ; 23 uV
9. 23109 Hz ; 22 uV
10. 25000 Hz ; 21 uV
11. 26607 Hz ; 19 uV
12. 29769 Hz ; 25 uV
13. 32693 Hz ; 47 uV (wideband, but not resolved well on SR785)
14. 35775-38594Hz ; peak 87 uV (wideband collection of unresolved lines in SR785)
15. 39964 Hz ; 27 uV
16. 42467 Hz ; 22 uV
17. 47287 Hz ; 5.2uV
18. 47762 Hz; 3.6uV
19. 75107 Hz ; 13uV (very large peak relative to surrounding background)
20. 98000 Hz ; 3.2uV
21. 101630 Hz ; 21uV (very large peak relative to surrounding background)

The CO2 power supply cables, which normally connected with a Delrin feedthrough, are now directly connected. Unfortunately this did not solve the problem of the low laser power. The max power output was ~5 watts and the power consumption was under 10 amps. After looking through the usual suspects I'm guessing that the RF driver has crapped out again. Replacing it will have to wait until an opportunity comes up. 

The AOM had it's power supply switched from the Instek (which was being shared with the laser) to the Kepco power supply. The AOM is now running at 25v and ~2 amps. This will be checked over when the laser is once again running full power.

Sheila, Daniel, Kiwamu

Since we moved the ALS fiber AOM from a fixed frequency drive to the IMC VCO on saturday, we have had some annoying ALS locklosses.  This morning we thought through what we are using as a frequency reference now, and made some changes to the way that we lock and engage tidal. 

• We request the arms to unlock after each lock loss, so that the tidal can bleed off, and don't ask them to lock again until the IMC is locked. 
• We are no longer using the slow servo that moved the IMC VCO to beign the COMM PLL in range.  This is no longer needed, and doesn't make sense anymore.  
• We start with each arm running local high bandwidth tidal on each arm, (which means that they are also following the IMC VCO through the fiber)
• We first lock COMM, and turn off the local tidal on the X arm.  Now the IMC length is following the X arm, and the X arm VCO stays in range because the fiber light also follows the IMC VCO
• Then we lock DIFF, as soon as DIFF starts to ramp on the gain, we turn off the Y arm local tidal.  The local tidal is needed to bring the DIFF PLL in range, but would cause a verry slow instability in the system if it stays on when DIFF is locked.  
• The common tidal servo now only has to compensate for the slow motion that really is tidal, (not micorseism).  We have been leaving it off until we get off of ALS, and this seems fine for now, although we might need to engage it earlier with a very low bandwidth if we want to keep ALS locked for long time periods. 

So the final configuration is that the Y arm is the reference, the X arm length follows the Y arm length, and the IMC follows the X arm.  This is working much better I think, we haven't had the frustrating locklosses this afternoon and evening. 

Elli, Sheila

Using the OMC suspension as an actuator for HAM6 centering caused large motion of OMC, and added scattering noise to DARM (17273.)  For this reason we rearranged the centering loops to center only on AS A and not AS B (alog 17325). This is what livinsgton does, but they only use AS A WFS for feedback.  We had difficulty with our ASC on monday 17577, which we though was due to the beam nt being well centered on WFS B, and indeed reverting our HAM6 centering fixed the problem.  Now we would like to see if we can use only one of our AS WFS for control. 

One option would be to move D ETM control to WFS B, however we saw that there is a sign flip in the WFS B signal between the CARM offset where we first engage the D etm wfs and the signals on resonance, this was similar to what was seen at LLO.  Today we looked into switching the BS and SRM loops from WFS B to WFS A.  First Elli tuned the phase of the indivual segments to minimize the SRM signal seem in the Q phase.  We were able to switch the BS loops over to WFS A, we replace the input matrix element with a -1 for AS A 36 Q yaw and -0.5 for AS A 36 Q pit.  We could close the loops like this and they seemed stable, but the build up in AS 90 was lower than when we locked using AS B.  In full lock we looked at this again, we were able to switch YAW over to AS A using the same matrix element, but the zero crossing for the pitch error signal was at an alingment where the build up was not very good.  

Once the BS was switched over to AS A, we had a look at switching over the SRM feedback in DRMI.  The offsets in the error signals were much smaller after we had already switched the BS control to AS A than before, and we did close the loops.  However, something became misaligned which was fixed as soon as we opened the loop.  

Aslo, we have had at least two lock losses in the last two days that I think were caused by engaging the SRC2 loop.  This is the loop from AS_C to SR2, which has a term in the output matrix that also feeds it to SRM.  The control signal sent to SRM has caused SRM to saturate in the two attached screen shots.  

J. Kissel

I've turned on the calibration lines that are injected into the DARM loop. Their frequency has been pre-chosen to be 34.7 and 538.1 [Hz] (see selection criteria from LLO aLOG 15870). For their amplitude, instead of going through the rigor of reverse-calibrating exactly the right amplitude in DARM_CTRL [counts] to get exactly a line of x [m] in DELTA L EXTERNAL to get an exact SNR of 30, I've just copied the amplitude Joe had chosen for comparable L1 sensitivity during ER6 (see LLO aLOG 15944).


Details:
- Important parameters of the line:
                       Channel                                    Parameter                   Value        Purpose
Line 1    H1:CAL-CS_GAMMA_LINE1_DEMOD_OSC_CLKGAIN    Line Amplitude (in DARM_CTRL [ct])    0.0112 [ct]     To track the DARM OLGTF near the UGF
          H1:CAL-CS_GAMMA_LINE1_DEMOD_OSC_FREQ       Line Frequency                         34.7 [Hz]      

Line 2    H1:CAL-CS_GAMMA_LINE2_DEMOD_OSC_CLKGAIN    Line Amplitude (in DARM_CTRL [ct])    0.957 [ct]      To track changes in the DARM Coupled Cavity Pole Frequency
          H1:CAL-CS_GAMMA_LINE2_DEMOD_OSC_FREQ       Line Frequency                         538.1 [Hz]
Attached is a desktop capture of the relevant screens. Where you actually enter in / change these important parameters is on the green-backgrounded DEMOD screens.

- The computation of the optical gain calibration is still off / zero, because I haven't entered in the values for the reference open loop gain at the line frequency (and various other dams are shut along the path to actually have it correct the DARM sensing function).

- All of the new optical gain compensation EPICs records had *not* been monitored but the SDF system, because the new channels did not, by default, have their SDF mask bits set to unity. So, I have to use sdf_set_monitor to turn on all the new bits in 
/opt/rtcds/userapps/release/cal/h1/models/h1calcs_safe.snap
and then update the table (only) for them to be monitored, and then I captured a new safe SDF file with all of the settings as shown in the screenshot.

- I've checked a 10 [Mpc] reference spectra from March 27th 2015 -- the 10 [hour] lock stretch, so I could get 1 [mHz] resolution -- for features at these calibration line frequencies. Nothing there! *phew*. See attached screenshots of "Reference DARM;" both the full spectra, and the zooms at 34.7 and 538.1 [Hz].

- After lots of hemming and hawing about the bandwidth of the DEMOD's signal bandpass and frequency of the DEMOD's demodulated outputs' low-pass, I decided to just try something "reasonable," and acknowledge that we'll have to iterate. As such, I chose a 1 [Hz] bandwidth for the band-pass and a corner frequency of 0.01 [Hz] for the lowpasses. The exact foton design strings are:
Band passes (4th order chebychev bandpass, with 1 [dB] ripple, with 1st and 2nd frequencies as defined below)
cheby1("BandPass",4,1,34.2,35.2)
cheby1("BandPass",4,1,537.6,538.6)
Low passes (3rd order elliptic low pass, with 1 [dB] ripple, with 40 [dB] stop-band suppression, with a corner frequency of 0.01 [Hz])
ellip("LowPass",3,1,40,0.01)
I attach bode plots.

- Things you only find out when you turn things on: the MEDM display of some critical channels like the line amplitude were displayed on the screen in the "truncated" format. That means that numbers less unity don't show up! This is obviously yuck, since the calibration line amplitudes are less than one DARM_CTRL counts. So, I've updated the 
userapps/release/cal/common/medm/CAL_CS_GAMMA_LINE_OVERVIEW.adl
userapps/release/cds/common/medm/LOCKIN_DEMOD.adl
MEDM screens to display a precision of either 3, 4, or 6 sig figs beyond the decimal by default, and committed to the repo.

Kiwamu, Sheila, Elli, TJ

This morning we had some difficulty with locking the X arm in IR for the inital alingment. We adjusted the gain, (to compensate for no longer changing the whitening gain), so the situation is back to what it used to be.  However, the loop doesn't seem like a verry good design.  Attached is a screen shot of the compensation filter and the measured open loop gain.  We tried to improve the phase right above the ugf by moving the pole at 100 Hz up to 300Hz , but this made the lock acquistion verry slow.  This is something that we need to come back to. 

Pcal lines running at 534.7 Hz (Xarm) and 540.7 Hz (Yarm) have been switched with one-another to cross check the calibration between the two arms. Now, the Xarm has a line at 540.7 Hz and Yarm as a line at 534.7 Hz. These will be switched back to its original position once we have a IFO locked data.This study is the continuation of what we reporrted in LHO alog 17582.

I suggested that if the vibrations of the HAM5-HAM6 septum plate were causing scattered light noise (note that Robert suspects not) one could try to damp the vibration mode with one of the SUS vibration absorbers. Dennis asked how effective this might be, and I estimate that it would be no more than slightly effective. 
I estimate that vibration mode of the septum plate is around 110 Hz (with a large margin of error)
I estimate that 1 VA might put a lower bound on the Q of 100-200.

more notes and some matlab calc can be seen in the "Secret SEI Log"
https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=712
( your ligo.org credentials will let you in)

A special version of awgtpman is used for the h1asc model running on h1asc0.  Because of this, the awgtpman process likely will not restart properly if the model is modified and restarted. 

If the h1asc model needs to be restarted, contact the CDS administrator staff or follow the instructions below:

1. Log on as controls to h1asc0:
me@opsws0:~$ ssh controls@h1asc0

2. Find the process ID of the currently running awgtpman for h1asc:

controls@h1asc0 ~ 0$ ps aux | grep awgtpman-2.9

3. The response should be similar to the following:

root     23365  0.1  3.1 280224 190864 ?     S  14:58   0:03 /opt/rtcds/lho/h1/target/gds/bin/awgtpman-2.9-asc-special -s h1asc -A -l /opt/rtcds/lho/h1/target/gds/awgtpman_logs/h1asc.log

4. The second field of the response is the process ID needed for the kill command, in this case 23365.  It changes each time the program runs.  Kill the process:

controls@h1asc0 ~ 0$ sudo kill -9 23365

Of course, you will use the real process ID, not the example ID shown here.

5. Restart the awgtpman for h1asc:

controls@h1asc0 ~ 0$ cd /opt/rtcds/lho/h1/target/gds/awgtpman_startup

controls@h1asc0 /opt/rtcds/lho/h1/target/gds/awgtpman_startup 0$ ./awgtpman_h1asc-new.cmd

6. There should be some text consisting of version strings that is output, and the AWG indicator on the overview screen for h1asc should turn green.

Why this is important

When the model is changed, a new mapping file is generated called tpchn_h1asc.par.  This file provides the association between testpoint channel names such as H1:ASC-AS_A_RF36_I1_ERR which dataviewer and other programs use, and channel numbers such as 32114 which the h1asc model uses.  If awgtpman is not restarted when the h1asc model is restarted, the mapping between names and channel numbers will likely be incorrect, and you may not be able to use a testpoint, or you may get the wrong data for a testpoint. 

The awgtpman for h1asc is different because a bug in the awgtpman software restricts the number of testpoints that can be opened for the model to an artificially low number.  A special version of awgtpman for h1asc was created to work around the bug until it can be fixed in a more permanent fashion.

730 - Karen/Cris To LVEA

906 - Stuart A, Restart SUS models for ITMY and ITMX

907 - Elli, to LVEA to check around HAM1 and HAM6

925 - Sudarshan, to E. Bay

958 - Sudarshan back

1033 - Elli, to IOT2

1100 - Elli, back

1205 - Jim B, Restart H1Broadcast0

1211 - Ed, LVEA

1300 - Jodi, to Ymid

1330 - Jodi, back

Scott L. Ed P. Chris S.

This A-Log will cover yesterday and today. The crew had an exceptional day yesterday cleaning 90 meters, finishing the section to the single door between X-1-7 and X-1-8 double doors. I attribute this increased productivity to the growing awareness of the crew to looking at the sections that may not be as bad as some of the others and looking ahead to certain sections that need more attention than others. This morning John and I went and inspected some of the sections and found them to be very clean. Results are posted here.

 Kudos to the cleaning crew on a great day. The remainder of the day today was spent relocating equipment, lights and support vehicles.

John and I did see some roller skid marks on the tube and took some pictures, 1 posted here and more to follow tomorrow.

Patrick T, Daniel S

This was a long time coming, but we finally have an automatic medm/adl generator for the EtherCAT system. For each data structure in TwinCAT, we generate 3 screens:

• A record screen in table format which contains all fields,
• An error screen which contains the error status including the individual error messages, and
• A brief error message screen which can be imported into other medm screens to indicate the status.

The attached screen shot shows a couple of examples for the x end station. The screen at the lower left is the overview screen accessible from the sitemap under the SYS button. The two screen at the top left are record and error screens for H1:ALS-X. All fields are substructures which link to other screens. The two screens to the right show the record and error screens for H1:ALS-X_REFL_LOCK. The fields represent mbbi, ao, ao, ao, (substructure link), bi, longin, bo, longout, and longout EPICS records in this order. The errors are individual messages with no further links. 

The generation is done in two steps:

• The TwinCAT EPICS ioc produces an aml file for each structure it encounters based on the tpy file (which is also used to generated the EPICS database). The ioc also reads the lists of error messages which are stored in separate files. The aml file contains the necessary macro substitutions for the final medm screens.
• The installation script to restart the EPICS interface generates the actual medm screens after the ioc has started up and finished its initialization work . The medm screens get installed in $(USERAPPS)/ecat/h1/medm at LHO.

For this to work Patrick had to modify how the error messages are stored in the TwinCAT code. We now have a constant array of strings containing them rather than hardcoded in the code. There is one of these for each structure type which gets written to a separate file with extension exp. This change should be transparent.

The updated code and scripts have been installed in the x end station. Screens are available for all stations, but for the vertex and y end they could be slightly out of synchronization until we upgrade them as well.

I installed a DSUB9 breakout board at the DSUB9 rear panel output from the output mode cleaner DC photodiode prewhitening amplifier board in rack ISC R5. This is to enable acquisition of broadband (initially 100kHz bandwidth) power spectral densities of the DC photodiode output. 

   Posted below are the March temperature and relative humidity data from the Long Term Storage (LTS) Dry Boxes in the VPW. DB1 and DB4 are in use and partly loaded with parts. DB2 and DB3 were turned on on 03/31/15 and will be reported next month. 

   The trends look good, with mean rH at 0.23% and 0.27% and temperature at 71F for both boxes. The humidity spikes are incursions into the cabinets to add or remove parts. I am not sure what caused the almost 10 degree temperature drop in DB1 (not recorded in DB4) on 03/23/15, however there were no spikes in the rH during this time. Will investigate if a trend develops.    

Koji, Evan

The NPRO shut off at around 08:11:00 UTC.

The interferometer was locked with no measurements or injections running.

With help from Evan Hall, Jeff Kissel and Ross Kennedy, got preliminary spectra from REFL-I and IMC-I, with the idea of identifying high frequency lines. A plot and some data are attached. Here are the frequencies of lines and clusters identified in these plots. They were taken with the SR785 box next to WHAM1, using the GPIB/ethernet bridge to the control room and Eric Quintero's readout scripts.

There are two attached figures, one with the two ASDs in separate planes, the other with them overlaid. Notice that the cavity length mode at around 36kHz is not in exactly the same place in the two channels, and neither is the first harmonic at around 70kHz. Other narrow peaks, however, do line up.

REFL-Q
Frequency ; ASD 
1. 2440Hz ; 21uVrms/rtHz 
2. 13.9kHz ; 16uVrms/rtHz
3. 34.4kHz ; 16uVrms/rtHz - broadband, bandwidth 1.2kHz
4. 40.4kHz ; 9.7uVrms/rtHz
5. 56.7kHz ; 13.0uVrms/rtHz
6. 60.9kHz ; 5.7uVrms/rtHz
7. 62.4kHz ; 7.4uVrms/rtHz
8. 65.6kHz ; 6.6uVrms/rtHz
9. 66.3kHz ; 6.3uVrms/rtHz
10. 70.2kHz ; 18.9uVrms/rtHz - broadband, bandwidth 3kHz 

IMC-I
Frequency ; ASD
1. 2453Hz ; 2uVrms/rtHz
2. 13.9kHz ; 16uVrms/rtHz
3. 38kHz ; 4uVrms/rtHz - broadband, bandwidth 1.2kHz, but does not line up with REFL-Q peak 3.
4. 40.6kHz ; 2.4uVrms/rtHz 
5. 56.5kHz ; 2.4uVrms/rtHz
6. 62.4kHz ; 2.4uVrms/rtHz
7. 65.6kHz ; 3.1uVrms/rtHz - double peak, just resolved.
8. 69.1kHz ; 3.1uVrms/rtHz
9. 76.6kHz ; 9.3uVrms/rtHz - broadband, bandwidth 3kHz, but does not line up with REFL-Q peak 10.