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ID Date Author Type Category Subjectup
  8054   Mon Feb 11 12:49:54 2013 JenneSummaryLSCResonant freq change - why? (and passive TT mode freqs)

Quote:

  Is it because of the change in the resonant frequency of the BS-PRM stack? How much the load on BS-PRM changed?
  Or is it because of the change in the resonant frequency of PR2/PR3

I claim that neither of those things is plausible.  We took out 1 PZT, and put in 1 active TT onto the BS table.  There is no way the resonant frequency changed by an appreciable amount due to that switch.

I don't think that it is the resonant frequency of the TTs either.  Here, I collate the data that we have on the resonant frequencies of our tip tilts.  It appears that in elog 3425 I recorded results for TTs 2 and 3, but in elog 3447 I just noted that the measurements had been done, and never put them into the elog.  Ooops.

Resonant frequency and Q of modes of passive tip tilts. 

  Vertical Yaw Pos Side
TT1 f0=20, Q=18 f0=1.89, Q=3.8 f0=1.85, Q=2 f0=1.75, Q=3.2
TT2 f0=24, Q=7.8 f0=1.89, Q=2.2 f0=1.75, no Q meas f0=1.8, Q=4.5
TT3 f0=20, Q=34 f0=1.96, Q="low" f0=1.72, Q=3.3 f0=1.85, Q=6
TT4 f0=21, Q=14 f0=1.88, Q=2.3 f0=1.72, Q=1.4 f0=1.85, Q=1.9
TT5 f0=20, Q=22.7 no measurement f0=1.79, Q=1.8 f0=1.78, Q=3.5

Notes:  "Serial Number" of TTs here is based on the SN of the top suspension point block.  This does not give info about which TT is where.  Pitch modes were all too low of Q to be measured, although we tried.

Tip tilt mode measurements were taken with a HeNe and PD shadow sensor setup - the TT's optic holder ring was partially obscuring the beam.

  16914   Tue Jun 14 19:34:06 2022 yutaUpdateSUSResonant frequency identification from the free swing test

[JC, Anchal, Yuta]

We are working on resonant frequency idendification from the free swing test done last weekend.
Table below is the resonant frequencies identified, and attached are the plots of peak identification for some of our new suspensions.
To identify the resonant frequencies, the kicks were done in each degrees of freedom so that we can assume, for example, SUSPOS will be mostly excited when kicked in POS and the heighest peak is at the POS resonant frequency.
For PR3, AS1 and ETMY, the resonant frequency idendification needs to be done in the order of POS, PIT, YAW, SIDE and identified frequencies need to be removed when finding a peak.
Other than that, the identification was done without any prior assumptions on the suspensions.
For ITMY, ETMY, PR2, PR3, AS1, AS4, yaw has lower resonant frequencies than pitch, as opposed to other suspensions.
For LO1, POS and PIT frequencies might be swapped because LLCOIL is not working (40m/16898) and POS/PIT kicks both might be excited SUSPOS/PIT.
LO1 coil output matrix was temporarily modified so that we use only two coils for POS/PIT/YAW excitation (Attachment #7), as we did for ITMY (40m/16899).

The scripts for the free swinging test and analysis live in /Git/40m/scripts/SUS/InMatCalc

     POS    PIT    YAW    SIDE
BS   0.990  0.748  0.794  0.959 
ITMY 0.987  0.739  0.634  0.948 fPIT > fYAW
ETMY 0.979  0.816  0.649  0.954 fPIT > fYAW
ITMX 0.978  0.586  0.758  0.959 
ETMX 0.962  0.725  0.847  1.000 
PRM  0.939  0.541  0.742  0.990 
PR3  1.019  0.885  0.751  0.989 fPIT > fYAW
PR2  0.996  0.816  0.724  0.999 fPIT > fYAW
SRM  0.969  0.533  0.815  0.985 
SR2  0.978  0.720  0.776  0.997 
LO1  0.926  1.011  0.669  0.993 POS AND PIT MIGHT BE SWAPPED
LO2  0.964  0.998  0.995  0.990 WRONG DUE TO STUCK (40m/16913)
AS1  1.028  0.832  0.668  0.988 fPIT > fYAW
AS4  1.015  0.800  0.659  0.991 fPIT > fYAW
MC1  0.967  0.678  0.797  0.995 
MC2  0.968  0.748  0.815  0.990 
MC3  0.978  0.770  0.841  0.969 
Attachment 1: LO1.png
LO1.png
Attachment 2: AS1.png
AS1.png
Attachment 3: AS4.png
AS4.png
Attachment 4: PR2.png
PR2.png
Attachment 5: PR3.png
PR3.png
Attachment 6: SR2.png
SR2.png
Attachment 7: Screenshot_2022-06-14_21-07-09.png
Screenshot_2022-06-14_21-07-09.png
  4495   Wed Apr 6 22:13:24 2011 BryanConfigurationGreen LockingResonating green light!

Every so often things just work out. You do the calculations, you put the lenses on the bench, you manually adjust the pointing and fiddle with the lenses a bit, you get massive chunks of assistance from Kiwamu to get the alignment controls and monitors set up and after quite a bit of fiddling and tweaking the cavity mirror alignment you might get some nice TEM_00 -like shapes showing up on your Y-arm video monitors.

So. We have resonating green light in the Y-arm. The beam is horribly off-axis and the mode-matching, while close enough to give decent looking spots, has in no way been optimised yet. Things to do tomorrow - fix the off-cavity-axis problem and tweak up the mode-matching... then start looking at the locking...

  10278   Sat Jul 26 14:45:33 2014 GabrieleMetaphysicsASCResponse of POP QPD

 Koji asked me to perform a simulation of the response of POP QPD DC signal to mirror motions, as a function of the CARM offset. Later than promised, here are the first round of results.

I simulated a double cavity, and the PRC is folded with parameters close to the 40m configuration. POP is extracted in transmission of PR2 (1ppm, forward beam). For the moment I just placed the QPD one meter from PR2, if needed we can adjust the Gouy phase. There are two QPDs in the simulation: one senses all the field coming out in POP, the other one is filtered to sense only the contribution from the carrier field. The difference can be used to compute what a POP_2F_QPD would sense. All mirrors are moved at 1 Hz and the QPD signals are simulated:

pop_qpd_all.png

This shows the signal on the POP QPD when all fields (carrier and 55 MHz sidebands) are sensed. This is what a real DC QPD will see. As expected at low offset ETM is dominant, while at large offset the PRC mirrors are dominant. It's interesting to note that for any mirror, there is one offset where the signal disappears.

pop_qpd_carrier.png

This is the contribution coming only from the carrier. This is what an ideal QPD with an optical low pass will sense. The contribution from the carrier increases with decreasing offset, as expected since there is more power.

pop_qpd_sb.png

Finally, this is what a 2F QPD will sense. The contribution is always dominated by the PRC mirrors, and the ETM is negligible.

The zeros in the real QPD signal is clearly coming from a  cancellation of the contributions from carrier and sidebands.

The code is attached.

Attachment 4: foldeddoublecavity.mist
classname FoldedDoubleCavity

# parameters
const Pin  1                # input power
const Lprc 6.752            # power recycling cavity length
const d_BS_PR3 0.401        # folding mirror distances
const d_PR2_PR3 2.081
const d_PRM_PR2 1.876
const c 299792458           # speed of light
const fmod 5*c/(4*Lprc)     # modulation frequency, matched to Lprc
... 51 more lines ...
Attachment 5: pop_qpd.m
% compile simulation class
clear classes
m = MIST('foldeddoublecavity.mist');

% create simulation object
s = FoldedDoubleCavity(8);

% set angulat motion
s.PRM.setMotionShape('pitch');
s.PR2.setMotionShape('pitch');
... 85 more lines ...
  10888   Tue Jan 13 01:11:51 2015 diegoUpdateLSCResponse of error signals to MICH EXC

For several MICH offsets, I measured the response of REFL33Q, ASDC and the ratio ASDC/POPDC to a MICH EXC. It appears that there is no frequency-dependent effect. The plots for MICH_OFFSET = 0.0 and 2.0 are slightly lower in magnitude: the reason is they were the first measurements done, and after that a little realignment of BS was necessary, so probably that is the reason.

 

 

Attachment 1: MICH_to_REFL33Q_ASDC_12Jan2015_1.pdf
MICH_to_REFL33Q_ASDC_12Jan2015_1.pdf
Attachment 2: MICH_to_REFL33Q_ASDC_12Jan2015_2.pdf
MICH_to_REFL33Q_ASDC_12Jan2015_2.pdf
Attachment 3: MICH_to_REFL33Q_ASDC_12Jan2015_3.pdf
MICH_to_REFL33Q_ASDC_12Jan2015_3.pdf
  585   Fri Jun 27 18:21:01 2008 JenneUpdateElectronicsResponse of the LO input on the MC demod board
The alarm handler has been flipping out saying that the LO input of the MC's demod board is too low, so at Rana's suggestion, Eric and I measured the response of the LO input. We used an SR345 function generator at 29.485MHz and several different amplitudes to make a table. The demod board should see an input from the LO between 0-2dBm. When I measured what was going into the LO input from the 29.5MHz delay line phase shifter, the LO input was seeing 4dBm. I'm going to put a 3dB attenuator between the phase shifter and the demod board.

Also, now that we have this table of response values, I'm going to change the settings of the alarm handler to something more reasonable.
Amplitude of 29.485MHz input sine wave [dBm]    |        Value of channel C1:IOO-MC_DEMOD_LO
--------------------------------------------    |        -----------------------------------
-10                                             |        -0.000449867
-8                                              |        -0.000449867
-6                                              |        -0.000449867
-4                                              |        0.000384331
-2                                              |        0.00526733
0                                               |        0.0199163
2                                               |        0.0492143
4                                               |        0.0931613
6                                               |        0.161523
8                                               |        0.229885
10                                              |        0.293364
  275   Sat Jan 26 18:48:43 2008 JohnSummaryComputersRestart iscepics
iscepics died this afternoon. We restarted it and restored settings from yesterday. I've written up instructions in the wiki.
  5396   Tue Sep 13 19:04:58 2011 SureshUpdateComputer Scripts / ProgramsRestarted Frame builder several times while compiling c1ioo, c1mcs and c1rfm

I restarted the frame builder at the following times

 

Tue Sep 13 14:53:49 PDT 2011

 

Tue Sep 13 16:46:32 PDT 2011

 

Tue Sep 13 17:24:16 PDT 2011

  1564   Fri May 8 10:05:40 2009 AlanOmnistructureComputersRestarted backup since fb40m was rebooted

Restarted backup since fb40m was rebooted.

  5828   Mon Nov 7 11:50:42 2011 JenneUpdateelogRestarted elog

Elog restart script killed the elog, but didn't restart it.  Restarted by hand.

  5829   Mon Nov 7 12:51:44 2011 ZachUpdateelogRestarted elog

I've noticed that it always takes running the script twice for it to actually work. I think there's something wrong with how it's doing it. I'll mess with it sometime the elog isn't getting much use.

Quote:

Elog restart script killed the elog, but didn't restart it.  Restarted by hand.

 

  8420   Sun Apr 7 20:49:19 2013 ZachUpdateGeneralRestarted elog

with the script, as it was down.

  8428   Tue Apr 9 01:46:40 2013 ZachUpdateGeneralRestarted elog

Again.

Quote:

with the script, as it was down.

 

  3648   Tue Oct 5 13:46:26 2010 josephb, alexUpdateCDSRestarted fb trending

Fb is now once again actually recording trends.

A section of the daqdrc file (located in /opt/rtcds/caltech/c1/target/fb/ directory) had been commented out by Alex and never uncommented.  This section included the commands which actually make the fb record trends.

The section now reads as:

# comment out this block to stop saving data

#
start frame-saver;
sync frame-saver;
start trender;
start trend-frame-saver;
sync trend-frame-saver;
start minute-trend-frame-saver;
sync minute-trend-frame-saver;
start raw_minute_trend_saver;
#start frame-writer "225.225.225.1" broadcast="131.215.113.0" all;
#sleep 5;

  667   Mon Jul 14 12:43:07 2008 JohnSummaryComputersRestarted fb40m, tpman and c1ass
  2998   Thu May 27 08:22:57 2010 AidanUpdateComputersRestarted the elog this morning
  4365   Tue Mar 1 08:42:18 2011 AidanUpdateelogRestarted the elog this morning

 The elog was dead this morning. I reanimated it. It is now undead.

Attachment 1: Zombie.gif
Zombie.gif
  4575   Wed Apr 27 20:14:16 2011 AidanSummaryelogRestarted with script ...
  4744   Thu May 19 00:15:20 2011 JenneUpdateelogRestarted, Italian-style

Aka, from a hotel in Pisa.

  4745   Thu May 19 00:22:21 2011 ranaUpdateelogRestarted, Italian-style

Quote:

Aka, from a hotel in Pisa.

 Restarted Thu May 19 00:21:49 2011 to recover from Jenne's Italian terrorism.

  10080   Fri Jun 20 11:43:30 2014 ericqUpdateComputer Scripts / ProgramsRestarting ELOG

Manasa let me know that the ELOG was down, and that she used the normal restart procedure, but then all entries were gone. 

This is because the ELOG has been moved on nodus, so going to the old place and running the restart script starts up the old dysfunctional ELOG installation. 

The proper place to restart the ELOG is now nodus:/export/home/elog/start-elog.csh

I'm updating the relevant 40m wiki page now. 

  15995   Mon Apr 5 08:25:59 2021 Anchal, PacoUpdateGeneralRestore MC from early quakes

[Paco, Anchal]

Came in a little bit after 8 and found the MC unlocked and struggling to lock for the past 3 hours. Looking at the SUS overview, both MC1 and ITMX Watchdogs had tripped so we damped the suspensions and brought them back to a good state. The autolocker was still not able to catch lock, so we cleared the WFS filter history to remove large angular offsets in MC1 and after this the MC caught its lock again.

Looks like two EQs came in at around 4:45 AM (Pacific) suggested by a couple of spikes in the seismic rainbow, and this.

  1464   Thu Apr 9 20:56:12 2009 YoichiHowToGeneralRestore the alignment. Write elog entries.
I often find that the mirrors are left mis-aligned (like in X-arm mode) when I come in for the locking, including tonight.
As Rob stated repeatedly in the past elog, leaving the mirrors mis-aligned for a long time without a reason is an abomination.
It will cause a slow drift of the mirrors and the lock acquisition work is severely slowed down as I have to run the alignment script many times.

I also found that the GPIB-Ethernet box (named teofila) was taken away from the SR785 hooked up to the CM board.
I found it connected to Alberto's setup. Instead, another GPIB box was left on the SR785 but not connected.
I couldn't find any elog entry about this.
This is totally unacceptable.
The SR785 has been used as a very important tool for monitoring the AO path loop gain during the power up.
You can use it if you need, but you have to note it in elog.

The other GPIB box left on the SR785 had a wrong name labeled on it. It had a name "ERMINIA", but the IP address written next to the name was actually assigned to "crocetta" in the DNS server on linux1. I don't know who made the label. I put a new and correct label on it.
Now I'm using crocetta for the SR785 so Alberto can keep using teofila.

Anyway, I think recently people are lazy about elog.
Whatever work you did, please put it in the elog even if you think it is trivial.
I also would like to see more detailed elog entries from people. Many of the recent elog entries are too simple or superficial that it is hard for other people to figure out what was really done.
  16238   Tue Jul 6 10:47:07 2021 Paco, AnchalUpdateIOORestored MC

MC was unlocked and struggling to recover this morning due to misguided WFS offsets. In order to recover from this kind of issue, we

  1. Cleared the bogus WFS offsets
  2. Used the MC alignment sliders to change MC1 YAW from -0.9860 to -0.8750 until we saw the lowest order mode transmission on the video monitor.
  3. With MC Trans sum at around ~ 500 counts, we lowered the C1:IOO-WFS_TRIGGER_THRESH_ON from 5000 to 500, and the C1:IOO-WFS_TRIGGER_MON from 3.0 to 0.0 seconds and let the WFS integrators work out some nonzero angular control offsets.
  4. Then, the MC Trans sum increased to about 2000 counts but started oscillating slowly, so we restored the delayed loop trigger from 0.0 to 3.0 seconds and saw the MC Trans sum reach its nominal value of ~ 14000 counts over a few minutes.

The MC is now restored and the plan is to let it run for a few hours so the offsets converge; then run the WFS relief script.

  16239   Tue Jul 6 16:35:04 2021 Anchal, Paco, GautamUpdateIOORestored MC

We found that megatron is unable to properly run scripts/MC/WFS/mcwfsoff and scripts/MC/WFS/mcwfson scripts. It fails cdsutils commands due to a library conflict. This meant that WFS loops were not turned off when IMC would get unlocked and they would keep integrating noise into offsets. The mcwfsoff script is also supposed to clear up WFS loop offsets, but that wasn't happening either. The mcwfson script was also not bringing back WFS loops on.

Gautam fixed these scripts temprorarily for running on megatron by using ezcawrite and ezcaswitch commands instead of cdsutils commands. Now these scripts are running normally. This could be the reason for wildly fluctuating WFS offsets that we have seen in teh past few months.

gautam: the problem here is that megatron is running Ubuntu18 - I'm not sure if there is any dedicated CDS group packaging for Ubuntu, and so we're using some shared install of the cdsutils (hosted on the shared chiara NFS drive), which is complaining about missing linked lib files. Depending on people's mood, it may be worth biting the bullet and make Megatron run Debian10, for which the CDS group maintains packages.

Quote:

MC was unlocked and struggling to recover this morning due to misguided WFS offsets. In order to recover from this kind of issue, we

  1. Cleared the bogus WFS offsets
  2. Used the MC alignment sliders to change MC1 YAW from -0.9860 to -0.8750 until we saw the lowest order mode transmission on the video monitor.
  3. With MC Trans sum at around ~ 500 counts, we lowered the C1:IOO-WFS_TRIGGER_THRESH_ON from 5000 to 500, and the C1:IOO-WFS_TRIGGER_MON from 3.0 to 0.0 seconds and let the WFS integrators work out some nonzero angular control offsets.
  4. Then, the MC Trans sum increased to about 2000 counts but started oscillating slowly, so we restored the delayed loop trigger from 0.0 to 3.0 seconds and saw the MC Trans sum reach its nominal value of ~ 14000 counts over a few minutes.

The MC is now restored and the plan is to let it run for a few hours so the offsets converge; then run the WFS relief script.

  16816   Thu Apr 28 09:12:18 2022 AnchalUpdateBHDRestoring arm alignment

This would be a daily first task in the morning. We'll need to check the status of arm alignment and optimize it back to maximum every morning for the rest of the day's work.

Today, when I came, on openin gthe PSL shutter, IMC was aligned good, both arms were flashing but YARM maximum transmission count was around 0.7 (as opposed to 1 from yesterday) and XARM maximum transmission count was 0.5 (as opposed to 1 from yesterday). I did not change the input alignment to the interferometer. I only used ITMY-ETMY to regain flashing count of 1 on YARM and used BS and tehn ITMX-ETMX to regain flashing count of 0.9 to 1 in XARM.

Even thought the oplevs were centered yesterday, I found the oplev had drifted from the center and the optimal position also is different for all ooptics except EMTY and BS. It is worth nothign that in optimal position both PIT and YAW of ITMY and ITMX are off by 70-90 uradians and ETMX Pit oplev is off by 55 uradians.

 

  16819   Thu Apr 28 18:07:04 2022 AnchalUpdateBHDRestoring arm alignment at EOD

Restored arm algiment to get 0.8 max flashing on YARM and 1 max flashing on XARM. I had to move input alignment using TT2-PR3 pair and realign YARM cavity axis using ITMY-ETMY pair.

I would like to advertise this useful tool that I've been using for moving cavity axis or input beam direction. It's a simple code that makes your terminal kind of videogame area. It moves two optics together (either in same direction or opposite direction) by arrow key strokes (left, right for YAW, up, down for PIT). Since it moves two optics together, you actually control the cavity axis or input beam angle or position depening on the mode.

 

  12138   Fri May 27 02:52:53 2016 ericqUpdateLSCRestoring high BW single arm control

I've been futzing with the common mode servo, trying to engage the AO path with POY for high bandwidth control of a single arm lock. I'm able to pull in the crossover and get a nice loop shape, but keep getting tripped up by the offset glitches from the CM board gain steps, so can't get much more than a 1kHz UGF.

As yutaro measured, these can be especially nasty at the major carrier transitions (i.e. something like 0111->1000). This happens at the +15->+16dB input gain step; the offset step is ~200x larger than the in-loop error signal RMS, so obviously there is no hope of keeping the loop engaged when recieving this kind of kick. Neither of the CM board inputs are immune from this, as I have empirically discovered. I can turn down the initial input gain to try and avoid this step occuring anywhere in the sequence, but then the SNR at high frequencies get terrible and I inject all kinds of crud into the mode cleaner, making the PC drive furious.

I think we're able to escape this when locking the full IFO because the voltages coming out of REFL11 are so much larger than the puny POY signals so the input-referred glitches aren't as bad. I think in the past, we used AS55 with a misaligned ITMX for this kind of single arm thing, which probably gives better SNR, but the whole point of this is to keep the X arm aligned and lock it to the Y-arm stabilized PSL. 

  209   Thu Dec 20 21:58:28 2007 AndreySummaryComputer Scripts / ProgramsResults for 2 previous XARM measurements have been added

I attached results (plots) of yesterday's daytime and overnight measurements to the initial reports about those measurements.

These are ELOG entries # 201 and # 205.
  199   Tue Dec 18 23:41:00 2007 AndreySummaryComputer Scripts / ProgramsResults of Mon/Tue overnight measurements (entry #194)

Here I inform our community about the results of the measurements of RMS values in XARM during the previous night from Monday to Tuesday (I announced those measurements in ELOG entry #194).

All the plots in today's report seem to agree well with the analogous plots from the night from Saturday to Sunday (those results are given in ELOG entry # 195).

All the intervals in which RMS have been calculated are the same as in yesterday's ELOG entry #195.

I plotted three results for RMS in the abovementioned three intervals in three different ways:

1) view from the top in the axes (Q_{ITMX}+Q_{ETMX})/2 and (Q_{ITMX}-Q_{ETMX}) -> first three graphs (attachments 1 -3);

2) view from the side in the same sum- and difference-axes -> next three graphs (attachments 4-6);

3) view from the side in Q_{ITMX} and Q_{ETMX} axes -> next three graphs (attachments 7-9, also attch. 12), above accelerometer spectra (attachments 10-11).

Also, I compared the ground noise level by comparing spectra of accelerometer signals at different times during that night. As a reminder, before my disease I installed one accelerometer near ITMX and another accelerometer near ETMX (see entries 161 and 172 in ELOG). The plots of ratios of accelerometer signals at different times (pairs of times that were used: 11PM and 2AM, 11PM and 5AM, 11PM and 8AM) are given below, see attachments 10-11. The program was running from 11PM on Monday till 9AM on Tuesday.

As I explained in the previous ELOG entry # 198, tonight I am taking experimental data in the narrowere interval from 1.00 to 4.50 with a smaller step 0.25.
Attachment 1: RMS_08HZ_Top_View.png
RMS_08HZ_Top_View.png
Attachment 2: RMS_3HZ_Top_View.png
RMS_3HZ_Top_View.png
Attachment 3: RMS_broad_Top_View.png
RMS_broad_Top_View.png
Attachment 4: RMS_08HZ_Side_View.png
RMS_08HZ_Side_View.png
Attachment 5: RMS_3HZ_Side_View.png
RMS_3HZ_Side_View.png
Attachment 6: RMS_broad_Side_View.png
RMS_broad_Side_View.png
Attachment 7: RMS_08HZ_Q_E_Q_I_Axes.png
RMS_08HZ_Q_E_Q_I_Axes.png
Attachment 8: RMS_3HZ_Q_E_Q_I_Axes.png
RMS_3HZ_Q_E_Q_I_Axes.png
Attachment 9: RMS_broad_Q_E_Q_I_Axes.png
RMS_broad_Q_E_Q_I_Axes.png
Attachment 10: Accelerometer_ITMX.png
Accelerometer_ITMX.png
Attachment 11: Accelerometer_ETMX.png
Accelerometer_ETMX.png
Attachment 12: RMS_broad_Q_E_Q_I_Axes.png
RMS_broad_Q_E_Q_I_Axes.png
  195   Tue Dec 18 00:51:39 2007 AndreyUpdateComputer Scripts / ProgramsResults of Saturday overnight measurements

As I indicated in the previous e-log entry (#194), I made overnight measurements in XARM in the night from Saturday to Sunday.

Root-mean-square values of the peaks in calibrated spectra were calculated, and I plotted them as functions of suspension gains in ITMX and ETMX "position" degrees of freedom.
More specifically, Q_ITMX means the value in the channel "C1:SUS-ITMX_SUSPOS_GAIN", while Q_ETMX means the value in the channel "C1:SUS-ETMX_SUSPOS_GAIN".

Root-mean-square values (RMS) were calculated during that night in three intervals:

1) around 0.8 HZ in the interval (0.6 Hz <-> 1.0 Hz);

2) around 3.0 Hz in the interval (2.0 Hz <-> 3.6 Hz);

3) in the broad interval from 0.6Hz to 3.6Hz.


I plotted three results for RMS in the abovementioned three intervals in three different ways:

1) view from the top in the axes (Q_{ITMX}+Q_{ETMX})/2 and (Q_{ITMX}-Q_{ETMX}) -> first three graphs (attachments 1 -3);

2) view from the side in the same sum- and difference-axes -> next three graphs (attachments 4-6);

3) view from the side in Q_{ITMX} and Q_{ETMX} axes -> next three graphs (attachments 7-9), above accelerometer spectra (attachments 10-11).


Also, I compared the ground noise level by comparing spectra of accelerometer signals at different times during that night. As a reminder, before my disease I installed one accelerometer near ITMX and another accelerometer near ETMX (see entries 161 and 172 in ELOG). The plots of ratios of accelerometer signals at different times (pairs of times that were used: 12AM and 3AM, 12AM and 6AM, 12AM and 9AM) are given below, see attachments 10-11.

Tomorrow I will try to compare the results with the second measurements that are being taken tonight.
Attachment 1: RMS_08Hz_top_view.png
RMS_08Hz_top_view.png
Attachment 2: RMS_3Hz_top_view.png
RMS_3Hz_top_view.png
Attachment 3: RMS_broad_top_view.png
RMS_broad_top_view.png
Attachment 4: RMS_08Hz_Qsum-Qdiff-axes.png
RMS_08Hz_Qsum-Qdiff-axes.png
Attachment 5: RMS_3Hz_Qsum-Qdiff-axes.png
RMS_3Hz_Qsum-Qdiff-axes.png
Attachment 6: RMS_broad_Qsum-Qdiff-axes.png
RMS_broad_Qsum-Qdiff-axes.png
Attachment 7: RMS_08Hz_Qaxes.png
RMS_08Hz_Qaxes.png
Attachment 8: RMS_3Hz_Qaxes.png
RMS_3Hz_Qaxes.png
Attachment 9: RMS_broad_Qaxes.png
RMS_broad_Qaxes.png
Attachment 10: Accel_ITMX.png
Accel_ITMX.png
Attachment 11: Accel_ETMX.png
Accel_ETMX.png
  202   Wed Dec 19 16:07:37 2007 AndreySummaryComputer Scripts / ProgramsResults of overnight measurements Tue/Wed night (entry #198)

As indicated in ELOG entry 198, I was making overnight measurements during last night from Tuesday to Wednesday.

I was changing the suspension damping gain in ETMX and ITMX in "position" degree of freedom between values of 1.00 and 4.50 with the step 0.25.

Results for RMS of peaks (A) at 0.8Hz, (B) at about 3.0Hz and (C) in the range from 0.6Hz to 3.7Hz ("RMS in a broad interval") are given below:

I plotted three results for RMS in the abovementioned three intervals in three different ways:

1) view from the top in the axes (Q_{ITMX}+Q_{ETMX})/2 and (Q_{ITMX}-Q_{ETMX}) -> first three graphs (attachments 1 -3);

2) view from the side in the same sum- and difference-axes -> next three graphs (attachments 4-6);

3) view from the side in Q_{ITMX} and Q_{ETMX} axes -> next three graphs (attachments 7-9)

Attachments 10 and 11 show ratios of accelerometer signals at different times of the night/morning.


A little discussion about these graphs:

1) The areas of minima and of rapid growth are the same for all the measurements during all three nights.

2) Tonight there was a strange spike for the values of Q_{ETMX}=2.5 and Q_{ITMX}=4.0. I interpret that as an error of experiment.

3) On all the plots from all three nights there is a wide area of minimum on the plots for RMS at 0.8Hz and for "RMS in the broad interval",
and the graph for "RMS at 3Hz" indicates a clearer minimum in a localized area for Q_{ITMX}=2+-1, Q_{ETMX}=2+-1. Note that this area 2+-1
is included into the wide region of minimum for "RMS at 0.8Hz" and "RMS in a broad range".

Therefore, my guess at this stage is that we can choose the optimized value of suspension damping gains for both Q_{ITMX} and Q_{ETMX} somewhere
around 2+-1. I would like to make another overnight measurement (tonight) in that narrowed region with a small step to have more certainty.

By the way, I realized that I was a little bit careless and at some plots Q_I stands for {Q_ITMX}, and Q_E stands for Q_{ETMX}.
Attachment 1: RMS_08Hz_Top_view.png
RMS_08Hz_Top_view.png
Attachment 2: RMS_3Hz_Top_view.png
RMS_3Hz_Top_view.png
Attachment 3: RMS_broad_Top_view.png
RMS_broad_Top_view.png
Attachment 4: RMS_08Hz_Side_view.png
RMS_08Hz_Side_view.png
Attachment 5: RMS_3Hz_Side_view.png
RMS_3Hz_Side_view.png
Attachment 6: RMS_broadband_Side_view.png
RMS_broadband_Side_view.png
Attachment 7: RMS_08Hz_Q_I-Q_E-axes.png
RMS_08Hz_Q_I-Q_E-axes.png
Attachment 8: RMS_3Hz_Q_I-Q_E-axes.png
RMS_3Hz_Q_I-Q_E-axes.png
Attachment 9: RMS_broadband_Q_I-Q_E-axes.png
RMS_broadband_Q_I-Q_E-axes.png
Attachment 10: Accelerom_ETMX.png
Accelerom_ETMX.png
Attachment 11: Accelerom_ITMX.png
Accelerom_ITMX.png
  15268   Thu Mar 12 01:33:21 2020 gautamUpdateLSCResuming locking activities

It's been a while since I've attempted any locking, so tonight was mostly getting the various subsystems back together.

  • Reconnected SR785 at 1Y3 to CM board for TF measurements.
  • POX/POY locking work fine
  • Locked PRMI (no ETMs) with carrier resonant, fixed PRM and BS alignment.
  • ALS-X noise is still elevated - disconnected it from the switchable delay line and now I'm directly piping the 3dB coupled part of the beat to the LO input of the demod board. But the high freq contribution to the RMS is still ~x2-x3 of what it was in November 2019. But the noise should only depend on the other (delayed) part of the beat (the discriminant is set thus).
  • With arms POX/POY locked, checked that there was no elevated coherence between POX_I/POY_I signals between 800 Hz - 1.2 kHz, which is where I see the excess noise in the laser frequency control signal (see Attachment #1). So this suggests that the IMC locking loop suppresses the noise to a level that the arm cavities don't witness it. It's probably still worth checking this out and fixing it, but it wasn't a show stopper.
  • Transition from POX/POY lock to ALS lock was smooth - I forgot to use the POX/POY photodiodes as OOL sensors to measure the noise in this config to see if it was elevated, but anyway, I was able to push on.
  • PRMI 3f locking worked okay.
  • Main thing I wanted to check today is to try the AO transition with a bit more IN1 gain on the CM board - hypothesis being the high frequency part of the CARM signal is buried in the noise if we run with -32dB of IN1 gain. 
    • Set IN1 gain to -10dB instead.
    • In this config, I checked that with the CARM offset at 0 (CARM still under purely ALS control), the CM_SLOW path was registering ~4000 cts pk-pk, which is healthily within the ADC's range.
    • I was able to engage the CARM_B path and semi-stabilize the arm powers (after compensating for the increased IN1 gain by decreasing the CARM_B gain) and turn on the integrator.
    • However, before I could try any AO path action, the IMC loses lock - too tired to try more tonight, I'll try again tomrrow.
Attachment 1: ExcessFreqNoise_LSC.pdf
ExcessFreqNoise_LSC.pdf
  3191   Mon Jul 12 02:21:01 2010 KojiConfigurationASCResurrection of MC WFS

I have resurrected the MC WFS on Friday night.
I have uncommented the WFS part of the MC autolocker.
The WFS total gain was empirically set to 0.1 such that the loops have no instability.

The loops somewhat worked through the weekend although they seemed to have the drift of the operating points
in accordance with the WFS spot.

  4697   Thu May 12 00:59:45 2011 ryan, ranaUpdatePSLReturn of the PSL temperature box

The PSL temperature box has returned to service, with some circuit modifications. The 1k resistors on all the temp. sensor inputs (R3, R4, R7, R8, R12, R12) were changed to 0 Ohm. Also, the 10k resistors R26, R28, R29, and R30 were changed to 10.2k metal film. The DCC document will be updated shortly. There is now an offset in the MINCOMEAS channel compared to the others, which will be corrected in the morning after looking at the overnight trend.

  5071   Sat Jul 30 19:06:25 2011 ryan, ranaUpdatePSLReturn of the PSL temperature box

Quote:

The PSL temperature box has returned to service, with some circuit modifications. The 1k resistors on all the temp. sensor inputs (R3, R4, R7, R8, R12, R12) were changed to 0 Ohm. Also, the 10k resistors R26, R28, R29, and R30 were changed to 10.2k metal film. The DCC document will be updated shortly. There is now an offset in the MINCOMEAS channel compared to the others, which will be corrected in the morning after looking at the overnight trend.

 Forgot to do this in May. Have just changed the values in the psl.db file now as well as updating them live via Probe.

To make the appropriate change, I took the measured offset (5.31 deg) and added 2x this to the EGUF and EGUL field for the MINCO_MEAS channel. (see instructions here)

Committed the .db file to the SVN.

attached plot shows 8 days of trend with 5.31 degC added to the black trace using the XMGRACE Data Set Transformations

Attachment 1: rctempbox.png
rctempbox.png
  310   Tue Feb 12 13:53:27 2008 robOmnistructureVACReturn of the RGA

The new RGA head was installed a few days ago. I just ran the RGAlogger script to see if it works, which it does. I also edited the crontab file on op340m to run the RGAlogger script every night at 1:25 AM. It should run tonight.
Attachment 1: RGA-080212.png
RGA-080212.png
  9939   Fri May 9 21:18:51 2014 KojiUpdateGreen LockingReverted X green light power

It is actually very tricky to measure the green power at the output of the doubling crystal as the IR often leaks into the measurement.
I checked the green beam powers on the X/Y/PSL tables.

CONCLUSION: There is no green beam which exceeds 5mW anywhere in the 40m lab.

Note: The temperature of the doubling crystal at the X end was optimized to have maximum green power. It was 36.3degC and is now 36.7degC.

X END:

When the angles of the wave plates are optimized, we have 539mW input to the doubling crystal.
With the Xtal temperature of 36.7degC, where the green power is maximized, the power right after
the harmonic separator (H.S.) was 9.6mW.

Xtal temp 36.7degC   ~~~
                      |

--539mW@IR-->{Xtal}-->/-->9.6mW-->{Mirror}-->4.69mW-->{Mirror}-->4.54mW-->{Faraday}
                    (H.S.)

If we believe these 4.69mW and 4.54mW are purely from the green, we have 4.8mW right after the H.S.
This corresponds to the conversion efficiency of 1.6%/W (cf. theretical number 2%/W)

By disabling the heating of the crystal, we can reduce the green light by factor of 60. But still the reading right after the H.S. was 5.3mW

Xtal temp 29.2degC   ~~~
                      |
--539mW@IR-->
{Xtal}-->/-->5.3mW-->{Mirror}-->285uW-->{Mirror}-->74.3uW-->{Faraday}
                    (H.S.)

Naively taking the difference, the green beam right after the H.S. is 4.4mW.

In either cases, the green power right after the oven is slightly less than 5mW.

Y END:

When the angles of the wave plates are optimized, we have 287mW input to the doubling crystal.
With the Xtal temperature of 36.0degC, where the green power is maximized, the power right after
the harmonic separator (H.S.) was 0.86mW.

Xtal temp 36.0degC   ~~~
                      |

--287mW@IR-->{Xtal}-->/-->0.86mW-->
                    (H.S.)

When the temperature was shifted to 39.2degC, the reading after the H.S. was 70uW. Therefore the contamination by the IR is small
in this setup and we can believe the above reading in 70uW accuracy. This 0.86mW corresponds to the conversion efficiency of 1.2%/W.

PSL

The incident IR is 80mW. We have 170uW after the H.S., which corresponds to the conversion efficiency of 2.6%/W. Maybe there is some IR contamination?
From the vacuum chamber total 1mW of green is derivered when both arms are locked and aligned.

Thus the total green power at the PSL table is less than 5mW.

  3468   Wed Aug 25 12:40:28 2010 josephbUpdateelogReverted back to 2.7.5 until further testing is done

So apparently the themes/configurations didn't work so nicely on some of the logbooks with 2.8.0, so I'm reverting to 2.7.5 until I can figure out (assuming I can) how to get them to display properly.

  7053   Mon Jul 30 17:24:45 2012 YaakovUpdateSTACISRevised sensor noise plot; dead PZT

The geophone noise in my last eLog was taken before any amplification of the signal, but what really matters is the noise after amplification, since it is this signal that the PZTs are driven by. The noise goes on to be amplified about 1000x before the geophone signal gets to the PZTs.

To obtain a more relevant noise plot, I multiplied the geophone noise by 1,000, the approximate gain of the amplification stage for the geophones (called the "compensator board", the semicircular board that sits toward the top of the STACIS). Below is a plot (sensor_noise.fig) that shows the noise for the geophones after amplification and the accelerometer noise (with accelerometers set with a gain of 100x, their highest).

sensor_noise.bmp

The actual signal from both these sensors has the right magnitude to drive the PZTs (whereas it was much too small in my last plot, where I looked at the sensors before any gain)- this means that for these sensors, both of which are outputting signals that are ready to provide feedback to the STACIS, the accelerometer noise is significantly lower than the geophone noise. This is good news, because it means that there could be a real advantage to using the accelerometers instead of the geophones.

In the process of investigating further advantages of the accelerometers, I believe I killed one of the horizontal PZTs in the spare STACIS (the eBay one). The story: I had that axis in closed loop, and I saw the STACIS shudder, heard a noise, and there was a faint acrid smell. I shut the STACIS off and took out the high voltage card at the base but couldn't find any visible signs of damage (like the current-limiting resistors which burn when a PZT shorts, acc. to old STACIS records). I then tried driving the PZTs with a sine wave, and there was no response in that axis (the other axes looked fine), which leads me to believe I either did unseen damage to the high voltage amplifier (for the y-axis) or killed the PZT itself.

Attachment 1: sensor_noise.bmp
  13391   Wed Oct 18 15:26:58 2017 johannesHowToCamerasRevision: CCD calibration

The units were still off in my previous post. Here's the corrected, sanity-checked version:

Camera IP Calibration Factor
192.168.113.152 85.8 +/- 4.3 pW*μs
192.168.113.153 78.3 +/- 3.9 pW*μs

I estimated the uncertainties based on a linear fit to the data I recorded with 75nW incident on the CCD and assumed a 5% uncertainty in that number. This is just an upper limit, to be safe. I had calibrated the power reading placing the Ophir power meter where the CCD would otherwise be and comparing it to the PD voltage of a picked off beam. In my previous figures the axes were mislabeled, so I reproduce them here:

Using the current camera position I recorded 50 exposures both with and without beam (XARM locked vs PSL shutter closed) and averaged the images to see how much the reading fluctuates. The exposure time was 10 ms, which left the maximum reported pixel value in all exposures below 3800 out of 4096. The gain setting was 100, which is what I used to calibrate the CCDs.

Counts with XARM locked 2.799 +/- 0.027 x107
Counts with shutter closed 3.220 +/- 0.047 x106
Power on CCD 193.9 +/- 2.2 nW
Power scattered into 2π (*) 254 +/- 39 μW
ETMX scatter loss (**) 25.4 +/- 3.9 ppm

(*) I calculated the lens positions to focus at a plane 65cm from the front lens. We're pretty close to that, but I can't confirm the actual distance easily, so I assumed a 5cm error on the distance, which is where most of the error is coming from. This is also assuming uniform scatter.

(**) This is assuming 10W of circulating power

Attachment 1: calib_20170930_152.pdf
calib_20170930_152.pdf
Attachment 2: calib_20170930_153.pdf
calib_20170930_153.pdf
  12535   Thu Oct 6 03:56:43 2016 ericqUpdateLSCRevival Attempt

[ericq, Gautam, Lydia]

We spent some time tonight trying to revive the PRFPMI. (Why PR instead of DR? Not having to deal with SRM alignment and potentially get a better idea of our best-case PRG). After the usual set up and warm up, we found ourselves unable to hold on to the PRMI while the arms flash. In the past, this was generally solved through clever trigger matrix manipulations, but this didn't really work tonight. We will meditate on the solution.

  12547   Tue Oct 11 02:48:43 2016 ericqUpdateLSCRevival Attempts

Still no luck relocking, but got a little further. I disabled the output of the problematic PRM OSEM, it seems to work ok. Looking at the sensing of the PRMI with the arms held off, REFL165 has better MICH SNR due to its larger seperation in demod angle. So, I tried the slightly odd arrangement of 33I for PRCL and 165Q for MICH. This can indefinitely hold through the buzzing resonance. However, I haven't been able to find the sweet spot for turning on the CARM_B (CM_SLOW) integrator, which is neccesary for turning up the AO and overall CARM gain. This is a familiar problem, usually solved by looking at the value far from resonance on either side, and taking the midpoint as the filter module offset, but this didn't work tonight. Tried different gains and signs to no avail.

  14051   Wed Jul 11 15:57:00 2018 aaronUpdateOMCReviving OMC electronics
Gautam showed me the electronics racks for the OMC PZTs and DAQ. I'm in the process of chasing down what channels we need, and confirming that we'll be able to plug the old antialiasing/imaging boards into the current DAC/ADC boards. I found what I think was Rob Ward's simlink model for the omc, located at
 
/cvs/cds/caltech/cds/rward-advLigo/src/epics/simLink/omc.mdl
 
Channels in this model:
  • 27 or 29 total ADC channels are used (depending whether we keep 2 spare adc chans)
    • 4 each go to ASC_QPD1/2 (8 chans total)
    • 5 go to TRANS_PD1, TRANS_PD2, REFL_PD, TRANS_PD1_UF, TRANS_PD2_UF. These PD are used for ASC and LSC.
    • 2 go to the LSC, one each for DVMDC, DVMAC, X3DC, and X4DC
    • 12 go to the ASC_PZT
    • 2 go to the SPARE_ADC (not sure what this is)
    • I think these channels are (or were at some point) defined in memory by /cvs/cds/caltech/chans/ipc/G1.ipc
      • I found this from elog 2860; it mentions that these should eventually be migrated over to a file C1.ipc, but I don't see any OMC channels in that file or any of the 'old' C1.ipc files, so I suppose it never happened or they were removed later
    • During this vent, we won't have ASC, so
  • 10 or 14 DAC channels are used (depending whether we keep 4 spare dac chans)
    • 2 from the LSC, one for CLK_OUT and one for "LSC"
    • 8 from ASC, including P1A, P1B, P2A, P2B, P1OSC, Y1OSC, P2OSC, Y2OSC
    • I think these channels are (or were at some point) saved to frames due to /cvs/cds/caltech/chans/daq/C1OMC.ini, which I found from elog 2073
    • At some point, the 33MHz mod depth was controlled by one of the spare OMC chans, C1:OMC-SPARE_DAC_CH_15. See elog 2126. I assume this is no longer the case, since c1omc is defunct.
    • Durnig this vent, we won't have ASC and don't need to CLK_OUT the LSC, so we may just need one DAC channel

As of at least Nov 2009, the .par file for the OMC was located at /cvs/cds/gds/param/tpchn_C2 (see elog 2316)

 
Electronics inventory:
  • Kepco HV supply, "OMC-L-PZT", labels indicate it goes to 250V, needs to be tested  ("TESTED OK 2014OCT12")
  • Tip/Tilt Piezo Driver, LIGO D060287
  • HV Piezo Driver, LIGO D060283
  • QPD Whitening Board, D060214
  • LIGO D050374/D050387
  • LIGO D050368/D050373

Need to check:

  • Can the ADC/DAC adapter boards (eg D0902006) drive whatever ~10V control signal we need across ~10m of SCSI cable?
  •  
  11482   Thu Aug 6 04:36:41 2015 ericqUpdateASCReviving PRC angular feedforward

Tonight, I've taken a bunch of data where the PRC is carrier locked and the ITM oplevs have the DC coupling FM turned on, as we use during locking. This is to inform new feedforward filters to stabilize the PRC angular motion, by using Wiener filtering with the POP QPD as the target, and local seismometers/accelerometers as witnesses. So far I've looked at the 1800 seconds leading up to GPS time 1122885600, but there has been plenty of locked time tonight if I need to retrieve more. 

I've also measured the PRM ASC output torque -> POP QPD spot motion with high (>0.95) coherence from 0.1Hz to 10Hz. 

Prefiltering so far consists of a 4th order elliptic LP at 5 Hz, with the target subtraction band being the 1-3Hz range. 

With offline FIR filtering, the RMS pitch motion is reduced by a factor of 3 just with the STS1_X data. IIR fitting remains to be done. 

The PRC yaw motion, which is marginally noisier, is a little more tangled up across X and Y. 

Plots / filters forthcoming pending more analysis. 

  14816   Mon Jul 29 19:08:55 2019 yehonathanUpdateLoss MeasurementReviving loss measurement by reflection

1. X arm is totally misaligned in order to measure the Y arm loss using the reflection method. Each measurement round consists of measuring the reflected power when the Y arm is aligned and when it is misaligned.

2. The measurement script used is /scripts/lossmap_scripts/armLoss/measureArmLoss.py. It generates a log file in the /logs folder specifying the alignment and misalignment times.

3. The data extraction script dlData.py processes the raw data in the log file and creates a hdf5 file in the /Data folder conataining the data of the measurement it self.

4. dlData.py labels the the aligned and misaligned datas incorrectly when the number of measurement is odd. I use only even number of measurements then.

5. In order to clip the chaotic transition between the aligned and misaligned states I use tDur attribute smaller than the actual sleep time used in the measurement script itself.

6. plotData.py (written by Gautam) and AnalyzeLossData.ipynb (written by me) can be used to calculate the loss and to plot some analyses (see https://nodus.ligo.caltech.edu:8081/40m/14568). They give roughly the same answer. The descripancy can be explained by the different modulation and ITM transmissions used.

7. I take a measurement of 8 repeatitions. I plot the measured reflected power alternating between the aligned and misaligned states. 

I find that the reflected power is repeatable to within 1%.

This is consistent with the transmission data plotted here which is also repeatable to within 1%.

8. I take an overnight measurement of 100 repeatitions.

  14664   Tue Jun 11 19:25:58 2019 aaronConfigurationBHDReviving the single OMC BHD design?

I drew out some idea of how we might use a single OMC to clean both paths of the BHD after mixing, without being susceptible to polarization-dependent effects within the OMC. Basically, can we send the two legs of the BHD into the OMC counterpropagating. I've attached a diagram.

I think one issue would be scattered light, since any backscatter directly couples into the counterpropagating mode, and thus directly to the PD. However, unless the polarization of the scattered light rotates it would not scatter back to the IFO. And, since the LO and signal mix before the OMC, this scattered light would not directly add phase noise.

Maybe more problematic would be that if the rejection at the PBS (or the polarization rotation) isn't perfect, light from the LO directly couples into the dark port. Can we get away with a Faraday isolator before the OMC? 

Diagram attached.

Attachment 1: singleOMC.pdf
singleOMC.pdf
  14685   Fri Jun 21 19:22:40 2019 KojiConfigurationBHDReviving the single OMC BHD design?

I think a Faraday rotator rotates the polarizations in a same way for both forward and backward beam, and it's not like in this figure.
And the transmission through multiple faradays will also be a big issue.

  9565   Wed Jan 22 15:24:11 2014 SteveSummaryVACRga scan after reboot

Quote:

[Jenne, Steve]

Steve noticed that the RGA was not logging data and that not all the correct connection lights were on, and he wasn't able to run the "RGAset.py" script (in ...../scripts/RGA/) that sets up the proper parameters. 

I looked, and the computer was not mounting the file system.  I did a remote shutdown, then Steve went in and pushed the power button to turn the machine back on.  After it booted up, it was able to talk to the file system, so I started ..../scripts/RGA/RGAset.py .  The first 2 times I ran the script, it reported errors, but the 3rd time, it reported no communication errors.  So, now that the computer can again talk to the file system, it should be able to run the cronjob, which is set to take data at 4am every day.  Steve will check in the morning to confirm that the data is there.  (The last data that's logged is 22Dec2013, 4am, which is right around when Koji reported and then fixed the file system).

 

 

 We are venting tomorrow. This give us an opportunity to fix sick vacuum controller computer. Jamie volunteered.

Remember to rough down cryo and ion pump volumes. Their pressure can be at 1 Torr range after years of accumulated outgassing.  Without total valve controls it is dangerous to have these air pockets. Some of their  gate valves can be leaking and that would explane the slower pumpdown speed. 

 

Attachment 1: Rgascan169dwarmingup.png
Rgascan169dwarmingup.png
Attachment 2: BlankMedmMustBeFixed.png
BlankMedmMustBeFixed.png
  15933   Wed Mar 17 15:04:20 2021 gautamUpdateElectronicsRibbon cable for chassis

I had asked Chub to order 100ft ea of 9, 15 and 25 conductor ribbon cable. These arrived today and are stored in the VEA alongside the rest of the electronics/chassis awaiting assembly.

Attachment 1: IMG_9139.jpg
IMG_9139.jpg
ELOG V3.1.3-