 Thu Jun 25 11:09:01 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab from 11pm to 4pm |
|
Wed Jun 24 22:47:21 2020, Yehonathan, Update, Wiki, Updated phase maps webpage
|
I uploaded the new phase maps measurements made by GariLynn to nodus and updated the optics phase maps page.
I
also added MetroPro and Matlab analysis for these phase maps. |
|
Wed Jun 24 22:33:44 2020, gautam, Update, SUS, EQ tripped all suspensions
|
This earthquake tripped all suspensions and ITMX got stuck. The
watchdogs were restored and the stuck optic was released. The IFO was re-aligned, POX/POY and PRMI on carrier locking all work okay. |
|
Wed Jun 24 10:14:56 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab today from 10am to 4pm. |
|
Mon Jun 22 10:43:25 2020, Jon, Configuration, VAC, Vac maintenance at 11 am
|
The vac system is going down at 11 am today for planned maintenance:
Re-install the repaired TP2 and TP3 dry pumps [ELOG 15417]
Incorporate
an auto-mailer and flag channel into the controls code for signaling tripped interlocks [ELOG 15413]
We |
 Mon Jun 22 20:06:06 2020, Jon, Configuration, VAC, Vac maintenance complete 
|
This work is finally complete. The dry pump replacement was finished quickly but the controls updates required some substantial debugging.
For one, the mailer code I had been given to install would not run against Python 3.4 on c1vac, the version run by the vac controls since about
a year ago. There were some missing dependencies that proved difficult to install (related to Debian Jessie becoming unsupported). I ultimately solved |
|
Tue Jun 23 17:54:56 2020, rana, Configuration, VAC, Vac maintenance complete
|
I propose we go for all CAPS for all channel names. The lower case names is just a holdover from Steve/Alan from the 90's. All other systems are
all CAPS.
It avoids us having to force them all to UPPER in the scripts and channel lists. |
|
Mon Jun 22 17:51:50 2020, gautam, Update, CDS, c1iscaux was down
|
The machine needed a hard reboot as it was un-ssh-able.
The exact time that the machine went down is unknown because the blinkys were not
DQ-ed. I've now added these to the EDCU to make these channels actually useful, and we may look back on the reliability (or otherwise) of the |
|
Mon Jun 22 13:16:38 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m today from 11am to 4pm. |
|
Fri Jun 19 19:21:25 2020, gautam, Update, General, PSL shutter re-opened
|
The PSL shutter was closed from the vacuum interlock trip. Today, I did the following:
Re-aligned input beam to PMC to recover high transmission / low reflection.
Re-set the LSC offsets.
ETMX watchdog
was tripped. Reset it.
Opened the PSL shutter, IMC autolocker was able to lock the cavity almost immediately.
Tested POX/POY locking, |
|
Fri Jun 19 14:03:50 2020, Jordan, Update, VAC, Forepump Tip Seal Replacement
|
Tip Seals were replaced on the forepumps for TP2 and TP3, and both are ready to be installed back onto the forelines.
TP2 Forepump Ultimate Pressure: 180 mtorr
TP3 Forepump Ultimate Pressure: 120 mtorr |
|
Fri Jun 19 11:02:10 2020, Chub, Update, General, custom feedthrough flanges are here!
|
| The four 4x25DSUB and single 8x25DSUB feedthrough flanges have arrived and will be picked up from the dock and brought to the 40M lab. |
|
Thu Jun 11 11:48:43 2020, gautam, Update, VAC, Vac failure
|
There appears to have been some sort of vacuum failure.
ldas-pcdev1 was down, so the summary pages weren't being generated. I have now switched over to ldas-pcdev6. I suspect some forepump failure,
will check up later today unless someone else wants to take care of this. |
|
Thu Jun 11 16:14:03 2020, gautam, Update, VAC, Vac failure - probable cause is serial comm glitch
|
Summary:
It looks like the main vacuum interlock was tripped due to a serial communication error from the TP2 controller. With Rana/Koji's
permission, I will open V1 and expose the main volume to TP1 again (#2 in last section). |
|
Thu Jun 11 17:35:34 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement
|
Summary:
The pumpspool UPS has its "Replace Battery"
indicator light on. Might be a good chance to change the UPS, but at the very least, we should put in fresh batteries (last replacement was in Aug |
|
Fri Jun 12 01:23:32 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement
|
1. I agree that it's likely that it was the temp signal glitch.
Recom #2: I approve to reopen the valves to pump down the main volume. As long as there is no frequent glitch, we can just bring the vacuum back
to normal with the current software setup. |
|
Fri Jun 12 17:32:40 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement
|
Jon and Koji remotely supported Jordan's resetting the TP2 controller.
Here is the instruction by Jon
From
the operator's console in front of the vac rack:
Open a terminal window (click the LXTerminal icon |
|
Fri Jun 12 19:02:52 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement
|
I still don't understand why restoring the vacuum is contingent on this functionality working. All the TPs have their own internal logic to shutdown
the pump if some damage threshold is exceeded. Plus, we have the pressure-sensor based interlocks to protect the main volume as well as pumps. While the
extra redundancy from the readbacks from the controller is useful, clearly it isn't the first line of defense? |
|
Fri Jun 12 19:23:56 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement
|
The vacuum safety policy and design are not clear to me, and I don't know what the first and second defense is. Since we had limited time and bandwidth
during the remotely-supported recovery work today, we wanted to work step by step.
The pressure rising rate is 20mtorr/day, and turning on TP3 early next week will resume the main-volume pumping without too much hustle. If you |
|
Fri Jun 12 19:33:31 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement
|
Didn't mean to sound whiny. I will wait until the vacuum team tells me it is okay.
Quote:
The vacuum safety policy and design are not clear to me, and I don't know what the first and second defense |
|
Tue Jun 16 13:35:03 2020, Jon, Update, VAC, Temporary vac fix / IFO usable again
|
[Jon, Jordan, Koji]
Today Jordan reconfigured the vac system to allow pumping of the main volume resume, with Jon and Koji remotely advising. All clear to
resume normal IFO activities. However, the vac system is operating in a temporary configuration that will have to be reverted as we locate replacement |
|
Wed Jun 17 16:27:51 2020, gautam, Update, VAC, Questions/comments on vacuum
|
I missed the vacuum discussion on the call today, but I have some questions/comments:
Isn’t it true that we didn’t digitally monitor any of the TP diagnostic channels before 2018 December? I don’t
have the full history but certainly there wasn’t any failure of the vacuum system connected to pump current/temp/speed from Sep 2015-Dec2018, whereas |
|
Thu Jun 18 11:00:24 2020, Jon, Update, VAC, Questions/comments on vacuum
|
Quote:
Isn’t it true that we didn’t digitally monitor any of the TP diagnostic channels
before 2018 December? I don’t have the full history but certainly there wasn’t any failure of the vacuum system connected to pump current/temp/speed |
|
Thu Jun 18 12:00:36 2020, gautam, Update, VAC, Questions/comments on vacuum
|
I agree there were MEDM fields, but I can't find any record of these channels being recorded till 2018 December, so I don't agree that they were
being digitally monitored. You can also look back in the elog (e.g. here and here)
and see that the display fields are just blank. I would then assume that no interlocks were dependent on these channels, because otherwise the vacuum interlocks |
|
Thu Jun 18 14:13:03 2020, Jon, Update, VAC, Questions/comments on vacuum
|
I agree there were MEDM fields, but I can't find any record of these channels
being recorded till 2018 December, so I don't agree that they were being digitally monitored. You can also look back in the elog (e.g. here
and here) and see that the display fields are just blank. I |
|
Thu Jun 18 15:46:34 2020, gautam, Update, VAC, Questions/comments on vacuum
|
So why not just have a special mode for the interlock code during pumpdown and venting, and during normal operation we expect the main volume pressure
to be <100uTorr so the interlock trips if this condition is violated? These can just be EPICS buttons on the Vac control MEDM screen. Both of these
procedures are not "business as usual", and even if we script them in the future, it's likely to have some operator supervising, so I don't |
|
Fri Jun 19 07:40:49 2020, Jon, Update, VAC, Questions/comments on vacuum
|
I think we should discuss interlock possibilities at a 40m meeting. I'm reluctant to make the system more complicated, but perhaps we can
find ways to reduce the reliance on the turbo pump readbacks. I agree they've proven to be the least reliable.
While we may be able to improve the tolerance to certain kinds of hardware malfunctions (and if so, we should), I don't see interlocks triggering |
|
Fri Jun 19 09:57:35 2020, gautam, Update, VAC, Questions/comments on vacuum
|
For this particular email service, ideally the email should be sent out as soon as the interlock is tripped, so this would require a line of code to
be added to the main interlock code. Which I guess would require a restart of the interlock service. So let me know when you guys plan to do the dry-pump
tip seal replacement operation (when I presume valves will be closed anyways) so that we can do this in a minimally invasive way. |
|
Fri Jun 19 08:47:10 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m today from 9am to 3pm. |
|
Thu Jun 18 22:33:57 2020, Jon, Omnistructure, VAC, Vac hardware purchase list
|
Replacement Hardware Purchase List
I've created a purchase
list of hardware needed to restore the aging vacuum system. This wasn't planned as part of the BHD upgrade, but I've added it to
the BHD procurement list since hardware replacements have become necessary. |
|
Thu Jun 18 15:25:08 2020, Jordan, Update, VAC, TP2 and TP3 Forepump removal
|
I removed the backing pumps for TP2 and TP3 today to test ultimate pressure and determine if they need a tip seal replacement. This was done with Jon
backing me on Zoom. We closed off TP3 and powered down TP3 and the auxilliary pump, in order to remove the forepumps from the exhaust line.
Close V1
Close V5
Turn off TP3
Turn off aux dry pump (manually)
Once the PTP3 foreline pressure |
|
Thu Jun 18 16:56:34 2020, Jordan, Update, VAC, TP2 and TP3 Forepump removal
|
Quote:
I removed the backing pumps for TP2 and TP3 today to test ultimate pressure and determine if they need a tip seal
replacement. This was done with Jon backing me on Zoom. We closed off TP3 and powered down TP3 and the auxilliary pump, in order to remove the forepumps |
|
Thu Jun 18 09:46:03 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m today from 9:30am to 4pm. |
|
Tue Jun 16 16:05:26 2020, Jordan, Update, General, N2 Replacement
|
| I replaced an empty N2 cylinder, there are now two empty tanks in the outside rack. |
|
Wed May 20 19:34:58 2020, Koji, Update, General, ITM spares and New PR3 mirrors transported to Downs for phasemap measurement
|
| Two ITM spares (ITMU01/ITMU02) and five new PR3 mirrors (E1800089 Rev 7-1~Rev7-5) were transported to Downs for phasemap measurement |
|
Thu Jun 4 00:21:28 2020, Koji, Summary, COC, ITM spares and New PR3 mirrors transported to Downs for phasemap measurement
|
GariLynn worked on the measurement of E1800089 mirrros.
The result of the data analysis, as well as the data and the codes, have been summarized here: |
|
Tue Jun 16 13:05:36 2020, Koji, Update, COC, ITM spares and New PR3 mirrors transported to Downs for phasemap measurement
|
ITMU01 / ITMU02 as well as the five E1800089 mirrors came back to the 40m. Instead, the two ETM spares (ETMU06 / ETMU08) were delivered to GariLynn.
Jordan worked on transportation.
Note that the E1800089 mirrors are together with the ITM container in the precious optics cabinet. |
|
Tue Jun 16 08:58:11 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m today at 10am to deliver optics to Downs and to replace the TP2 controller. |
|
Fri Jun 12 11:40:14 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab today from 12pm to 4pm. |
|
Thu Jun 11 11:14:12 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab today from 11am to 4pm. |
|
Sat Jun 6 14:07:30 2020, Jon, Update, BHD, Stock-Part Mode-Matching Telescope Option
|
Summary
For the initial phase of BHD testing, we recently discussed whether the mode-matching telescopes could be built with 100%
stock optics. This would allow the optical system to be assembled more quickly and cheaply at a stage when having ultra-low loss and scattering is less
important. I've looked into this possibility and conclude that, yes, we do have a good stock optics option. |
|
Mon Jun 8 11:50:02 2020, Hang, Update, BHD, Astigmatism and scattering plots 6x
|
We consider the astigmatism effects of the stock options. The conclusions are:
1. For the AS path, the stock should work fine for the phase-one of BHD, if we could tolerate a few percent MM loss. The window for
length adjustment to achieve >99% MM for both s and t is only 1 mm for 1% RoC error (compared to ~ 1 cm in the customized case). |
|
Mon Jun 8 12:49:07 2020, Koji, Update, BHD, Astigmatism and scattering plots
|
| Can you describe the mode matching in terms of the total MM? Is MM_total = sqrt(MM_vert * MM_horiz)? |
|
Mon Jun 8 17:40:22 2020, Jon, Update, BHD, Astigmatism and scattering plots
|
MM_total = (MM_vert + MM_horiz) / 2.
The large astigmatic MM loss in the LO case is mainly due to the strong LO4 curvature (R=0.15m) with a 10 deg AOI. I looked again at whether
LO1 could be increased from R=5m to the next higher stock value of 7.5m, as this would allow weaker curvatures on LO3 and LO4. However, no, that is not |
|
Mon Jun 8 21:45:47 2020, Jon, Update, BHD, Astigmatism and scattering plots
|
| Hmm? T1300364 suggests MM_total = Sqrt(MM_Vert * MM_Horiz) |
|
Thu Jun 11 09:37:38 2020, Jon, Update, BHD, Conclusions on Mode-Matching Telescopes
|
After further astigmatism/tolerance analysis [ELOG 15380, 15387]
our conclusion is that the stock-optic telescope designs [ELOG
15379] are sufficient for the first round of BHD testing. However, for the final BHD hardware we should still plan |
|
Wed Jun 10 14:00:33 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab from 10am to 4pm today. I will also replace an empty N2 cylinder. |
|
Tue Jun 9 15:02:56 2020, eHang, Update, BHD, Astigmatism and scattering plots
|
Using the updated AOI's for the LO path: (4.8, 47.9, 2.9, 4.5) deg for (LO1, LO2, LO3, LO4), we obtain the following results.
First two plots are scattering plots for the t and s planes, respectively. Note that here we have changed to 0.5% fractional RoC error and 3
mm positional error. We have also changed the meaning of the colors: pink:MM>0.98; olive 0.95<MM<=0.98, and grey MM<=0.95. It seems that both |
|
Tue Jun 2 14:05:24 2020, Hang, Update, BHD, MM telescope actuation range requirments
|
We computed the required actuation range for the telescope design in elog:15357. The result is summarized in
the table below. Here we assume we misalign an IFO mirror by 1 urad, and then compute how many urad do we need to move the (AS1, AS4) or (LO1, LO2) mirrors
to simultaneously correct for the two gouy phases. |
|
Tue Jun 9 14:55:43 2020, Jon, Update, BHD, MM telescope actuation range requirments
|
I don't think we ever discussed why the angular RMS of the ETMs is so much higher than the ITMs. Maybe that's a separate matter because, even
assuming the worst case, the actuation range requirement is
(0.82 μrad RMS) x (15 μrad/μrad) x (10 safety factor) = 0.12 mrad |
|
Tue Jun 9 09:35:02 2020, Jordan, Update, General, Presence at 40m
|
| I will be in the Clean and Bake lab today from 9:30am to 4pm. |
|
Mon Jun 8 18:14:55 2020, gautam, Update, CDS, Vertex FEs crashed
|
Summary:
Around 5pm local time, the three vertex FEs crashed. AFAIK, no
one was in the lab or working on anything CDS related, so this is worrying. |
|
Fri Jun 5 08:44:50 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m, in the Clean and bake lab today from ~9am to ~3pm. |
|
Thu Jun 4 08:45:41 2020, Jordan, Update, General, Presence at 40m
|
| I will be at the 40m, in the Clean and bake lab today from ~9am to ~3pm. |
|
Wed Jun 3 19:19:11 2020, gautam, Update, SUS, All watchdogs tripped
|
This EQ seems to have knocked all suspensions out. ITMX was stuck.
It is now released, and the IMC is locked again. It looks like there are some serious aftershocks going on so let's keep an eye on things. |
|
Wed Jun 3 11:20:19 2020, gautam, Update, DetChar, Summary pages
|
Summary:
The 40m summary pages have been revived. I've not had to make any manual
interventions in the last 5 days, so things seem somewhat stable, but I'm sure there will need to be multiple tweaks made. The primary use of the pages |
|
Tue May 26 01:58:57 2020, gautam, Update, Electronics, Some electronics thoughts
|
A big factor in how much IFO locking activities can take place is how cooperative the IMC is.
Since the c1psl upgrade, the IMC duty cycle has definitely deteriorated. I took a measurement of the dark noise at the IMC error point with 1
Hz FFT binwidth, with all electrical connections to the IMC servo board except the Acromag and Eurocrate power disconnected. I was horrified |
|
Wed Jun 3 01:40:13 2020, gautam, Update, Electronics, More electronics woes
|
There were many locklosses from the point where the arm powers were somewhat stabilized. Attachments #1 and #2
show two individual locklosses. I think what is happening here is that the BS seismometer X channel is glitching, and creating a transient in the angular |
|
Tue May 26 19:19:30 2020, Hang, Update, BHD, BHD MM-- effects of astigmatism
|
Please see the attached doc.
I think the conclusion is that if the AS1 RoC error is not significantly more than 1%, then with some adjustment of the AS1-AS3 distance (~ 1
cm), we could find a solution that simultaneously makes the AS path mode-matching better than 99% for the t- and s-planes. |
|
Tue May 26 10:04:54 2020, Jordan, Update, General, N2 Replacement
|
| Replaced empty N2 tank, left tank at ~2000 psi, right tank ~2600 psi. |
|
Wed May 20 20:10:34 2020, rana, John Z, Update, Computer Scripts / Programs, NDS2 server / conf updated - seems OK now
|
We noticed about a week ago that the NDS2 channel lists were not getting updated on megatron. JZ and I investigated; he was able to fix it all
up this afternoon by logging in and snooping around Megatron.
Please try it out and tell me about any problems in getting fresh data. |
|
Thu May 21 15:31:26 2020, gautam, Update, Computer Scripts / Programs, NDS2 service restarted
|
The service had failed at 16:09 yesterday. I just restarted it and am now able to fetch data again.
Unrelated to this work: I restarted the httpd service on nodus a couple of times this afternoon while experimenting with the summary pages.
Quote:
|
|
Fri May 22 10:37:41 2020, rana, Update, Computer Scripts / Programs, NDS2 service restarted
|
was dead again this morning - JZ notified
current restart instructions (after ssh to megatron):
cd /home/nds2mgr/nds2-megatron |
|
Mon May 25 10:54:41 2020, rana, Update, Computer Scripts / Programs, NDS2 service restarted
|
so far it has run through the weekend with no problems (except that there are huge log files as usual).
I have started to set up monit to run on megatron to watch this process. In principle this would send
us alerts when things break and also give a web interface to watch monit. I'm not sure how to do web port forwarding between megatron and nodus, so |
|
Fri May 22 10:14:47 2020, Jordan, Update, General, Nitrogen Replacement
|
| I was in the lab for Clean and Bake activities and I replaced an empty N2 tank. Left tank is at 2600 psi right tank at ~1300 psi. |
|
Fri May 22 01:43:18 2020, gautam, Update, Electronics, RF electronics trouble
|
To test a hypothesis, I have left the PSL shutter closed. I notice significant glitches in the dark electronics offsets on all the 11 MHz photodiode
I/Q demodulated input channels, which appear coherent. These are non-negligible in magnitude - for now they are uncalibrated in cts, but for an estimate,
the POX11 channel shows a shift of ~20 cts (~200uV at the input to the whitening board), while the PDH fringe is ~200 cts pk2pk. A first look is in |
|
Wed May 20 18:45:22 2020, Hang, Update, BHD, BHD mode-matching study--corner plot & adjustment requirement
|
As Rana suggested, we present the scattering plot of the AS path mode matching for various variables. The plot is for the
AS path, Plan 2 (whose params we summarize at the end of this entry).
In the corner plot, we color-coded each realization according to the mode matching. We use (purple, olive, grey) for (MM>0.99, 0.98<MM<=0.99, |
|
Sat May 9 17:01:08 2020, Yehonathan, Update, Loss Measurement, 40m Phase maps loss estimation
|
I took the phase maps of the 40m X arm mirrors and calculated what is the loss of a gaussian beam due to a single bounce. I did it by simply calculating
1 - (overlap integral)^2 where the overlap is between an input Gaussian mode (calculated from the parameters of the cavity. Waist ~ 3.1mm) and the reflected
beam (Gaussian imprinted with the phase map). The phase maps were prepared using PyKat surfacemap class to remove a flat surface, spherical surface, centering, |
|
Wed May 13 15:13:11 2020, Yehonathan, Update, Loss Measurement, 40m Phase maps loss estimation
|
Koji pointed out during the group meeting that I should compensate for local tilt when I move the beam around the mirror for calculating the loss map.
So I did.
Also, I made a mistake earlier by calculating the loss map for a much bigger (X7) area than what I thought. |
|
Thu May 14 12:21:56 2020, Yehonathan, Update, Loss Measurement, 40m Phase maps loss estimation
|
I finished calculating the X Arm loss using first-order perturbation theory. I will post the details of the calculation later.
I calculated loss maps of ITM and ETM (attachments 1,2 respectively). It's a little different than previous calculation because now both
mirrors are considered and total cavity loss is calculated. The map is calculated by fixing one mirror and shifting the other one around. |
|
Thu May 14 19:00:43 2020, Yehonathan, Update, Loss Measurement, 40m Phase maps loss estimation
|
Perturbation theory:
The cavity modes , where q is
the complex beam parameter and m,n is the mode index, are the eigenmodes of the cavity propagator. That is: |
|
Tue May 19 15:39:04 2020, Yehonathan, Update, Loss Measurement, 40m Phase maps loss estimation
|
I have a serious concern about this low angle scattering analysis:
Phase maps perturb the spatial mode of the steady-state of the cavity, but how is this different than mode-mismatch?
The loss that I calculated is an overall loss, not roundtrip loss. |
|
Mon May 18 18:00:16 2020, Hang, Update, BHD, BHD mode-matching study
|
[Jon, Tega, Hang]
We proposed a few BHD mode-matching telescope designs and then preformed a few monte-carlo experiments to see how the imperfections would
change the story. We assumed a 2 mm (1-sigma) error on the location of the components and 1% (1-sigma) fractional error on the RoC of the curved mirrors. |
|
Tue May 19 15:24:06 2020, rana, Update, BHD, BHD mode-matching study
|
It would be good to have a corner
plot with all the distances/ RoCs. Also perhaps a Jacobian like done in this
breathtaking and seminal work. |
|
Fri May 15 19:10:42 2020, gautam, Update, SUS, All watchdogs tripped, now restored
|
This EQ in Nevada seems to have tripped all watchdogs. ITMX was
stuck. It was released, and all the watchdogs were restored. Now the IMC is locked. |
|
Fri May 15 09:18:04 2020, Jon, Update, BHD, BHD telescope designs accounting for ASC
|
Hang and I have reanalyzed the BHD telescope designs, with the goal of identifying sufficiently non-degenerate locations for ASC actuation. Given
the limited room to reposition optics and the requirement to remain insensitive to small positioning errors, we
conclude it is not possible put sufficient Gouy phase separation between the AS1/AS2 and LO1/LO2 locations. However, we can make the current layout work |
|
Tue May 12 17:51:25 2020, rana, Summary, Computer Scripts / Programs, updated LESS syntax highlight on nodus
|
apt install source-highlight
then modified bashrc to point to /usr/share instead of /usr/bin |
|
Thu May 14 00:47:55 2020, gautam, Summary, Computer Scripts / Programs, pcdev1 added to authorized keys on nodus
|
This is to facilitate the summary page config fines to be pulled from nodus in a scripted way, without being asked for authentication. If someone knows of a better/more secure way for this to be done, please let me know. The site summary pages seem
to pull the config files from a git repo, maybe that's better? |
|
Thu May 14 00:21:03 2020, gautam, Update, LSC, CM board boosts
|
Summary:
I think the boosts that are currently stuffed on the CM board are too aggressive to be usable for locking the interferometer.
I propose some changes. |
|
Tue May 12 18:16:17 2020, gautam, Update, LSC, Relative importance of losses in the arm and PRC
|
Attachment #1 is meant to show that
having a T=500ppm PR2 optic will not be the dominant contributor to the achievable recycling gain. Nevertheless, I think we should change this optic to
start with. Here, I assume: |
|
Tue May 12 20:16:31 2020, Koji, Update, LSC, Relative importance of losses in the arm and PRC
|
Is \eta_A the roundtrip loss for an arm?
Thinking about the PRG=10 you saw:
- What's the current PR2/3 AR? 100ppm? 300ppm? The beam double-passes them. So (AR loss)x4 is added. |
|
Tue May 12 22:47:49 2020, gautam, Update, LSC, Relative importance of losses in the arm and PRC
|
Yes, \eta_A is the (average) round-trip loss for an arm cavity. I'd estimate this is ~100ppm currently. I edited the original elog to fill in this
omission.
The RC mirror specs require some guesswork - the available specs for the Laseroptik mirrors (PR3) are for a 48 degree angle of incidence, and |
|
Mon May 11 00:12:34 2020, gautam, Update, LSC, RF only PRFPMI
|
Finally - Attachment #1. This plot
uses 16 Hz EPICS data. All y-axes are uncalibrated for now, but TRX/TRY are normalized such that the POX/POY lock yields a transmission of 1. CARM UGF
is only ~3 kHz, no boosts were turned on yet. |
|
Fri May 8 14:27:25 2020, Hang, Update, BHD, New SRC gouy phase
|
[Jon, Hang]
After updating the 40 m finesse file to incorporate the new SRC length (and the removal of SR2), we find that the current SRM radius curvature
is fine. Thus a replacement of SRM is NOT required. |
|
Tue May 5 23:44:14 2020, gautam, Update, ASC, IMC WFS
|
Summary:
I've been thinking about the IMC WFS. I want to repeat the sort of analysis done at LLO where a Finesse model was built and some inferences
could be made about, for example, the Gouy phase separation b/w the sensors by comparing the Finesse sensing matrix to a measured sensing matrix. Taking |
|
Thu May 7 09:43:21 2020, rana, Update, ASC, IMC WFS
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| This is the doc from Keita Kawabe on why the WFS heads should be rotated. |
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Thu May 7 10:58:06 2020, gautam, Update, ASC, IMC WFS
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OK so the QPD segments are in the "+" orientation when the 40m IMC WFS heads are mounted at 45 deg. I thought "+" was the natural
PIT/YAW basis but I guess in the the LIGO parlance, the "X" orientation was considered more natural.
Quote:
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Wed May 6 00:31:09 2020, gautam, Update, ALS, Optomechanics during CARM offset reduction
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Summary:
The apparent increase in the ALS noise (witnessed in-loop, e.g. Attachment
#2 here) during the CARM offset reduction may have an |
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Fri May 1 01:49:55 2020, gautam, Update, ALS, ASY commissioning
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Summary:
It appears that the EY green steering PZTs have somehow lost their bipolar actuation range. I will check on them the next time I go to the lab
for an N2 switch. |
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Fri May 1 22:44:17 2020, gautam, Update, ALS, ASY M2 PZT damaged
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I went to EY and saw that the HV power supply was only putting out 50 V and had hit the current limit of 10 mA (nominally, it should be 100 V, drawing
~7mA). This is definitely a problem that has come up after the power shutdown event, as when I re-energized the HV power supply at EY,
I had confirmed that it was putting out the nominal values (the supply was not labelled with these nominal numbers so I had to label it). Or maybe I broke |
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Sat May 2 02:35:18 2020, Koji, Update, ALS, ASY M2 PZT damaged
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| Yes, we are supposed to have a few spare PI PZTs. |
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Thu Apr 30 07:29:01 2020, Chub, Update, VAC, N2 delivered.
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Hi All,
The new nitrogen cylinders were delivered to the rack at the west entrance. We only get one Airgas delivery per week during the stay-at-home
order, but so far they've not let us down. |