 Mon Mar 28 16:19:23 2011, steve, Frogs, Photos, visithing 5th graders 
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| Suresh is captivating his audience with gravity waves on last Friday, March 25 |
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Fri Oct 8 17:36:16 2010, steve, Frogs, Photos, visiting undergrads
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| Prof Alan Weistein guided the 24 student through the 40m. His performance was rated as an enthusiastic 9.5 |
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Fri Sep 16 16:07:28 2011, steve, Update, SAFETY, visitors safety training
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| Paul, Mirko and Katrin visiting grad students received the 40m basic safety training. |
 Tue Feb 7 19:14:59 2017, Johannes, Update, CDS, vme crate backplane adapter board layout
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After fighting with Altium for what seems like an eternity I have finished putting my vision of the vme crate backplane adapter board into an electronic
format. It is dimensioned to fill the back space of the crate exactly. The connectors are panel mount and the PCB attaches to the connectors with screws,
such that the whole thing will be mechanically much more stable than the current configuration. A mounting bracket will attach to horizontal struts that |
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Tue Jan 31 22:15:02 2017, Johannes, Update, CDS, vme crate backplane adapter boards
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I made a crude sketch for how Lydia and I envision the connector situation on the back of the vme crates to be solved. Essentially the side panels of
each crate extend about 2" (52 mm) beyond the edge of the DIN connectors. This is plenty of space for a simple PCB board. The connector of choice
is D-Sub. We can split the 64 used pins into 2x 37 D-Sub OR (2x25 pin + 1x15pin). The former has fewer cables, but a few excess unused leads. A quick google |
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Wed Feb 22 16:55:16 2012, Jamie, Update, SUS, wacky state of SUS input matrices
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While Kiwamu and I were trying to investigate the the vertex glitches we were noticing excess
noise in ITMX, which Kiwamu blamed on some sort of bad diagonalization. Sure enough, the ITMX input matrix is in the default state [0], not
a properly diagonalized state. Looking through the rest of the suspensions, I found PRM also in the default state, not diagonalized. |
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Thu Feb 23 02:20:07 2012, Zach, Update, SUS, wacky state of SUS input matrices
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This reminds me that the whole Dr. SUS situation never got taken care of. Where I left off, I was having issues
pulling 40m data with NDS2 (which is what all the diagonalization scripts use).
What is the deal with 40m+NDS2? If it is till no-go, can we have a consensus on whether |
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Wed Apr 21 10:09:23 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals
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Theoretically the waist position of a Gaussian beam (1064) in our PPKTP crystal differs by ~6.7 mm from that of the incident Gaussian beam.
So far I have neglected such position change of the beam waist in optical layouts because it is tiny compared with the entire optical path.
But from the point of view of practical experiments, it is better to think about it. |
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Tue Apr 27 14:18:53 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals
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The mode profile of Gaussian beams in our PPKTP crystals was calculated.
I confirmed that the Rayleigh range of the incoming beam (1064 nm) and that of the outgoing beam (532 nm)
is the same. |
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Thu Jul 29 21:13:39 2010, Dmass, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals
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Quote:
The mode profile of Gaussian beams in our PPKTP crystals was calculated. |
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Thu Jul 29 22:58:25 2010, kiwamu, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals
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- As you said, I just calculated the waist position in the crystal because the speed of light changes in a medium and eventually the waist position also
changes.
- Yes, I did. Once you get a beam with the right waist size, you just put your crystal at the waist position with the offset. |
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Fri Jul 30 00:02:15 2010, Dmass, Update, Green Locking, waist positon of Gaussian beam in PPKTP crystals
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Quote:
- As you said, I just calculated the waist position in the crystal because the speed of light changes in a medium and |
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Wed Sep 9 20:52:45 2020, rana, Summary, IOO, wandering line in IMC
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since the summary pages are working again, I was clicking through and noticed that there's a wandering peak in the whitened IMC spectrogram that
goes from 10-30 Hz over the course of a day.
https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20200909/ioo/ |
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Mon Aug 10 15:25:05 2015, Steve, Update, PEM, wasp nest
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The wasp nest will be removed tomorrow from from the out side of the east arm window.
The resonant frequency of the newly arrived gravity bee detector is not known.
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Fri Nov 20 16:18:56 2009, rob, Configuration, SUS, watchdog rampdown
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I've changed the watchdog rampdown script so it brings the SUS watchdogs to 220, instead of the 150 it previously targeted. This is to make tripping
less likely with the jackhammering going on next door. I've also turned off all the oplev damping. |
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Wed Dec 9 17:51:03 2009, kiwamu, Update, SUS, watchdogs
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Please do not touch the watchdogs for all SUSs except for MCs,
because I am going to measure the free swinging spectra for ITMs, ETMs, BS, PRM, SRM tonight.
Today, it is good chance to summarize those data under atmospheric pressure. |
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Thu Dec 1 17:33:18 2011, kiwamu, Update, SUS, watchdogs fixed
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The watchdogs' issue has been solved and they are now working fine.
It was just because one of the Sorensens had been off. |
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Mon Aug 23 15:24:24 2010, kiwamu, Configuration, SUS, watchdogs off
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For the new CDS test, I turned off the watchdogs for PRM, SRM, BS, ITMs and MCs.
I will restore these watchdogs after several hours from now.
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Tue Dec 7 20:38:17 2010, kiwamu, Update, SUS, watchdogs off at ITMX and ETMX
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I am leaving ITMX and ETMX freely swinging, so that later I can take the spectra and diagonalize the input matrices.
Please don't restore the watchdogs until tomorrow morning. |
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Wed Dec 8 22:47:09 2010, kiwamu, Update, SUS, watchdogs off at ITMX and ETMX
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Tonight, swing again.
Please do not restore the watchdogs until tomorrow (Dec.9) morning.
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Mon Nov 16 16:18:34 2015, gautam, Update, General, water leak along Y-arm?
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A Caltech maintenance staff dropped by at around noon today, and told me that he had seen a small puddle of water on the other side of the door along
the Y-arm that is kept locked (about 10m from the end-table, on the south side of the arm). He suspected a leak in the lab. Koji and I went down to the
said door and observed that there was indeed a small puddle of water accumulated there. There isn't any obvious source of a leak on our side of the |
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Tue Nov 17 10:06:53 2015, Steve, Update, General, water leak in east arm
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Quote:
A Caltech maintenance
staff dropped by at around noon today, and told me that he had seen a small puddle of water on the other side of the door along the Y-arm that is kept |
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Fri Sep 18 14:25:00 2009, rob, Omnistructure, PSL, water under the laser chiller
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rob, koji, steve
We noticed some water (about a cup) on the floor under the NESLAB chiller today. We put the chiller up on blocks and took off the side panel
for a cursory inspection, but found no obvious leaks. We'll keep an eye on it. |
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Fri Sep 18 16:05:08 2009, Jenne, Omnistructure, PSL, water under the laser chiller
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Quote:
rob, koji, steve |
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Thu Nov 19 09:25:19 2009, steve, Update, MOPA, water was added to the laser chiller
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| I added ~500 cc of distilled water to the laser chiller yesterday. |
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Mon Feb 18 18:28:01 2013, yuta, Bureaucracy, Alignment, we are going to pump down
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We will start preparing for pumping down. Main goal for this is to demonstrate PRFPMI using ALS.
Here are to-dos before we pump down.
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Thu Dec 14 08:59:17 2017, Steve, Update, General, we are here
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Wed May 27 10:54:09 2009, rob, Update, PSL, we don't understand the chiller (broken)
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Quote:
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Wed May 27 15:59:44 2009, rob, Update, PSL, we don't understand the chiller (broken)
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steve, alberto, rob
After some futzing around with the chiller, we have come to the tentative conclusion that the refrigeration unit is not working. Steve called
facilities to try to get them to recharge the refrigerant (R-404a) tomorrow, and we're also calling around for a spare chiller somewhere in the project |
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Fri Nov 9 11:38:38 2012, jamie, Update, General, we're closing up
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After a brief look this morning, I called it and declared that we were ok to close up. The access connector is almost all buttoned up, and both
ETM doors are on.
Basically nothing moved since last night, which is good. Jenne and I were a little bit worried about how the input pointing might have been |
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Fri Nov 30 21:27:24 2007, rana, DAQ, PEM, weather / stacis / c1pem1
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I was trying to add some Seis BLRMS channels to the c1pem1 processor so that we could have DMT trends.
Then I found that none of the Weather channels have been working for a year or so. I could also not
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Wed Dec 12 22:24:48 2007, tobin, Frogs, PEM, weather station
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I poked at the weather station briefly this evening.
* There's almost nothing in the elog about it.
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Thu May 14 17:41:10 2015, rana, Update, PEM, weather station and Guralp maintenance
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Today Steve and I tried to recenter the Guralps. The breakout box technique didn't work for us, so we just turned the leveling screws until we got
the mass position outputs within +/-50 mV for all DoF as read out by the breakout box.
Some points: |
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Tue Apr 8 09:08:54 2008, steve, Configuration, PEM, weather station disconnected
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We can not leave cables in the walkways and go on vacation.
I disconnected the weather station from the DAQ
Every Tuesday is janitor day in the 40m.
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Wed Jun 4 10:18:52 2008, steve, Update, PSL, wedged SS beam trap
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I moved the SS trap over to the psl table.
Texas super # 8 was used from the large shipment.
TXs#8 scattering measured as before, meaning the polishing is good.
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Wed Sep 30 02:01:28 2009, rob, Update, Locking, week
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It's been a miserable week for lock acquisition, with each night worst than the last. The nadir was around Sunday night, when I couldn't even get
a PRM to lock stably, which meant that the auto-alignment scripts could not finish successfully. It now appears that was due to some XYCOM mis-settings.
We've also been having problems with timing for c1susvme2. Attached is a one-hour plot of timing data for this cpu, known as SRM. |
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Tue Aug 9 03:05:05 2011, kiwamu, Summary, General, weekly report
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Summary of the week ending Aug 8th. Number of elog entries = 56
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Wed Jul 30 12:03:44 2008, Masha, Summary, Auxiliary locking, weekly summary
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I've been learning about mode matching/beam propagation, so I can work on getting more
light into the fiber and increase the phase noise signal. I am also looking into phase
lock loops and noise in the fiber stabilization system to understand the noise sources
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Wed Aug 6 13:57:44 2008, Masha, Summary, Auxiliary locking, weekly summary
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Finished second progress report.
Working on improving the sensitivity of the Mach Zehnder to more accurately measure the fiber noise. Making more stable mounts that have fewer degrees |
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Wed Jun 30 12:13:39 2010, Sharmila, Katharine, Update, WIKI-40M Update, weekly update
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Weekly Project Update:
We are studying Haixing's circuit diagram for the quadrant maglev control circuit. We have analyzed several of the sub-circuits and plotted |
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Wed Jul 21 12:03:14 2010, Katharine, Sharmila, Update, WIKI-40M Update, weekly update
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This past week, we levitated our small cylindrical magnet (with the flag made from heat shrink). Though the levitated magnet didn't appear very
jittery to the eye, we looked at the PD current on the scope and could see oscillations that corresponded to the flag hitting the sides of the OSEM.
The oscillations were more pronounced as we gently hit/vibrated the lab bench, and by pounding on the bench Rana knocked the levitated magnet completely |
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Wed Jul 22 18:04:14 2009, rob, Omnistructure, Computers, weird noise coming from Gigabit switch
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| in the rack next to the printer. It sounds like a fan is hitting something. |
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Thu May 12 18:21:19 2011, kiwamu, Update, IOO, welcome back IP_POS
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IP_POS is back.
I reconnected the cable to an interface card : D030238-A which has been labeled as "IP POS". |
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Thu Oct 28 09:16:17 2010, steve, Update, PEM, welding in the vertex area
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Fire-smoke sensors in the vertex area #2-31, 2-30 east, 2-32 south/MC2 and 2-37 old control room area are turned off to accommodate the welding
activity of folding crane. These sensors will be reactivated at 3:30pm today.
Stay out of the 40m lab: IFO room till 6 pm today. |
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Tue Oct 5 17:39:21 2010, steve, Configuration, VAC, west access connector removed
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Kiwamu, Koji, Yutah, Rana, Jan and Steve
We removed the west access connector this afternoon. |
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Mon Aug 5 16:28:41 2019, yehonathan, Update, Loss Measurement, what is going on with the loss measurements ?
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We hypothesize that the systematic error in the loss measurement can come from the fact that the requirement on the alignment of the cavity mirrors is
not stringent enough.
We repeat the loss measurement with 50 measurements. This time we change the thresholds for the error signals of the dither-align in the measureArmLoss.py |
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Mon Aug 1 17:47:37 2011, steve, Update, ASC, what is not working
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SUS-ETMY_QPD is not responding. It is reading zero in dataviewer and 4,400 counts on QPD MEDM screen.......must be wrong cable connected
IP-POS is sick. Last time alive 7-19-2011
IP-ANG beam is clipping on pick-up mirror at ETMY chamber. This will have to be fixed at the vent. The qpd itself is responding to light. |
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Wed Feb 27 14:53:02 2013, Steve, Update, LSC, what is the Fibox ?
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Fibox FBAI-M 20bit units were connected with multimode
fibre. This pair of fiber is not protected in the cable tray. |
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Mon Feb 27 18:33:11 2012, jamie, Update, PSL, what to do with old PSL fast channels
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It appears that the old PSL fast channels never made it into the new DAQ system. We need to figure out what to do with them.
A D990155 DAQ Interface card in far right of the 1X1
PSL EuroCard ("VME") crate is supposed output various PMC/FSS/ISS fast channels, which would then connect to the 1U |
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Thu Oct 14 00:53:44 2010, kiwamu, Update, SUS, what's wrong with MC2
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It turned out that the DC alignment of MC2 from epics doesn't helathily work.
For example, the pitch slider does drive the yaw alignment as well.
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