 Tue Jan 5 09:18:38 2010, Alberto, Omnistructure, Electronics, Universal PDH Box Stored in the RF Cabinet
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| FYI: I stored the Universal PDH boxes in the RF cabiner in the Y arm. |
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Tue Jan 5 13:23:45 2010, Alberto, Omnistructure, Environment, turning page
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In the lab there are lots of old posters with outdated autocad drawings, or printouts with schematics of old electronics hanging on the walls.
Can we get rid of those and start giving the lab a fresh and modern look? |
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Fri Jan 8 10:03:04 2010, Alberto, Omnistructure, LSC, SPOB shutter was closed
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This morning I found that there was no light on the SPOB PD. I went looking at the photodetector and I found that the shutter in front of it was closed.
I switched the shutter driver from n.c. to n.o. which had the effect of opening it.
I guess we inadvertently closed the shutter with Rana when last week we were tinkering with the ITMY camera. |
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Sat Jan 9 09:47:03 2010, Alberto, Update, LSC, Problems trying to lock the arms
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This morning I've been having problems in trying to lock the X arm.
The X arm's filter FM6 in the LSC screen starts blinking as it was halfloaded. Then the transmitted power drops from 1 to ~0.5 and eventually
the arm loses lock.
To me it looked like a computer related issue. So I decide to reboot C1ISCEX by powercycling it.
That doesn't |
 Sat Jan 9 11:07:30 2010, Alberto, Update, LSC, Problems trying to lock the arms
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Quote:
This morning I've been having problems in trying to lock the X arm. |
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Sat Jan 9 15:02:01 2010, Alberto, Update, ABSL, PRC scanning
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I scanned the PRC in the frequency range of 30-60 MHz, untill the PLL lost lock. But everything is working fine.
The PRC remained lock
for all time, with SPOB at ~1000.
I'm leaving the lab now, planning to come back tomorrow.
I turned the flipping mirrors down and
closed the mechanical shutter of the auxiliary NPRO. |
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Sun Jan 10 16:05:51 2010, Alberto, Omnistructure, Environment, Lab Thermostats Temperature Lowered by 1 deg F
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Rana noticed that recently the temperature inside the lab has been a little bit too high. That might be causing some 'unease' to the computers with the
result of making them crash more often.
Today I lowered the temperature of the three thermostats that we have inside the lab by one degree:
Y arm thermostat: from 71 to |
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Mon Jan 11 09:18:44 2010, Alberto, Update, General, Measurement running
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I'm working on the AbsL experiment. A measurement which involved the PRC locked is running at the moment.
Please make sure of not interfering with the interferometer until it is done. Thank you. |
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Mon Jan 11 10:01:06 2010, Alberto, Omnistructure, Environment, Lab Thermostats Temperature Lowered by 1 deg F
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Quote:
Rana noticed that recently the temperature inside the lab has been a little bit too high. That might be causing some |
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Mon Jan 11 11:06:53 2010, Alberto, Update, ABSL, Measurement running
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Quote:
I'm working on the AbsL experiment. A measurement which involved the PRC locked is running at the moment. |
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Mon Jan 11 16:59:14 2010, Alberto, Update, ABSL, Interferometer Busy
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I'm currently running a measurement on the PRC.
Please don't interfere with the IFO until it is done. Talk with Alberto if you've been intending to work inside the lab.
Thank you. |
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Mon Jan 11 19:36:13 2010, Alberto, Update, ABSL, Measurement running
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Leaving for dinner. Back in ~1hr.
I left a measurement running. Please don't interfere with it till I'm back. Thanks. |
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Tue Jan 12 09:37:05 2010, Alberto, Update, ABSL, IFO available
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I finished measuring the AbsL for this morning. The IFO is again available.
Please don't mess up with the interferometer though. I'll be back in a couple of ours |
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Wed Jan 13 12:01:06 2010, Alberto, Update, Computers, c1dcuepics, c1lsc rebooted this morning
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Since last night the alignemtn scripts couldn't work.
c1lsc wasn't working properly because attempts to lock the X arm would try to control
ETMY and attempts of locking the Y arm, wouldn't actuate any optics.
Also, another sign of a malfunctioning c1lsc was that one of the LSC filter
modules, FM6, couldn't get loaded properly. It looked like only half loaded on the LSC MEDM screen.
On the other hand, plotting the trend of |
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Wed Jan 13 12:03:00 2010, Alberto, Update, ABSL, Measurement now running. Please be careful
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At the moment I'm running a measurement on the PRC and I'm planning to leave it going for the time we'll be at the 40m meeting.
Please be careful in the lab. Thank you. |
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Sun Jan 17 19:18:55 2010, Alberto, Update, Computers, Boot fest to restart the computer and c1iscey not responding.
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Thi afternoon I found that the RFM network in trouble. The frontends sync counters had railed to 16384 counts and some of the computers were not responding.
I went for a bootfest, but before I rebooted c1dcu epics. I did it twice. Eventually it worked and I could get the frontends back to green.
Although trying to burtrestore to snapshots taken at any time after last wednesday till today would make the RFM crash again. Weird. |
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Mon Jan 18 18:34:01 2010, Alberto, Update, ABSL, Measurement in progress
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I started a long measurement of the PRC's transmissivity. I'm leaving the lab and I'm going to be back at about 8 tonight. Please do not disturb the
interferometer. it is important that the MC and the PRC stay locked all the time. |
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Mon Jan 18 20:58:40 2010, Alberto, Update, ABSL, Measurement in progress
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Quote:
I started a long measurement of the PRC's transmissivity. I'm leaving the lab and I'm going to be back at about 8 tonight. |
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Tue Jan 19 12:54:39 2010, Alberto, Update, ABSL, Measurement in progress
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| A measurement will be running for the next hour. Please be careful. |
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Tue Jan 19 16:21:18 2010, Alberto, Update, ABSL, Watchdogs not working and then fixed
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This afternoon the watchdogs stopped working: they didn't trip when the suspension positions crossed the threshold values.
I rebooted c1susaux (aka c1dscl1epics0 in the 1Y5 rack), which is the computer that runs the watchdog processes.
The reboot fixed the problem. |
Wed Jan 20 20:11:56 2010, Alberto, Update, ABSL, Some preliminary results from measuring PRC's transmissivity for an amplitude modulated beam 
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Here I'm posting a plot showing a set of measurements that I made in the past few days to determine the absolute length of the PRC cavity.
As
in my other AbsL measurements, I inject an auxiliary laser beam into the cavity and look at the transmission. In the PRC case, the beam is injected through
the dark port and I look at a pick-off of the REFL beam. The aux laser is phase locked to the PSL beam and I control the differential frequency between |
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Fri Jan 22 02:54:06 2010, Alberto, Update, ABSL, Overnight measurement
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I'm leaving a measurement running overnight. It should be done in about one hour.
Tomorrow morning, If you need to use the interferometer, and you don't want to have the auxiliary beam going onto the dark port, you can turn down
the flipping mirror and close the NPRO's mechanical shutter. |
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Fri Jan 22 14:40:49 2010, Alberto, Update, ABSL, Overnight measurement
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Quote:
I'm leaving a measurement running overnight. It should be done in about one hour. |
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Mon Jan 25 16:30:37 2010, Alberto, Update, ABSL, 166 MHz sideband turned off
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I turned off the modulation at 166MHZ becasue I don't need it if I'm only locking the PRC.
It was introducing extra amplitude modulations of the beam which interfered with the AbsL's PLL photodiode.
I'm going to turn it back on later on. |
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Mon Jan 25 16:46:33 2010, Alberto, Update, ABSL, 166 MHz sideband turned off
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Quote:
I turned off the modulation at 166MHZ becasue I don't need it if I'm only locking the PRC. |
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Wed Jan 27 11:02:30 2010, Alberto, Update, ABSL, PRC Cavity Length
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I fitted the data from scanning the PRC by changing the beat frequency of the auxiliary laser beam with the PSL beam.
The data points
that I've taken so far over the entire frequency range (0-300 MHz) are not continuous. For several reasons the PLL was unable to maintain
lock for such a large range and I had to break it into smaller segments. The measurements to acquire them stretched over a too long period of |
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Thu Jan 28 09:14:51 2010, Alberto, Configuration, Computers, c1iscey, c1iscex, c1lsc, c1asc rebooted
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This morning the LSC scripts wheren't running properly. I had to reboot c1iscey, c1iscex, c1lsc, c1asc .
I burtrestored to Monday January 25 at 12:00. |
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Thu Jan 28 09:17:32 2010, Alberto, Update, LSC, 166 Modulation turned off
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| I temporarily turned off the 166 modulation. |
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Fri Jan 29 12:06:58 2010, Alberto, Update, ABSL, Measurement running today at lunch time
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| I just started a measuremtn that will be running for the next hour or so. Please be careful with the interferometer. |
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Fri Jan 29 13:14:49 2010, Alberto, Update, ABSL, Measurement running today at lunch time
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Quote:
I just started a measuremtn that will be running for the next hour or so. Please be careful with the interferometer. |
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Tue Feb 2 15:30:03 2010, Alberto, Frogs, Treasure, Wild Oats
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FYI. Sitting on the top shelf of George I found an opened jar of raspberry jam and an opened jar of creamy peanut butter. Both are branded Wild Oats
Market.
Wikipedia:
"Wild Oats Markets was an operator of natural foods stores and farmers markets
in North America... Whole Foods officially completed their buyout of Wild Oats on August 27, 2007 [...]" |
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Tue Feb 2 18:15:47 2010, Alberto, Update, elog, Elog restarted it
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Zach made me notice that the elog had crashed earlier on this afternoon.
I just restarted it with the restarting script.
Instructions on how to run the last one are now in the wiki page. Look on the "How To" section, under "How to restart the elog". |
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Wed Feb 3 10:46:12 2010, Alberto, Update, elog, elog restarted
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Again, this morning Zach told me that the elog had crashed while he was trying to post an entry.
I just restarted it. |
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Mon Feb 8 14:13:03 2010, Alberto, Update, ABSL, PLL Characterization
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Lately I've been trying to improve the PLL for the AbsL experiment so that it could handle larger frequency steps and thus speed up the cavity scan.
The maximum frequency step that the PLL could handle withouth losing lock is given by the DC gain of the PLL. This is the product of the mixer's
gain factor K [rad/V ], of the laser's calibration C [Hz/V] and of the PLL filter DC gain F(0). |
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Mon Feb 8 14:56:17 2010, Alberto, Update, ABSL, Suddenly a much better alignment of PRC
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I just aligned PRM and locked PRC and I noticed that SPOB is much higehr than it used to be. It's now about 1800, vs 1200 than it used to be last week.
Isn't anyone related to that? If so, may I please know how he/she did it? |
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Mon Feb 8 15:41:51 2010, Alberto, Update, ABSL, Suddenly a much better alignment of PRC
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Quote:
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Tue Feb 9 09:07:06 2010, Alberto, Update, ABSL, PLL Characterization
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Quote:
Lately I've been trying to improve the PLL for the AbsL experiment so that it could handle larger frequency steps |
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Tue Feb 9 10:10:58 2010, Alberto, Update, ABSL, back to analog
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I want to try to do the measurement with the network analyzer used as local oscillator, instead of the Marconis that I'm using now. Tha could give me
better noise rejection. It would also give me information about the phase.
Also I wouldn't dislike abandoning the GPIB interfaces to acquire data. |
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Tue Feb 16 09:51:22 2010, Alberto, Update, Green Locking, take some optics away from the ETM end table
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Quote:
In the last two days Steve and I took some optics away from the both ETM end |
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Tue Feb 16 10:01:16 2010, Alberto, Configuration, LSC, Arms and PRC not locking
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Since last Friday either the arms or the PRC can't lock.
The montors show the beam flashing on the end mirrors, but the cavity can't get locked. The error signal looks fine. I suspect a computer problem.
Also PRC can't lock. SPOB is suspiciously stuck at about -95. Although that's not a fixed number, but covering the by hand the SPOB PD on the ITMY |
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Tue Feb 16 15:25:00 2010, Alberto, Configuration, LSC, Arms and PRC not locking
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Thu Feb 25 15:49:05 2010, Alberto, AoG, CDS, New IO Chassis for the new CDS
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Yesterday Kiwamu and I went to Downs to take all the available parts of the IO chassis that Gary and I had put together over there.
We've
got only 3 of the 5 that we need for the Upgrade. The other 2 are currently being used for some other purpose in Downs labs.
I'm
not sure about what each chassis has supposed to contain. They all also look different from each other.
Anyway, it looks like there should |
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Wed Mar 3 18:32:25 2010, Alberto, Update, 40m Upgrading, 11 MHz RFPD elctronics
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** Please add LISO file w/ component values.
I designed the circuit for one of the 11 MHz photodiodes that we're going to install
in the 40m Upgrade.
This is a simple representation of the schematic: |
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Thu Mar 4 08:43:35 2010, Alberto, Update, 40m Upgrading, 11 MHz RFPD elctronics
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Quote:
** Please add LISO file w/ component values.
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Thu Mar 4 19:53:56 2010, Alberto, Update, 40m Upgrading, 11MHz PD designed adjusted for diode's resistance; 55 MHz RFPD designed 6x
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After reading this
study done at LIGO MIT in 1998 I understood why it is difficult to define an effective impedance for a photodiode.
I read a few datasheets of the C30642GH photodiode that we're going to use for the 11 and 55 |
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Thu Mar 18 12:27:56 2010, Alberto, Update, ABSL, PLL reconstructed
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Quote:
Last night (Mar 17) I checked the PLL setup as Mott had some difficulty to get a clean lock of the PLL setting. |
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Tue Mar 23 15:38:26 2010, Alberto, Update, elog, elog just restarted
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I found the elog down and I restarted it.
Then, after few seconds it was down again. Maybe someone else was messing with it. I restarted an other 5 times and eventually it came back up. |
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Tue Mar 23 22:46:43 2010, Alberto, Update, 40m Upgrading, REFL11 upgraded
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I modified REFL11 according to the changes lsited in this
schematic (see wiki / Upgrade 09 / RF System / Upgraded RF Photodiodes ).
I tuned it to be resonant at 11.06MHz and to have a notch
at 22.12MHz.
These are the transfer functions that I measured compared with what I expected from the LISO model.
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Wed Mar 24 14:52:02 2010, Alberto, Update, Green Locking, two NPRO PLL
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Quote:
Now some pedestals, mirrors and lenses are left on the PSL table, since we are on the middle way to construct a PLL |
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Wed Mar 24 14:57:21 2010, Alberto, Update, 40m Upgrading, REFL11 upgraded
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Hartmut suggested a possible explanation for the way the electronics transfer function starts picking up at ~50MHz. He said that the 10KOhm
resistance in series with the Test Input connector of the box might have some parasitic capacitance that at high frequency lowers the input impedance. |