Sanjit discovered that the Gur1 channels are all digital 0. We determined that this began on July8, 04:00 UTC (~9pm on the 7th?).
It's digital zero, so we suspect a software thing. Just to check, we put a sine wave in, and didn't see anything. Gur2 seems totally fine, and the sine wave input showed up nicely on dataviewer. What's going on? Sabotage to prevent this paper from getting done? Dmass trying to get his paper done before me???
Investigations are ongoing.... Joe claims it's not his fault, since his shenanigans near the PEM rack were on days before, and days after this, but not on the 7th.
I just rebooted c0dcu1, which didn't help anything. Joe said he'd try to give me a hand tomorrow.
Joe got on the phone with Alex, and Alex's magic Alex intuition told him to ask about the RFM switch. The C0DAQ_CTRL's overload light was orange. Alex suggested hitting the reset button on that RFM switch, which we did. That fixed everything -> c0dcu1 came back, as did the frame builder. Rana had pointed out earlier that we could have brought back all of the other front ends, and enabled the damping of the optics even though the FB was still down. It's okay to leave the front ends & watchdogs on, and just reboot the FB, AWG, and DAQ_CTRL computers if that is necessary.
Anyhow, once the FB was back online, we got around to bringing back all of the front ends (as usual, except for the ones which are unplugged because they're in the middle of being upgraded). Everything is back online now.
After all of this craziness, all of the Guralp channels are working happily again. It is still unknown why they starting being digital zero, but they're back again. Maybe I should have rebooted the frame builder in addition to c0dcu1 last night?
This is regards to zero signal being reported by the channels C1:PEM-SEIS_GUR1_X, C1:PEM-SEIS_GUR1_Y, and C1:PEM-SEIS_GUR1_Z.
I briefly swapped Guralp 1 EW and Guralp 2 EW to confirm to myself that it was not on the gurlap end (although the fact that its digital zero is highly indicative a digital realm problem). I then unplugged the 17-32, and then 1-16 channel connections to the 110B. I saw floating noise on the GUR2 channels, but still digital zero on the GUR1 channels, which means its not the BNC break out box.
There was a spare 110B, unconnected in the crate, so to do a quick test of the 110B, I turned off the crate and swapped the 110Bs, after copying the switch configuration of the first 110B to the second one. The original 110B was labeled ADC 1, while the second 110B was labeled ADC 0. The switches were identical except for the ones closest to the Dsub connectors on the front. All those switches in that set were to the right, when looking down at the switches and the Dsub connectors pointing towards yourself.
Unfortunately, the c0duc1 never seemed to come up with the new 110B (ADC 0). So we put the original 110B back. And turned the crate back on.
The fb then didn't seem to come back quite right. We tried rebooting fb40m it, but its still red with status 1. c0daqctrl is green, but c0dcu1 is red, although I'm not positive if thats due to fb40m being in a strange state. Jenne tried a telnet in to port 8087 and shutdown, but that didn't seem to help. At this point, we're going to contact Alex when he gets in around 12:30.
I moseyed into the control room this morning, to find ITMX and ITMY both with their watchdogs tripped. ITMY (new convention) wouldn't damp. Koji discovered that there was a sign flip in 2 of the sensors. A set of reboots of c1susvme1&2 fixed the problem.
A side note: For the ETMs, the OSEM sensor readouts are gigantic (~20,000), whereas for the similar channels on all other optics, the readouts are on the order of 1. After some looking around, it seems that this is just the way things have been (for at least 100 days), and the filters in the SUSPOS and other SUS filter banks have a high pass filter to take care of this. It's weird, but it seems to be the way it is, and the ETMs damp, so it's all good.
We were on Team Cleanroom, while Kiwamu and Alberto were on Team Chamber. Team Cleanroom suspended and balanced 2 Tip Tilts this afternoon.
One of the TTs that was suspended today is the one which was broken on Friday (see elog 3278). We resuspended it using the regular 0.0036" diameter wire (91um). We balanced it using the HeNe oplev, and then set it aside. This TT has serial number 2.
We noticed that, like the previous 2 TT suspensions (this one before it was broken, and the one actually installed in the BS chamber on Friday, which is #3), there seems to be a little bit of hysteresis in the pointing. The difference comes if we poke the top of the mirror holder and observe the place the reflected beam spot comes to rest at, and if we poke the bottom of the mirror holder. The beam spot stays a little higher when we poke the top vs. when we poke the bottom.
To combat this, we tried suspending our second TT of the day (the one that Kyung Ha and I had half finished) using thinner wire for the mirror holder. We used the 0.0017" diameter wire (43um) that is used for the SOSes. Unfortunately, it still seems like there is a similar hysteresis. The thin-wire TT has serial number 4.
While working on TT4, we recalled that we have to include rubber dampers for the vertical blade springs. Oooops! We used some of the leftover #4-40 screws with viton tips that Zach and Mott had made for Earthquake stops to damp the vertical resonance of the blades. We measured the Q factor by flicking the blades up or down. We changed the oplev setup to be a shadow sensor setup, and watched the ringdown of the vertical mode on the 'scope. We counted #cycles/time = frequency, and the t(1/2) time for the exponential ringdown to calculate the Q. For the shadow sensor, we positioned the QPD in line with the initial HeNe beam, and placed the edge of the mirror holder clamp partially in the beam, so the beam was partly occluded. When the mirror shook up and down, more or less of the beam was blocked, and we could see this power fluctuation on the 'scope.
Using the formula Q = pi f0 T1/2 / ln(2) = 4.53 f0 T1/2, where T1/2 is the the time it takes for the amplitude to decay by half, we measured a Q of 31 for the vertical mode with no damping, and a Q of 14 with damping. Koji confirmed the calculation and put it into wiki.
We need to go through the other TTs that have been assembled and give them their rubber dampers.
We took measurements of the Q of all the modes that we could think of for TT#4, and then repeated several of the same measurements for TT#2. We noticed that when we took off the backplane and then replaced it on TT#4, the pitch pointing had changed, so we had to repeat the balancing procedure by slightly shifting the position of the wire clamps relative to the mirror holder. No fun. We decided to quit removing the backplanes.
The main conclusion of this evening's measurements of TT#4 is that everything looks very close to the design ideas. Good work team!
'Free Swinging' values (just for interest)
Vert, no damping: Q = 31.4
Pitch, no damping (ECD backplane removed): Q = ~700
Yaw, no ECDs: Q = ~900
Pos, no ECDs (no measurement) - we had already put the backplane back on, and didn't want to take it off again.
Vert, with damping: Q = 14.3
Pitch, with ECDs: overdamped, so Q < 1/2
Yaw, with ECDs: Q = 2.3
Pos, with ECDs: Q = 1.4
Side, with ECDs: Q = 1.9
We also measured the resonant frequency of each of the ECDs for this TT (since we had the backplane removed anyway...)
ECD UL: 10.05Hz
ECD UR: 10.15Hz
ECD LL: 10.21Hz
ECD LR: 10.21Hz
Yaw, with ECDs: Q = 7.0
Vert: Problematic. No damping, f = 25.9Hz, Q = 36. With rubber dampers, f = 20.0Hz, Q = 42. Yes, you read that right. The frequency is lower, and the Q is higher *with* the damping. Perhaps our brains are fried. Perhaps we've discovered new, inconsistent physics (awfully unlikely....). We'll revisit this again tomorrow to figure out what mistake we're making.
[Koji, Jenne, Kiwamu]
This is to describe the work that went on in the Cleanroom today. Kiwamu's entry will detail the tidbits that happened in the chamber.
We engraved the periscope mounts with the mirror info for the mirrors which were placed in the periscope. We also engraved the barrels of the optics with their info, for posterity. Koji carefully put the mirrors into the periscopes. Since we have wedged optics, the goal was to have the front HR surface of the mirror parallel to the plane of the mount, and leave a bit of space behind one side of the optic (if we just pushed the optic fully in, the HR surface wouldn't be flat, and would send the beam off to the left or right somewhere). Once the mirrors were mounted in the periscopes, we checked the vertical levelness of the outcoming beam. For the first periscope (the one which has been installed on the BS table), the beam was deflected upward (2.5)/32 inches over 55inches. This corresponds to a 1.4mRad vertical deflection. The second periscope (which will eventually be installed on the OMC table) had a deflection of 1/32 over 55inches, or 0.6mRad. We did not check the side-to-side deflection for either of the periscopes.
We also engraved one more DLC mount with mirror info, and put a mirror into the mount. This is one of the optics that was placed onto the BS table today, which Kiwamu will describe.
We removed TT#3 from the BS chamber so that it could have rubber vertical dampers installed, and be characterized. For future reference, the #'s of the Tip Tilts refers to the serial number of the suspension block piece, which forms the top horizontal bar of the frame.
I brought the GUR2 seismometer back from Bridge so I can get some more MC/Seismic data during the next week while we're pumped down, before we start doing things to the PSL table. Both of the Gur Seismometers are connected back up to the breakout box as of ~3:27pm today. Alastair still has the handheld controller thing (which I use for mass centering, on occasion), since he'll want the seismometer back in a week or two when I'm done with it.
Something is wrong with both X channels of the Guralps. Alastair claimed that he and Frank didn't do anything bad when they opened up the breakout box, but I am suspicious.
While I'm at it, a reminder that Jan and his SURF student Greg still have the Ranger, disassembled over in Bridge. They made a note in their elog, but not in the 40m elog when they took it back again.
Whenever you're done with the Mode Cleaner for the next week, please make sure it is locked, nicely aligned and happy before you leave. Also please make a note of what you're doing and when, so that I know what is good data and what is data with unusual conditions.
In other, semi-bad news (but already recovered from), when I was finishing putting the Guralp Breakout Box back in the rack, I bumped the power strip that is on the top back side of the rack, near the corner that the door opens on (not the corner the door hinges on). I turned the power strip back on, and I think everything that is connected to it came back okay. Anyhow, my bad. Sorry.
Today's seismometer diagnosis activities are still underway, this is just an update (since I did some reboots):
Problem 1: X and Z channels on both seismometers were flipped. I unplugged an X cable (East/West on the cable labels) and the Z channel (vert) would go to floating ADC zero. Rana suggested that the ADCs sometimes have random channel hopping, and that a reboot of the c0dcu1 computer which handles the PEM ADCU should fix this problem. I keyed the c0dcu1 / c0daqawg crate, those computers came back just fine, and the channels were no longer flipped. This is a good thing. Although now it's actually the Z channels that were / are bad on both seismometers, not the X's.
While rebooting those computers, c1iovme, c1sosvme, c1susvme1 and c1susvme2 crashed. I rebooted them, although for the first few power cycles c1susvme1&2 couldn't mount /cvs/cds/caltech. Eventually they did, and life is good again. Except that the seismometers are still funny.
Some more progress, but still not complete:
Jan and I looked at all of the Gur channels on a 'scope (battery, so as not to be grounded), and 5 of the 6 looked good. We were looking at the BNCs just as they go into the ADC. The one which still looks bad is Gur1Z. The 'scope just doesn't see any signal on that channel.
In addition, the ADC's BNC input #4 (which normally has Gur2Z) looks totally shot. When it's floating, the signal on dataviewer definitely doesn't look floating. I'm probably going to have to move over to another channel, and just give that one up (this ADC already has several channels which have been declared bad, so maybe it's not a surprise that this can happen?)
Since one of the Gur signals looks bad (Gur1Z) and one of the ADC channels looks bad (usual Gur2Z), I switched the Z channels on the ADC board, so the channel being saved as Gur1Z is in fact Gur2Z. This is valid as of ~1:15am until further elog notice.
During my investigations into why Gur1Z is funny, I also looked at the signal on the BNC octopus cable coming straight from the output of the Guralp Breakout Box (this is the cable which goes from "ADC Out" on the back of the box which is a 37 pin D-sub to 9 differential BNCs), and sometimes I saw zero on the 'scope, but sometimes there was a signal which would coincide with jumping tests. Whenever there was a signal however, it was always a way lower amplitude (at least by a factor of 10?) than the other channels.
All of this craziness led to me pulling the Guralp box to investigate.
Upon opening the box, I recalled that the channels go in order: Vert, NS, EW. The Gur1Z channel is that first vert channel, and it's the one which always had a blue input capacitor rather than a surface mount one. Being suspicious of Frank and Alastair, since they seemed unhappy with my capacitor choices, I wondered if they had wiggled the blue cap, and tore something loose. Just in case, and to make things seem more uniform, I replaced the blue cap with a surface mount 1uF cap. (Actually its 0.909uF, replacing the 0.905uF blue cap, according to the black DMM that measures capacitance.) While I was in there, since it had been a problem in the past (elog 2811), I relflowed the solder on some of the resistors, especially near the output op amp.
Anyhow, none of that may have been necessary. All 6 of the Gur channels were examined on a 'scope, using clip doodles to measure the various Test Points on the circuit. I looked at all of the TPs in Gur1Z, and I didn't find that any particular stage was any noisier than the others. Also, all 6 of the Gur channels seemed totally fine in terms of sending a good signal to the output of the box, including Gur1Z which is currently under investigation. All of the channels passed the "output looks ~20x the input" test, and for approximately equal thumping on the ground all 6 channels seemed to have similar amplitude outputs. The Z channels on both channels one and channels two were a little bigger than the X's or Y's, but the 2 Z channels were about the same. This test was done using Guralp2 and the Gur2 cable on both channels 1 and 2, and then checked with Guralp 1, using the Gur2 cable on channels 1. The Vert1 channel always seemed good.
I now am suspicious of one or more of the cables: either the Gur1 cable from the seismometer to the box, or the Vert1 channel of the octopus cable. I'm satisfied that the BNC cables running through the cable tray are okay (although it might not hurt to check that they all successfully send a sine wave...) I opened up the backshell of the Gur1 cable, on the end that connects to the breakout box. Nothing seemed amiss. I still need to Beep the cable to check its connections, and look at the octopus cable.
Recap / Current Status: Breakout Box is reinstalled, both seismometers hooked up. The Z channels on the seismometers are swapped at the ADC input. The dataviewer channels Gur1_X, Gur1_Y, Gur1_Z (which is actually Z of Gur2 seismometer) and Gur2_X, Gur2_Y are all good. Nancy is going to leave the MC in a happy place, and note the time when she's done. Tomorrow I'll check out the cables for the Gur1Z seismometer channel.
After some cable swapping this morning, I have determined which cable is bad. It's the Gur1 cable between the seismometer and the breakout box. This is a milspec -> 37pin d-sub cable. I'll pull out the cable and have a look at it after lunch.
So, I was wrong about which cable it was, probably in my rush to get some lunch. The actual culprit was the octopus cable that Bob made waaay back in the day (~2 years ago) to go from the "ADC out" of the breakout box (37pin Male Dsub) to 9 BNCs. As it turns out, the Gur1Z channel of that cable was broken on both ends!!!
On one end, we have the 37 pin Dsub. The cable used was so thick (way too thick for this application) that it made a super rigid connection between the wires and the connector, and any bending of the cable stressed this connection, despite the strain-relief of the backshell. The Gur1Z connection snapped off when I was gently wiggling the connections to check them out. Also, since the wires were all so thick, they didn't really fit into the hole in the backshell, so 2 or 3 of them were squished.....straight through the insulation so that several channels were shorted together / potentially shorted to ground. This may explain some of the nasty behavior that Rana and I had seen (although I might have forgotten to elog? My bad.) that even with the inputs of the breakout box all terminated, there was high coherence between the channels. Terminated inputs should give random noise, so this was fishy.
On the other end of the cable we have the 9 BNCs. I had finished redoing the 37pin end of the cable, and was 'beeping' it to check it out, when to my dismay I found that the Gur1Z channels (the inside and the outer shield of the BNC connector) were shorted together. I removed these 2 wires from the Dsub connector to confirm that the BNC was at fault. Koji looked at the BNC with me after I chopped it off of the cable. Bad news strikes again. To get the wires to fit in the inner pin of the BNC connector, the cable-maker had cut off several strands of the wire to make it skinnier. It appears that over the years these cut-off strands wiggled their way to touching the outer shield. This appears to be a danger for all of the BNCs on this cable: a little bit of torque (which one might expect during plugging and unplugging a BNC) and the 2 sides of the differential measurement will be shorted together.
I then decided to start afresh and make my own cable. I found some AWG26 8-twisted-pair cable laying around underneath the Yarm (since this was all I could find, I was just going to do the Gur1 and Gur2 channels, and leave out the Gur3's). The 37 Dsub side was easy, but I seem not able to connect such skinny wire to the BNC connectors in a robust way. Since this bad cable has so far cost me ~2.5 16-hour days of grief, I don't want my new version of it to also be bad. At this point, I await the advice of one wiser than I. I think BNC connectors are designed for something a little closer to ~20AWG, but I could be wrong. Also, they are obviously optimized for coax cable. So what I have now is never going to be great. Maybe tomorrow I can go to the Electronics Shop / Store and buy BNC connectors that are meant to be soldered-to. That would be awesome.
Since I currently have no functional cable to go from Breakout box to ADC, the Guralps are unplugged for tonight.
Conclusions for the day / evening: Frank, Alastair and Jenna are mostly absolved of blame, although the traveling to Bridge and opening and closing the box (which usually involves more plugging and unplugging of cables) probably didn't help this cable out too much. Also, Bob definitely owes me a Sugar Napoleon or something.
In other news, since the Gur2Z ADC channel is totally wacked, I have taken over (but not renamed) the Ranger channel for Gur2Z for now. Jan still has the Ranger hostage over in Bridge, so this is okay for now.
After much hassle, the Guralp cable from the ADC Out of the breakout box to the ADC is fixed, and everything is plugged in and working again. The seismometers are back in their regular positions at the ends of the MC, ready for some excellent seis/MC combo data.
I solidified the change of putting the Gur2Z channel into a different BNC input on the ADC. The C1ADCU_PEM.ini file has been changed so that what used to be the Ranger's channel is now recognized as Gur2Z.
Also, I changed the same .ini file to reflect Koji's move of ACC_MC1_Z to the old AUDIO_MIC2 channel, so now all 6 Accelerometer channels have the same calibrations again.
Another big change is the change from old-left-handed convention to new-right-handed convention. The seismometers are aligned the same way they always have been (with the North-South markers aligned with the MC), but now the North-South output is plugged into the BNC on the ADC that is associated with Gur*_X, and the East-West output is plugged into the ADC channel associated with Gur*_Y. This is true for both Guralp Seismometers.
So, now we have:
Gur1_X = Gur1_NS = ADC#10
Gur1_Y = Gur1_EW = ADC#11
Gur1_Z = Gur1_Vert = ADC#12
Gur2_X = Gur2_NS = ADC#2
Gur2_Y = Gur2_EW = ADC#3
Gur2_Z = Gur2_Vert = ADC#24
SEIS_Ranger_Y = no longer in the .ini file
Nancy has the Mode Cleaner for her work for the night, and is going to leave the MC happy, locked, autolocker on, WFS enabled, the works, and write down in the elog the time that she's finished. After that, I'm taking MC/seismic data all weekend long. During the weekend, if at all possible, please don't go into the IFO room, especially near the Mode Cleaner. If you do need to go into the IFO room, please elog the time you went in, and the time you left so I can correlate it with my data. This is actually important, so please stick a quick elog entry in if you even think about opening the doors to the IFO room. It is much appreciated.
More of the same.
Who is putting weird figures into the elog?!?! I haven't checked lately, but this is what usually crashes the elog. It's been happening a lot lately, and it might be the .pdf's.
Let's play a new game. We'll call this game "Everyone only use .png files for the next week" Ready? GO!
We characterized Tip Tilts numbers 2 & 3 today. Recall #4 is the one which Koji and I measured some time ago, and #s 1 & 5 have yet to be suspended (that's on the to-do list for tomorrow).
When we began looking at #3 (the one which had been in the BS chamber for a few days, but was removed for characterization) we found that the pitch pointing was way off. The beam was way too low after reflection. So we adjusted that (and got it right on the first try....a miracle!). This does however make me pretty concerned about our in-chamber pointing. Are we destroying our pointing during travel between the cleanroom and the chambers? Is there anything we can do about it? Pointing doesn't seem to be lost when we move them around on the tables in the cleanroom, ie we can pick up a TT, move it, leave it for a while, move it back to the oplev, and the pointing still seems okay. But the TT which was sent to the chambers came back with bad pointing. I'm sure this is related to the hysteresis we see in the pointing if we poke the top of the mirror holder versus the bottom when exciting pitch motion.
For both #2 and #3, we measured the frequency and Q of Pitch, Yaw, Pos, Side, Vert motion. For the Vert motion, we measured both without and with EQ stops as dampers. For the other modes, all were measured with the ECD backplane in place. Pitch and Yaw were measured with reflection off of the mirror surface onto the PD, while Pos, Side and Vert were measured using the wire clamp on the mirror holder to obscure the beam as a shadow sensor.
Pitch: Overdamped, no freq measured, Q < 1/2
Yaw: freq ~1.8Hz, Q between 2-7
Pos: freq ~1.75Hz, Q too low to measure, but above critically damped
Side: freq ~ 1.8Hz, Q~5
Vert no dampers: freq ~20Hz, Q~36
Vert with dampers on outer screws: freq~24Hz, Q~8,
Pitch: no freq measured. Q~1/2? Upon being excited in Pitch, the beam started down way below the photodiode, came up a little past its DC place, and went back down a tiny bit. So not quite overdamped.
Yaw: freq ~1.96Hz, Q very low
Pos: freq ~1.72Hz, Q~3
Side: freq ~1.85Hz, Q~6
Vert no dampers: freq ~20Hz, Q~75
Vert with dampers on outer screws: freq ~20Hz, Q~34 (Frequency stayed constant....we did several measurements both with and without the dampers...but the half life time changed significantly)
Things we noticed: Koji and I had been concerned the last time we were looking at TT#2 because the frequency got lower and the Q seemed to get higher when we added the damping to the vertical blades. Yoichi and I did not find that to be true today. We did notice, however, that the EQ stop screws with the viton had been placed in the holes closer to the clamping point, whereas with TT #4 the screws had been placed in the holes farther from the clamping point. We moved the screws on TT #2 to the outer holes, and noticed that the frequency increased slightly, and the Q significantly decreased. We then followed this outer-hole philosophy when installing screws in TT #3.
To Do List: We need to suspend the ECDs and the Optics for the remaining two Tip Tilts, and to characterize them. We also (probably farther-future) need to take transfer functions using a shaker / shake table with our spare Tip Tilt. After all the TTs are suspended and have their modes measured, we will be ready for installation into the chamber during the next vent.
The elog was so dead this time that the restart script didn't work. I followed the restart-by-hand instructions instead, with success.
The final 2 Tip Tilts (#1 and #5) have been suspended. We have designated #5 the spare. It looks like there might be a teensy bit of dust on the AR surface of the optic in #5, right near the edge of the coating. Not a critical issue if this one is the spare, although we should see if we can blow it off with the Nitrogen. Both #1 and #5's optics were suspended using the thicker wire, 0.0036" diameter. This leaves 4/5 TTs with this thick wire, and 1 of the 5 has the thin wire.
To do still: Balance both #1 and #5, and then measure the modes of each. Then we'll be ready to install them into the chambers, and we'll reserve #5 for shake table TFs for some later date.
Just for added interest, I tried a different method when the restart script broke. The "start-elog-nodus" script has a line "kill elogd". This seems not to be actually killing anything anymore, which means the elog can't restart. So this time I went for "kill <pid number>", and then ran the startup script. This worked. So it's the "kill elogd" which isn't working reliably.
Hooray!!! The Tip Tilts are completely done! The only things remaining are (1) Install 4 TTs in chambers sometime in September and (2) do shake tests / take TFs of the spare.
Today we balanced and characterized #'s 1 and 5. All 5 TTs are waiting happily on the flow bench in the cleanroom for installation.
Bad CDS team. Bad.
Thoughts on where to take the pickoff for the SHG for the PSL-green? We discussed today at the meeting the possibility of putting a 90/10 beam splitter right after the PMC, so that the green team would get somewhere between 100-200mW.
I think op540m has finally bitten the dust. I noticed that both of its screens were black, so I assumed that it had crashed due to known graphics card issues or something. But upon closer inspection, it is way more dead than that. I checked that it does have power (at least the power cable is securely plugged in at both ends, and the power strip its on is successfully powering several other computers), but I can't make any lights or anything come on by pressing the power button on the front of the computer tower.
Immediate consequences of op540 not being operational are the lack of DMT, and the lack of Alarms.
Joe is doing an autopsy right now to see if its really dead, or only 'mostly dead'.
EDIT: Joe says maybe it's the power supply for the computer. But he can't turn it on either.
Like a new phoenix, the 40m PSL is in the process of being reborn...
We cleared many old optics and components (including Alberto's favorite periscope) off of the north end of the PSL table. Some optics are stored on the SP table, others on the shelf inside the PSL enclosure.
The new Innolight 2W NPRO is on the table, the PMC has been moved, and the main path of the laser has been sketched out using steering mirrors. Since we still don't have a beam, we're roughly placing all of our optics, and we'll finalize the alignment after turning on the laser.
Using a leveled HeNe, I checked the height of optics we should use to match the height of optics in the chambers by shining the light at the first steering mirror in the chamber, and ensuring that the beam hit the center of that optic . Since the new PSL table height is identical to the AP table, it's not a surprise that from now on we will be using a 4" beam height on the PSL table, rather than the old PSL 3" beam height.
On the to-do list is to make a plate with 4 through holes to raise the PMC up by 1 inch, and to make an adapter plate (or come up with another plan) for mounting the AOM that goes directly after the NPRO/Faraday, among many other things. We also still need to make some space for the RefCav to be put in its new place on the table, and then install it with Steve's help.
As it turns out, data seems to fall off the 16Tb drives after ~20 days. Which makes it a good thing that I saved all of my raw data from my good Mode Cleaner / seismic weekend for offline Wiener Filtering in the following secret place:
It's not linked to the svn, since it's a boatload of data.
More PSL progress.
The new laser was raised to a 4 inch beam height using basically the most randomly thrown together method possible. (It'll work just fine for aligning things, but we seriously need to get a nice block made.) The PMC and the nice Osamu-mirror mount to go into the PMC also have temporary risers, so we'll need to replace them with the real deal as soon as we get things back from the shop.
So far we've got (1) the lens after the laser, (2) a Half Wave Plate (no quarter wave plate yet), (3) steering mirror that will go after the EOM, (4) 2 steering mirrors to get into the PMC, in addition to all of the stuff that we did the other day. With all of this stuff we've got the beam hitting the 1st PMC mirror. We still don't have the EOM and AOM in the beam path however.
To get the rough alignment that we did, we turned on the new 2W NPRO, operating at the minimum power we could see on a card. We turned it off after use, so it is still off. Steve, we left the cable for the interlock sitting on the PSL table on the NW corner....can you please hook it up tomorrow? Also, after the interlock is installed we should go back to regular running laser hazard mode.
This totally creeped me out when I found it wandering around on the floor not so far from my desk:
Rana and I were poking around on the PSL table today, getting a few more items raised to the correct height.
I checked the polarization state of the new NPRO by using a HWP to minimize the transmission through a PBS cube, and then compared the power transmitted through the cube vs. reflected. When the NPRO current was 0.772 \pm 0.001 (as read on the LCD), the transmission through the cube was 1.44mW, while the reflected was 10.53mW. The reading of the Ophir power meter with no incident light was 0.03mW. This factor of 10 means that the NPRO beam is ~10% circularly polarized and ~90% linearly polarized. In order to improve the beam, we need a Quarter Wave Plate, which it turns out we don't have. We need a QWP!
After that, using the linearly polarized part of my beam (maximizing the transmission through the PBS by rotating my HWP by 45deg), I tried to tune the angle of the polarizers that Rana pulled out of the MOPA. I think I'm confused / too tired, because I can only get the polarizer to reflect a bunch of light, and I can't get it to pass any significant amount of light through, no matter where in its actuation range I put it (It's on a rotation stage with a few degrees of range). It should just be a Brewster's Angle thing, and since I already have P-pol coming through the BS cube, this shouldn't be so hard.....
In any case, it may not be useful to do the final fine tuning of these polarizers until they are in their final places. The hacky stack of mounts that I have has some slop in the position / alignment of the base of the polarizer, so no matter what we'll have to redo the tuning after the mounts are finalized.
On the one hand, SHAME ON ALL PEOPLE WHO DON'T ELOG THINGS, such as the moving of scripts directories (it was a pain to figure out that that's part of why the backup scripts are broken). On the other hand, the moving of the scripts directories brought to light a critical problem in the backup scheme. None of the frame files have been backed up since Joe replaced fb40m with fb, on ~23 Sept (I think).
What went down:
The frame builder was replaced, and no backup script was started up on the new machine. Sadface. Crontab doesn't work yet on the new machine, and also the 'ssh-add' commands give an error:
controls@fb /cvs/cds/rtcds/caltech/c1/scripts/backup $ ssh-add ~/.ssh/id_rsa
No such file or directory
controls@fb /cvs/cds/rtcds/caltech/c1/scripts/backup $ ssh-add ~/.ssh/backup2PB
No such file or directory
Thus, I know that the backup was never running on the new fb. However, the check-er script runs on nodus, and looks at the logfile, and since there was no script running, it wasn't adding to the log file, so the last log was an "Okay, everything worked" entry. So, the check-er script kept sending me daily emails saying that everything was okie-dokey.
Since all of the scripts were moved (Joe said this happened on Friday, although there's no elog about it), the check-er script, and all of the rest of the backup scripts point to the wrong places (the old scripts/backup directory), so I didn't receive any emails about the backup either way (usually it at least sends a "Hey, I'm broken" email). This clued me in that we need to check things out, and I discovered that it's all gone to hell.
Since I can't add the ssh clients to the new fb, I can't actually log in to the backup computers over in Powell-Booth to check when the last legitimately successful backup was. But I suspect it was just before the fb was replaced.
So, we need to get Crontab up and running on the new Frame Builder machine so that we can run cron jobs, and we also need to figure out this backup hullabaloo. I think I'll email / call Dan Kozak over in downs, who was talking about upgrading our backup scheme anyway.
We've put the old PRM and SRM (which were living in a foil house on the cleanroom optical table) into Steve's nifty storage containers. Also, we removed the SRM which was suspended, and stored it in a nifty container. All 3 of these optics are currently sitting on one of the cleanroom optical tables. This is fine for temporary storage, but we will need to find another place for them to live permanently. The etched names of the 3 optics are facing out, so that you can read them without picking them up. I forgot to note the serial numbers of the optics we've got stored, but the old optics are labeled XRM ###, whereas the new optics are labeled XRMU ###.
Koji chose for us PRMU 002, out of the set which we recently received from ATF, to be the new PRM. Suresh and I drag wiped both sides with Acetone and Iso, and it is currently sitting on one of the rings, in the foil house on the cleanroom optical table.
We are now ready to begin the guiderod gluing process (later tonight or tomorrow).
We've aligned the guiderod and wire standoff to the PRM, each partly. They have both been aligned to the correct distance above the scribe lines, but they have not yet been centered forward/backward along the thickness of the optic. So, we're working on it...
This afternoon I epoxied the guiderod and wire standoff to the new PRM. I also epoxied the magnets that Suresh picked out to the dumbbell standoffs. We'll let them all cure over the weekend, and then I'll glue the magnets to the optic on ~Monday.
Notes about the epoxy:
Previously, we had been using the "AN-1" epoxy, which is gray, with a clear hardener. Bob recommended we switch to "30-2", which is clear with clear, and has been chosen for use in aLIGO. Both were vacuum approved, but the 30-2 has gone through ~2 months of testing at the OTF (Optics Test Facility?) over in Downs under vacuum, to check the level of outgassing (or really, non-outgassing).
The 30-2 is less viscous than the AN-1, and it takes less glue to do the same job, so we should keep that in mind when applying the epoxy. When I put the glue next to the guiderod and standoff, it got wicked along the length of each rod, which is good. I can't reach the whole length of the rod with my glue applicator because the fixture holding them in place blocks access, so the wicking is pretty handy.
I've also added the updated version of my Status Table for the suspensions.
As the suspension work winds down (we'll be completely done once the ETMs arrive, are suspended, and then are placed in the chambers), I'm going to start working on the RF system.
Step 1: Figure out what Alberto has been up to the last few months.
Step 2: Figure out what still needs doing.
Step 3: Complete all the items listed out in step 2.
Step 4: Make sure it all works.
Right now I'm just starting steps 1 & 2. I've made myself a handy-dandy wiki checklist: RF Checklist. Hopefully all of the bits and pieces that need doing will be put here, and then I can start checking them off. Suggestions and additions to the list are welcome.
[Jenne, Suresh, Thanh (Bram's Grad Student)]
When we removed the grippers from the magnets on the PRM, one of the face magnets broke off. This time, the dumbbell remained glued to the optic, while the magnet came off. (Usually the magnet and dumbbell will stay attached, and both come off together). I had 3 spare magnet-dumbbells, but only one of them was the correct polarization. The strength of the spare magnet was ~128 Gauss, while the other magnets glued to the PRM are all ~180 Gauss. We considered this too large a discrepancy, and so elected to reuse the same magnet as before.
We removed the dumbbell from the optic using acetone. After the epoxy was gently removed, we drag wiped the AR face of the optic (Acetone followed by Iso, as usual), being careful to keep all the solvent away from all the other glue joints. We cleaned off the magnet with acetone (it didn't really have any glue stuck on it...most of the glue was stuck on the dumbbell), and epoxied it to a new dumbbell.
The PRM, as well as the magnet-dumbbell gluing fixture are in the little foil house, waiting for tomorrow's activities. Tomorrow we will re-glue this magnet to the optic, and Thursday we will balance the optic.
This still leaves us right on schedule for giving the PRM to Bob on Friday at lunchtime, so it can bake over the weekend.
Since MC2_TRANS is, in fact, MC2 Transmission, and not an oplev at all (it's not red, and it's not a lever, although it does use a QPD), I propose that the name be changed to something sensical, since calling it an oplev is completely non-sensical. The name change should happen sooner rather than later, to avoid confusion.
Today, we fixed OPLEV stuff, MCL filters, and time stamps.
What we did:
5. Checked OPLEV for MC2 by pointing a laser pointer to QPD. (For MC2, OPLEV is just a transmission beam position monitor)
Each quadrant looked like they are connected to the right channel numbers.
DTT has only SUS and "X02" channels under C1 in the drop down channel selection menu. Basically, we can't measure any fast channels with DTT. I keep getting the error: "Unable to select testpoints." Sadface.
Similar things are true for DataViewer. The same limited number of fast channels, and no data found:
Server error 13: no data found
datasrv: DataWriteRealtime failed: daq_send: Illegal seek
Is this a framebuilder problem? Is this something that the CDS team has on the to-do list?
We took a look-see at the PRM after the gluing from last night. The balance is still okay. The reflected beam is a teeny bit below the laser aperture (center of the beam maybe ~2mm below, so ~1mRad low). This is within our okay range, since the DC offset that the OSEMs will give will be even more, and the coils can definitely handle this kind of offset.
We took the optic out of the tower, and gave it to Bob and Daphen to bake over the weekend.
At Koji's request, we disassembled 2 of the old Green suspension towers that have been sitting along the X-arm forever (read that last word in a 'Sandlot' voice. Then you'll know how long the suspensions have been sitting there).
They are now hanging out in plastic trays, covered with foil. They will now be much easier to store.
We should remember that we have these, particularly because the tables at the top are really nice, and have lots of degrees of freedom of fine adjustment.
Atm1, there is one more of these old suspension towers
Over the weekend, Bob and Daphen gave the PRM a 48hr. vacuum bake. This afternoon Suresh and I placed it back in the wire in the tower. We used the microscope-on-translation-stage technique to make sure the scribe lines on each side of the optic are at the same height, and then secured the PRM using all of the EQ stops. It is wrapped in foil, and ready for its journey into the IFO room. When we next have the BS chamber open, we should put the PRM in, and move the current PRM to its final place on the ITMY table as the SRM.
Dear whomever setup the camera on the SW corner of the PSL table,
It would be handy if, even for temporary setups, all cables went underneath the white frame around the PSL table. As it is now, the cables are in the way of the door. The door is pretty much closed all the way, but if someone were to open other doors, the far door can easily be pushed all the way to the end of the track, thus squishing the cables. Squished cables are bad cables.
Joon Ho and I took a look at the RF stuff that Alberto left, and we determined that we've got most everything that we need. On Monday, Joon Ho will list off the stuff that we're missing, and we'll have Steve order it.
Joon Ho also replaced the temporary front panel to the RF generation box with Alberto's fancy new panel. Pics are here (although you have to sign in as foteee to see them).
Work on the frequency distribution box will continue on Monday.
We have put together the new-old ETM towers. These are the ones which were hanging out on the flow bench down the arm for years and years, and have recently been re-baked. Interestingly, these are predominantly steel, whereas the newer ones are mostly aluminum. This caused momentary drama while we scrounged for the correct screws (we needed more silver-plated screws than anticipated, since we were screwing into steel and not aluminum), however the miscellaneous clean hardware collection came to the rescue. We did however use up all of the 1/4-20 3/4" silver plated screws, so hopefully no one else needs more later...
We only found 5 (enough for one of the two towers) spring plungers which are used to hold the OSEMs in place. Suresh is sending an email to Steve to ask him to buy some more, so we can get them cleaned in time for use. This is important, but not super urgent, since we have ~ 2 weeks before the ETMs will be ready for installation.
Koji has not yet had a chance to inspect the ETM data sheets and choose for us which pair of ETMs to use (ATF sent the 4 ETMs in matched pairs). So we will not begin the "arts and crafts" until tomorrow-ish.
We pondered the idea of clamping the PRM optic to measure the OSEM noise. So we opened up the BS tank to give this a try. We rediscovered that Jenne is too short to reach the other side of the PRM tower, so we couldn't fully clamp the optic (when is Jaime coming again? He's kind of tall...) If we only did the back 2 EQ stops, the optic would still be able to rock, and thus defeat the purpose of clamping anyway. So we didn't go for it.
While we were in there we saw that the SRM OSEMs were just hanging out on the table, and decided to go with them. See Valera's elog for details on our measurement. We closed up the tank without making any changes to anything.
In other news, we still need to figure out how to change up the connectors to get those OSEMs over to the ITM table. This needs to happen pretty soonish.
[Steve, Jenne, Suresh, Koji]
The remaining test mass chambers have been opened, and have light doors in place. Now we can do all of the rest of the IFO alignment, and then (hopefully) button up before the New Year.
Today has been a downright miserable day in the world of suspension work. Thumbs down to that:
Yesterday, we had glued 2 full sets of magnets to dumbbells. Today, half of those broke. I think I put too thin of a layer of glue on the magnets when gluing them to the dumbbells. All magnet/dumbbell assemblies should pass the test of being picked up by the dumbbell while the magnet is stuck to the optical table or a razor blade. 6 of the 12 magnets failed this test. Suresh soaked the dumbbells that had been used in acetone, and scrubbed them, so we can reuse them when we reglue things tomorrow. By some miracle, we have exactly one full set intact (for each set of 6, we need 4 of one direction and 2 of the other). This was frustrating, but not yet a deal-breaker. That part comes next....
I got ETMU05 nicely aligned in the magnet gluing fixture, and then was on my last check of whether the side magnets would be glued in the correct place when I realized that the fixture is all wrong for the ETMs. This final check was added to the procedure after the drama with the ITMs of having the side magnets glued incorrectly as a result of the fixture being specific to the wedge angle of the optic. Kiwamu and I had set the fixture to be just right for the ~1deg wedge corner station optics, but the ETMs have a 2.35deg wedge (according to the Coastline spec sheet, which is consistent with our measurements when placing the guiderod and standoffs). Suresh and I need to reset the height of the optic in the fixture using more teflon sheets, but we don't have a whole lot of options ready in the cleanroom. We're going to cut some more pieces and ask Bob to clean them tomorrow. Since the way the fixture holds the teflon is a little hoaky, Suresh suggested just resting the optic on teflon pads, rather than screwing the teflon to the fixture, and then putting the optic on the pads. We'll try Suresh's method tomorrow, and hopefully it will be pretty easy.
At least the guiderods and standoffs were successfully glued to the optics....
Here's the updated Status Table. I don't think we're going to be able to have an ETM ready for the chambers early next week, but we should still be able to have both ready for the Monday after Thanksgiving. The spring plungers arrived today, and were given immediately to Bob and Daphen for cleaning.
Suresh and I glued the intact-from-the-first-round magnets to ETMU05. I accidentally got too much glue on one of the dumbbells (the glue was connecting the dumbbell to the gripper - bad news if we let that dry), and while I was cleaning it, the magnet broke off. So I used one of the ones that Suresh had re-glued last night, and he is putting that one back together after some cleaning.
To set the fixture, Suresh had the great idea of using small pieces of foil underneath the teflon pads to set the height of the optic in the fixture. The optic still rests on the teflon pads, but with the foil we have finer control over how the optic sits. Neat. Since both ETMs are the same, we shouldn't have to do any more adjustment for the other ETM.
The updated Status Table:
A story about minor disasters, and crises averted:
Once upon a time, in a cleanroom not so far away..... there lived an optic. To preserve anonymity, we shall call him "ETMU05". This optic had a rough day. When removing the grippers from the magnet-to-optic fixture, 4 out of 6 magnets broke off the dumbbells (the dumbbells were still securely glued to the optic...these had come out of the same batch that had problems last week, same problem). The remaining 2, LL and LR, were sadly of the same polarity. This is bad, because it means that the "humans" taking care of "ETMU05" didn't check the polarity of the face magnets properly, and ensure that they were laid out in an every-other pattern (LL and UR having the same polarity, and LR and UL having the opposite). So, the humans removed all magnets and dumbbells from ETMU05. All remaining glue was carefully scrubbed off the surfaces of ETMU05 using lens paper and acetone, and the magnets and dumbbells were sonicated in acetone, scrubbed with a lint-free wipe, sonicated again, and then scrubbed again to remove the glue. ETMU05 had a nice cleansing, and was drag wiped on both the AR and HR surfaces with acetone and iso. ETMU05 is now on vacation in a nice little foil hut.
His friend, (let's call him ETMU07) had a set of magnets (with polarities carefully confirmed) glued to him. The cleaned magnets and dumbbells removed from ETMU05 were reglued to their dumbbells, and should be dry by tomorrow.
.....And then they lived happily ever after. The End.
The revised schedule / status table:
Joe showed me what was what with adding DAQ channels, and I have begun building a simulink model to acquire the PEM channels.
My models is in: /cvs/cds/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/c1pem.mdl
Next on the to do list in this category: test which input connector goes with which channel (hopefully it's linear, exactly as one would think), and give the channels appropriate names.