I cleaned up the south Electronics bench today.
The other two, as well as several of the desks are in some chaotic state of degradation. Please clean up your areas and put away projects which do not need to remain staged for several months. Try to eliminate "that's not mine" and "I don't know who's that is" from your vocabulary. Fight back against entropy!
Summary: Third unsuccessful attempt at getting ETMX suspended. I think we should dial the torque wrench back down to 1.0 N m from 1.5 N m for tightening the primary clamp at the top of the SOS tower. No damage to magnets, standoff successfully retrieved (it is sitting in the steel bowl)
Unfortunately I don't know of a more deterministic way of deciding on a "safe" torque with which to tighten the bolts except by trial and error. It is also possible that the clamping piece is damaged in some way and is responsible for these breakages, but short of getting the edges chamfered, I am not sure what will help in this regard.
Unrelated to this work: earlier today before the first wire failure, while I was optimistic about doing fine pitch balancing and gluing the standoff, I set up an optical lever arm ~3m in length, with the beam from the HeNe on the clean bench at 5.5 in above the table, and parallel to it (verified using Iris close to the HeNe and at the end of the lever arm). I also set up the PZT buzzer - it needs a function generator as well for our application, so I brought one into the cleanroom from the lab, isopropanol wiped it. The procedure says apply 5Vrms triangular wave at 1000Hz, but our SR function generators can't put out such a large signal, the most they could manage was ~2Vrms (we have to be careful about applying an offset as well so as to not send any negative voltages to the PZT voltage unit's "External input". All the pieces we need for the fine pitch balancing should be in the cleanroom now.
I set up a test inverting amplifier circuit using the LT1677 opamp:
The input signal was a sine wave from the function generator with peak to peak amplitude of 20 mV and a frequency of 500 Hz and I received an output with an amplitude of about 670 mV and the same 500 Hz frequency, agreeing with the expected gain of -332k/10k = -33.2:
So now I know that the LT1677 works as expected with a negative supply voltage. My issue with Den's original circuit is that I was getting some clipping on the input to pin 2, which didn't seem to be due to any of the capacitors- I switched them all out. I set up a modified version of Den's circuit using a negative voltage input to see if I could fix this clipping issue:
I might reduce the input voltages to +5V and -5V- I couldn't get my inverting amp circuit to work with +12V and -12V. I'll start testing this new circuit next week and start setting up some amplifier boxes.
Unbaked steel music wire from "Ca Fine Wire Co" from 24" od spool, od 0.0017" used. Identical to the one that broke.
The set up as shown with silver plated screws-washers on clamp. The unused clamp edges were sanded on P800 paper at 45 degrees just not to be very sharp.
Use your finger to feel the sharpness of edge and sand till it gets a little bit not so sharp. The drawing note is "sharp edges" on wire clamp for low loss, high Q in mind.
The wire broke at the midle with single load 295 grms
The wire hold on overnight at single load 242 grms Vezo torque wrench is not accurate! This test was performed ~ 1.5Nm DO NOT USE THIS NUMBER! (added at 8-10-2016)
This gives us a factor of 2 safety with loop suspended of 250 grms small optic.
While the air bake oven situation is being improved, how about to buy a cheepo toaster oven at Target, BestBuy, or anywhere?
We don't need precise temp control for the glue cure test. At LLO I saw that they are using cooking grade oven for this purpose.
(Of course, we should not use this oven for foods once it is used for epoxy)
I have a fryer temp sensor in my office on the freezer stole from the 40m long time ago. You should be able to measure high temp.
If you have such an oven, I'd love to borrow it for the OMC lab later, as I expect to work on epoxy bonding later.
The question arose whether we can get good enough data to diagonize our OSEM sensing matrices in air.
I just took a look at the BS spectra over the last six hours (~10PM-4AM), and the SNR looks good. The BS diagonalization itself doesn't seem so great; the POS is hugely coupled into pitch and yaw, and the angular motions are themselves coupled to each other at around 10%.
NB: use a flat-top window when you really care about peak heights that don't fall exactly on an FFT bin.
I would've liked to check this for the PRM and SRM too, but one of the PRM sensors continues to be dark, and I just noticed that all of the SRM OSEM signals are dark. ughhhh
I tried to recompile the modbusApp binary for linux-arm acrhitecture since I suspected someting wrong with it. But still the problem persists; I can connect to acromag but cannot access the channels. I have also reconfigured new acromag bus works terminal XT 1221-000 and I want to test if I could access its channels. My target is to complete this acromag setup work before sunday morning so that I can focus towards having some useful results for my presentation.
Tonight's progress on ETMX:
Since the air bake oven we had been using is out of commision, we're not sure where to do our EP30 test runs. If we are fortunate, we can get the fine pitch balance done tomorrow while Bob is still around, so he can help us quickly bake the test dots, so we can do the standoff gluing.
I'd recommend replacing the wire and grinding down the clamp to prevent cutting the wire. Since we have almost never replaced clamps, many of them probably have grooves from the wires and can make unpleasant cuts. Better safe than sorry in this case.
While ETMX magnets were curing, I wanted to try and suspend ETMY in the endchamber, put in the OSEMS and see if the magnets aligned well with the coils, and run the same type of diagnostics we have been doing for ETMX. However, while I was trying to slip the optic into the wire, the UL magnet on ETMY broke off. I recovered the magnet and now both optic and magnet are back in the cleanroom. The magnet dumbbell has been cleaned with acetone and then sandpaper to remove residual epoxy - it remains to clean the residue off the optic itself before re-gluing the magnet tonight
I also noticed that the existing wire in the suspension had a kink in it. It looks fairly sharp, and I think we should change the wire while re-inserting the optic. Putting the optic into an existing loop of wire is tricky, as if you go in from the front of the suspension cage, the magnets on the AR side attract the wire, and makes it quite difficult to loop the wire around. I have to think of some way of holding the wires in place while the optic is being placed, and then, once the optic is roughly in position, slip the wire into the grooves in the standoffs.
I took the opportunity to replace the face OSEM coil holder screws while the chamber was open.
EDIT 9 August 2016: It was in fact the LR magnet that was knocked off.
I took some pictures with the digital microscope of the aluminum standoffs removed from ETMX. The first one had some leftover epoxy still attached, so I was able to distinguish which part of the groove was occupied by the wire. A better microscope would help (this one has a maximum magification of 80, 200 or so would be much better) but I was still able to see what looks like a second minimum inside the groove at the wire location (see Attachments 1 and 2). The bottom edge of the standoff shows the profile of the groove on the opposite side from the glue. I took several photos with different lighting angles and at different locations on the microscope stage and convinced myself that this was not just an artificial effect. I also took photos of the groove in a different place and did not see this feature (Attachment 3).
The other standoff in the same container had no visible damage to the groove or to the body of the rod. I rotated it under the mocroscope and could celarly see the 'V' shape all the way around. The smooth undanaged groove caught the light more easily and was obvious. The damaged one is scratched around much of the surface, but the undamaged standoff is very smooth. Eric, were both aluminum standoffs in the container with the extra ruby one taken off ETMX, or was one of them new? in any case, see Attachement 4 for a comparison. The believed damage is somewhat visible on the top edge of the lower standoff in the photo.
[Edit:] Also, in the drawings it looks like the specified radius for the bottom of the groove (0.001 in) is smaller than the radius of the wire (0.00085 in). This would prevent having two clean points of contact like Steve and Gautam were describing as the goal. This is also true of drawings for the new Sapphire guiderods, though the dimensions are in metric units the specified radius of the groove bottom is smaller than the wire's diameter, but larger than its radius. Maybe this providied the initial ability for the wire to move around and carve two distinct grooves.
Brief summary, some pictures and such follow in the daytime.
The epoxy needs at least 12 hours of room temperature air curing, so no touchy until 3:30PM on Jul 28!
Attachment #1 - After multiple trials shimming the magnet gluing rig with teflon spacers, we think that we managed to find a configuration in which the side magnet edge is between 0.25 mm and 0.5 mm from the groove in the ruby wire standoff in which the wire will sit.
Attachment #2 - Zoomed in view of the side magnet.
Of course we won't know until we suspend the optic, but we believe that we have mitigated the misalignment between the side OSEM axis and side magnet.
The short term plan is to try and suspend ETMY in the end chamber and have a look at the alignment between all magnets and OSEM coils for it. Once the epoxy on ETMX is cured, we will try and suspend the optic again, this time taking extra care while tightening the wire clamps.
Unrelated to this work: Bob just informed me that we had left the air bake oven on overnight - this unfortunately melted the plastic thermocouple inside.
The clamp is in the machine for milling off the grooves. It's condition is normal. The edges needs some 800 sand paper so it is not sharp anywhere.
How did those nicks get on the edge? Fortunatelly they did not aligned with the wire.
I recreated Den's microphone amplifier circuit on a solderless breadboard to test it and make sure it does what it's supposed to. So far it seems like everything is working- I'll do some testing tomorrow to see what the amplified output is like for some test noises. Here's the circuit diagram that Den made (his elog as well https://nodus.ligo.caltech.edu:8081/40m/6651):
I'm not sure why he set up the circuit the way he did- he has pin 7 grounded and pin 4 going to +12V while in the datasheet for the opamp (http://cds.linear.com/docs/en/datasheet/1677fa.pdf), pin 7 goes to positive voltage and pin 4 goes to negative voltage. There's some other strange things about the circuit that I don't really understand, such as the motivation for using no negative voltage source, but for now I'm going to stick with Den's design and then make some modifications after I have things working and a better understanding of the problem.
Here's my current plan:
-Make sure Den's amplifier works, test it out and make changes if necessary
-Make multiple amplifier circuits on soldering breadboard
-Either make a new amplifier box or reuse Den's old box depending on how many changes I make to the original circuit
-Solder EM172s to BNC connectors, set them up around the floor suspended
-Get the amplifier box hooked up, set up some data channels for the acoustic noise
-Add new acoustic noise tab to the summary pages
Den also mentioned that he wanted me to measure the coupling of acoustic noise to DARM.
For the rest of this vent, at least, we need to start using the EQ stops more frequently. Whenever the suspension is being worked on clamp the optic. When you need it to be free back off the stops, but only by a few hundred microns - never more than a millimeter.
Best to take our time and use the stops often. With all the magnets being broken off, its not clear now how many partially cracked glue joints we have on dumbells which didn't completely fall off.
While tightening the bolts on the ETMX wire clamp, the wire broke. All four face magnets broke off.
Fortunately, no pieces were lost.
2005 ALL oplev servos use Coherent DIODE LASERS # 31-0425-000, 670 nm, 1 mW
Sep. 28, 2006 optical lever noise budget with DC readout in 40m, LIGO- T060234-00-R, Reinecke & Rana
May 22, 2007 BS, SRM & PRM He Ne 1103P takes over from diode
May 29, 2007 low RIN He Ne JDSU 1103P selected, 5 purchased sn: T8078254, T8078256, T8078257, T8078258 & T8077178 in Sep. 2007
Nov 30, 2007 Uniphase 1103P divergence measured
Nov. 30, 2007 ETMX old Uniphase 1103P from 2002 dies: .............., running time not known......~3-5 years?
May 19, 2008 ETMY old Uniphase 1103P from 1999 dies;.....................running time not known.....~ ?
Oct. 2, 2008 ITMX & ITMY are still diodes, meaning others are converted to 1103P earlier
JDSU 1103P were replaced as follows:
May 11, 2011 ETMX replaced, life time 1,258 days or 3.4 years
May 13, 2014 ETMX , LT 1,098 days or 3 y
May 22, 2012 ETMY, LT 1,464 days or 4 y
Oct. 5, 2011 BS & PRM, LT 4 years, laser in place at 1,037 days or 2.8 y
Sep. 13, 2011 ITMY old 1103P & SRM diode laser replaced by 1125P ..........old He life time is not known, 1125P in place 1,059 days or 2.9 y
June 26, 2013 ITMX 622 days or 1.7 y note: we changed because of beam quality.........................laser in place 420 days or 1.2 y
Sep. 27, 2013 purchased 3 JDSU 1103P lasers, sn: P893516, P893518, P893519 ......2 spares ( also 2 spares of 1125P of 5 mW & larger body )
May 13, 2014 ETMX, .............laser in place 90 d
May 22, 2012 ETMY,
Oct. 7, 2013 ETMY, LT 503 d or 1.4 y............bad beam quality ?
Aug. 8, 2014 ETMY, .............laser in place 425 days or 1.2 y
Sept. 5, 2014 new 1103P, sn P893516 installed at SP table for aLIGO oplev use qualification
May 23, 2016 ITMX dead laser sn P845648 replaced after 1062 days [2.9 yrs] by 1103P, sn P859884, with output output 2.6 mW, nicely round beam quality at 15 meters.
July 27, 2016 2 new 1103P from Edmonds in: P947034 & P947039, manf. date April 2016,
Today, we did the following:
I will have another look at the spectra tomorrow morning, to see if the damping improves overnight.
We have no number for the CFM without calculation. We can't assume a random number like 10-15
Thanks for checking this out Koji
The builder in 1996 was Process System International, Inc ( Westborough, MA ) It does not exist any longer or I just could not find them. Flow diagramm at Atm1
Should I be keep looking for a company who could quote us for building a similar smaller unit with 10 - 15 cfm flowrate?
Note: my intension with the two mobile-overhead HEPA filter was the same as John Worden's " clean air overpressured tent " at chamber entrance.
Atm2, Our unit has 650 cfm, velocity 90 fpm at resistance 0.5" It may be enough to give a little overpressure if we seal it well to the chamber
We use to use them to minimize dirt getting inside the chanbers.
I've visited the purge clean air system at LHO Yarm mid-station with John Worden.
The system is described C981637. There is a schematic in C981637-06-V (Vol.6).pdf although the schematic has some differences (or uncorrected mistakes).
This system is intended to provide positive pressure when a soft cover is attached to a chamber door. When the door is open, the purging does not help to keep the chamber clean because the flow is too slow. This protection has to be done with overhead HEPA filters (22x5000cfm). It may be possible that this purge air helps the tube not to allow dusts to come in. But before using this, the chambers and the tubes have to be cleaned, according to John.
- Here at the site, the purge air system is started up a day before the vent. This system is used for the vent air, the purge air, and turbo foreline filling.
- Air intake (attachment 1): At the site, the air is intaken from the VEA. We want to incorporate somewhat clean air instead of dirty, dusty, outside air.
- Initial filter (attachment 2): a high volume filter before the compressors.
- The compressors (attachment 3, 4) are 5x 6 horse power air compressor each goes up to 160 psi. They are turned on and off depending on the demand of the air. Which is turned on is revolved by the controller to equalize the compressor usage hours.
- The compressed air goes through the air cooler (heat exchanger) to remove the heat by the compressor work.
- This air goes through prefilters and accumulated in the air receiver (100psi) (attachment 5). This receiver tank has an automated vent valve for periodical water drainage at the bottom.
- The accumulated air is discharged to twin drier towers (attachment 6, blue). The tower is operated by the controller (attachment 7) alternately with a period of 4min (or 10min by setting). When one of the towers is working, a humid air comes from the bottom and the dry air is discharged from the top. A part of the dry air goes into the other tower from the top to the bottom and dries the tower. There is a vent at the bottom to discharge water periodically.
- The dried air goes through 4 types of filters. After the last filter, all of the plumbing should be made of stainless steel to keep cleanliness.
- The air goes to the pressure reducing regulator (attachment 8, gray). The final flow speed at the chamber side is 50cfm max, according to John.
- The lower pressure air goes through the final filter (attachment 8, blue). As the pressure is low, this filter is big in order to keep the volume of the air flow.
- The purge air is supplied to the chamber side with KF50 (attachment 9). There is a vent valve (attachment 10) for safety and also to run a dry air for at least a day before the use to clean up the supply line. The purge line is disconnected when no in use.
- The entire system (attachment 11) and size comparison (attachment 12).
c1susaux (which controls watchdogs and alignments for all non-ETM optics) was down, the last BURT was done yesterday around 2PM.
I restarted via keying the crate. I restored the BURT snapshot from yesterday.
Summary: We did some preliminary tests to check if at least one of the side magnet positions is usable for the side OSEM. We mainly wanted to check how much dynamic range we lose because of the sub-optimal longitudinal positioning of the side magnet. We found that when the side magnet was mainly moving along the axis of the side OSEM (with minimal yaw motion as gauged by eye), the PD voltage bottomed out at ~80 counts (while the completely unoccluded readout was ~800 counts).
ITMY side : Magnet od 1.9 mm so wire to magnet gap ~ 0.2-0.3 mm
Steve, please look into getting some plated magnets (either SmCo or NdFeB is OK) of this size so that we can install cleaner magnets by the next vent.
(Full resolution versions of the photos in this ELOG are on picasa)
The OSEM gender changers were not in the box labelled as such, we need these to be able to use the OSEMS to see just how bad the side magnet alignment is, and to do any kind of damping for the fine pitch balancing. The hunt is on.
In the meantime, Gautam and I checked out the standoff seating, and alignment of the face OSEMS (after slightly adjusting the wire length - I guess some sagging is still happening).
With a bit of poking, we convinced ourselves that we sat the standoff in contact with the optic's barrel. Amazingly, we were able to maintain the coarse pitch balance of the optic.
We then partially inserted the face OSEMS, to check their magnet alignment. ("partially" means that the OSEM is not actually enclosing the magnet, we don't want to knock anything off) They seem ok, but not perfect. These magnets were not removed or reglued, so presumably their alignments should be unchanged.
Looks pretty great. However, there's two problems:
1) Some of the MEDM screens don't show the time. You can fix this by editing the screens and copy/paste from screens which have working screens.
2) The snapshot script seems to not grab the full MEDM screen sometimes.
These are not a very big deal, so you can get the microphones working first and we can take care of this afterwards.
The MEDM screen capture tab is now working and up on the summary pages: https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20160725/medm/
Please let me know if you have any suggestions or notice any issues.
When Koji and I were gluing magnets to ETMY, we decided to position the side magnet based on the empirically observed offsets from the standoff groove seen at other side magnet locations. Specifically, we figured that the magnet should be glued 1.25mm closer to the HR surface than the wire groove.
However, Steve has told me that he believed that this distance should be something like 0.5mm.
I used the 1.25mm figure when gluing the ETMX side magnets, which now do not align well to their OSEM mounts. While it is certainly possible that I made an error when shimming the fixture, I think it is also possible that this figure was incorrect.
Sadly, after poring through the DCC and various elogs, I have not been able to come up with a definitive answer on what this offset should actually be.
One approach is to examine the suspension tower dimensions. I.e. when subject only to gravity, the wire loop should lie in the plane of the back face of the top block of the suspension, as it is constrained by the clamps. Thus, the standoff grooves also lie in this plane. The center of the side OSEM mounting holes are about 1.64mm in front of this plane, which is larger than the 1.25mm figure that Koji and I came up with. Examining the picture Gautam posted of the marginal magnet/OSEM alignement, we see that this figure would in fact move the magnet in the wrong direction...
ELOGs in which the intitial side magnet gluing and fixture shimming are detailed do not reference the absolute position of the side magnet, nor do they include any pictures of their fixture setup. (Some links for the curious: 2652 2654 2668)
The DCC isn't much help either, as it is not clear what version of the gluing fixture we actually have. There is a drawing for a 40m specific version, but it includes swappable side-magnet-pickle-picker-slots to achieve different positions for different (circa 2001) optics; this is not the kind of fixture we currently have in our possesion. (https://dcc.ligo.org/D010131) I have discovered that some versions of this fixture (https://dcc.ligo.org/d990168) include an assumed 0.5deg wedge angle and thus position the two side slots differently. Although the fixture we have has no identifying marks on it whatsoever (naturally), I measured the two side slots to be different in axial position by roughly 0.6mm, which is consistent with a 0.5deg wedge. Furthermore, the sign of this difference indicates that this fixture ring is designed for the opposite wedge orientation than our ETMs, which have a 2.5deg wedge, making this fixture wrong by 3deg (which is ~4mm over the diameter of the optic).
We did not account for this for either ETMX or ETMY, so this is another source of error, but this does not give us much guidance on what the real absolute magnet position should be.
Today, we attempted to progress as far as we could towards getting the mirror suspended and gluing the second wire standoff. We think we have a workable setup now. At this stage, the suspension wire has been looped around the magnet, the second wire standoff has been inserted, coarse pitch balancing has been done, and we have verified that side OSEM/magnet positioning is tenable. Details below.
Attachment #3 - Unglued stand off with wire in the groove, mirror freely suspended.
Attachment #4 - Glued stand off with wire in the groove, mirror freely suspended. Clearance between wire and magnet looks reasonable.
Attachment #5 - Barrel of optic (underside), mirror freely suspended. The wire seems to be in a reasonable orientation along the barrel, albeit not perfectly parallel.
Koji just pointed out that we should check that the unglued ruby standoff is in good contact with the barrel of the optic. Attachment #1 suggests that maybe this is not the case. If you zoom into Attachment #1, it is not clear if the standoff is sitting on the glue.
Please find the new attached plots and the new script.
%temperature data outside the enclosure on channel 2
%temperature data inside the enclosure on channel 3
%sampling frequency in Hz
We have worked on the FC painting on ITMX and ITMY. We also replaced the OSEM fixing screws with the ones with a hex knob.
This was done except for the SD OSEM as the new screw was not long enough. We left an allen-key version of the screw for the SD OSEM.
All the full-resolution photos can be found on g-photo.
Attachment1: The barrel was pretty dusty. Some dusts were observed on the HR face but it was not so terrible. The barrel and the HR face were blown with the ionized N2 and then wiped with IPA. The face wiping was done n a similar way as the drag wiping.
Attachment2: FC was applied to the HR surface.
Attachment3: The AR surface was also painted with FC. The brush touched the coil holder.
Attachment4: The brush touched the coil holder. Another PEEK tab was applied to remove this FC stain on the metal holder.
Attachment5: This is the result of successful removal of the FC stain.
Attachment6: The OSEM arrangement before removal. We confirmed that the OSEM arrangement was as described on Wiki.
Attachment7/8: The ITMX was obviously a lot dirtier than ITMY. The barrel accumulated dusts.
Attachment9: This is the HR face picture with large dusts on it.
Attachment10: The HR surface was painted with FC.
Attachment11: This is the AR surface with FC painted.
The code for frequency warping contained a "printf()" command, which had caused the system to crash in one another instance (refer elog 12320) . Hence, I tried running the code tody by removing this line. Unfortunately, this did not work. the model still crashed. Attached is the screenshot of the FE status.
I have made the changes as suggested by Gautam.
One step forward, two steps back...
While attempting to suspend ETMX, I broke off a side magnet
It is now gluing
(This is *not* the one that was previously glued. I.e., now both ETMX side magnets have been reglued)
1) I have added the status summary of the DAFI block to the main FE status overview screen in the c1lsc cloumn. (attachment 1)
2) I have edited all the kissel matrix buttons appropriately, and given them appropriate lables. (attachment 2)
Summary: I have added an arbitrary math block to the DAFI model, which takes two inputs, say X and Y, and can perform various unary and binary operations on them:
Attachment 1 shows the existing DAFI gui, updated with cascading of various DSP blocks, upto three levels, button-based ENABLE and DISABLE controls for all blocks except arb. math (the control on arb. math. is achieved by clicking on the block.) On clicking the arb. math block one is taken to the dedicated arb. math screen, which has enable buttons for all the processes listed above. A screenshot of this screen is in attachment 2. There is one control input, which controls all the unary operations on X and the binary operations on X and Y, and another control input which controls the unary operations on Y. switching on a particular arb. math process gives a particular control input, which choses the appropriate section of the code. At a time, only one process from the top grey block (corresponding to unary operations on X and binary operations on X and Y) and one process from the bottom grey block (corresponding to unary operations on Y) can be selected. Thus, the outputs which go from the arb. math block to the intermediate matrices (MATRIX1L or MATRIX2L) are:
a) Either an output of unary operation on X or a binary operation on X and Y, the specific one depending upon the control input,
b) Output of a unary operation on Y, again the specific one depending upon the control input
Thus there is apparent asymmetricity in the action of the arb. math block on the two inputs. However, this is done in order to reduce to total number of outputs and control signals, and this can be easily taken care of by interchanging the inputs before the block.
While compiling this code, the c1lsc machine had crashed once, it was found that this was due to a stray "printf()" command in the c code. This glich in the code now stands rectified There is a possibility that the previous incidents of the code crashing could also be due to the existence of a printf() command.
Preliminary Testing: I have done a preliminary testing of the arb math block, i.e. verified that on enabling the sin and cos processes, the output is less that 1, on swithching on the process of weighted avarage and multiplication, the output looks like it is right, for a few simple values of A, B, C, like 0, 1, etc. The delay block however is giving zero output for delay of more than 6 samples.
Summary: There was always a constant humming noise in the output of speakers of both the audio channels. Tried to resolve the problem. Details are given below:
Details: The source of the noise was the typical 60 Hz (and harmonics), ~13 mV peak to peak output, in at least three channels of the DAC. (two coming from the DAF module, and one not related to the DAF.) Attachment 1 shows the noise in both the DAF channels. As compared to that, the signal coming through the AGC weak, about 6 mV RMS, about the same order as noise. In order to resolve this, the gain of the AGC was increased, so that the RMS output voltage of the Fibox (FBAO, the one at the output) was about 1.23 V RMS. It is approximately equal to +4 dBu, which is the typical expected output of the Fibox, according to the datasheet.
The heat drives the ants to the lab! Make sure the light doors are tight on the chambers.
I have measured the transfer function of temperature fluctuations inside the enclosure to that of the temperature fluctuations outside. The transfer function has been estimated by using 'tfestimate' which is library function in Matlab and which estimates the transfer function based on Welch's method. The attached plots shows the transfer function of the temperature inside the enclosure to that of outside temperature.
In order to determine a relation between temperature inside the enclosure to that of the outside temperature, I have calculated the mean squared coherence. I have used Matlab's 'mscohere' library function which uses Welch's method to calculate the coherence. Attached plot shows the coherence between the temperature across the enclosure.
Also, I have attached the matlab script which I used for generating these plots.
The new ETMX ruby guide rods are slightly thicker than the old aluminum ones; specifically 1.27mm vs 1.0mm.
Since we did not change the guide rod location in response to this fact, the vertical position of the suspension point changes, which in turn changes the dynamics of the suspension. Specifically, since the standoff is placed below the guide rod, the suspension point is lowered, which makes the pitch mode softer. I crunched a few numbers and have determined that this effect should not be a problem.
Given the wiki's value of the ETMX pitch resonance frequency of 0.829 Hz, I predict a the new pitch resonance frequency of 0.800 Hz.
(wiki link: https://wiki-40m.ligo.caltech.edu/Suspensions/Mechanical_Resonances)
A useful document about the dynamics of our suspension can be found at T000134
From this document, one will find that the effect of changing the suspension point height over the optic center of mass,`b`, on the pitch resonance frequency (while keeping all other dimensions equal) to be:
The top of the standoff is fixed by the guide rod, so let's say that b' is given by the position of the center of the Ruby standoff. This is then smaller than the previous b by the differences in the radii of the standoffs:
The nominal value of b is 0.985mm. Thus, the pitch resonance frequency is changed by factor of 0.965, i.e. 3.5% smaller. Then, taking the wiki value of 0.829 Hz results in 0.800Hz, a 30mHz decrease.
Cheater cable to be used in clean room pitch gluing alingment.
Satelite amp needs to be there.
Atm 2-3, The ETMs suspension damping cable are connected at the end racks. All others go to 1X5
Atm 4-5, The other end of this cable in the high cable tray at 1X3 as shown. We'll disconnect the shorty and move the end to ETMX ( or any sus at 1X5 )
RGA background scan
Vacuum Status: Chamber Open
All chamber annuloses are vented. Vac Monitor screen is not communicating with gauges. The valve position indicator are working.
RGA is pumped by Maglev through VM2
The epoxy arrived. Eric managed to remove the excess glue below the guiderod with a razor blade (see attachment 1). The magnet and dumbell that came apart were reglued successfully and passed the stregth test of picking up the magnet from the table by the dumbell, so the magnet was glued back on the optic and is setting in the gluing apparatus (see attachment 2).
We double checked the polarity against the side magnets on ETMY. Because of the gluing position strategy (a fixed distance toward the HR side from the groove location), the other side magnet appears slightly below the center of the gluing barrel, which after some discussion with Koji was determined to be ok.
I set up a simple HEPA filter dryer to dry your clean room garment before you can put it away into your storage box.
Our lab is dusty ! This is specially important when we are vented. Please wipe things daily and cover item with foils .... etc.
Our new graduate student Lydia received 40m specific safety training.
We moved ITMY from its original position to a place near the access point. We took the OSEMs off first, and noticed that the short flat head screw driver was still a little too long to properly reach the set screws for the lower OSEMs. We were able to gradually loosen them, though and thus remove the lower OSEMs as well. We had to move a cable tower out of the way, but used clamps to mark its position. After making sure the optic is held by its earthquake stops, we moved it to its cleaning location. All magnets are still attached.
c1lsc FE is up and running.
2) The machine was manually rebooted.
3) c1daf was recompiled and installed, with the problematic piece of code removed.
4) NTP timing was adjusted.
5) Frame Builder was restarted.
6) All models on c1lsc machine were restarted.
Attachment 1 shows the CDS status after the recovery. I wont be trying to run frequency warping immediately, I will first finish implementing the other harmless modules first.
I took off the silicon rubber heaters which were used by a SURF last year for heating the enclosure. The heater data sheet has mentioned the power dentsities, but I doubted the values. So I wanted to measure the actual power density by these heaters. I think the rubber heaters are broken somewhere within, the surface is not heated evenly. Although I don't have a good quantative reason to use, I was thinking to use a thermoelectric cooling module for the enclosure.
From the data I collected few days back, I am trying to obtain a transfer function of temperature inside the enclosure to that of outside. My aim is to measure the pole frequency of temperature fluctuations inside the enclosure relative to the outside fluctuations.