During the cleaning today, we found many legacy lab items. Here are some policies what should be kept / what should be disposed
sudo yum install grace
Once again, I found the door to the outside in the control room open when I came in ~1215pm. I closed it.
I moved the N2 check script and the disk usage checking script from the (sudo) crontab of nodus to the controls user crontab on megatron .
2 Mon - 5 Thu WFS work (Nancy)
2 Mon - 4 Wed
Jenne: Seismometer fix / Seismic measurements on the PSL table
TT characterization (with Koji)
Preparations ETM suspensions (optional: may be in later weeks)
Kiwamu: CDS test for SUS (may be involving Koji)
Alberto: RF system prep.
All: For 5th and 6th: PSL cabling works Koji
5 Thu PSL Table prep
6 Fri PSL Table prep / Likely to shut down the PSL
9 Mon PSL Table prep / shutting down of the PSL (optional)
10 Tue PSL box Frame lifting
12 Thu PSL table tapping
16 Mon - 17 Tue concrete pouring preparation
19 Thu - 23 Fri Tripod placement
24 Tue - 26 Thu concrete pouring
I have analyzed the temperature data that we have collected for the past 10 days or so from the X-end temperature sensor that is accessible via Acromag.
The average temperature was 20.74 Celsius, noticeably cooler than the average 24 Celsius in the control room. The day-night temperature variations are clearly visible.
And here is the power spectrum density of these variations:
The red line indicates the frequency of the day-night cycle (1/24hrs), while the green line indicates twice the frequency of the day-night cycle. We can see that the two lines align fairly well with the peaks, which is to be expected. Here I used n_avg=3 in Paco's spec_dens() function, but I am not sure this is the right value to use. Please let me know if you have suggestions in this regard.
As for the noise estimates of the detector used to collected these data, I am not sure how to get those. The above temperature data was collected using a detector that no one knows where exactly it is in the lab, and I don't even know what type of sensor it is. Perhaps there is a way to get a noise estimate from the data that I collected? Again, please let me know.
However, we have a rough estimate for the noise of the AD590 sensor made by Kira that we calibrated and used for the step response test. We estimated this by calculating the standard deviation of the signal measured from the 0 C ice bath. This translates to 0.0134 C. We will probably repeat this measurement in a better way (once we build our own version of the sensor) because the duration of the actual 0 C measurement was just around 2 minutes.
On Wednesday, Rana showed me that there are two AD590 sensors in the PSL/FSS refcav. It seems that one of the sensors is inside a box which is insulated with foam, while the other sensor is just outside the foam. It is likely that even the sensor outside the foam is not reading the environment temperature, but the difference between the two sensors gives us a good idea of the effects of the foam. Here are the plots:
As you can see, RCTEMP seems to have higher variations than RMTEMP. There is also an offset, probably due to the heat disippated by the hardware inside the box. In the freuquency domain:
where we can clearly see that there is a big difference in intensity at frequencies higher than 0.01 Hz. Moreover, RMTEMP (which is indside the box) has the lower intensity, thus showing that the foam is a low-pass filter. The same story can be seen in the coherence plot:
I have since wanted to hopefully use RCTEMP's readings to make a frequency spectrum like the one I made before using the server temperature sensor. However, I am still struggling to download the data from the channel for periods larger than a few hours. I would need data for at least 5 days in order to capture the very low end like 1/24hr.
It is feeling cold in the office area. According to the digital wall clock near the coffee machine, it is 19C. Rana bumped the thermostat setpoint up by 2F (from 75F to 77F). We need to setup long-term monitoring.
I was in the lab from 1630-1830. I have located and visually inspected all the parts required for the magnet regluing / optic cleaning parts of the planned vent, except the fresh batches of scpectroscopic grade solvents. I was in the cleanroom part of the clean and bake lab from 1630-1700.
Koji and I had a walkthrough of the Y Arm and raised questions of what accommodations we can make for the lab.
· The HP3563A Control System Analyzer - is this needed in the lab ? Has anyone used this ?
· We have the black instrument rack the is behind 1X2 Rack. We can move this by Section Y8 of the beam tube, where the step ladders are stored currently.
· We will remove the bulky cart from the lab space. This has been used consistently to store items on and forget about. It is better to not have it at all.
· The small optical breadboard which is along Y-Arm should be prepared for usage. Cardboard boxes under the table will be searched through and put into a google sheet.
· Save the 1U cases from the modules that are by section Y10.
· Cleanroom garments and wardrobes should be moved by the dress area along Y arm.
·Issue : We are currently using 3 cabinets along the Y arm for Cleanroom apparel.
·There are HEPA Filter replacements under section Y11. We should swap these out with the mobile HEPA Booth because these filters have been in air and most likely aren’t as clean as they should be anymore. This will be done before our next vent.
· Koji and I agreed that 6ft x 4ft is a good Length and Width for the cleanroom that is being assembled. This will give us ~1 ft of clearance on 3 sides of the table.
These weren't present last week. The peaks are present in the EX PDH error monitor signal, and so are presumably connected with the green locking system. My goal tonight was to see if the arm length control could be done using the ALS error signal as opposed to POX, but I was not successful.
I looked into this issue today. Initially, my thinking was that I'd somehow caused clipping in the beampath somewhere which was causing this 2kHz excitation. However, on looking at the spectrum of the in-loop error signal today (Attachment #1), I found no evidence of the peak anymore!
Since the vacuum system is in a non-nominal state, and also because my IR ALS beat setup has been hijacked for the MZ interferometer, I don't have an ALS spectrum, but the next step is to try single arm locking using the ALS error signal. To investigate whether the 2kHz peak is a time-dependent feature, I left the EX green locked to the arm (with the SLOW temperature offloading servo ON), hopefully it stays locked overnight...
EX green stayed locked to XARM length overnight without a problem. The spectrogram doesn't show any alarming time varying features around 2 kHz (or at any other frequency).
I sketched up the first encounter we will have when moving the optical table out. I'm assuming the table has already been turned onto its side. Next will be manuevering the table into the aisle along X-Arm. Solidworks' "Move Component" feature always me to move the table and see collisions. The feature stops the component from dragging and highlights the two faces which have made contact. I have not yet gotten to take the dimensions of the MC2 chamber and table, this will bethe tightest spot, so I want to get precise measurements. Though, it looks like we wont have any issues getting the table into the aisle. Atachment #1 is a top view that shows we have clearence, ~5 -7.5 in on both sides, and attachment #2 is a sectional view to show a clear pathway for pulling the table into the aisle.
Object that are Red are computer racks and Wood are walls.
Larisa Thorne received 40m lab specific, basic safety training. She will attend P. King's Basic Laser Safety Training Session tomorrow.
Larry stopped by today and had to disconnect the m25 machine (this is the 1st GC machine on the left as you walk into the control room) because its IP was conflicting with a machine over in Downs. Do not use 22.214.171.124 as the IP on this machine as this is already assigned to someone else. They couldn't figure out the root password to change it which is why it is not currently plugged into the network, and is not to be until an appropriate IP is assigned.
They've asked that whoever set the machine up to please contact them (extension 2974).
I accidently shut off the laser at 19:34 with the emergency shutoff button while trying to tap into a video line for the Sensoray device.
We reset the interlock and restarted the PSL. The end AUX lasers seem to have come back online fine. PMC and mode cleaner locked back up quickly.
I've plotted some transfer functions showing the response at POB DC to laser frequency (phase) noise. There are transfer functions for multiple CARM offsets. Basically, the transfer function looks like the DARM transfer function when the CARM is at zero offset, and is super-wonky elsewhere. POB-DC is not a good CARM signal for intermediate stages of lock acquisition in a dual-recycled interferometer. We should look into switching back to REFL-DC.
Here are the corresponding transfer functions for REFL-DC.
I hereby award the previous rainbow transfer functions the plot innovation of the month award for its use of optical frequency to denote CARM offset.
The attached movie here shows the sensing matrix (minus MICH) as a function of CARM offset. There are 3 CARM signals plotted:
GREEN - tonights starting CARM signal - REFL_DC
RED - my favorite CARM signal - REFL 166 I
CYAN - runner up CARM signal - POX 33 I
The laser power seems to have become more stable after fixing the laser chiller. The power is lower than it used to be (MOPA amplitude 2.5 versus 2.7) but, as shown in the attchement, it became more steady.
We unpacked the content of the amplifier crate in front of the water fountain (see attachments). Inside we found:
1. Amplifier head. (attachment 1)
2. Amplifier electronics and pump diodes (attachment 2).
3. Optical fiber (attachment 3).
4. 2 Long water hoses (~2m) and 2 short ones.
5. Network cable.
6. A wooden plate.
7. Cable sleeve (attachment 2)?
8. Some manuals will be uploaded to the wiki soon.
Please don't move/touch any of that stuff
Things that we need to consider/obtain:
1. A suitable power cable (attachment 4) with suitable power ratings (800W according to the amplifier specs). The connector head is C19 I believe.
2. A chiller. Rana says Aidan knows where to find one. Should we chill the amplifier head as well?
3. A mounting plate for the amplifier head with good thermal conductivity.
4. The pump wavelength is 808nm, we need to get suitable safety goggles.
5. Where to put the big electronics box. Preferably on 1X1 or 1X2.
6. How do we arrange the different components on the table? We also need to mode match the beam into the amplifier.
A couple of years ago, I got some info about the amplifier setup at the sites from Terra - sharing here in case there is some useful info in there (our setup will be rather different, but it looked to me like our Amp is a 2017 vintage and it may be that the performance is not the same as reported in the 2019 paper).
collection of docs (table layout in 'Proposed....setup') : https://dcc.ligo.org/LIGO-T1700046
LVC 70W presentation: https://dcc.ligo.org/LIGO-G1800538
I guess we should double check that the beam size everywhere (in vacuum and on the PSL table) is such that we don't exceed any damage thresholds for the mirrors used.
Some more relevant documents provided by Matt:
Phase III:70W amplifier integration at LIGO
70W amplifier External Shutter
aLIGO PSL high power attenuator
I surveyed a bit the 1X1/2 area to plan for the installation of the laser amplifier.
There is a vacancy at the bottom of 1X2 (attachment 1). I measured the dimensions of the diode box (DB) and it should fit. The optical fiber bundle is 75m long and should reach the amplifier head on the table easily.
According to the specs, the maximum power consumption of the DB is 800W (typically 600W), it should probably have its own circuit breaker. It can easily draw more than a few amps. The rack power strips are connected to this 4 socket box (attachment 2), is this just another power strip? It is connected to a circuit breaker with a 30A rating. How do we proceed from here?
In any case, we will need at least 2 meters of power cable.
I also tried to find a suitable place for a water chiller. A few suggestions are in the attachments. Basically either between the electronics shelves and the small rack next to 1X2 or next to the small rack close to the optical table. Maybe put it where the ladder sits and find another place for the ladder. Other options?
We would also need a windows machine running the Beckhoff software. The idea is that all the different laser components (DB, chillers, interlocks, switches) are connected to the EtherCat (over the ethernet infrastructure) so that the Beckhoff code can recognize a failure and switch off everything.
The things that are monitored:
1. Is the NPRO on?
2. Is the flow rate from the chillers enough?
3. Is the temperature of the diodes in the normal range?
4. Is one of the interlocks open?
5. Was one of the emergency buttons pushed?
6. Was the key switch on the DB turned to OFF?
The DB is EtherCat ready but the rest of the signals need to be interfaced somehow. Do we have to buy these EtherCAT terminals?
I went to the TCS lab to take a look at the chillers lying around. I spotted two chillers:
1. Thermoflex1400 (attachment 1,2). Spec sheet.
2. Polyscience Recirculator 6000 series (attachment 3,4). Manual.
The Thermoflex has various communication ports. The Recirculator doesn't have any communication ports, but it is connected to a flow meter with what seems to be an electronic readout (attachment 5). Manual.
Both chillers have similar capacity ~ 4 gallons/minute. Thermoflex has 2 times more reservoir capacity than the Recirculator.
None of them seem to be Bechkoff-ready.
I guess we can have interlock code handling mixed signals Beckhoff+Non beckhoffs?
According to the aLIGO 70W amplifier interlock concept the flow rate of the chiller should be between 5 and 40 l/min. The chillers I found in the TCS lab both have around 15 l/min flow rate so we should be fine in that regard.
Assuming that the power consumption of the diode box is ~800W and that the optical output power of the diode is ~ 300W of optical power, the chillers need to be able to remove the remaining power. At room temperature, they both have enough cooling capacity according to their specs.
As for the idea to put the chiller and diode box in the drill room: There are not a lot of options here. The only viable place is the SW corner (attachment 1). I was told this place is used sometimes for liquid nitrogen dewar. Alternatively, if possible, we can move the fire extinguishers to the SW corner and use the NW corner. In that way, we don't have to clear all the junk from the SW corner, as long as the extinguishers are still accessible.
I made a sketch (attachment 2) showing a possible setup for a diode box + chiller rack. The fiber and network cable can go through the hole in the wall that already exists for the N2. It will have to get bigger though (attachment 3). The rack would also need to host some Acromag unit to convert the communication channel of the chiller/flow meter to Ethernet. The Acromag on 1X7 has no spare channels.
The only power socket in the room, to which the drill is connected, is circuit #36 which is connected to panel L in the lab. The breaker's ampacity seems to be 20A if I'm reading the number on the breaker correctly.
Since the laser is off, Jenne and I rasied the chiller-chiller (small AC in the Control Room) set point temperature to 73 degree F (from 68F) to save people from shivering.
I tried measuring the coupling of PSL intensity noise by driving some broadband noise bandpassed between 80-300Hz using the spare DAC channel at 1Y3 that I had set up for this purpose a couple of weeks ago (via a battery powered SR560 buffer set to low-noise operation mode because I'm not sure if the DAC output can drive a ~20m long cable). I was monitoring the MC2 TRANS QPD Sum channel spectrum while driving this broadband noise - the "nominal" spectrum isn't very clean, there are a bunch of notches from a 60Hz comb and a forest of peaks over a broad hump from 300Hz-1kHz (see Attachment #1).
I was able to increase the drive to the AOM till the RIN in the band being driven increased by ~10x, and saw no change in the MICH error signal spectrum [see Attachment #1] - during this measurement, the RFPD whitening was turned on for REFL11, REFL55 and AS55, and the ITM coil drivers were de-whitened, so as to get a MICH spectrum that is about as "low-noise" as I've gotten it so far.
I tried increasing the drive further, but at this point, started seeing frequent MC locklosses - I'm not convinced this is entirely correlated to my AOM activities, so I will try some more, but at the very least, this places an upper bound on the coupling from intensity noise to MICH.
GV Oct 6: This coupling is probably not correct - Finesse outputs TF magnitude in units of W/W, and not W/RIN.
Since I was foiled (by lack of DAC) in my attempt to measure the coupling of laser intensity noise to MICH in the DRMI (no arms) configuration, I decided to try understanding the effect with a simulation.
For this purpose, I used my DRMI Finesse model - this had mirror positions tuned for locking and photodiode demod phases tuned to give a sensing matrix model that wasn't too far from an actual measurement (within factor of a few). So the model seems okay for a first pass at estimating this coupling.
Measuring transfer functions in Finesse is straightforward - use the fsig command to modulate some quantity (in this case the input beam intensity), and use the pd2 detector to demodulate the effect of this modulation at the port of interest (in this case AS55_Q).
**Note that to apply a modulation to an input beam (i.e. Laser) in Finesse, the keyword for the "type" argument given to fsig is "amp" and not "amplitude" as the manual would had me believe. In fact, there seem to be quite a few such caveats. The best way to figure this out is to go to the pykat installation directory, find the file components.py, and look for the fsig_name for the component of interest. It is also indicated in the same file, via the canFsig argument, if that property of the component can be modulated for transfer function measurements.
Attachment #1 shows the result of such a sweep.
To estimate what the actual contribution to the displacement noise is, I used the DQ-ed MC transmission (recorded at 1024Hz) from the DRMI lock, computed the ASD using scipy.signal.welch, divided by the nominal MC transmission of ~15,000 counts to convert to RIN/rtHz. The RIN was then multiplied by the above calculated coupling function, and divided by the sensing matrix element for AS55_Q (in units of W/m) to give the curve shown in Attachment #2. If we believe the simulation, then Laser Intensity Noise shouldn't be the limiting noise between 10Hz-1kHz.
I will of course measure the actual coupling and see how it lines up with Attachment #1 - would be a nice additional validation of the Finesse model. I will also try using the Finesse model to estimate some other coupling transfer functions (e.g. Laser Frequency Noise, Oscillator Noise).
The absence of evidence is not evidence of absence.
I've checked the state of the laser interlock switch and everything looked normal.
It's may be the janitor's doing.
I noticed that the HEPA filers were off. They are turned on at 20%
The 2W Innolight was turned on.
I have just turned on the PSL Innolight laser. The laser shut down with unknown reason a day ago.
I wanted to make sure Alex's system of Diode laser + laser controller + optical splitter was working fine and then make a manual measurement for AS55 PD. Manasa was supervising my work and helping me with unhooking the fibers and taking power meter readings. I have tuned on the power to REF DET from under the POY table.
I switched on the laser sitting in the 1Y1 rack and turned up the driving current to 240mA. On checking the laser power readings at AS55 (AS table) and REF DET (POY table) simultaneously, we got readings of 1.6mA and 2.4mA respectively. This much difference in readings was not expected and I did not continue taking the readings for transimpedence measurement.
I will rectify if this unequal splitting of power by the 1x16 optical splitter is going to cause any difficulties for the automated PDFR system measurement technique and resolve it if needed.
Summary of work done over the last two days
Immediate next steps: