We are ready to put the heavy doors back on the chambers and do some test pumpdowns tomorrow morning if Jon gives us the go-ahead. Also, Koji made the OMC resonate some of the AUX beam light we send into it
I did the following:
I think this completes the pre-pumpdown alignment checks we usually do. The detailed plan for tomorrow is here: please have a look and lmk if I missed something.
IFO P1=1mT PSL shutter is opened
The pumpdown has started at 8:38am
Manasa was here to confirm good alignment of the IFO
Inner jam nuts of AC bellow were torqued to 45 ft/lbs and door nuts were check on opened chambers.
Annulos were roughed down to 500 mTorr
Oplev servos turned off, PSL and green shutters closed before pumpdown started
The vacuum system went down over the weekend due to a loss of N2 pressure (We are down to our last tank of N2). I have brought the vacuum system back up to nominal state.
I first changed the N2 cylinder and to suopply the valves. WITHOUT N2, THE VALVES WILL NOT OPEN. Normal operation PSI for N2 is ~65-80 PSI, view this from C1:VAC-N2_pressure. After swapping out the tanks I proceeded to pump down the vacuum with a simple procedure,
- First, opened V4 and V5
- Open VASE, VASV, VABSSCI, VABSSCO, VAEV, VAEE
- Open VA6
- Open V1 to pump down the main volume.
All the turbopumps are running at nominal speed and we are pumping down nicely.
Cold cathode gauge CC1 -h (horizontal) just coming on 9.2e-5 Torr
P2 is the fore line pressure of the maglev. One can see the 4 Torr load during switching over to turbo pumping.
CC4 5e-9 Torr is the performance of the maglev pumping on the RGA only.
The annuloses are not pumped now. They are closed off to see how much outgassing plus leak they have.
Configuration: vacuum normal, annuloses not pumped
Precondition: 14 days at atm, IOO chamber north door was taken off as a new entrance, the ETMX chamber was not opened.
What is new in the vacuum system: new P1 pirani gauge, gold plated clean allen wrench and ..........what else was dropped?
Note: the wireless laptop did not fail once all day yesterday. I want to give credit to the person who is responsible for this.
[chub, bob, gautam]
[jon, koji, gautam]
I'm leaving all suspension watchdogs tripped over the weekend as part of the suspension diagonalization campaign...
Pumping again after 7 days at atmosphere.
BS, ITMY and OMC chambers were open only.
Checked: jam nuts, viewport covers and beam shutters.
Oplev servo turned off and medm screens shots taken.
New item in vacuum: green shade 14 glass beam block at IR-input [ from the PSL ] viewport to block green reflection-scatter.
Reminder: viewport is not AR coated for green!
IFO pressure 1.7E-4 Torr on new not logged cold cathode gauge. P1 <7E-4 Torr
Valve configuration: vac.normal with anunulossess closed off.
TP3 was turned off with a failing drypump. It will be replaced tomorrow.
[koji, rana, gautam]
1100 - EY chamber inspected, no issues were found --> EY heavy door on
1200 - OMC chamber was inspected. OM6 was marginally tweaked to bring the beam down a little in pitch, and also a little northwards in Yaw. --> Heavy door on.
1230 - Pumpdown started. Initially, the annuli volume was pumped down. The procedure calls for doing this with the small turbopumps. However, V7 was left open, and hence, in the process, the TP1 foreline pressure (=P2) hit ~30 torr. This caused TP1 to shutdown. We were able to restart it without issue. This case was not caught by the interlock code, which was running at the time. It should be recitified.
1330 - OMC breadboard clean optics and DCPD hardware were wrapped up and packed into tupperware boxes and stored along the south arm. OMC cavity itself, the OMMT, and the breadboard the OMC was sitting on are wrapped in foil/Ameristat and stored in cabinet S13, lower 2 shelves.
1915 - P1a = 0.5 torr pressure reached. Switched over to pumping the main volume with TP1, backed by TP2 and TP3, which themselves are backed by their respective dry pumps and also the AUX drypump for some extra oomph. All cooling fans available in the area were turned on and directed at the turbo pumps. RV2 was used to throttle the flow suitably.
It was at this point that we hit a snag - RV2 has gotten stuck in a partially open position, see Attachment #1. We can see that the thread doesn't move in response to turning the rotary dial. Fortunately, the valve is partially open, so the main volume continues to be pumped - see Attachment #2 for the full history of today's pumping. We are leaving the main volume pumped in this configuration overnight (TP1 pumping main volume backed by TPs 2 and 3, which are in turn backed by their respective drypumps and also the AUX dry pump). I think there is little to no risk of any damage to the turbo pumps, the interlocks should catch any anomalies. The roughing pumps RP1 and RP3 were turned off and that line was disconnected and capped.
What are our options?
We need some vacuum experts to comment. Why did this happen? Is this an acceptable failure mode of the valve?
2230 - P1a = 0.025 torr. The pressure is coming down with log-linear scale. x0.1 per 2.5 hours or so.
Main volume pressure as of 11:30AM 2020/11/10
Jamie and Steve
We closed ITMX and ITMY chambers and started pumping around 11am
What we did before:
1, turned off AC power to PZT Jena HV ps
2, checked jam nut positions
3, cheched single o-ring shims
4, closed psl out shutter
We missed to check that we had the green transmitted to the PSL after flipping the SRC and PRC folding mirrors.
There is no green transmission reaching the PSL even after locking the arms to green.
We should fix this tomorrow. The BS heavy door should come off.
Steve! Do not start pump down tomorrow !
This plot shows the trend of the OL during the past several hours of roughing pumping.
The big steps at the start of the pump down is NOT due to the pumping, but is instead the "recentering" that Yuta did. Looks like he was unable to find zero on the ETMY.
Some of the rest of the drift is probably just the usual diurnal variation, but there does seem to be some relation to the pumping trend. I guess that the shift of ~0.3 in the ITMX and ITMY pitch is real and pressure related.
We need to figure out how to put the OL calibration factor into the SUS-OL screens.
I've been plugging away at Altium prototyping the high-voltage bias idea, this is meant to be a progress update.
I need to get footprints for some of the more uncommon parts (e.g. PA95) from Rich before actually laying this out on a PCB, but in the meantime, I'd like feedback on (but not restricted to) the following:
I also don't have a good idea of what the PCB layer structure (2 layers? 3 layers? or more?) should be for this kind of circuit, I'll try and get some input from Rich.
*Updated with current noise (Attachment #2) at the output for this topology of series resistance of 25 kohm in this path. Modeling was done (in LTspice) with a noiseless 25kohm resistor, and then I included the Johnson noise contribution of the 25k in quadrature. For this choice, we are below 1pA/rtHz from this path in the band we care about. I've also tried to estimate (Attachment #3) the contribution due to (assumed flat in ASD) ripple in the HV power supply (i.e. voltage rails of the PA95) to the output current noise, seems totally negligible for any reasonable power supply spec I've seen, switching or linear.
Tonight I built a simpler version of what will be the new general-purpose precision temperature controller. This one is built on a breadboard and will be used for RFAM testing at the 40m until a better version is made. Some differences between this version and the final one:
So, how it works:
I have tested the circuit using a spare resistive heater and a potentiometer to simulate the RTD. First I tested the sensing and drive circuits separately, then I connected the sensor output to the drive input and modulated the potentiometer resistance while monitoring the current. The circuit behaved as expected.
When I got to the 40m, it struck me that the resistance I had chosen (115 ohms) corresponded to 40 C, which I realized might be above what we could reach with the current we can provide. I used the Newport 6000 via telnet to drive the heater at several current values and see what the resistance became. I found that with I = Imax/2 ~ 0.6, the resistance was around 113 ohms (it was ~111 at room temp). So, I switched the reference resistor in the leg above the PT100 from 115 -> 113.
I then plugged everything in while monitoring the heater current and AD620 output (error signal), and it seemed not to do anything. I was tired so I figured I'd leave it for tomorrow.
Here is a sketch of the schematic, as well as some pictures:
A prototype freq divider has been made which works up to ~40MHz.
74HC4060 (14bit binary ripple counter) divides the freq of the input signal, which is comverted by the comparator LT1016
into the rectangular signal. The division rate is 2^14.
Attachment1: Circuit diagram
Attachment2: Photo, the prototype bread board
Attachment3: Photo, the spectrum of the freq divided output. The 40MHz input has been divided into 2.4k.
There are the 3rd and 5th harmonics seen. The peak was pretty sharp but the phase noise was not evaluated yet.
The circuit was made on the prototype bread board which is apparently unsuitable for RF purposes.
Indeed, it was surprising to see its working up to 40MHz...
In order to increase the maximum freq of the system we need the following considerations
I have implemented a proto-ASC in the ASS model.
In an ASC block within the ASS model, I take in the POP QPD yaw, pit, and sum signals. I ground the sum, since I don't have normalization yet (also, the QPD that we're using normalizes in the readout box already). The pit and yaw signals each go through a filter bank, and then leave the sub-block so I can send the signals over to the SUS model, to push on PRM ASCPIT and ASCYAW.
In doing this, I have removed the temporary PRM ASCYAW connection that Koji had made from the secret 11'th row of the LSC output matrix (see Koji's elog 8562 for details from when he implemented this stuff).
LSC, SUS and ASS were recompiled, and restarted. I also restarted the daqd on the fb.
I am working on making the Proto-ASC less "proto". I have put IPC senders in the LSC model to send the cavity trigger signals over to the ASS model, for ASC use. I'm partially done working on the ASC end of things to implement triggering.
LSC should be compile-able right now, ASS is definitely not. But, I expect that no one should need to compile either before I get back in a few hours. If you do - call me and we'll figure out a plan.
I have finished my work on the LSC and ASS models for now. The triggering is all implemented, and should be ready to go. There are no screens yet.
I have *not* compiled either the LSC or the ASS, since Rana and Manasa still have the IFO.
The proto-ASC now includes triggering. I have updated the hacky temp ASC screen to show the DoF triggering. I have to go, but when I get back, I'll also expose the filter module triggering. So, for now we may still need the up/down scripts, but at least the ASC will turn itself off if there is a lockloss.
Today I implemented protection of the vac system against extended power losses. Previously, the vac controls system (both old and new) could not communicate with the APC Smart-UPS 2200 providing backup power. This was not an issue for short glitches, but for extended outages the system had no way of knowing it was running on dwindling reserve power. An intelligent system should sense the outage and put the IFO into a controlled shutdown, before the batteries are fully drained.
What enabled this was a workaround Gautam and I found for communicating with the UPS serially. Although the UPS has a serial port, neither the connector pinout nor the low-level command protocol are released by APC. The only official way to communicate with the UPS is through their high-level PowerChute software. However, we did find "unofficial" documentation of APC's protocol. Using this information, I was able to interface the the UPS to the IOLAN serial device server. This allowed the UPS status to be queried using the same Python/TCP sockets model as all the other serial devices (gauges, pumps, etc.). I created a new service called "serial_UPS.service" to persistently run this Python process like the others. I added a new EPICS channel "C1:Vac-UPS_status" which is updated by this process.
With all this in place, I added new logic to the interlock.py code which closes all valves and stops all pumps in the event of a power failure. To be conservative, this interlock is also tripped when the communications link with the UPS is disconnected (i.e., when the power state becomes unknown). I tested the new conditions against both communication failure (by disconnecting the serial cable) and power failure (by pressing the "Test" button on the UPS front panel). This protects TP2 and TP3. However, I discovered that TP1---the pump that might be most damaged by a sudden power failure---is not on the UPS. It's plugged directly into a 240V outlet along the wall. This is because the current UPS doesn't have any 240V sockets. I'd recommend we get one that can handle all the turbo pumps.
Pin 1: RxD
Pin 2: TxD
Pin 5: GND
Baud rate: 2400
Data bits: 8
Stop bits: 1
agreed - we need all pumps on UPS for their safety and also so that we can spin them down safely. Can you and Chub please find a suitable UPS?
However, I discovered that TP1---the pump that might be most damaged by a sudden power failure---is not on the UPS. It's plugged directly into a 240V outlet along the wall. This is because the current UPS doesn't have any 240V sockets. I'd recommend we get one that can handle all the turbo pumps.
The controls (fast and slow both) think ITMX is ITMY and ITMY is ITMX.
After some poking around today, I have convinced myself it is sufficient to simply swap all instances of ITMX for ITMY in the C1_SUS-AUX1_ITMX.db file, and then rename it to C1_SUS-AUX1_ITMY.db (after having moved the original C1_SUS-AUX1_ITMY.db to a temporary holding file).
A similar process is then applied to the original C1_SUS-AUX1_ITMY.db file. These files live in /cvs/cds/caltech/target/c1susaux. This will fix all the slow controls.
To fix the fast controls, we'll modify the c1sus.mdl file located in /opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/ so that the ITMX suspension name is changed to ITMY and vice versa. We'll also need to clean up some of the labeling
At Kiwamu and Bryan's request, this will either be done tomorrow morning or on Monday.
So the steps in order are:
1) cd /cvs/cds/caltech/target/c1susaux
2) mv C1_SUS-AUX1_ITMX.db C1_SUS-AUX1_ITMX.db.20110408
3) mv C1_SUS-AUX1_ITMY.db C1_SUS-AUX1_ITMY.db.20110408
4) sed 's/ITMX/ITMY/g' C1_SUS-AUX1_ITMX.db.20110408 > C1_SUS-AUX1_ITMY.db
5) sed 's/ITMY/ITMX/g' C1_SUS-AUX1_ITMY.db.20110408 > C1_SUS-AUX1_ITMX.db
8) Modify c1sus model to swap ITMX and ITMY names while preserving wiring from ADCs/DACs/BO to and from those blocks.
9) code; make c1sus; make install-c1sus
10) Disable all watchdogs
11) Restart the c1susaux computer and the c1sus computer
Here' s aquick update before we leave for lunch. We have managed to calculate some filter that would go on the POS column in MC2 output matrix filter banks aka F2A aka F2P filters. In the afternoon if we can come and work on the IMC, we'll try to load them on the output matrix. We have never done that so it might take some time for us to understand on how to do that. Attached is the bode plot for these proposed filters. Let us know if you have any comments.
Motivation: I want to make another measurement of the out-of-loop ALS beat noise, with improved MM into both the PSL and EX fibers and also better polarization control. For this, I want to make a few changes at the EX table.
Barring objections, I will start working on these changes later today.
I started working on the EX table. Work is ongoing so I will finish this up later in the evening, but in case anyone is wondering why there is no green light...
To do in the eve:
gautam 1245am: Fiber cleaning was done - I'll upload pics tomorrow, but it seems like the fiber was in need of a good cleaning. I did some initial mode-matching attempts, but peaked at 10% MM. Koji suggested not going for the final precisely tunable lens mounting solution while trying to perfect the MM. So I'll use easier to move mounts for the initial tuning and then swap out the DT12s once I have achieved good MM. Note that without any attenuation optics in place, 24.81mW of power is incident on the collimator. In order to facilitate easy debugging, I have connected the spare fiber from PSL to EX at the PSL table to the main EX fiber - this allows me to continuously monitor the power coupled into the fiber at the EX table while I tweak lens positions and alignment. After a bit of struggle, I noticed I had neglected a f=150mm lens in my earlier calculation - I've now included it again, and happily, there seems to be a solution which yields the theoretical 100% MM efficiency. I'll work on implementing this tomorrow..
I am currently working on an optical arrangement consisting of a QPD that measures the fluctuations of an incoming HeNe laser beam that is reflected by a mirror. The goal is to add a second QPD to the optical arrangement to form a linear combination that effectively cancels out the (angular) fluctuations from the laser beam itself so that we can only focus on the fluctuations produced by the mirror.
In order to solve this problem, I have written a program for calculating the different contributions of the fluctuations of the HeNe laser and fluctuations from the mirror, for each QPD (program script attached). The goal of the program is to find the optimal combination of L0, L1, L2, and f2 that cancels the fluctuations from the laser beam (while retaining solely the fluctuations from the mirror) when adding the fluctuations of QPD 1 and QPD 2 together.
By running this program for different combinations of distances and focal lengths, I have found that the following values should work to cancel out the effects of the oscillations from the HeNe laser beam (assuming a focal length of 0.2 m for the lens in front of the original QPD):
L0 = 1.0000 m (distance from laser tube to mirror)
L1 = 0.8510 m (distance from mirror to lens in front of QPD 1)
L2 = 0.9319 m (distance from beamsplitter to lens in front of QPD 2)
f2 = 0.3011 m (focal length of lens in front of QPD 2)
Based on these calculations, I propose to try the following lens for QPD 2:
1’’ UV Fused Silica Plano-Convex Lens, AR-Coated: 350 - 700 nm (focal length 0.3011 m). https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=6508
I have mounted 2 2" G&H high reflective mirrors, to be used in the new POP path. Manasa and Annalisa are doing green things on their respective arms, so I will hopefully be able to install the new POP path after dinner tonight.
Here are photos of the current POP path, and my proposed POP layout. In the proposed layout, the optical components whose labels are shaded are the ones which will change.
Attachment #1 is a sketch of the proposed setup to measure the PM response of the EX NPRO. Previously, this measurement was done via PLL. In this approach, we will need to calibrate the DFD output into units of phase, in order to calibrate the transfer function measurement into rad/V. The idea is to repeat the same measurement technique used for the AM - take ~50 1 average measurements with the AG4395, and look at the statistics.
Some more notes:
After familiarizing myself with Altium, I drew up the attached schematic for the ISS to be used in the CTN experiment. The filename includes 'abbott-switch' as I am using an Altium component (the switch, in particular), that he created. The MAX333A actually has 20 pins on a single component, but the distributed component that he created is useful for drawing uncluttered schematics. I won't be using all of the pins on this switch, but for completeness, I have included the 3rd and 4th portion of the full component in the upper right hand corner.
Currently, the schematic includes the voltage reference (AD586), a LP filter for the reference signal, the differential amplifier stage to obtain the error signal and then finally all of the filter stages. The schematic does not include the RMS detection and subsequent triggering of each filter stage. The TRIGGER 1 signal is a user input (essentially the on button) while the TRIGGER 2 signal will flip the second switch when the RMS noise has decreased sufficiently after the first filter stage has been turned on.
PCB layouts will be done once I understand that part of Altium
NOTE THAT I HAVE DELETED ELOG 8798 AS IT WAS A DUPLICATE OF THIS ONE.
I wanted this elog to be in reply to a previous one and I couldn't figure out how to change that in an elog I already submitted.
Following Tara's noise budget, I have developed the following ISS, whose transfer function was computed with LISO and is also displayed below. The transfer function was computed from the output of the differential amplifier circuit (i.e. it does not include the portion of the schematic in the dashed box). The differential amplifier is included for completeness. Essentially, the resistor values of this portion (and even the voltage reference if need be) can be modified to handle various signals from PDs in different experiments. Some filtering may also be applied to the signal from the voltage reference. In previous designs for the ISS, a ~30 mHz low-pass filter applied to the output of the voltage reference has also been proposed.
LISO was also used to compute the input-referred noise of this circuit. Using the response function of Tara's PD the noise spectrum was converted from [V / sqrt(Hz)] to [W / sqrt(Hz)] and then subsequently converted to a frequency noise spectrum, specifically [W / sqrt(Hz)] to [Hz / sqrt(Hz)], using the following transfer function which couples RIN to frequency noise in the CTN experiment. In these particular units, we can make a direct comparison between the inherent noise contribution from the servo itself and other more significant noise contributions shown earlier in Tara's noise budget. Indeed, the servo contributes significantly less noise.
This servo has been prototyped on a breadboard and will soon be characterized with the SR785. Additionally, schematics will be drawn up in Altium and eventually put on PCB.
Additional servos for other experiments can be designed once various requirements for noise suppression are explicitly formalized.
I've been developing an idea for making a direct measurement of the SRC Gouy phase at RF. It's a very different approach from what has been tried before. Prior to attempting this at the sites, I'm interested in making a proof-of-concept measurement demonstrating the technique on the 40m. The finesse of the 40m SRC will be slightly higher than at the sites due to its lower-transmission SRM. Thus if this technique does not work at the 40m, it almost certainly will not work at the sites.
The idea is, with the IFO locked in a signal-recycled Michelson configuration (PRM and both ETMs misaligned), to inject an auxiliary laser from the AS port and measure its reflection from the SRC using one of the pre-OMC pickoff RFPDs. At the sites, this auxiliary beam is provided by the newly-installed squeezer laser. Prior to injection, an AM sideband is imprinted on the auxiliary beam using an AOM and polarizer. The sinusoidal AOM drive signal is provided by a network analyzer, which sweeps in frequency across the MHz band and demodulates the PD signal in-phase to make an RF transfer function measurement. At the FSR, there will be a AM transmission resonance (reflection minimum). If HOMs are also present (created by either partially occluding or misaligning the injection beam), they too will generate transmission resonances, but at a frequency shift proportional to the Gouy phase. For the theoretical 19 deg one-way Gouy phase at the sites, this mode spacing is approximately 300 kHz. If the transmission resonances of two or more modes can be simultaneously measured, their frequency separation will provide a direct measurement of the SRC Gouy phase.
The above figure illustrates this measurement configuration. An attached PDF gives more detail and the expected response based on Finesse modeling of this IFO configuration.
I set up a free-space beat on theNW side of the PSL table between the IR beam from the PSL and from EX, the latter brought to the PSL table via ~40m fiber. Initial measurements suggest very good performance, although further tests are required to be sure. Specifically, the noise below 10 Hz seems much improved.
Attachment #1 shows the optical setup.
Yehonathan came by today so I had to re-align the arms and recover POX/POY locking. This alllowed me to lock the X arm length to the PSL frequency, and lock the EX green laser to the X arm length. GTRX was ~0.36, whereas I know it can be as high as 0.5, so there is definitely room to improve the EX frequency noise suppression.
Attachment #2 shows the ALS out-of-loop noise for the PSL+X combo. The main improvements compared to this time last year are electronic.
Mix the beams in free space. We have the beam coming from EX to the PSL table, so once we mix the two beams, we can use either a fiber or free-space PD to read out the beatnote.
I noticed this behaviour since ~Dec 20th, before the power failure. The bulb itself seems to work fine, but the projector turns itself off after <1 minute after being manually turned on by the power button. AFAIK, there was no changes made to the projector/Zita. Perhaps this is some kind of in-built mechanism that is signalling that the bulb is at the end of its lifetime? It has been ~4.5 months (3240 hours) since the last bulb replacement (according to the little sticker on the back which says the last bulb replacement was on 15 Aug 2017
Koji, Gautam, Johannes
We quickly checked the situation of the projector in the control room.
- We found that the proejctor was indicating "lamp error".
==> Steve, could you remove the projector from the ceiling and check if it still does not work?
If it still does not work, send it back to the vender. It should be covered by the previous service.
- Zita seemed happy with the DVI output. We tried the dual display configration and VGA and DVI are active right now.
The DVI output (from RADEON something video card) is somewhat strange. We probably need to look into the video display situation.
Last documented replacement in Nov 2018, so ~7 months, which I believe is par for the course. I am disconnecting its power supply cable.
In fact the projector is still working. The lamp timer showed ~8200hrs. I just reset the timer, but not sure it was the cause of the shutdown. I also set the fan mode to be "High Altitude" to help cooling.
I heard a popping sound in the control room; the projector lightbulb has blown out.
Bulb replaced. Projector is back on.
Projector light bulb blown out today.
This bulb was blown out on Feb 4, 2017 after 2 months of operation.
Three replacement bulbs ordered
Rana can discribe how it happened.
IF A LAMP EXPLODES
Shipped out for repair.
It is back and running fine witth bulb 4-13-2017
I replaced the projector video and power cables with longer ones, and zip-tied them to the ceiling and wall so they don't block the image.
Update: We don't have our BIG screen
There was no light from the projector when I came in this morning. I suspected it might have to do with the lifetime of the bulb. But turning the projector OFF and ON got the projector working....but only for about 10-15 seconds. The display would go OFF after that. I will wait for some additional help to dismount it and check what the problem really is.