 Thu Jan 10 10:39:27 2019, anchal, DailyProgress, NoiseBudget, New noise budget code is ready, but
|
The new noise budget code is ready. However, there are few discrepancies which still need to be sorted.
The code could be found at https://git.ligo.org/cit-ctnlab/ctn_noisebudget/tree/master/noisebudget/ObjectOriented
Please look into How_to_use_noiseBudget_module.ipynb for |
 Mon Aug 12 11:56:21 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy
|
Adding more specifics:
Discrepancy #1
Following points are in relation to previously used
noisebudget.ipynb file.
One can see the two different values of effective coating coefficient of thermal expansion (CTE) at the outputs of cell 9 and cell 42.
For |
Tue Aug 13 11:59:56 2019, anchal, DailyProgress, NoiseBudget, Checking the differences between old and new noisebudget 
|
I saved the traces of old and new noise budgets as txt files and then plotted them together to understand the differences between the codes. One can
refer to CTN:2250 for a summary of calculations of old noise budget.
Coating Brownian Noise:
Old noise budget uses a simple formula from Harry |
|
Tue Aug 13 17:05:53 2019, aaron, DailyProgress, NoiseBudget, Checking the differences between old and new noisebudget
|
Have you seen this related paper on direction dependent loss that might be interesting?
What are the specifics of the discrepancy? If your TR effect changes, it won't have perfect cancellation with TE, so thermo-optic noise could
indeed be much worse. |
|
Tue Sep 24 15:40:33 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy 2
|
Today I ran the two codes with the same parameter values to check if the effective reflectivities calculated during the calculation of thermo-optic nose
matches. They do match exactly actually. Attached is an over plot.
Coating effective coefficient of thermo-refractive effect comes out to be: |
|
Tue Sep 24 17:11:13 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy 2 (More)
|
Also, I found that the effective reflectivities from the top surface of layers calculated in Evans
et a. PRD 78, 102003 (2008) were different from reflectivities calculated by matrix method in Hong et al. PRD 87, 082001 (2013). |
|
Tue Sep 24 19:39:06 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles
|
Gabriele suggested that I plot the estimated coating Brownian noise for different values of bulk and shear loss angles and compare with the old code.
The expectation is that the estimated noise should vary smoothly and should agree with old result where bulk and shear loss angles are taken the same.
In the first plot, I have plotted estimate coating Brownian noise for CTN experiment over the nominal range of bulk and shear loss angles. Since this range |
|
Fri Sep 27 16:40:49 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles Better Plots
|
| Better Plots attached. |
|
Mon Sep 30 11:14:41 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles 2D Plots
|
2D Heat Maps
Edit: Added comparison plot as well. |
|
Mon Sep 30 12:25:24 2019, rana, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles 2D Plots
|
| but then we lost the comparison with the old calculation somehow... |
|
Mon Sep 30 20:08:42 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Beam Radius
|
Variation of the estimate of coating Brownian noise as beam spot radius on the mirror changes. Plotted in displacement noise as the frequency conversion
factor is dependent on cavity length and beam radius also depends on that. |
|
Tue Oct 1 13:46:49 2019, anchal, DailyProgress, NoiseBudget, Using bayesian inference to estimate loss Angles
|
I used the method described in Section V of https://arxiv.org/abs/1406.4467, to do a bayesian inference
using mechanical ring-down measurements of coating loss angles by Steve Penn (recently reported in https://dcc.ligo.org/LIGO-G1901676)
as a prior. I assumed all probability distributions to be gaussian. We are clearly not close to measuring the Brownian noise as with present uncertainty |
|
Wed Oct 2 15:13:27 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Beam Radius
|
I updated this calculation by adding curves for contribution through bulk loss angle and shear loss angle separately. Rana suspected that shear loss
and bulk loss should behave differently with the change in beam radius on the mirrors. But apparently the Hong
et al. calculations do not suggest that way. I checked this analytically too. The definitions of Eq. (96) of power spectral densities of coating thickness |
|
Wed Oct 23 13:21:12 2019, anchal, DailyProgress, NoiseBudget, Fixed all discrepancies.
|
I ran the code for aLIGO coating structure and tried to reproduce fig5 and fig7 of Hong
et al. paper. It turned out that the derivatives of the complex reflectivity were not matching with the paper. I rewrote the code, with a fresh mind
without looking at previous code and voila, after increasing computation time slightly due to more brute force calculations, I was able to reproduce the |
|
Fri Jun 12 12:34:08 2020, anchal, DailyProgress, NoiseBudget, Resolving discrepancy #1 concretly
|
I figured out why folks befor eme had to use a different definition of effective coating coefficent of thermal expansion (CTE) as a simple weighted average
of individual CTE of each layer instead of weighted average of modified CTE due to presence of substrate. The reason is that the modification factor is
incorporated in another parameter gamma_1 and gama_2 in Farsi et al. Eq, A43. So they had |
|
Mon Jun 15 17:58:02 2020, anchal, DailyProgress, Documentation, CTN paper
|
I've just finished a preliminary draft of CTN paper. This is of course far from final and most figures are placeholders. This is my first time writing
a paper alone, so expect a lot of naive mistakes. As of now, I have tried to put in as much info as I could think of about the experiment, calculations,
and analysis. |
|
Wed May 13 18:07:32 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis
|
I did this analysis last with bare-bones method in CTN:2439. Now I've improved this much
more. Following are some salient features:
Assuming Uniform prior distribution of Bulk Loss Angle since the overlap with Penn |
|
Fri May 15 12:09:17 2020, aaron, DailyProgress, NoiseBudget, Bayesian Analysis
|
Wow, very suggestive ASD. A couple questions/thoughts/concerns:
It's typically much easier to overestimate than underestimate the loss angle with
a ringdown measurement (eg, you underestimated clamping loss and thus are not dominated by material dissipation). So, it's a little surprising that |
|
Fri May 15 16:50:24 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis
|
It's typically much easier to overestimate than underestimate the
loss angle with a ringdown measurement (eg, you underestimated clamping loss and thus are not dominated by material dissipation). So, it's a little
surprising that you would find a higher loss angle than Penn et all. That said, I don't see a model uncertainty for their dilution factors, which can |
|
Fri May 22 17:22:37 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis
|
I talked to Kevin and he suggested a simpler straight forward Bayesian Analysis for the result. Following is the gist:
Since Shear Loss Angle's contribution is so little to the coatings' brownian noise, there is no point in trying to estimate it
from our experiment. It will be unconstrained in the search always and would simply result in the whatever prior distribution we will take.
So, |
|
Mon May 25 08:54:26 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis with Hard Ceiling Condition
|
I realized that using only the cleaned out frequencies and a condition that estimated power never goes above them at those places is double conditioning.
In fact, we can just look at a wide frequency band, between 50 Hz to 600 Hz and use all data points with a hard ceiling condition that estimated noise
never goes above the measured noise in any frequency bin in this region. Surprisingly, this method estimates a lower loss angle with more certainty. This |
|
Tue May 26 15:45:18 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis
|
Today we measured further low noise beatnote frequency noise. I reran the two notebooks and I'm attaching the results here:
Bayesian Analysis with frequency cleaning:
This method only selects a few frequency bins where the spectrum
is relatively flat and estimates loss angle based on these bins only. This method rejects any loss angle vaue that results in estimated noise more than |
|
Thu May 28 14:13:53 2020, anchal, DailyProgress, NoiseBudget, Bayesian Analysis
|
I'm listing first few comments from Jon that I implemented:
Data cleaning can not be done by looking at the data itself. Some outside knowledge can be used to clean data. So, I removed all the
empirical cleaning procedures and instead just removed frequency bins of 60 Hz harmonics and their neighboring bins. With HEPA filters off, the latest |
|
Sun May 31 11:44:20 2020, Anchal, DailyProgress, NoiseBudget, Bayesian Analysis Finalized
|
I've implemented all the proper analysis norms that Jon suggested and are mentioned in the previous
post. Following is the gist of the analysis:
All measurements taken to date are sifted through and the sum of PSD bins between 70 Hz to 600 Hz (excluding 60 Hz harmonics and region |
|
Mon Jun 1 11:09:09 2020, rana, DailyProgress, NoiseBudget, Bayesian Analysis Finalized
|
what is the effective phi_coating ? I think usually people present bulk/shear + phi_coating.
|
|
Thu Jun 4 09:18:04 2020, Anchal, DailyProgress, NoiseBudget, Bayesian Analysis Finalized
|
Better measurement captured today.
Final result of CTN experiment as of June 4th 9 am:
|
|
Thu Jun 11 14:02:26 2020, Anchal, DailyProgress, NoiseBudget, Bayesian Analysis Finalized
|
I realized that in my noise budget I was using higher incident power on the cavities which was the case earlier. I have made the code such that now it
will update photothermal noise and pdhShot noise according to DC power measured during the experiment. The updated result for the best measurement yet
brings down our estimate of the bulk loss angle a little bit. |
|
Mon Jun 15 16:43:58 2020, Anchal, DailyProgress, NoiseBudget, Better measurement on June 14th
|
Final result of CTN experiment as of June 15th 5 pm:
with shear loss angle taken from Penn et al. which |
|
Tue Jun 23 17:28:36 2020, Anchal, DailyProgress, NoiseBudget, Better measurement on June 22nd (as I turned 26!)
|
Final result of CTN experiment as of June 23 5 pm:
with shear loss angle taken from Penn et al. which |
|
Wed Jun 24 21:14:58 2020, Anchal, DailyProgress, NoiseBudget, Better measurement on June 24th
|
Final result of CTN experiment as of June 24 9 pm:
with shear loss angle taken from Penn et al. which |
|
Fri Jun 26 12:38:34 2020, Anchal, DailyProgress, NoiseBudget, Bayesian Analysis Finalized, Adding Slope of Bulk Loss Angle as variable
|
I added the possibility of having a power-law dependence of bulk loss angle on frequency. This model of course matches better with our experimental results
but I am honestly not sure if this much slope makes any sense.
Auto-updating Best Measurement analyzed with allowing a power-law slope on Bulk Loss Angle: |
|
Tue Sep 15 15:13:44 2020, Anchal, Notes, Environment, HEPA filters switched on. Measurement stopped.
|
I have switched on HEPA filters to high, both on top of the main table and on top of the flow bench.
Continuous measurement is stopped hereby. This experiment is finished. |
|
Wed Sep 23 00:21:02 2020, aaron, Misc, Equipment loan, HP 8560E SA to Cryo
|
I entered CTN just before (Wed Sep 23 00:22:11 2020 ) to borrow a spectrum analyzer, which I took to Cryo. Wore shoe covers, goggles. Sanitized goggles
and door after. |
|
Sat Oct 10 08:43:30 2020, anchal, Summary, Electronics Equipment, Red Pitaya and Moku characterization
|
I set up Red Pitaya, Wenzel Crystal, and Moku at my apartment and took frequency noise measurements of Red Pitaya and Wenzel Crystal with Moku.
Method:
Wenzel Crystal was powered on for more than 5 hours when the data was taken and has an output
of roughly 24483493 Hz. This was fed to Input 2 of Moku with a 10dB attenuator at front.
Red pitaya was on signal generator mode set to 244833644 |
|
Mon Nov 9 16:53:55 2020, Radhika, Notes, Computers, Brought home Dell laptop
|
I have brought home the following item, provided by Paco:
Black Dell Laptop and charger.
|
|
Tue Nov 24 16:23:26 2020, Paco, Misc, Equipment loan, broadband EOM
|
| Borrowed 1 (new focus) broadband EOM from CTN for temporary use in Crackle (2 um OPO experiment) |
|
Thu Nov 26 11:26:14 2020, agupta, Summary, TempCtrl, Cavity temperature estimate
|
Measurement and estimation method:
125N-1064
Thermal continuous tuning coefficient is 5 GHz/V
The south cavity is locked with nominal settings with slow PID switched on.
The
cavity was first allowed to equilibrate at the nominal setpoint of cavity heater currents of 0.5 W common power and -0.09358 W Differential power.
After |
|
Mon Nov 23 10:58:46 2020, anchal, Notes, Laser, North laser not switching on, power supply display not working
|
The north laser power supply display is not working and when the key is turned to ON (1) position, the status yellow light is blinking. I'm able
to switch on the south laser though with normal operation. But as soon as the key of the north laser power supply is turned on, the south laser goes back
to standby mode. This is happening even when the interlock wiring for the north laser is disconnected which is the only connection between the two laser |
|
Mon Nov 23 14:56:59 2020, Koji, Notes, Laser, North laser not switching on, power supply display not working
|
I suspected the interlock failure. Can you replace the interlocking wire with a piece of wire for the troubleshooting?
There probably is a spare LWE NPRO controller at the 40m. |
|
Mon Nov 30 10:28:08 2020, Anchal, Notes, Laser, North laser not switching on, power supply display not working
|
I shorted the interlock terminals on the North laser power supply and still as soon as I turn the key to 'ON' position, the south laser drops
to standby mode and the north laser power supply display does not switch on with the status yellow led blinking asynchronously. I still do not understand
why the two laser operations are coupled. South laser power supply does not share anything other than the power distribution board with the North power |
|
Mon Nov 30 21:31:56 2020, Koji, Notes, Laser, North laser not switching on, power supply display not working
|
I can't answer the last question, but I just tell you my experience on the AC power supply. The OMC Lab used to have a LWE NPRO and every time I
plugged low quality AC adapters (like one for CCD adapter), NPRO came back to StandBy. So I suppose that you have a large electrical spike on the AC line
when the North laser shuts down for whatever reason. |
|
Tue Dec 1 12:04:10 2020, Radhika, Notes, Equipment loan, Brought home low-noise preamplifier
|
I have brought home the following items (provided by Anchal):
1. Low-noise Preamplifier (Model SR560)
2. Two serial-to-USB adapters |
|
Wed Dec 2 13:43:43 2020, anchal, Summary, Equipment loan, Transferred two gold box RFPDs to 40m
|
I transferred two Gold Box RFPDs labeled SN002 and SN004 (both resonant at 14.75 MHz) to 40m. I handed them to Gautam on Oct 22, 2020. This elog post
is late. The last measurement of their transimpedance was at CTN/2232. |
|
Mon Dec 7 19:02:26 2020, Paco, Notes, Equipment loan, UPDH box
|
| Borrowed Universal PDH box from CTN lab (D0901351) and a mounted Faraday isolator (Thorlabs) for use in Crackle. |
|
Wed Dec 9 18:13:12 2020, Paco, Misc, Equipment loan, new focus 1811
|
| Borrowed two broadband PDs (new focus 1811) and one power supply unit (new focus 0901) from CTN into Crackle. |
|
Tue Dec 15 12:59:14 2020, anchal, Notes, Equipment loan, Moved Marconi and Rb Clock to Crackle lab
|
| Moved the rack-mounted Marconi 2023A (#539) and SRS FS725 Rb Clock to crackle lab (See SUS_Lab/1876). |
|
Wed Jan 27 15:12:05 2021, Anchal, Notes, Environment, Small leak or drip in the lab on West End
|
I noticed small amount of water on the floor (Attachment 1) on the west end of the lab. Immediately above it is a pipe which I don't know what it
does. One can see another drop forming at the edge of this pipe (Attachment 2). This water is slowly dripping on the side of the pipe (Attachment 3). I
could trace it out to coming from somewhere on the top (Attachment 4 and 5). |
|
Thu Feb 11 18:01:39 2021, Anchal, DailyProgress, InstrumentCharacterization, SR560 Intermodulation Test
|
I added script SRIMD.py in 40m/labutils/netgpibdata which allows one
to measure second order intermodulation product while sweeping modulation strength, modulation frequency or the intermodulation frequency. I used this
to measure the non-linearity of SR560 in DC coupling mode with gain of 1 (so just a buffer). |
|
Wed Sep 30 11:13:28 2020, anchal, Notes, Equipment loan, Took home moku and wenzel crystal for characterization
|
I have brought home the following items from CTN Lab today:
Moku with SD Card inserted and charger.
Ipad pro with USB-C to USB-A charging cord
Wenzel
5001-13905 24.483 MHz Crystal Oscillator
HP E3630A triple output DC power supply
One small 5/16 spanner
4 |
|
Tue Nov 24 16:16:53 2020, anchal, Notes, Equipment loan, Transferred moku to Cryo lab
|
I transferred the following form my home to Cryo lab (Cryo_Lab/2587) today:
Moku with SD Card inserted and charger.
Ipad pro with USB-C to USB-A charging cord
|
|
Wed Jan 27 15:11:13 2021, anchal, Notes, Equipment loan, HP E3630A returned
|
I have brought back HP E3630A triple output DC power supply.
|
|
Tue Feb 23 11:05:28 2021, anchal, Notes, Equipment loan, Took home moku and wenzel crystal for characterization
|
Returned all remaining stuff to CTN:
Wenzel 5001-13905 24.483 MHz Crystal Oscillator
One small 5/16 spanner
4 SMA-F to BNC-F adaptors
4
SMA-M to BNC-F adaptors
2 10 dB BNC Attenuators
4 BNC cables
Also returned the Red Pitaya accessory box to CTN. |
|
Wed Aug 18 11:12:47 2021, aaron, Misc, Electronics Equipment, SR560 to cryo
|
I borrowed one two unused SR560 from CTN to Cryo. The first one had periodic noise at 100 Hz (operated in low noise AC coupled mode, G=100, with
a 30 kHz lowpass). |
|
Fri Jan 28 15:18:27 2022, Anchal, Summary, Equipment loan, CTN raided by 40m tribes
|
[Anchal, Paco]
CTN was raided today afternoon between 2 pm and 3 pm by 40m tribes. They have taken away precious Acromag units which are a very scarce resource
these days. Following units were taken (Attachment 1): |
|
Mon Aug 22 20:18:21 2022, Anchal, Summary, NoiseBudget, Birefringence noise in thermo-optic noise
|
I followed the analysis of this recently published paper Jan Meyer et al 2022 Class. Quantum Grav.
39 135001 to calculate the birefringence noise in the CTN experiment. Interestingly, the contribution from birefringence noise after my first attempt
at this calculation looks very close to what we were calculating as coating thermo-refractive noise before. If this were true, our experiment would have |
|
Tue Aug 23 19:56:21 2022, Anchal, Summary, NoiseBudget, Birefringence noise in thermo-optic noise
|
I made a few changes in my calculations today, which changed the noise contribution of this photoelastic noise (coatTPE) to roughly half of the individual
contribution from coating thermo-refractive (coatTR). If this was true, it would significantly affect thermo-optic optimization, although not totally destroying
it. I admit there is an outcome bias in this statement, but this noise estimate fits |
|
Tue Aug 23 22:04:24 2022, awade, Summary, NoiseBudget, Birefringence noise in thermo-optic noise
|
Interesting.
The obvious go to measurment here would be two-lasers-one-cavity to measure the residual between the two polarisaiton modes of one of the cavities.
Is the experiment in a state where this could be done easily? |
|
Thu Aug 25 19:38:01 2022, Anchal, Summary, NoiseBudget, Birefringence noise in thermo-optic noise
|
Quote:
The obvious go to measurment |
|
Thu Aug 25 19:19:27 2022, Anchal, Summary, NoiseBudget, Looking at the measured and estimated photothermal transfer functions
|
The photothermal transfer function measurement made back in 2014 showed some cancellation of thermo-optic noise, but there were some irregularities with
the modelled transfer function even back then. Here in attachment 1, I have plotted the measured photothermal transfer function, along with the estimated
transfer function with and without adding a term for thermal photoelastic (TPE) channel. |
|
Fri Aug 26 15:56:38 2022, Anchal, Summary, NoiseBudget, Checking with Martin Fejer's calculations
|
Martin Fejer recently gave two talks in a coatings workshop where he showed calculations regarding the thermal photoelastic channel. I have not been
able to under the logic behind some of the calculations yet, nevertheless, I used his formulas for our coatings to get an alternative idea of this noise
coupling. |
|
Wed Dec 7 11:01:24 2022, aaron, Summary, Safety, airflow monitor installation
|
Rueben from Technical Safety Services installed and calibrated an Apex 1000 airflow monitor for the fume hood in CTN. Its power supply should remain
plugged in to the outlet directly below the unit. Attachment 1 is the testing certificate. We can contact Shelley in H&S tomorrow to receive their
report on the work. |
|
Thu Jul 13 20:38:33 2023, Koji, Summary, Laser, North (lower) NPRO controller is broken
|
Anchal mentioned that one of the lasers is not functional. I checked what's the situation.
The combination of the south laser and the controller (upper) works well.
The combination
of the north laser and the controller (lower) does not work.
The combination of the north laser and the controller (upper) |