Elli, Nergis, Daniel, Evan
Today we did a preliminary measurement of the Schnupp asymmetry to be 9.0cm +/- 1cm. We injescted a beam from the auxiliary laser on IOT2R which can be offset in frequency from the main laser. We measured the power of this beam at the AS port using a 1611 photodiode on ISCT6. With the michelson locked to a bright fringe, we measured the variation of auxiliary laser power with frequency at the AS port. Due to the Schnupp asymmetry, the power should change as the auxiliary laser offset from the carrier increases as cos(scnupp_assymetry*2*pi*f_offset/c).
By fitting a curve to our measured data, we can get an estimate of the Schnupp asymmetry. I did a fit using least squares fitting to a quadratic to get 9.0cm +/-1cm Schnupp asymmetry. The measured data and curve fitting codes are attached. Evan hopes that we can reduce our error estimet by doing the curve fitting more elegantly.
Summary
Attached are two plots showing the measured data, along with least-squares fits (using scipy.optimize.curve_fit
). The horizontal axis is the detuning frequency of the aux laser from the PSL (and the sign is arbitrary). The vertical axis is rf power of the AS port beat note, as measured with an HP4396 (so these watts are electrical, not optical).
For both the upper and lower fringes, I've fit to a quadratic using the formula a(f−h)2 + k (the "vertex" form), where f is the detuning frequency. For the lower fringe, I find the minimum-power frequency occurs at f− = −840(3) MHz, and for the upper fringe I find f+ = 815(4) MHz. The uncertainties come entirely from the fitting routine; I have not included the measurement uncertainties (which we estimate to be 0.5 dBm or so). The Schnupp asymmetry is then found via the formula 2π(f+ − f−) LS / c = π; with this I find LS = 90.6(3) mm, where the errors come from the fit alone. I believe the difference between this uncertainty (<1%) and the uncertainty reported above (11%) is that the above analysis involves some covariances in the fitted parameters, and these must be accounted for when propagating the uncertainty forward to the Schnupp asymmetry.
More details
Instead of using the vertex form for the parabola, one can fit using the formula af2 + bf + c (the "standard" form). The minimum-power frequency is then f = −b/(2a). I ran a fit using this functional form, and for the upper fringe frequency I found a = 1.54e-4, b = -0.241, and c = 1.03e2. The nominal value of f+ is then 815 MHz. To find the uncertainty, I examined the covariance matrix of the fit parameters:
Cov | a | b | c |
---|---|---|---|
a | 2.28e-10 | -3.74e-07 | 1.51e-04 |
b | -3.74e-07 | 6.15e-04 | -0.250 |
c | 1.51e-04 | -0.250 | 102 |
To find the variance var(f), we need the variances var(a) and var(b), as well as the covariance cov(a, b); the formula to find var(f) is then given in this Wikipedia article. Applying this formula gives an uncertainty [i.e., sqrt(var(f))] of 4 MHz, in agreement with the fit to the vertex form. If instead cov(a, b) is left out, I find that the reported uncertainty is much larger (114 MHz), and more in line with the larger uncertainty reported earlier.
The code I've used is attached.
Sheila, Keita, Nergis, Evan, Alexa
With our beloved x-arm back, we began the alignment process:
1. Aligned TMSX with ITMX baffled PDs (and ETMX misaligned). For reference:
Volts | Gain | TMSX (P,Y) | |
ITMX PD1 | 2.3 | 0dB | (-16,-245) |
ITMX PD4 | 2.4 | 0dB | (52,-306) |
2. Aligned ITMX with the ETMX baffle PDs (and ETMX misaligned). Again, for reference:
Volts | Gain | ITMX (P,Y) | |
ETMX PD1 | -0.87 | 0dB | (6,-24) |
ETMX PD4 | -0.85 | 0dB | (49.9,13.5) |
Yes, the ETMX baffle PDs have a negative voltage!!
3. We realigned ETMX by hand. We had to increase the max pitch PV limit from 440 to 500. We hope those were set arbitrarily; the DAC was not saturating with these higher slider values. We were able to lock the x-arm on green to a buildup of 1.4-sih, which is good.
Unfortunately the green wfs servo did not wok and would misalign the arm. We did have to turn on the ITMX ISC_INF_LOCK and MO_LOCK, and TMSX M1_LOCK filters. Unfortunately this was not the culprit. It appeared that the wfs error signal had an offset, but we did li. We want to continue with locking.
We found that TMSX had the gains for the M1 lock filters both in the filter bank gain setting and in the cal filter which was engaged. Once we set the filter bank gains to 1, the WFS worked fine. We've captured safe.snaps of both TMSX and ITMX with the configuration where the WFS were working.
Alexa, Sheila, Nergis, Evan
We took a quick measurement of the X arm loss using the same technique as LHO#15919. For ASAIR_A_LF, we have Pon = 1267(5) ct, Poff = 1293(3) ct, giving an equivalent loss of 78(18) ppm for the ETM.
Today I spent sometimes setting up the calibration filters for LSC DARM in h1oaf. It should be functional now.
What I did:
Also, the second attached png is a screen shot of the latest DARM calibration setup. This is set up for a single ETM configuration where either ETMX or ETMY is not in use. If one wants to feed DARM back to both ETMs, an extra factor of two should be added somewhere. Note that the L1 (UIM) stage currently has a gain of 0.5 as shown in the screen shot n order to simulate the digital gain in SUS-ETMX_L1_LOCK_L_GAIN.
Following the RCG2.9 upgrade yesterday, I have created SDF files for the following systems: IOP, PEM, SUSAUX, TCS, CAL, PSL, ODC. In each case I have made all channels monitored, and removed the obsolete FEC-nn_GRD_[ALH,SP,RB] channels from the safe.snap sdf file. Modified files have been commited to SVN with the exception of CAL (I get an svn error with this working directory).
Latest SDF_OVERVIEW MEDM screen shot attached. All monitored systems are now green for channel matching.
S. Biscans, J. Kissel, N. Mazumder, H. Paris, H. Radkins, B. Shapiro, J. Warner After an extremely productive two weeks -- thanks to the new years present of Narwita, Seb, Hugo, and Brett all arriving within the same few days -- I figure it would be good assess where the LHO SEI team's priorities lie from here on. In particular, what *other* things that we could be doing to improve *all* the platforms instead of continuing to bang our head against the HAM3-0.6-[Hz]-feature wall. Here're the remaining activities, sort of prioritized, and split into "Improve the chamber noise performance" and "improve the maintainability / extensibility" groups. Improve The Chamber Noise Performance: All Chambers Benefit to IFO - ST 01 L4C Feed Forward (all 6 DOFs), improve 1 to 10 [Hz] performance - Sensor correction gain matching (all 3 DOFs), improve 0.08 to 3 [Hz] performance BSCs Only - Z to RZ subtraction, reduce BSC optic's yaw below 0.08 [Hz] - Implement Slow MICH, reduce MICH velocity, improving lock acquisition - Finish ITM HEPI Z to RX/RY Tilt Decoupling, reduce BSC optic's yaw below 0.08 [Hz] HAMs Only - HAMs 2,3,4,5 Isolation Loop Gain Increase improve 0.5 [Hz] to 20 [Hz] performance - Continue HAM3 0.6 [Hz] feature investigation improve 0.6 [Hz] performance Improve the Maintainability / Extensibility: - BSC-ISI Noise Budget Model - HAM-ISI Noise Budget Model - HEPI Noise Budget Model - Assess guardian vs. watchdog robustness of bringing all chambers to OFFLINE from FULLY_ISOLATED - Put MATCH OUTPUT channels on Sensor Correction overview screen - Storing more than just RZ on HEPI alignment - Hook IOP SWWD signals up to ISI USER watchdog - Install HEPI saturable integrators - Remove HEPI / ST0 L4C Sensor Correction path from ISI models - Differential Pump Pressure signals are noisy possibly from poor electrical grounding - Switch ETMX to using differential pressure signal - Assess whether switching to differential pressure affects platform noise performance
Removed one of the PEM AA chassis to troubleshoot some bad channels. Troubleshooting/repairs is taking longer than expected but should have the unit back in service sometime tomorrow morning. D1001421 Serial Number S1001053.
Unit has been repaired and reinstalled.
Kyle and Gerardo opened the XEND to the beam tube today.
The turbo was valved out, the ion pump valved in, and the gate valve to the tube/80K pump opened.
Plot attached. The pressure has fallen from 1e-6 to 8e-8 and is still moving the right way.
The clean room remains on at X-end, righ above BSC9, clean room will be dealt with by facilities tomorrow.
(Kyle R, Gerardo M)
Removed and replaced the annulus ion pump.
NOTE:
Currently there is a pump cart pumping this annulus system, will remain there until system pressure is down enough to turn on the ion pump.
J. Kissel, K. Izumi Kiwamu is making sure the online calibration filtering (currently in the "OAF" model, will eventually be in the "CAL" model) is reasonably up-to-date. In doing so, we discovered that the two ETMs have different damping loop filters installed and ON. Most filter modules are as expected, according to the original, low noise, Level 2.1 quad design (see LGO aLOG 6760). However, in FM3 of the L and Y banks of both ETMX and ETMY, there are filters called "resg1" and "+12dB" respectively. They are ON only in ETMX. After a little digging down memory lane, we recalled that in attempts to get ALS DIFF up and running last time (see e.g. LHO aLOG 15025), before we lost the arms, we had copied over LLO's damping filters' differences at the time -- described in detail in LHO aLOG 14959. However, as indicated in LHO aLOG 15037, having the filters constantly ON never got captured in any sort of configuration control, because ALS and LSC control was bouncing between using ETMX and ETMY depending on the functional-state and state-of-confusion for each test mass. We have now turned both FM3's of L and Y filter banks ON, and changed the DAMP_STATE_?_GOOD state to match the current state with those ON. We have not yet captured a new safe.snap in this configuration, but we'll do so ASAP. A note -- the ITMs do NOT have these "bonus" LLO filters installed, so FM3 is therefore OFF.
Replaced bad projector lamp on left side projector in control room. NOTE: The lamp socket internal to the projector has badly overheated and the plastic mount that holds the socket pins has lost it's integrity. If you smell smoke in the control room, this projector should be powered off. This seems to be a common problem with these projectors.
For the Schnupp asymmetry measurement, one of the patch panel connectors on ISC R1 (by the PSL) is now wired to another patch panel connector on ISC R3 (by HAM6). The wiring is as follows:
Initially, all these ports were labeled as "spare" and most of them were terminated.
The connector on ISC R1 will be driven by an rf signal from an IOT2R PD. The connector on ISC R3 will go into a spectrum analyzer.
DAQ was restarted to sync up with temporary h1iscey model change which was applied in the last hour.
restarted h1iscey model, looks like it wasn't started completely due to obsolete wiki restart instructions.
We only restored PIT of HEPI2 (H1:HPI-HAM2_IPS_RY_SETPOINT_NOW) yesterday, but there was a change in ROLL (RX) on the order of 10 urad that was not restored, which might affect the input pointing.
Also, there was a jump in ROLL in HEPI3, again on the order of 10 urad, which would affect POP and ALS beam position on ISCT1 as well as POP sled in HAM3.
These DOFs were brought back to pre-maintenance levels.
I don't know/remember why, but it seems that a new set of angle setpoints is made for HEPI such that the system starts new with free-hanging position after each restart. Seems like this free hanging position changes over time.
Since any change in HEPI angle (RX, RY and RZ) on HAM2 and HAM3 would affect many things related to the alignment, most notably pointing references like IM4 transmission QPD and POP sled, it's a good idea to keep the set points unchanged over multiple restarts.
I've done a survey a of all the SEI Guardians with regard to the position dofs that are restored (maintained everytime.)
HAM_ISIs maintain every dof but the HAM_HEPIs only maintain the RZ dof. I'd say this is backwards given the range and more importantly hysteresis of HEPI.
While at it, for the BSCs: their HEPIs all maintain the RZ dof, the ETMs maintain their pitch and the ITMY maintains pitch roll and X dof to deal with ACB install and Initial Alignment. The BSC ISIs maintain NO dof.
It certainly makes sense to me that at least the HAM2 & HAM3 RX & RY dofs are also restored along with the RZ. Don't know why we wouldn't do this with HAMs 4, 5 & 6 too. The X Y & Z dofs are probably okay to let wander but commissioners can comment.
Jim, Dave: WP5003
This morning we upgraded H1 FE and DAQ to RCG2.9. First the DAQ was upgraded and restarted. Then FE startup scripts were changed, model startup scripts changed.
Then a "make installWorld" was ran to install the models which were compiled yesterday. The H1.ipc file generated yesterday was re-installed.
We tested a reboot-restart first on a non dolphin FE (h1susauxh2) and then on a Dolphin FE (h1seib1).
We then restarted all frontends in the MSR by power cycling the computers, and end station frontends by rebooting the computers. We ended up having to powercycle h1iscex because it got stuck in reboot. In the MSR when we were restart testing, h1susb123 got stuck on reboot and needed a power cycle which Dolphin crashed the other MSR machines.
We got to a stable system with DAQ and FE reboots proceding correctly. We had 6 front end IOP models with large IRIG-B excursions into the 1000-2000 counts. The h1oaf0 IOP took 4 hours to return to normal IRIG-B range. One IOP went below zero (999998) which caused IPC errors on models receiving its channels. This fixed itself in about 10 minutes.
We noticed a single ADC error on the h1ioplsc0, which was cleared with a DIAG_RESET.
We noticed the DAQ frame size is smaller now. For science frames 670MB to 610MB (10% reduction) and commissioning frames 1.2GB to 1.0GB (20% reduction). We suspect new common models are the reason for this.
I linked Jamie's SDF_OVERVIEW MEDM screen to the SITEMAP under the GRD section. We are configuring the IOP, PEM and PSL systems.
This closes WP5003
Frame size reduction was bogus. I checked too soon after the reboots when systems were not fully engaged and the frame was compressing zeros. After a few hours of ifo operation the frame sizes came up to nominal. Attached plot show commissioning and science frame sizes for the past two days.