I locked the arm cavity for about half an hour but the lock broke when I enabled the isolation on ITMY ISI and the HEPI and ISI watchdogs tripped. After that I couldn't' restore the watchdogs anymore. The arm is currently unlocked.
The ALS reference cavity was in an unstable mode and the PLL could not get locked. I re-locked the refcav with these settings: Coarse 384 Fine 206 Common 300 Fast 638 Offset 194 The fiber output has dropped from ~300 uW to 80 uW since Bram installed a Faraday at the output of the reference cavity. As a consequence the beat note amplitude is about -25 dBm (-35 dBm at the monitor spigot of the phase/freq discriminator board). I had to increase the laser power otherwise the amplitude would have been even smaller. The PLL is now locked again, with the laser at the end station set to 42.27 degrees. Locking the PLL was tricky. One of the switches in the CMB_A MEDM screen was actually stuck in an open state, although it appeared to be closed on the screen. the switch was malfunction and it had a state value of 65536 instead of 1 or 0. I forced it to be 1 by EZCAWRITE. Also there CMB_A board Input1 gain is now limited to -16 or less, vs -6 as it used to be, because the PLL becomes unstable at -15 and up. This is strange since the loop gain phase is flat up to 80 kHz and the phase margin is large (~60 degrees up to 80 kHz; the UGF is 10 kHz). I suspect something might be wrong with the slow control interface of CMB_A.
I reset all the watch dogs on the ITM HPI and ISI. ITM ISI is in damping state. Didn't press the isolate stage command.
I try to lock the arm (remotely), but it seems that H2:ALS-Y_FIBR_SERVO_FASTMON (e.g. the CMB-A fast output, which is the fiber locking feedback signal to the laser PZT) is railed at -10V. The beatnote frequency readout is at 60 MHz, but not sure if that is real or not. Should go out to EY to make sure all is well. (PS. to engage the fiber locking open the 'Laser' screen and press 'on' at the lower left).
I turned off the FIBR servo (CMB-A), to make sure the temperature doesn't walk away.
The OAT RefCav monitor signal seems to be ok (~0.1 mW).
Turned off ETMy ring heater
[David T, Cheryl V and Deepak K]
[David T, Cheryl V and Deepak K]
The backup of h1boot and h2boot still slows the EPICS associated with the front end systems. Even though I only backup at 5am daily, the slow down is still evident at that time. Until the root cause of this problem can be resolved, Jim and I came up with a totally inelegant solution of slowing down the data rate of the network switch ports which connect h1boot and h2boot to the backup machine. These ports were demoted from 1GB to 100MB. We tested both h1boot and h2boot backups. They take about an hour each (compared with 20mins previously). The disk I/O rate keeps below 5MB per 5 second average. The EPICS problems were previously observed to occur when the disk I/O exceeds 8MB per 5 second average.
A large percentage of the backups concern the awgtpman log files which can be many 100MB each. We will work next Tues on installing new awgtpman code to reduce the logging content of these files.
The arm cavity is unlocked right now due to issues with the HEPI on ITMY.
I have installed the IOP SUS watchdog system for the H1 HAM2,3 systems. The sus systems are h1sush2a and h1sush34, the seismic system is h1seih23. Following the LLO system, the suspension systems being monitored are
HAM2: PR3
HAM3: PR2 and MC2
If any of these sus system trip, the DACs on h1seih23 (HEPI and ISI in HAMS 2,3) are tripped via the Dolphin IPC.
Currently SEI HAM2,3 is permanently tripped due to missing PR3 OSEMS. I will reconfigure the system into a working state when the ISI are unlocked in HAM2/3.
The H1 IOP watchdog MEDM is available from the H1 SITEMAP
I turned on the ETMY ring heater around 23:47 UTC, requesting 630mA in each segment. I'm going to leave it running overnight and into the weekend to get a good measurement of the thermal time constants.
After finishing assessing and adjusting the roll and pitch of the suspensed PR2 optic, we started adjusting the 14 OSEM positions. During the coarse of this, we broke a magnet off of the PR2 optic. Mark Barton and Travis are looking into regluing it onto the optic within the suspension, in an effort to retain some sort of schedule for next week while our team is stretched over to LLO. Lesson learned is that the EQ stops need to be set very close while adjustments are being made. I thought this was the case when we were working on it, but clearly not close enough. It's unfortunate that the top BOSEM adjustment tools and your hand are very close to the suspension wire making knocking the suspended masses around easy.
Mitchell, Jim & Hugh The first layer of the additional payload mass (D0901075) on the West side of HAM (90kg) has been bolted down to the table; we did this Thursday. There is still 210kg to go.
Remain to Do: At ISI: Complete Cable SN Inventory, Replace Act Windows, Confirm Cable security for flight. At HAM5: Loosen Door Bolts, Clean around Doors, Remove Doors, Remove Top Conflat, Remove Legs from A-Frames, Position A-Frames at Chamber, Install I-Beams, Position I-Beams per Procedure, Position Cart under Beams, Fly ISI, etc... Thanks to Christina, Karen, Cris, MarkD, ScottL, DevilEd, Jim, Mitchell, Greg, & Eric
Prior to venting, I sprayed helium around the welds which join the thin-wall MC tube to the thick flanges. The LD background was 3.5 x 10-9 torr*L/sec -> no responses. I did not spray all of the welds on the MC nozzles, roll seams or roll butt joints, however. Also, PT120A wasn't working today. I think that I had drug my fall protection tether across the gauge pair the other day during leak testing and must have interrupted the cable connection. I eventually had to remove and re-installed its cable to get it going which fixed it.
Cheryl moving TCS lasers into HAM 6 bay Kyle soft closed GV-5, venting vertex for ISI install into HAM5
Restarted models on the sei test stand (stormy), cpu for the iop was pegged.
The H2 ITMY and ETMY have been re-centered with the cavity beam locked at approximately 10:05 for ITMY and 10:55 for ETMY. The cavity was locked at the time. One particular note, all of the electronics for the ETMY optical levers (laser, whitening chassis, power supply) were running off a power strip that was disconnected sometime in the past few days and this caused a loss in signal. Please don't do this.
Morning (8-noon) Notes
OAT Work: Aiden & crew had the reins for Ring Heater work
Craning activity: HAM5 ISI had it's Container top removed and the ISI is staged in a cleanroom
H2 ITM/BS CPU Meter went to a MINOR alarm state (value = 13) at 8:27am
Thomas centering oplevs for ITMy & ETMy
Mark Dodson making measurements around BSC8 10-10:15
Kyle is inquiring about venting section of HAM5.
Patrick is covering the afternoon.
I turned on the Ring Heater this morning to a nominal 30W of electrical power. We've yet to fully determine the ratio of the radiated power to electrical power, but the most recent number is approximately 2.5W radiated power per 6W electrical power.
I measured the spherical power of the HWS beam - probing the ETM thermal lens and surface deformation and compared it to the results from a simple COMSOL model of the predicted thermal lens + surface deformation [no fitting]. The results are shown in the attached plot. Bear in mind that the scale of the predicted model will be affected by the delivered power (dependent on the radiated to electrical power ratio) and that the HWS is still operating on a nominal calibration for the optical system - rather than a measured calibration.
The results are quite similar but there are obvious differences in the time constant. At the moment I would put that down to the simplicity of the COMSOL model - it doesn't include the flats on the sides of the ETM, or the reaction mass or the time constant associated with the ring heater itself.
However, this is the first real aLIGO measurement of thermal lensing with the HWS.
Caution: this is not solely the surface curvature of the ETM - the optical path distortion from the thermal lens is roughly 10x larger than that of the surface curvature.
10-Aug-2012 11:34AM - replaced plot. I had added the incorrect sign to the surface deformation in the model. I've fixed this.
Extra information:
Ring Heater on at 1028555836
Requested current: H2:TCS-ETMY_RING_HTR_SEG1_DC_I_SET_OUTPUT
Measured current: H2:TCS-ETMY_RING_HTR_SEG1_I_MON_OUTPUT
Requested current | Measured current | Measured V across RH | Electrical power (V*I) | |
Upper RH segment | 630mA | 623.4mA | 21.485V | 13.394W |
Lower RH segment | 630mA | 623.0mA | 21.458V | 13.368W |
HWS Channels:
Defocus @ HWS: H2:TCS-ETMY_HWS_POLYFIT_SPHERICAL_POWER [m^-1]
Defocus @ ETM: (1/mag^2)*H2:TCS-ETMY_HWS_POLYFIT_SPHERICAL_POWER [m^-1]