10:51 I restarted the h1slow-cds epics gateway due to Beckhoff IOC work.
Done
Done
Breaking for lunch
Koji and I will be in the PSL today for replacing IO_MB_M2 as a preparation of the high power laser.
The attached was the current best alignment.
All models have stopped on h1seih45 at 1073754093, having suffered an ADC timeout. It's possible that the timing fiber was disconnected for work, not sure of the cause. I am going to reboot the computer after removing it from the dolphin network.
Computer rebooted, all models are running.
This was necessary because the model stopped running when I swapped ADC 1 and 2 ribbon cables in the IO chassis.
I started working on the arm cavity alingment this morning, we have flashes of 400 counts on the transmitted PD (ALS COMM), the refl PD drops from 19500 to 19000, and a spot is clearly visible on the ETM camera (scren shots attached). This can sort of lock for a few seconds. I'm heading to the X end to look at the locking.
Also. MC1 misalinged so we can see green on the ITM without confusion from the IR.
[Stefan, Kiwamu]
We are now in the process of checking/adjusting the suspensions as our length actuators.
One thing I am confused at this moment is the length transfer function of PRM and PR2. I did the same TF measurement as for the BS length drive for comparison, and found that the TF were 1/f above 10 Hz rather than 1/f^2 (see the attached). There must be some stupid reason because otherwise we wouldn't be able to lock PRX or PRY. I will revisit this issue tomorrow.
(Alexa, Daniel, Sheila)
PLL Beatnote:
PLL Open Loop Transfer Function:
PLL Noise Spectrum -- via IMON of PFD (S1000758)
PLL Servo Board Transfer Function:
Shot Noise of PLL BBPD:
The missing SR785 measurement:
PLL Open Loop Transfer Function:
Input 1 pol: NEG, Common Compensation: ON, Generic Filter: ON, Fast Option: ON, Fast Gain: -8dB, Input 1 Gain: 0db, Boost 1:ON rest OFF
It was not advertised well but the HEPI isolation loop actually caused the alignment jump of [+25, -8] urad according to IPS in HEPI when it was turned on Friday evening (attached). We've never had a good alignment after that but this might be a coincidence. This is not a huge deal but annoying nevertheless.
When I started to restore the known good alignment of HEPI by giving new setpoints to HEPI it tripped the watchdog repeatedly because IPS completely railed, and later I was told that that was the reason why SEI gave up on restoring the original alignment.
Anyway, I was sufficiently annoyed and relieved the HEPI offset by pushing TMSX as far as we can in a hope that this is the last time I'm annoyed by the difference between offset-only and isolated (because we'll always isolate from here on).
In a retrospect I didn't have to go back to offset-only, I could have just changed the setpoints, but that's what I did due to various reasons. Anyway, In the end, I obtained this: (H1:HPI-ETMX_IPS_RY_SETPOINT_NOW, RZ)=(-389800, 111650).
I also copied these numbers and put them in H1:HPI-ETMX_IPS_RY_TARGET and RZ.
IPS are still yellow (about 20000 cts on V1 and V2) but not railing.
Just so that it's clear:
Alexa, Daniel, Sheila....we have safely returned from EX and completed our work there for the evening
| TMSX (PIT, YAW) w/ PD Voltage | ITMX (PIT,YAW) w/ V | ETMX (PIT, YAW) w/ V | |
| PD1 | (205. -206) w/ ~2.5, 0dB | (84.5, -45) w/ 6.5, 0dB | (242.0, 95.5) w/ .36V, 0dB |
| PD4 | (274.5, -268) w/ ~2.5, 0dB | (52.5,-78) w/ 6.7, 0dB | (265.5,65.5) w/ .4V, 0dB |
| aligned | (239.75, -237) | (68.5,-61.5) | (253.75, 80.5) |
| slider cal [urad/urad] | (1.04, 1.16) | (1.17, 1.14) | (1.53, 1.20) |
After HEPI offset was relieved by moving TMS PIT, initial alignment was attempted again, and we got the above. The power level is consistent with the original alignment (alog 9064).
However, strange thing is that the ETMX slider calibration seems to have changed by a factor of two-ish for both P and Y (Ref: alog 9126 and alog 9087). Because of this, I cannot totally kill the possibility that we're fooled by multiple bounces though it's very unlikely because the power levels are the same as before. (But the question is, did somebody mess with SUS?) Tomorrow we need to start with the "aligned" numbers above and see what happens.
| TMSX slider cal (P, Y) [urad/urad] | ITMX | ETMX | |
| Dec 24 2013 | (1.04, 1.14) | (1.2, 1.1) | (0.8, 0.6) |
| Jan 06 2014 | (1.04, 1.14) | (1.17, 1.14) | (0.90, 0.51) |
| Jan 13 2014 | (1.04, 1.16) | (1.17, 1.14) | (1.53, 1.20) |
Keita and Alexa writing as Sheila.
I noticed that LLO was running their main ion pump at 7kv in the end station. Ours was set to 5kv.
Today at 22:30 UTC I set the voltage to 7kv. The immediate response has been a small increase in pressure at PT510. We'll watch for a few days and see where it goes.
Here is the last 11 hours of pressure. Looks like the 7kv is doing its thing.
[Dick, Daniel, Koji]
The POP 2f demodulator unit previously installed on row 28 of the ISC R2 rack (c.f. this entry ) was replaced with the 2f demod unit.
This unit has a 24MHz LPF and a 80MHz HPF on CH1 and CH2, respectively, forming a diplexer configulation for 18MHz (2xf1) and 90MHz (2xf2) signals.
Therefore, the temporary power splitter for the POP 2f path was removed.
Because of this action, we expect that the demod phase for the POPAIR18 and POPAIR90 were changed.
The 3f demods (CH3/4) still have the power splitter. This will be removed when the 3f diplexer unit is installed on row 27.
We also cleaned up some of the RF cables:
- The REFLAIR9 cable plugged on row 34 is now routed through the patch panel on row 27.
This means that the demod phase of the REFLAIR_A_RF9 was changed.
- The cable for REFL9 was made and connected to the demodulator on row 34.
- Unnecessary connectors/cables were removed from the patch panel on row 29.
We also added the cables between the greeen PFDs and the PLL error signals, as well as 2-pin LEMOs between the PLL servo outputs and the VCO tune inputs.
Then I adjusted the demod phase of REFLAIR_A_RF9 by toggling the swtiches of the phase shifter. This was adjusted for PRX. I haven't done it for REFL_A.
Last set of TFs on H1-SR2 showed a longitudinal to yaw cross coupling at 1.51 and 2.77Hz. I adjusted the Coil Holder and recentered the BOSEMs. There were only two of the four Coil Holder Mounting Brackets installed, (which may be a source of the noise in this suspension and a contributor to the cross coupling) when the earlier TFs were taken. The missing two Mounting Brackets required modification due to misaligned mounting slots. These modifications were not completed in time to be installed on the suspension before it was moved to the LVEA. One of the Mounting Brackets was modified correctly; and has been installed on the suspension. The second Mounting Bracket was not modified correctly and will need to be reworked before it can be installed. Three of the four Mounting Brackets are now clamping the Coil Holder to the Weldment. I have started a new set of TFs on H1-SR2, to see if the BOSEM adjustment and the addition of the third Mounting Bracket will improve the performance of the suspension over that revealed in the earlier TFs.
For my own apparent nomenclature, the "coil mount brackets" that Jeff is referring to is actually the tablecloth mounting brackets which attach it to the structure.
