[Washimi, Takahashi]

• We removed the 1kg ballast ring from the IP. The resonant frequencies for L and T were close to the reference (klog).
• We investigated the IM H1 OSEM. Details are here.
• We adjusted the H1 OSEM position to 2800 (near the middle of the dynamic range). The H1 OFFSET in "K1 SRM IM OSEMINF FILTERS" was changed from -6315.5 to -3700.
• We checked the height of the TM/RM. One laser leveler (red) was set to the height reference on the chamber (Pic. 1). The other laser leveler (green) was set to the red line (Pic. 2). The red line consisted of the X+ side wire breaker on the RM (Pic. 3), and was 0.5mm higher than the marker on the front ring of the RM (Pic. 4). The green line also consisted of the X- side wire breaker on the RM (Pic. 5), and consisted of the marker on the front ring of the RM (Pic. 6).
• We adjusted the gap of the EQ stops and took pictures of them.

This afternoon, I entered PSL and offloaded manually IP1 PZT PIT and YAW, which are used as DOF4 PIT and YAW controls. After that, IMC seems to be stable without any satuaration.

We checked the IP transfer functions after removing the third 1kg ballast ring.  The resonant frequencies of the IP were changed from 59 to 66mHz for L and from 66 to 70mHz for T. They were close to the reference (63mHz for L, 70mHz for T).

[Washimi, Takahashi]

We investigated the IM H1 OSEM. The transfer function was recovered when the OSEM position was in the linear range, 5600 (Pic. 1). We swapped the stellite box channel for H1 and H2. The output was changed (Pic. 2) as shown in the table. Ch. 1 output was smaller than that of Ch. 2 in both cases. The satellite box has a problem. The transfer function of H1 using Ch. 2 showed a gain higher than the reference (Pic. 3).

I offloaded the BF GAS with the FR.

[Washimi, Takahashi]

We adjusted the suspension.

• After offloading the BF and F1 GAS filters, we adjusted the V1/2/3 OSEM positions to the center of the range.
• We removed the 1kg ballast ring from the IP. The resonant frequencies for L and T were changed (klog).
• We investigated the small gain of the H1 OSEM in the IM transfer functions (Pic. 1). We checked the forward voltage of the diodes and resistance at the feedthrough flange (Table). They were normal. We calibrated the OSEM output by moving the IM body in the 1/4 pitch of the M4 screw for the EQ stop (Pic. 2). The maximum value was 7500 counts (Pic. 3). The calibrated coefficient was 0.136 um/count (Pic. 4). The original coefficient was 0.299 um/count.

[Tanaka, Ushiba, Hirose]

In preparation for the PRCL and SRCL measurements, we replaced the PDH Local Oscillator(LO) for the GRX with the measurement LO and checked the number of optical components.

• We prepared an LO to do phase-locked loop (PLL) using the sub-laser and main-laser beams by combining them in the POS table. A phase-locked loop (PLL) cannot operate properly unless the LO has a lower noise level than the phase noise. The LO for the GRX’s PDH is a High-spec LO (photo1 below) that can also be used for the PLL, so we will use this one. We replaced the LO for the PDH with a new one(photo1 above, photo2, photo3) that satisfied for PDH.
• For this experiment, we plan to use the mirrors, HWP, PBS, and lenses stored in the front room of the PSL. Mirror mounts, lens mounts, HWP mounts, IRIS, and other items will be taken from the areas around the POP and IMCREFL.
• We confirmed the number of optical components(excluding the 2-inch mirror) in the current PSL front room, so I posted the details(JGW-T2415582-v6) on JGWdoc.

I checked the IP transfer functions after removing the second 1kg ballast ring.  The resonant frequencies of the IP were changed from 55 to 59mHz for L and from 63 to 66mHz for T. They are still lower than the reference (63mHz for L, 70mHz for T).

I offloaded the F0 GAS with the FR.

[Ikeda, YamaT]
 

Abstract

In recent these days, we replaced IO chassis from V1 to V2.
(K1TEST0 in klog#33560, K1IX1 in klog#36572, K1IY1 in klog#36625, K1EX0 in klog#36654, and K1EY0 in klog#36692).
Real-time models on these front-ends seemed to work well.
But they had a problem that a IRIG-B timing took so long time to be stable when the cold boot of the front-end computer was performed.

Last weekend, we realized that this might be caused by a mix-up of different fiber-optic cables.
So we replaced fiber-optic cables of K1TEST0, K1IX1, K1IY1, and K1EX0 to the correct combination.
After then, the issue of the timing synchronization taking too long no longer occurred.

We had no enough time to go to Y-end today, so we will do same thing for K1EY0 tomorrow.
 

Details

The V2 IO chassis uses a new cable connection standard, and some of its specifications are different from those of the V1 IO chassis. The most significant difference is that the data transfer cable between the front-end computers and the IO chassis has been changed from custom-made HIB optical fiber to standard MTP fiber (OM3). Thanks to this change, we are no longer constrained by the limited availability of HIB cables and we can provide additional IO chassis as spare ones and/or for new instruments in future e.g. filter cavity.

In addition to this change, timing fiber cable in the IO chassis was also changed to the OM3 cable. Strictly speaking, the SFP port of the timing slave was directly accessible from the front panel on V1 IO chassis and any SFP module could be attached, so there were no internal cables. In other words, it is more accurate to say that the interface was changed rather than the cable standard.

Until now, OM1 cables have been installed for multimode optical fiber, not just for timing signals. (Since single-mode fiber, OS1, is used for long-distance connections, this is slightly off-topic.) So the most of timing slaves in the V1 IO chassis were connected to the timing fanout with OM1 cable and we had reused them for V2 IO chassis when we had replaced IO chassis from V1 to V2.

Although the real-time models themselves were running well also in this configuration, there remained a mystery as to why it took several hours for the IRIG-B timing to stabilize after a cold boot of the front-end computer. Figures 1 and 2 show the fluctuations in the IRIG-B value following a cold boot on EY0 and IX1, respectively. Both of them shows that it takes o(hours) time to stabilize the IRIG-B value within normal range (5-20us). And also, for EY0 (Fig.1), it's reproduced in 3 times trial.

The IRIG-B value is not the primary source of timing synchronization but merely serve as a cross-check. However, if they fall outside the normal range, RFM and Dolphin communication will fail. As a result, a global control cannot be done. Even if it took so long time to stabilize IRIB-B value, it finally went to normal range. So we was able to resume global control by waiting this fantastic time. But waiting time as o(hours) was serious from the view point of effective downtime of the digital system for keeping commissioning time and also observing time.

At first, we didn’t realize the relation between the IRIG-B issue and fiber cables standard, but we finally noticed that OM1 and OM3 cables have different core diameters (62.5 μm and 50 μm, respectively) and that mixing them can cause speed reductions and instability especially for the long distance connection in Ethernet case. To be honest, I wasn’t sure if the same discussion applied to Timing synchronization, but We decided to try unifying the fiber cable as OM3.

After replacing the fiber cable, we didn't need to wait that IRIG-B timing was stabilized. And it's not reproduced in a few times power-cycle. After replacing the fiber cable, we didn't need to wait that IRIG-B timing was stabilized. And it didn't appear also in a few times power-cycle. So we concluded that the IRIG-B issue was induced by the mismatch of the optical fiber standard. Today, we was able to complete a replacement work for K1TEST0, K1IX1, K1IY1, and K1EX0. Reaming K1EY0 will be processed tomorrow.

[Washimi, Takahashi]

We recovered the flags touching the OSEM bodies in the IM. We rotated the IM with the yaw picomotor, aligning the TM with the F0 yaw FR. The H3 flag was released easily (Pic. 1 and 2), then the H1 (Pic. 3) and V2 (Pic. 4) flags touched the OSEM bobies. Though we tried to find good relative geometry between the IM and the IRM, we could not find it. The strategy was changed; we adjusted the positions of the OSEM bodies, moving the base panel of the OSEMs. The axial positions of the H1, H3, and V1 OSEMs were also adjusted. We rotated the H2, H3, and V3 flags to be perpendicular to the LED-PD line in the OSEM.

We have updated the k1vissrmt model file and removed unnecessary DAQ channels.

Requests from Ushiba-san and R.Takahashi-san
Related to K-Log#36664
[K1SRM]
 model: k1vissrmt
 detail: Change the input ADC channels for ACC_H1, 2, and 3 from 20, 21, and 22 to 21, 22, and 23

Request from YamaT-san
 We have commented out K1EDCU_TESTIOC.ini from the DAQ master file.
 

[Nakagaki, Tanaka, Ushiba, Hirose]

We plan to set up a new sub-laser and optics on the POS table in order to perform absolute measurements of PRCL and SRCL. Therefore, it is necessary to draw up a layout for the POS table such as JGW-T1909623.　Today's work confirmed the current configuration of the optics. 

• There was an optical setup for the GRY lock (green optical fibre from the PSL room, a mirror for Fibre Noise Cancellation, a PD for Phase Noise Cancellation, and an RFPD for PDH signal detection) that performed a similar function to the GRX lock on the POP table.
• Furthermore, for IR light, there were PDs for S-polarisation and P-polarisation for dark matter measurements.

We have asked Nakagaki-san to draw up detailed diagrams of the optics. This will be posted in JGWdoc or Klog.

With Hayakawa-san, SawadaH-san, TakahashiM-san, Yamaguchi-san, Ohmae-san

The Ncal pylons were moved from the X-end parking area to its original location under the beam pipe inside the X-end experimental room.

Before the relocation, the following preparations were performed:

• The protective cover used during the transportation through the 3 km tunnel was removed.
• One of the pallets was found to be dirty, so it was replaced with a clean one available inside the tunnel.

Pictures: link

I measured the spectra of the FLDACCs. They look fine. The displacement noise was less than 0.1um/rHz at 0.1Hz.

I checked the IP transfer functions after removing the 1kg ballast ring.  The resonant frequencies of the IP were changed from 51 to 55mHz for L and from 59 to 63mHz for T. They are still lower than the reference (63mHz for L, 70mHz for T).

[Nakagaki, Ikeda, YamaT]

We could solve the issue of missing PCIe card by replacing DAC#2.
After then ADC and DAC noise were measured for all channels and finally k1iy0 came back online.

Note that PEM speaker output cable is now unplugged from AI chassis because timing synchronization cannot be recovered with plugging speaker.
Please connect it when it'll be used.
According to experience on MCF, after the timing synchronization is established once, it can be connected.
But it sometimes makes an OS hang-up, so it's better to be unplugged again after using.

-----
Solving missed PCIe card issue
Today, we tried to reproducibility of yesterday's situation at first by removing BO card and then swapping DAC#0 and DAC#1. But OS couldn't find the DAC#1. So we concluded that removing BO card is not an ensured way to operate two DACs. Next, we replaced DAC#1 from S1809372 to S2516731. Then, two DACs could be operated even if BO card was also installed and reproducibility was also verified by power cycles in several times. We haven't identified a reason why S1809372 didn't work properly. But we doubt two cases now and will check them on the test bench.
1. That DAC was just damaged by the issue of speaker.
2. LIGO firmware wasn't applied to that DAC. (It was not purchased by DGS. So we don't know a detail of it.)

Noise measurement
After all PCIe cards were operated properly, noise level was measured for all ADC/DAC channels as shown in attached figures. Measurement configurations were completely same as ones in K1IX1 (klog#36586), K1IY1 (klog#36641), and K1EX0 (klog#36663). Measurement files were stored in /users/DGS/measurements/ADC/K1EY0/2026/0403_V2_IO_CHASSIS/.

RFM board replacement
When we were cleaning all stuffs up at the end of our work, we noticed RFM connection made an error bit. This was because a usage of wrong SFP modules single-mode or multi-mode. At the 1st floor of end stations, RFM fibers were laid by single mode fiber. On the other hand, the new V4 front-end computer which had been used as K1IY0 in the past had a multi-mode RFM board. So we moved single-mode RFM board from the old V3 front-end computer to the new V4 front-end computer and RFM connection came back online and GDS_TP screen showed all green. As the result, a remaining spare RFM board is multi-mode one.

Remaining concern
Only remaining concern is that it takes a few hours for synchronizing IRIG-B when a cold boot of the front-end computer is performed. In the past, similar things often occurred when down time became so long and a room temperature changed largely maybe because it took long time to be stable in the temperature of a crystal oscillator of timing slave. On the other hand, in this time, it takes long time even when a down time is only a few seconds. Such a thing wasn't reproduced in the test bench. So we have no idea to solve this issue now.

Fortunately, because this issue doesn't occur when the front-end computer is rebooted (there seems to be some difference between reboot and cold boot), we don't face this issue not so frequently. But reproducing and solving it on test bench is required from the view point of reducing a down time. If it's caused by the environment in the mine, we may need an additional test in the mine in stead of using test bench.