The EYC Q-mass has stopped measurements due to a sensor malfunction. This is suspected to be because the pressure exceeded the threshold of the protection circuit. The EYC Q-mass is now complete.
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PEM (Tool)tatsuki.washimi - 18:09 Tuesday 30 December 2025 (36002)
Print this reportSnow gauge at Atotsu
I located the snow gauges at Atotsu temporarily.
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FCL (Air)shinji.miyoki - 21:48 Monday 29 December 2025 (36001)
Print this reportComment to Temp Adjustment (35984)
I added heater power by 600W at EYC 1F to increase the temp in the EYC area around 22:00.
MIR (General)takashi.uchiyama - 19:50 Monday 29 December 2025 (36000)
Print this reportComment to Frost on ITMs? (35997) Fig. 1 shows vapor pressure of several materials. According to this figure, the temperature at which H2O evaporates is 170K@1E-3Pa, 160K@1E-4Pa, 150K@1E-3Pa.
Fig. 2 shows changes of vacuum pressure in several places. After 12/26, when the duct shield cryocoolers were turned off, the pressure increased from 1E-5Pa to around 1E-3Pa, so it is thought that it was necessary to keep the temperature of the mirror at about 170K to prevent water adsorption.
Fig. 3 shows summary of temperature of cryogenic payloads at 6:32. 165K@IX/Y 174K@EX 168K@EY
If there is no water adsorption in EX/Y, IX/Y may also see water starting to evaporate with a temperature increase of several K.
GVetmx was closed by the interlock at 6:057 on December 29, 2025, because the vacuum pressure at X_30 reached 1E-3 Pa.
Finally, all the GVs around the cryostats were closed.
MIF (General)takaaki.yokozawa - 10:00 Monday 29 December 2025 (35998)
Print this reportComment to TCam photo session 251225 (35968)I checked the TCam image by the Yuzurihara-san's fitting tools. Fitting results
From the results, ITMX, ITMY and ETMY didn't move so much from the reference point (14th Nov,), but ETMX moved 2.1 mm (0.0885[mm/count]*24[count]) in Yaw direction. (Figure)
I don't know why only ETMX moved in yaw direction, I will check the history.
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MIR (General)takafumi.ushiba - 23:49 Sunday 28 December 2025 (35997)
Print this reportFrost on ITMs?
Tcam images of ITMX and ITMY seemed to change drastically from yesterday. Figure 1 and 2 show the Tcam images of ITMX and ITMY today and yesterday, respectively. It might be due to frosting on mirrors by increasing vapor pressure of water molecules due to warming up of duct shields.
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takashi.uchiyama - 19:50 Monday 29 December 2025 (36000)
Print this report Fig. 1 shows vapor pressure of several materials. According to this figure, the temperature at which H2O evaporates is 170K@1E-3Pa, 160K@1E-4Pa, 150K@1E-3Pa.
Fig. 2 shows changes of vacuum pressure in several places. After 12/26, when the duct shield cryocoolers were turned off, the pressure increased from 1E-5Pa to around 1E-3Pa, so it is thought that it was necessary to keep the temperature of the mirror at about 170K to prevent water adsorption.
Fig. 3 shows summary of temperature of cryogenic payloads at 6:32. 165K@IX/Y 174K@EX 168K@EY
If there is no water adsorption in EX/Y, IX/Y may also see water starting to evaporate with a temperature increase of several K.
GVbsy and GVbsx was closed by the interlock at 10:27 on December 28, 2025, because the vacuum pressure at BSY reached 1E-3 Pa.
We also turned on heater of both side of IYC at 19:40, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
We turned on the heater on the BRT side of duct shield of EYC at 19:40, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
Now, both side of EYC duct shields are heating up.
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VIS (General)takafumi.ushiba - 13:47 Sunday 28 December 2025 (35994)
Print this reportRequest ISOLATED state to Type-A suspensions
Since GV at both X and Y arms were closed and arm alignment cannot be checked by GR and IR flshes, I requested the ISOLATED state for all Type-A suspensions.
Note:
I don't touch BS, so the reason why BS is ISOLATED state would be the earthquake.
The EYC Q-mass has stopped measurements due to a sensor malfunction. This is suspected to be because the pressure exceeded the threshold of the protection circuit. The EYC Q-mass is now complete.
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CRY (Cryostat EY)takashi.uchiyama - 8:47 Sunday 28 December 2025 (35992)
Print this reportComment to Start warming up EY (35790) Since I failed upload the screenshot of the heater control panel for the Arm side of the duct shield yesterday, I upload it here.
We turned on the heaters on both side of the duct shield of IXC at 8:19, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
Now, both side of IXC duct shields are heating up.
I uploaded the screenshot of the heater control panel. Fig. 1: IX-Arm side. Fig. 2: IX-BS side.
We turned on the heater on the Arm side of duct shield of EXC at 8:18, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
Now, both side of EXC duct shields are heating up.
Since I failed upload the screenshot of the heater control panel for the BRT side of the duct shield yesterday, I upload it here. Fig. 1: EX-BRT side. Fig. 2: EX-Arm side.
GVitmy was closed by the interlock at 19:09 on December 27, 2025, because the vacuum pressure at Y_00 reached 1E-3 Pa. After closing GVitmy, the vacuum pressure in IYA (Top-Left of the attached figure) is still 1E-3 Pa.
GVitmx was closed by the interlock at 14:30 on December 27, 2025, because the vacuum pressure at X_00 reached 1E-3 Pa. After closing GVitmx, the vacuum pressure in IXA (Top-Right of the attached figure) is decreasing.
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CRY (Cryostat EX)takashi.uchiyama - 8:30 Saturday 27 December 2025 (35987)
Print this reportComment to Start warming up EX (35789)2025/12/27
We turned on the heater on the BRT side of duct shield of EXC at 8:15, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
Note that we did not turned on the Arm side at this time.
CRY (Cryostat EY)takashi.uchiyama - 8:27 Saturday 27 December 2025 (35986)
Print this reportComment to Start warming up EY (35790)2025/12/27
We turned on the heater on the arm side of duct shield of EYC at 8:15, because the temperature of this duct shield was enough higher than 150K. The heater power is about 8W.
Note that we did not turned on the BRT side at this time.
CRY (Cryostat EY)takashi.uchiyama - 7:46 Saturday 27 December 2025 (35985)
Print this reportComment to Start warming up EY (35790)2025/12/27
GVetmy was closed by the interlock at 5:59 on December 27, 2025, because the vacuum pressure at Y_30 reached 1E-3 Pa. After closing GVetmy, the vacuum pressure in EYC is decreasing.
Since the temperature of the BRT side of the duct shield is still under 150K, increase of the vacuum pressure in EYC due to water evaporation may happen later again.
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FCL (Air)shinji.miyoki - 22:24 Friday 26 December 2025 (35984)
Print this reportTemp Adjustment
Because stopping the cryocoolers for duct shields at all area, the heater powers were adjusted at each station.
Corner station: change rthe setting temp from 18 to 21 for the precision cooler near SR2.
X end station: Heater power from 0 to 900W.
Y end station: No adjustment at present.
Comments to this report:
shinji.miyoki - 21:48 Monday 29 December 2025 (36001)
Print this report
I added heater power by 600W at EYC 1F to increase the temp in the EYC area around 22:00.
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