KAGRA Logbook

OBS (Summary)

koji.nakagaki - 17:16 Sunday 13 July 2025 (34547)

Operation shift summary

Operators name: Hirose, Nakagaki
Shift time: 9-17 (JST)

Check Items:

VAC: No issues were found.
CRY cooler:
  10:00 We contacted Ushiba-san and Kimura-san because we found a 10K difference in temperature checks. (Fig1)
               Kimura-san checked Q-Mass and said no urgent action was needed. (Fig2)
  16:00 Issue could not be confirmed. (Fig3, Fig4)

Compressor: No issues were found.

IFO state (JST):

09:00 The shift was started. The status was "OBSERVING".
17:00 This shift was finished. The status was "OBSERVING".

Problem with EY-TCam images not displaying in control room (Klog #34542)

Images attached to this report

Comments to this report:

shinji.miyoki - 8:57 Monday 14 July 2025 (34552)

EY_4K_REF3_50K temp is now over 110K. Then the temperature of EY_4K_REF4_50K also exceeded the critical temperature. So slight H2O is expected to be released.

The vacuum level at the EYT side slightly increased from 3.6 to 4.1 x 10^-6 Pa. No changes in vacuum level at the EYGV side. No serious temp changes in the duct shields.

One concern is the temperature of EY_80_SHIELD_TOP is now increasing, and we should avoid it will over the critical temperature.

Images attached to this comment

34552_1752450718_Screenshot from 2025-07-14 08-47-13.png

shinji.miyoki - 9:51 Monday 14 July 2025 (34553)

This is the first time trouble for this cryocooler. According to the past same troubles in IX, the increase to 120K took one day, and it started cooling just after peaking, and it took 5 days to reach 90K. Of course, there are no guarantees for recovery.

shinji.miyoki - 6:41 Tuesday 15 July 2025 (34558)

EY_4K_REF3_50K temp seems to start a slight decrease. While the outer shield (EY_80K_SHIELD_TOP) temp keeps increasing. We need several days of monitoring.

Images attached to this comment