[Uchiyama, Nakagaki]
We have changed the operation thresholds of the center's GV closure devices (3 locations) to the following values.
- [GV BSX & BSY] 9.4e-6 Pa
- [GV ITMX] 7.8e-6 Pa
- [GV ITMY] 6.9e-6 Pa
[Yamaguchi, Nakagaki]
We have changed the operation thresholds for the GV closure devices at the X and Y ends.
Together with yesterday's work, the set values for each device are as follows
- [ETMY] 9.6e-6 Pa
- [ITMY] 6.9e-6 Pa
- [BSY&BSX] 9.4e-6 Pa
- [ITMX] 7.8e-6 Pa
- [ETMX] 2.0e-5 Pa
The vacuum gauge used for the interlock system of GVexa fluctuated a lot.
The value sometimes reached 1*10^-5 Pa.
The sensor value of the trigger CC-10 near EXA fluctuates around (0.5~2) x 10^-5 Pa every several seconds. 2x10^-5 Pa was the threshold value for closing.
On the other hand, the CC-10 value at X-27 and at the EXC arma side never fluctuates. So this fluctuation is regarded as fake. Although Uchiyama-kun and Nakagaki-san replaced the electrical part of this CC-10 recently, this fluctuation did not stop. So we need to change its body itself.
The attached figure shows the value from the CC-10 at EXA in Light green. It obviously fluctuated a lot in the past several hours.
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I also confirmed that the indicator lamp at EXA GV was RED.
Kimura-san and YamaK-san will go to the KAGRA site, open GV, and set a higher value for the threshold tomorrow.
Kimura, K Yamamoto, Ushiba(remote), Uchiyama(remote)
We opened GVexa at 9:50.
Today's safety shift (Kimura-sama and Yamamoto-sama) visited the Xend to open GVexa. Kimura-sama checked the vacuum gauge's D-sub connector, but nothing was found. Since we could not recover the vacuum gauge's situation, we decided to deactivate the interlock system for GVexa.
Please be careful of the actual leak event which will be reported via e-mail because the IM temp reached around 140K.