[Nakano, Shigeo Nagano, Kokeyama, Kawamura, Miyoki (remote) on 5th June]

In addition we changed the temperature setting (to 24deg C) of the PSL room, two dehumidifies (Mitsubishi MJ180-MX) were installed inside the PSL enclosure to avoid the condensation. Water is drained by hoses to the outside tunnel drainage ditch.

Resulting humidity in the PSL room is now 60% max and 34% min, whereas 70% max, 43% min before. We believe condensation won't happen.

However, there are still very rapid humidity raise at every cycle of the AC control. When the temperature goes up and the AC goes off, humidity goes up very rapidly for about 10 mins. After that, humidity starts dropping, presumably due to the new dehumidifire. It can be explained as follows: water cooling AC has drains to remove condensations inside the AC, and water is draining from there. Once the AC stops and heat exchange stops, while fan is still being on, condensation water in the AC goes out to the air suddenly. (Miyoki-san's hypothesis

For the long them, we need a better AC which dehumidifies not only the air circulating inside but also the air supplied from the outside. Also AC should be able to keep running, instead of turning on and off to control the temperature.

Plots are humidity and temperature data of PSL front room (FIELD_PSL), PSL room in front of the AC (FIELD_PSL2), and PSL clean area (BOOTH_PSL). The latter two are new sensors installed on Friday. Comparing the PSL front room (FIELD_PSL) and PSL room in front of the AC (FIELD_PSL2), humidity of the latter is several % higher than the former. So we assume that humidity before the temperature used to be about 80% max!!