Aso, R. Takahashi, Akutsu

Synopsis

Two things: (1) Again with 10 W IMC output, we searched for other ghost beams but could not take care anything more. (2) We installed four viewport windows.

Details

After the photo session (27254), Aso-san checked if the OMC could lock and yes.

According to Washimi-san and Yokozawa-san, in the past tapping tests, the upper part of the beam tube in plus Y and the large flange in the minus X were sensitive for the tapping, so I tried to find such unknown ghost beams around there with 10W IMC output but could not find any vivid ghost beams; a part of OFI seemed shining (Fig. 1; the real photo obtained in the photo session by Washimi-san and Yokozawa-san), but I was not sure... actually I was out of the desiging group of the OFI structure including ghost beam cares. So we gave up to do further treatement for now.

We installed four general-purpose windows to the OMC chamber. Two CF203 ones are on the large flanges in the minus Y and minus X direction. One CF152 one is at the +X+Y position near OMMT1. Another CF152 one is in the -X+Y positoin near OFI. Later on, some gige cameras will be installed on these windows to see scattered light in the chamber, after Kimura-san and his collegues finish sealing the large flange parts.

Notions

Afternoon, Kimura-san pointed out that we should use "IPD"-dedicated metal gaskets insted of usual ones for the ICF152 directly attached to the body of the chamber, because there found leaks in the past, according to him, and he thought the main reason of the leak would be the flange would be bent during welding. After discussion, this time we will leave the currently-installed viewports. For your reference, the high-quality viewport window for AS has the same structure, but not with the IPD metal gasket, but so far no severe leak.