I removed the windows of both tubes. The windows of the long tube are a little bit dirty, maybe the energy dropping was caused by the leakage. The most possibility is the leak from the windows. Firstly it's diffcult to take the window from the holder, I dropped some ethonal into the gap between window and the holder, the window became loose and was easy to remove. I cleaned windows carefully. Unfortunately I found there was a light breakage inside the window, we should order new window for the long tube.
I installed all windows in the afternoon, and made the passivation for both tubes. Before my leaving I filled the Helium into the chambers by 1500 mbar for leakage checking. I will continue to passivate the tubes.