Notes and questions from a first integration in Catania of the DOM top hemisphere

Picture of a first workspace for DOM integration The black little table is the support for DOM integration. In the table will be mounted the system to maintain still the PMT structure during gel pouring ( work in progress) NOTE: this kind of support allow us to use non specific table for assembly, and also we can remove the support when we dont need that, and use the free space on the table, reducing the needed number of work tables

Before the assembly, the breakings in the structure have been filled by means of acetyl black silicone applied in the internal surface to avoid contact with the gel

Picture of the top hemisphere used for the assembly It was an hemisphere tested during the miniDOM production The mushroom was already glued into the hemisphere

Gluing of the manometer The manometer was inserted into the structure The space around it has been filled with acetyl black silicone  NOTE: during the gel pouring the gel went inside the manometer, flowing between the manometer and the plastic window. The manometer doesn’t work  NOTE: the surrounding silicone applied after the mounting didn’t stop the gel  QUESTION: How to close tight the window of the manometer?  QUESTION: if we cover the lateral part of the manometer’s window with silicone before the mounting, it can yet go inside the structure?

Mounting of the ring light concentrator We pulled a little corner of the cover before mounting We removed the cover after the ring mounting  NOTE: in this way we manage the rings with the cover, and remove that only after positioning  NOTE: the lot of the rings didn’t fit with the structure  NOTE: where possible, we mounted the junction of the rings close to the pin in the structure, but it was not possible for all the rings  NOTE: it was very difficult to maintain still the ring in the structure  NOTE: little space between the two parts of the junction  QUESTION: could be used a glue if the ring doesn’t stay still in the structure?

Gluing of the PMT structure on the mushroom  NOTE: a little space remained between mushroom and structure due to the thikness of the silicone  QUESTION: Do we have to apply a weight on the structure during silicone harshing?

Gel preparation and pouring 2 kg of gel (A:B=1.5:1) was mixed into a can It was poured into a second can with a valve The gel in this latter container was degassed  NOTE: in this way we don’t need to pour the gel after the deassing, avoid the production of air bubles  NOTE: in this way we waste two containers for each gel pouring…expensive? After degassing we positioned the can upon the structure, connected the valve to the tube, and opened the valve ( the system used is an old setup. It will be replaced …)

 NOTE: very slow flow. We scared about polimerization that can start before the end of the phase  NOTE: all the phase kept almost 1 hour  QUESTION: We used a tube of 10 mm of diameter? I remember 8 mm in the specifications  NOTE: to speed up the flowing, we added 1 kg of gel into the can, to give an additional weight QUESTION: could be it a way to speed up the flowing better than positionig the can in a very high position?  NOTE: between the tube and the insert into the structure, the gel went outside

Sad results of the gel polimerization NOTE: 1.2 Kg of gel was used for top hemisphere NOTE: in each of the part where the structure has that shape, we had a lot of air bubbles QUESTION: Is that shape of the structure able to let the air bubbles flowing to the top? QUESTION: do we have done some mistakes? NOTE: air bubles all around the interface between the mushroom and the PMT structure NOTE: unfortunately we cannot say if the bubbles have been produced during gel pouring or during gel polimerization