1. WA105 General Meeting at CERN 21 & 22-January-2014 Enrique Calvo Alamillo

2. 1.Goals. 2.Support proposal. 3.Next. 2

3. The idea of this proposal, it is following the 3x1x1 solution from Adamo, create a common support frame structure that will be used to support the PMT with its electronic base, the Mu-metal shielding (if needed) and the transparent window (acrylic) coated by TPB. The main requirement will be avoid introduce stress on the PMT, shielding and window due to the fixation on the support frame structure, during the manipulation and temperature gradient, during the operation. This could be achieved avoiding over constraining those elements inside of the support frame structure at any situation. And could be carried out maintaining the PMT floating inside of the support frame structure, leaving enough gap between those elements and the support frame structure, taking into account the different situations that will suffer this assembly. 3

4. Assembly Composed by:  8’’ Hamamatsu PMT R5912-02 MOD with a custom ‘Ciemat base’  1 mm thick Mu-metal shielding.  4 mm thick transparent (at ~400 nm) window (acrylic GS233(0F00)) coated by TPB.  Support frame structure of 304 L Stainless steel and Nylon 6.6 pieces assemblies by A4 stainless steel screws. Views of the 3D proposal 4

5. Assembly without the Mu-metal shielding. Assembly without the Mu-metal shielding and without windows, with the TPB coated PMT. 5

6. 6x6x6 prototype proposal. External dimension can be modified. ArDM and 3x1x1 prototype. 6

7. Different elements of the assembly, that can be combined with the same structure. This structure needs to be fixed by one welded piece to the vessel floor of the detector. Or bolted on some auxiliary structure sited on the detector floor. 7

8. 2.1. Support frame structure gap between elements 2.1.1. Mu-metal (If needed). Mu-metal will suffer deformation by temperature of about -0.7mm on the worst case. Relative to the structure of about 0.3 mm. But have a gap of 2 mm taking into account the fabrication/assembly tolerances. To avoid stress in the elements we will maintain the PMT, Mu-metal and transparent windows floating inside of the support frame structure. The support frame structure of stainless steel will suffer deformation by temperature (dt=~220ºC) of about -1mm and the Nylon pieces of about -0.3 mm on the worst case. This structure it is not a rigid piece, can absorb certain strain to avoid introduce deformation/stress to the PMT. The PMT will suffer a buoyancy force of about 4 kg vertically, this will be absorbed by the structure on the top nylon pieces. 8

9. The acrylic windows will suffer deformation by temperature of about -7.3mm on the worst case. Relative to the structure of about -6.5 mm. This setup will permit to absorb differences of 8-10 mm. 2.1.2. Transparent windows. 9

10. The borosilicate glass of the PMT will suffer deformation by temperature of about -0.15 mm. Relative to the structure (Inox+Nylon) of about +0.5 mm maximum. The PMT will be assembled with at least 1 mm gap. 2.1.3. PMTs. 10

11. 2.2.1. Acrylic GS233-0F000. 2.2. Fabrication of the pieces. Those pieces will be produced by laser cut from 2030x1520x 4 mm3 plates. And coated by TPB. 2.2.2. Mu-metal. Those pieces will be custom produced by the supplier. 11

12. 2.2.3. Nylon 6.6. Those pieces will be produced by milling machines from plates. Mu-metal. PMTs. 12

13. 2.2.4. Stainless steel pieces. will be produced by laser cut from 2, 3 and 8 mm plates. 13

14. These will be finalized by CNC bending and forming machine. These pieces will be produced by turning machines. 14

15. 3. NEXT. -Produce a prototype by next collaboration meeting. -Test with the cryogenic PMTs in a cryogenics setup, including a coated TPB windows and the Mu-metal shielding, during 2015. -Produce the 36 (+ spares) mechanical assemblies, beginning 2016. 15