FDIRC PMTs dimensional tolerance

1. FDIRCPMTs dimensional tolerance • from Hamamatsu… “Dimension We measured the window size. The test result was as follows: SERIAL NO.        A [mm]        B [mm] ---------------------------------- AA0965                51.98        51.95 AA0967                51.89        51.94 AA0968                51.96        51.97 AA0969                51.87        51.89 AA0993                51.93        51.93 AA1012                51.86        51.75AA1013                52.00        51.99 AA1015                51.88        51.91 AA1019                52.03        52.04AA1028                51.79        51.78 The result showed that the size was smaller than the specs (52.0 mm +/- 0.3 mm). However, we assume that there should be tube to tube and/or lot to lot variation in the size, so we would like to keep the specs of 52.0 mm +/- 0.3 mm. “ Knowing these values for our PMTs will allow to define the smaller PMTs pitch, thus connectors pitch on pcb Massimo Benettoni

2. FDIRCFE boards lodging and cooling • Long FE boards plugged on PMTs and backplane • FE boards plugging as inside crate slots • Power dissipation: up to 1 kW/sector ? • 32 FE boards, about 30 W/each ? • +1 pcb concentrator (33° board): W? • + 1 backplane: W? • FE boards cooling must be uniform and efficient for all of them • concern: convective cooling vs boards pitch: 12 mm • E.g: closed air circuit through heat hexchanger and air filter • Heat exchangers receive deionized cool water from outside the “SOB” • Fans ensure proper air flow Massimo Benettoni

3. FDIRCFE boards lodging and cooling • FE boards plugging as inside crate slots • +1 pcb concentrator (33° board): any dissipation? • + 1 backplane: any dissipation? • On board fans to perform as much as possible uniform and efficient cooling • Case and panels will make closed air circuit through heat hexchanger and air filter • Heat exchangers receive deionized cool water from outside the “SOB” • Fans must ensure proper air flow • Efficiency of air cooling must be proved Massimo Benettoni

4. FDIRCFE boards lodging and cooling Massimo Benettoni

5. FDIRCConvective heat cooling of PCBs • FE boards surface (two faces): 6dm2 • Assuming not all the board surface exchange with same efficiency (due to heat concentrated in some area/components) • let assume 50% area reduction= 3 dm2 • Need to dissipate 30W on 3 dm2 . • Let assume Dt (board-air) of 10°C, • Need convective coefficient of a≈ 100 W/ m3°K • Typical values found (literature) a≈ 50÷200 W/ m3°K ? • Here geometry does not seems favourable … should we expect low a ? • Air specific heat (volumetric, atm. pressure, 300°K) = 1.184 kJ/m3°K • Accepting air Dt of 10°C, Flow must be 0.084 m3/s = 304 m3/h = 5 m3/1’ • 304m3/h = 84.5 dm3/s • Flow section 1x10x34 cm2 = 340 cm2 = 3.4 dm2 • speed = flow/section = 25 dm/s = 2.5 m/s …. Seems low for such high a . . Massimo Benettoni

6. FDIRCExample of heat hexchanger (from Lytron TM) Massimo Benettoni

7. FDIRCConclusion: some open issues • Magnetic shield: still needed? Which thickness, specs, requirements? • Fbox to be finalized, build prototype, test • Buttons material, tests • Fbox handling and insertion fixture and procedure • Tools and procedure for Fbox+barbox handling • PMTs positioning, C-fiber honeycomb, PMTs optical contact • PMTs replacement procedure • PMT retainement • first iteration to integrate FE boards, PS etc in the 3D model • FE boards fitting, replacement, connection, cooling Massimo Benettoni