Mass production and mechanical structure P. Pakhlov (ITEP)

Comparison with T2K Use and imrpove T2K experience. Why we have to differ?: Belle KLM strips are at least 2 times wider to reduce cost (light ~ 1/sqrt{width}) and (some of them) 1.5 times longer (light ~ exp(-length)). We need to be economical and try to collect as much light as possible to keep high efficiency at far end!  T2K: 1 mm Kuraray Y11 fiber. We are going to use 1.2 mm fiber, taking advantage of ~ 1.3 X 1.3 mm 2 SiPMs (both Hamamatsu and CPTA produce this size).  T2K: fibers have dry connection to the strips. We glue fiber to the groove to increase the light collection by : equally efficient for both central groove (Fermilab strips) and sawed groove (Kharkov strips).  T2K aluminized the polished end and got ~70% mirroring efficiency. We glue the 3M mirror to the far end; this double the light yield from the far end. T2K BelleII D1.2 mirror

Strips mass production Operations, required to produce strip segment:  Quality control of fibers (automatized with fiber rewind)  Cuting fibers and polishing fiber ends (to be done simultaneoulsy for hundreds fibers);  Glueing the mirror to the far end (experience of T2K group from INR, Moscow is useful);  Glueing fiber inside the strip groove (experience from OPERA)  Glueing the SiPM housing to the strip;  Quality control of SiPMs (and database for 16k SiPMs);  Glueing the SiPM to the housing and soldering to preamplifier;  Glueing 15 strips into one segment (good for transportation, match with 16 channels electronics, 5 segments fit the existing iron gap size); Unlike T2K we do not use substrate because of different thermal expancion of polysterol and good materials for skin (G10, Al etc) Estimated time and manpower:  Strip production (12000 kg) 4 – 6 months.  Fiber production (30 km) ?? (to be checked with Kuraray)  SiPM production (16 k) ?? (to be checked with Hamamatsu and CPTA)  Glueing: ~ 20 – 30 min/strip * 16 k = (3 – 5) man-years;  Mounting segments to frame: 2 hours * 4 man/sector * 104 = 0.3 man-year preliminary To be elaborated during full size prototype production (fall 2009)

Mechanical structure The weight of one sector with RPC: Al frame 20 kg two Al covers 2 * 30 kg RPC 120 kg Plastic support str 40 kg Cables/strip masks etc 20 kg Total 250 kg The weight of one sector with scintillator strips: Al frame 20 kg Scintillator 120 kg Support str 20 kg Cables etc 10 kg Total 170 kg Al sector frame is required for transportation at B4, mounting/dismounting in iron gaps. The existing ones are obviously fit the gap well (and are not cheap): try to reuse them

Rigidity of the frame and structure for segment mounting  Acceptance is similar to the present one with RPC (the inner part can be milled to circle, provided the mirrored fiber is slightly shorter)  Rigidity of the frame is provided by the net of Al profiles in x and y directions welded or screwed to the frame.  Segments are screwed to the Al profiles in few points, as polysterol thermal expansion is much bigger than that of Al.

Mounting  Using T-beams: the x-y profiles are welded together and to the frame; segments are inserted from the top and screwed to the profiles  Using I-beams: The x-y profiles are welded together; segments are inserted from one side; then the assembled x-y net is screwed to the frame.

With the present configuration the installation is only possible when KEKB optics near IR is dismounted. Ineterference with time schedule for KEKB installation? No chance to repair? Can this be improved? Sector installation, repair

Plans by TDR Elaborate the mass production operations, Design the necessary machinery, Fix (at least estimate reasonability of few possibilities) the mechanical structure! In the moment all sizes are flexible, however once we order the strips, it is not easy to change the sizes, Produce full size prototype using Fermilab & Kharkov strips and Hamamtsu and CPTA SiPMs, Deliver the prototype to KEK and check the compatibility with mechanical structure, Choose the producers for strips, SiPMs.