Ultra Low Mass Mechanics with CO2 Cooling for a Future 4 Layer Barrel Pixel Detector Silvan Steuli Roland Horisberger Stefan König CMS Upgrade Workshop FNAL 20 Novemer 2008

Current BPIX Mechanics Two identical half shells 1 type of fullmodule 2 types of halfmodules At least 100 different cablelenghts

Wishlist BPIX mechanics for 2013 Only one type of modules Simpler mechanics Two identical half shells All modules with same cablelenght More clearance between half shells Layer 1 closer to beampipe (44mm → 39mm) BPIX wheels adjustable in X andY (±3mm) → adapt to real situation → safer tolerances CO2 cooling ....

Possible number of faces 18 faces (the current BPIX layer 1) Top face displaced inwards Bottom face displaced outwards Half shells are not equal This design requires: # faces = even number 16 faces (BPIX Layer 1, 2013) Top & bottom faces displaced outwards Half shells are equal This design requires: # faces = multiple of 4

New BPIX layout for 2013 (proposal) Two identical half shells 1 type of fullmodule only Layer 1: R 39mm; 16 faces Layer 2: R 68mm; 28 faces Layer 3: R 109mm: 44 faces Layer 4: R 160mm: 64 faces Clearance to beampipe 4mm

Clearance to beampipe support Insertion: Minimum clearance to beampipe support is 10.5mm @ z= 1635mm.

3D view BPIX halfshell mechanics 2013 Adjustable wheel Half BPIX detector only one endflange shown

3D view BPIX detector mechanics 2013

h coverage of 4 Layer Pixel System 10 20 30 40 50 Number of pixel modules in 4 layers system ~1.8 times of old 3 layers system.

Transverse View of 4 Layer Barrel with FPIX Envelope BPIX supply tube BPIX cabling envelope FPIX envelope need approval soon!

Modified Mechanics for CO2 Cooling Cooling pipes stainless steel. Diameter d = 1.50mm and wall thickness t = 50mm  pmax = 275 bar safety factor 3  pop = 90bar Layer 1 r=3.9cm Diamond filled Araldite 19 Nov 2008 test @ 90 bar Old New

Temperature Distribution of module around CO2 tube Temperature profile of halfside of new BPIX module Silicon Sensor (t=300mm) ROC 75 mm ROC Power 120mW 2/3 Periphery 2mm 1/3 Pixel area 8mm C-fibre facets(t= 300mm)  heat transfer to tube is ok with reduced option !

Cooling Pipe Connections to Supply Tube Micro-SERTO Stainless tubes D=1.5mm, t= 50mm 20 coolling loops per half shell  2 m loop length !

Cassette with rails for pixel-insertion tests Rails for FPIX / BPIX Ribs to emulate TIB & bulkhead inner envelope Cassette made out of Corapan (aluminium-styrofoam sandwich) Rails milled out of 15mm PVC plates Better studies for further pixel detector installation. Corapan rail cassette top lid and top rails not shown

New wheelset for next shutdown New detector top wheel New detector bottom wheel exchangeable spacer exchangeable spacer Old detector top wheel Old detector bottom wheel

Summary Very low mass mechanics for new 4 layer BPIX looks feasable Outer layer 4 has stiffness, layer 1,2 & 3 in very low mass construction Long pigtail modules & ultra low mass construction with CO2 cooling should give large factors in material budget. Impact parameter term due to multiple scattering in FPIX region (h =1.5–2.3) should reduce substantial New BPIX layout with one module type only  # faces = multiple of 4 Layer 1 radius reduces from 44mm  39mm Future BPIX wheelsets adjustable  adapt to real beampipe position Workout detailed design of new BPIX mechanics and fabricate in 3D stereo lithography model inclusive new supply tubes  insertion tests, clearances ! Cassette with rails for pixel-insertion tests design completed → fabrication