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

• ....

• 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

Possible number of faces

• 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 detectoronly one endflange shown

3D view BPIX detector mechanics 2013

10

0

20

10 20 30 40 50

Number of pixel modules in 4 layers system ~1.8 times of old 3 layers system.

coverage of 4 Layer Pixel System

Transverse View of 4 Layer Barrel with FPIX Envelope

BPIX supply tube

FPIX envelope

BPIX cabling envelope

need approval soon!

Modified Mechanics for CO2 Cooling

Cooling pipes stainless steel. Diameter d = 1.50mm and wall thickness t = 50m

Layer 1 r=3.9cm

Diamond filled Araldite

pmax = 275 bar safety factor 3 pop = 90bar

d

tp yield2max

Old

New

19 Nov 2008test @ 90 bar

Temperature Distribution of module around CO2 tube

Temperature profile of halfside of new BPIX module

Silicon Sensor (t=300m) ROC 75 m

C-fibre facets(t= 300m)

heat transfer to tube is ok with reduced option !

ROC Power 120mW2/3 Periphery 2mm1/3 Pixel area 8mm

Cooling Pipe Connections to Supply Tube

20 coolling loops per half shell 2 m loop length !

Micro-SERTO

Stainless tubesD=1.5mm, t= 50m

Cassette with rails for pixel-insertion tests

• Corapan rail cassette top lid and top rails not shown

• 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.

New wheelset for next shutdown

New detector top wheel

Old detector top wheel

New detector bottom wheel

Old detector bottom wheel

exchangeable spacer

exchangeable spacer

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 (=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