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STAR PIXEL Detector - Mechanical

April 2008

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STAR PIXEL Mechanical

Mechanical requirements and constraints Participants PIXEL mechanical system Work on mechanical stability with rapid installation Work on air cooling Work on detector integration into STAR

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Tracking from outside in to locate the vertex

Outer layers provide hit to track association and a measure of momentum

PIXELS, inner two layers provide high resolution vertex location

Required Resolution TPC SSD ~ 1 mm SSD IST ~ 400 m IST PXL 2 ~ 400 m PXL 2 PXL 1 ~125 m PXL 2 + PXL 1 Vertex ~ 40

m

TPC

PXL 1

SSD

IST

PXL 2

smaller is always better,no limiting requirement

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PXL pointing resolution and associated requirements

Multiple coulomb scattering limited – no reason to have better hit resolution than 9 m

hit resolution sets limit of pixel to pixel mechanical stability – better than 9 m

PXL unit stability set by pointing resolution of IST – better than 125 m (see previous slide)

=(13 19GeV/pc) m

1=2=9 m

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Mechanical effort

Eric Anderssen (Project Engineer), LBNL engineer working on ATLAS pixels is phasing into our pixel program – full time end April 2008 (carbon composite expert)

Contracted ARES Incorporated for analysis on cooling, precision mount design and refinement of ladder stability. Phone meetings weekly

First results – May need Sub-Ambient Cooling to meet goals set at time of

contract Precision Mount Sources of Sector Mechanical instability, temperature variation,

gravity and air flow under control Latest number for moisture adsorption encouraging but needs further

work First stage report received

Results of Hygro-Thermo-Structural Stability (and vibration) Kinematic mount design and load transfer

Some parallel analysis effort at LBNL

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Pixel support structure – current development

2.5 cm radius

8 cm radius

Inner layer

Outer layer

End view

ALICE style carbon support beams (green)

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HFT Pixel Structure Installed (Concept)

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‘D-Tubes’ covered byPixel Services

Articulation Pantograph

Beam Pipe Supports

Articulation GuidesSupport Rails and TableAlso supports External Service ‘Card Cages’

‘ISC’

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Follower guided insertion operation

Open Closed

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Clears Beam Pipe overLarge Diameter

Clearance for Beam Pipe Supports andKinematic Mounts

Final Motion engages

Kinematic M

ountsArticulationRegion

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Pixel placement concept Detector assembly slides in on rails Parallelogram hinges support the two detector halves while sliding Cam and follower controls the opening of the hinges during insertion

and extraction Detector support transfers to kinematic dock when positioned at the

operating location

pixel support hinges

cam followers and linear camslide rails

sliding carriageReason for no bottomBeam Pipe support…

kinematic dock

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Components Developed with Ares

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Kinematic Mounts Inlet Duct

‘Strong Back’ with Cam-Follower(part of articulation hinge)

‘D’ Tube

Load Transfer Mechanisms

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Load Transfer from insertion table to Mounts

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Requires that all of delivery system, and kinematic mounts are available by then (half if only 2 sectors installed)

New Beam Pipe, ISC, Articulated rails/D-tube, and Modified East Cone

Engineering Installation

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Sector/ladder design—what was analyzed

thinned MAPS chips2 cm by 2 cm, 50 µm thick

multilayer aluminum kaptonflex circuit cable for signal and power thin carbon composite substrate

carbon composite support beam

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Heat loads defined by region on MAPS chips and End of Ladder electronics

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Internal Fins base lined for further Analysis

Flow rates of 4-8m/s used—produces flow in the 50CFM range, which seems reasonable

Fins required to improve heat transfer area, given Heat Transfer coefficients for air of this velocity

Fins also improve some of the structural deformation modes, but add material Don’t know how to build fins yet Have not modeled air flow, so cooling rates likely optimistic

Fin size and position likely needs further optimization Need to build prototypes to guide this

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Eric Anderssen

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For flow on inside only, most recent result

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Displacement from imposed Thermal Distribution

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No Silicon

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Parallel LBNL analysis effort indicates that a very low shear adhesive is necessary to control thermally induced deformations.

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Hinge analysis—Mount Engagement Forces

15kgf (~150N) applied at end of magenta links (rigid elements)

Stresses are low (from an alternate analysis not shown)

Deflections are shown on Y axis only (note reversal)

Max Deflection is 0.14mm (negative Y)

Aim is to show that Hinge, under insertion load will hold kinematic mounts within appropriate acceptance window of Kinematic Mounts

Analysis shows this is currently acceptable

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-0.14mm

+0.015mm

+Y

Analysis of initial hinged parallelogram concept; additional concepts are also being investigated to understand if an even simpler solution is available.

Analysis shows that this is viable

~0mm

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Cut Apart Current Cones August 2009

Old East Cone and most of Beams to be reused to support New West Cone

Old West cone refurbished into New East Cone in Berkeley Cut Carbon Elliptical Beams avoiding Al Insert

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Send to BerkeleyKeep at Brookhaven

Eric Anderssen

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Modified East Cone and Install with New West Cylinder

View as Temporary Fix—Should be ACAP (as cheap as possible) Supports end of New West Cone/FGT Replicates Old Beam Pipe Interfaces Includes SSD if required Only for summer ’09 to ‘10

Wholly Machined/Bonded Solution Tooling to locate Buck Plate while bonding is

required…Buck Plate aimed forEasy Swap of replacement

Some Tooling Required…

~1.5m

Eric Anderssen

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Goal—Swap-in Replacement and Install pixels – summer 2010

Should BeSame Length

New East Cone with Cylindrical Shell made from Old West Cone

Swap in by matching Bolted Interface to New West Cone…

ModificationWill Take UpLength…

Include SSD interface On Shell

Eric Anderssen

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ISC fits inside and is supported by the cone

ISC supports IST on outsideISC ISC supports pixel and beam pipe inside

Inner Support Cylinder (ISC)

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Layout of Insertable Cone Structures in IFC

Note that SSD and FGT will likely be installed before internal system (IST/PXL) is available If SSD not installed could pre-integrate on outside of New East Cone prior to opening…

Aim is for quick integration of these during any one opening As much pre-integration as possible prior to opening is a priority

ISC with Beam Pipe and IST are inserted first into Cone Structure (with FGT and SSD installed)

ISC needs to be removed to install IST if it lags pixels

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Gap for ISC services Required thru ISC support off of NCS

SSDIST-15C(?)

Room Temp

Pixels Cartooned in

Anderssen

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ISC Integrated with IST and Beam Pipe

Smaller cylinder has both IST and Beam pipe supports Integrated Integrate IST first on Small Cylinder where appropriate (MIT or BNL) Insert Beampipe and fix on mounts

Requires long bench to support Beam Pipe until full load transfer to ISC Right hand side eventually cantilevered by this structure for insertion into Cone

Structure

Add large cylinder, transfer Beampipe to top support no permanent bottom support—interferes with Pixel insertion rails/tooling)

Dress IST Services on outside of large Cylinder

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Separate Cylinders (bolted Interface)

Asymmetric Beampipe Allows for Articulation of Pixels to small Radius prior to insertion into smaller cylinder

Double support provides moment constraint for insertion

Include Service Penetration/Seal

Insertion Rails

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Assembly Sequence Aims at Parallel Integration

PXL

PXL Insertion (after Cone in STAR)

ISC

IST

ISTIST Integration

Beam Pipe Integration

FGT

SSD

SSD

NCS

SSD Integration

FGT Integration(COMPLETED PRIOR)

PXL IS Insertion(includes BP and IST)

ISCIST

IST

Insertion into STAR

SSD Integration Done independently

(as required)

’09-10?

Intention to place PXL engineering ‘patch’ system as early as possible—preceding IST Installation

IST/ISC follows FGT by ~1yr

Pixel Compatible BP ‘should’ be ready…

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Summary

PIXEL mechanical initial analysis on cooling, support stability finished

Next step is prototyping with the return of Eric Anderssen to full time STAR effort

Initial work progressing on integration and overall detector and beam pipe support and instillation.