# Presentation: 863983

## STAR PIXEL Detector - Mechanical

- April 2008

## 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

## 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

## 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/pc) m

- 1=2=9 m

## 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

## Pixel support structure – current development

**2.5 cm radius**

**8 cm radius**

**Inner layer**
**Outer layer**

**End view**

**ALICE style carbon support beams (green)**

## HFT Pixel Structure Installed (Concept)

*‘**D-Tubes’ covered by*
*Pixel Services*

*Articulation Pantograph*

*Beam Pipe Supports*

*Articulation Guides*

*Support Rails and Table*
*Also supports External *
*Service ‘Card Cages’*

*‘**ISC’*

## Follower guided insertion operation

*Open*

*Closed*

*Clears Beam Pipe over*
*Large Diameter*

*Clearance for *
*Beam Pipe Supports and*
*Kinematic Mounts*

*Final Motion engages*
*Kinematic Mounts*

*Articulation*
*Region*

## 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 cam*

*slide rails*

*sliding carriage*
*Reason for no bottom*
*Beam Pipe support...*

*kinematic dock*

## Components Developed with Ares

*Kinematic Mounts*

*Inlet Duct*

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

*‘**D’ Tube*

*Load Transfer Mechanisms*

## Load Transfer from insertion table to Mounts

## Engineering Installation

- 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

## Sector/ladder design—what was analyzed

*thinned MAPS chips*
*2 cm by 2 cm, 50 **μm thick*

*multilayer aluminum kapton*
*flex circuit cable for signal and power*

*thin carbon composite substrate*

*carbon composite support beam*

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

## 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

**Eric Anderssen**

## For flow on inside only, most recent result

## Displacement from imposed Thermal Distribution

*No Silicon*

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

## 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

*-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*

## 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

*Send to Berkeley*

*Keep at Brookhaven*

- Eric Anderssen

## 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 for*
*Easy Swap of replacement*

*Some Tooling Required...*

*~1.5m*

- Eric Anderssen

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

*Should Be*
*Same Length*

*New East Cone with Cylindrical Shell made from Old West Cone*
*Swap in by matching Bolted Interface to New West Cone...*

*Modification*
*Will Take Up*
*Length...*

*Include SSD interface On Shell*

- Eric Anderssen

## Inner Support Cylinder  (ISC)

- ISC fits inside and is supported by the cone

- ISC supports IST on outside

- ISC

- ISC supports pixel and beam pipe inside

## 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

*Gap for ISC services Required thru ISC support off of NCS*

*SSD*

*IST*

*-15C(?)*

*Room Temp*

*Pixels Cartooned in*

**Anderssen**

## 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

*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*

## Assembly Sequence Aims at Parallel Integration

*PXL*

*PXL Insertion (after Cone in STAR)*

*FGT*

*SSD*

*SSD*

*NCS*

*SSD *
*Integration*

*FGT  Integration*
*(COMPLETED PRIOR)*

*PXL IS Insertion*
*(includes BP and 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...*

## 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.