thomas jefferson national accelerator facility page 1 ipr october 18-20 - 2011 independent project...

Thomas Jefferson National Accelerator Facility

IPR October 18-20 - 2011

Independent Project Review of 12 GeV Upgrade Jefferson Lab

October 18-20, 2011

SVT Mechanical Design at JLAB

Saptarshi Mandal



Outline

• Overview of mechanical aspects of Barrel Silicon Tracker (BST)

• Discussion of mechanical and thermal design• Assembly of the detector• Quality Assurance of the detector• Summary



Central Tracker

CTOF

Solenoid

SVT

SVT Support and Alignment System



Features of BST

• Four region barrel• Region 1: 10 modules; Region 2: 14 modules; • Region 3: 18 modules; Region 4: 24 modules

• Acceptance 35o – 125o

• Operating Temperature 20o – 25oC

• Low mass inside acceptance region



Position Accuracy

• Module position accuracy (knowledge of position)

±54 µm, ±1350 µm, ±270 µm in X,Y,Z

X

Z

Z

X



Barrel Silicon Tracker

Downstream Support

Ring

HFCB

Support Tube

Tedlar Window

Carbon Shell

Cold Plate

Modules



Cold Plate

Provides mechanical support to the BST

Provides cooling for the electronics on the modules

Copper Insert

Coolant Channel



Cold Plate and Support Rings

Downstream Support

Ring

Upstream Support

Ring

Module

Module is supported between upstream and downstream support rings

Module is positioned by accurately machined pin holes in the two rings and the stave

(Region 3 shown)

Cold Plate



BST Section View

Coolant Channel

Stave Support & Conductor

Module

Upstream Support

Ring

Insert



Cold Plate Prototype

Copper Inserts with fins

Cooling Channel

Cold Plate is in two parts --

One part with cooling channel machined in it

Second part with slots machined to accommodate inserts

Adhesive used – 3M DP 190



Prototype contd.

Upstream Support

Ring

Stave Support & Thermal

Conductor



Detector Assembly

During Assembly- R3 Assembled R3

Locating PinAssembly to be done in clean room environment

Assembly sequence – R1R2R3 R4

Modules are positioned by accurate locating pins

Modules are fastened down for good thermal contact at upstream end

Design allows for removing an entire region as a unit



Module

Functions• Mechanical support and positioning

of sensors and electronics

• Cooling of ASICs

Features• Carbon skin (.250 mm) with Rohacell

71 core (2.5 mm)

• Rohacell 71 core replaced by copper core (2.5 mm) under electronics

• Kapton bus cable used for grounding on top and bottom surface

Fastening Hole

Hole for Locating Pin

Slot for Locating

Pin

Sensors

Bus Cable



Module Close-up View

Rohacell 71

Pitch Adapter

Copper Heat Sink

ASIC

Carbon Fiber

Silicon Sensor



Stave with Electronics

HFCB



Stave Deformation

Deflection based on gravityBoundary Condition: Fixed-

PinnedWeight of electronics ~20 gm

Max. Deflection : ~21 m



Barrel Deformation

Deflection based on gravity

Max. Deflection : ~22 m (in horizontal modules)



Stave Temperature Distribution

Heat Input : 3W (Expected input ~2W)

Coolant: WaterCoolant temperature: 15oC

Nitrogen Purge at 20oCHeat Sink Material : Copper

Peak Temperature : 23oC



Highlights of Quality Assurance Plan

• Visual inspection of each module

• Dimensional accuracy check of modules using CMM to ensure compliance with engineering drawings

• Dimensional accuracy check of cold plate and all thermal and structural components to ensure that they meet drawing specifications

• First article tests of mechanical and thermal components to check engineering design

• Position of each module measured and recorded during assembly to provide accurate knowledge of position of each module



Summary

• FEA showed deflections and temperature to be within acceptable range

• Prototype of the cold plate demonstrated the feasibility of the cooling method to be used

• Quality Assurance plan is well developed

thomas jefferson national accelerator facility page 1 ipr october 18-20 - 2011 independent project...

Documents

modules region

downstream support ringsmodule

entire region

modules acceptance

copper core

thermal designassembly

svt mechanical design

finscooling channelcold