Introduction Stave design and construction Simulation & prototypes Stave components Stave construction Modules Superstructure Frame and Box Summary

LHCb UT UPSTREAM TRACKER– Mechanics and Cooling –

Ray Mountain Syracuse UniversityBurkhard Schmidt CERN

for the LHCb UT Group

R. Mountain, Syracuse University FORUM on Tracking Detector Mechanics 2

Outline

• Introduction• Stave design and construction

Simulation & prototypes Stave components Stave construction

• Modules• Superstructure

Frame and Box

• Summary and plans

6/16/2015

UPSTREAM TRACKER:INTRODUCTION


LHCb Detector

• Four planes of silicon strip sensors

• To be located upstream of magnet, between VELO and Tracking System

• Replaces current TT

• Installation scheduled 2018–2019

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Future location of Upstream Tracker

Upstream Tracker (UT)


ELECTRONICS

ELECTRONICS VOLUME

VOLUME

UT Schematic Representation (1)

Four planes of sensors – Box/Frame retract – beam pipe is captured by UT

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RAIL

FRAM

E FRAME

PSLV/HV

PSLV/HV

COOLING MANIFOLD

BOXA

@ service boxes

BOXC

SERVICES SERVICES

SERVICES SERVICES

END-MOUNTS

SENSORS

STAVES mountedon FRAME

READOUT ELECTRONICS

READOUT ELECTRONICS


UT Schematic Representation (2)

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• 4 planes constructed using “staves” with silicon on both sides, partially overlapping in the x-direction to ensure 100% coverage

• higher segmentation in the region surrounding the beam pipe

• Inner detectors with circular cut to maximize acceptance

• Electronics located near sensors to allow segmentation & improved signal/noise

• Basic mechanical unit “stave”

UTaX

STAVE DESIGN

6/16/2015 R. Mountain, Syracuse University FORUM on Tracking Detector Mechanics 7


UT Stave Design (1)Stave • Main mechanical element of the UT• Provides for the mounting and precise

positioning of the silicon sensors• Comprised of competing mechanical,

thermal and electronic elements• Vertical support • Stiff sandwich structure • Integrated with the cooling system

Components of fully-loaded stave• “Bare” stave: basic innermost structural

support / cooling tube• Data-flex: signal readout / power

distribution / control lines• Module: Sensor / hybrid / stiffener,

mounted on both sides of stave

Adapting ATLAS-type Integrated Stave concept

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“FULL-LOADED” STAVE

SENSOR

ASICs

COOLING TUBE

99.5 mm wide~1640 mm long

HYBRID-FLEX

DATA-FLEX

MODULE


UT Stave Design (2)

Bare Stave: CFRP (Carbon Fiber Reinforced Polymer) face sheets epoxied to foam core in sandwich structure with embedded cooling tube, all-epoxy construction

Foams: thermal foam for heat transfer, lightweight structural foam for rigidity of sandwich structureCooling Tube: Ti 2.275 mm OD, 135 um wall, “snake” shape, runs under all ASICs and edge of each sensorGoals: Keep sensors at –5°C or below, uniform ΔT=5°C across sensor, ASICs < 40°C (6 mW/ch, 0.768 W/asic)

SENSOR

~3.5 mmthick

ASICs

STIFFENER

WITH

ANCHOR TABS

EXTERIOR (FULL-LOADED STAVE)

INTERIOR(BARE STAVE)

COOLING TUBE “SNAKE”-SHAPED (displaced for clarity)

FOAM (STRUCTURAL)

FOAM (THERMAL)

99.5 mm wide~1640 mm long

~8 mm thick

BEAMPIPECUTOUT

CARBON FIBER SHEETS (BOTH FRONT AND BACK)

HYBRID-FLEX

DATA-FLEX

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SIMULATIONS & PROTOTYPES


Thermal Simulations

FEA analysis to aid in stave design workComparison of two major designs: Snake vs Straight CO2 Cooling Tube

Thermal Loads: • ASICs @ 6 mW/ch est. yields 68 W/stave max• Self-heating in silicon after 50 fb-1 is small, ~260 mW/sensor max• Data-flex heat load ~10% power dissipation in stave

Analysis of full stave model (highest power case, including thermal barriers) indicates both designs would meet our goals, with snake design slightly better

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S. CoelliM. Monti

Straight Tube DesignSnake Tube Design


Demonstrator Comparison

Full-Scale Prototypes (with CO2 blow-through system) were constructed to compare the two designsBoth demonstrators had the TDR module design, both used same construction techniques (though Straight Tube demonstrator used thermal vias and additional carbon foam, compared to FEA model) Flow-rate and pressure were adjusted for each run, stability reached, then repeated for different settings (equilibrium temperature is sensitive to these settings)

Results from the comparison of the cooling behavior of the two designs:– Both designs successfully reached target temperature (–5°C on sensors) and below– Both designs achieved approximately ΔT=5°C across sensor– Snake-Tube demonstrator reaches target temperature with lower flow and higher pressure (i.e. more “easily”) than two straight tube

demonstrator (compare red and blue curves for similar settings)

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Positions of RTDs on Demonstrators

Snake Tube Design Straight Tube Design

W. Lentz

STAVE COMPONENTS


CFRP Face SheetsFace sheets • K13C2U high-modulus carbon fibers in

EX1515 epoxy matrix, 45gsm• Layup is a three-layer stack of prepreg in

0/90/0 orientation• This emphasizes stiffness of the sheet

while allowing for thermal conductivity in both in-plane dimensions

The facings are easily cut and formed to the sizes we need

We have obtained several batches of facings and have found them to be of good quality and good uniformity

Fabrication by Composite Workshop at University of Liverpool (Tim Jones)

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(D) Ringo(C) George

abraded surfaces

1550

mm


Thermal FoamThermal foam core component • Allcomp K-9 carbon foam• High thermal conductivity (~35 W/m.K), low

mass density (0.2 g/cm3)• Open cell foam• Machinability is good

Ideal for spreading the heat transfer from a small tube to the large area required to cool the ASICs and sensors.

The machining of the foam is easy and the resulting surface can be made clean for epoxy.

Epoxy uptake measurements• Takes epoxy up into carbon foam to a depth

about equal to the size of voids, typ. 400-600 um

• Consider it a layer of ~0.5 mm which is a mix of epoxy and carbon foam, 70:30 roughly

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carbonfoam

carbon foammass (long)

5% spread


Structural FoamStructural foam core component• Evonik Rohacell 51 IG, a commercially-

available polymethacrylimide (PMI) polymer foam

• Solid, not thermally conducting, very low mass density (0.051 g/cm3)

• Closed-cell foam• Machinability is good

Typically used in aerospace and industry as core material for a sandwich structure.It is used as core in this design, and not as a structural element by itself. Machined surface is left with opened foam bubbles so epoxy contact area increased, increasing the adherence.

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Rohacell

rohacellmass

2% spread


Cooling TubeCooling Tube• Titanium CP2 alloy• OD 2.275 mm, 135 um wall thickness• Manufactured by High Tech Tubes Ltd.

UK

Development by ATLAS (Richard French, University of Sheffield) and we have benefitted greatly from their expertise and help

Snake shape has been designed to run under all ASICs and one edge of all sensors in a stave.

Tube Issues:• Bending• Fittings• Deformation

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Tube Bending

Prototype tool: Bend one “wave” (four bends), then index and repeatProduction tool: Bend entire tube with single tool (no indexing), will ensure better repeatability, compensate for neutral axis shift and springback

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spools & handle

Tool based on design by Ian Mercer (Lancaster)

3 m tube

adjustable stops


Bending Deformation: LongitudinalMeasure wall thickness• Bend sections of tube, encase

samples in epoxy• Grind radial and longitudinal

cross sections, polish surface• Image under digital microscope• Measure points on radii, bin

Wall thickness as a function of bend angle• Fish-shaped (expected) • Inner bend thickening,

wrinkling• Outer bend thinning• Bending bunches material

forward into the bend• Consistent with studies carried

out by H. Yang¹, N.C. Tang²

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J. Servatius

photomicrograph

¹ Yang et al. / Chinese Journal of Aeronautics 25(2012)1.² Tang / International Journal of Pressure Vessels and Piping, 77(2000)751.


Bending Deformation: TransverseTechnique is the same• Measure points on inner/outer

surfaces at even intervals on circumference

Wall thickness as a function of azimuthal angle • Slight egg-like shape (expected),

follows from longitudinal results

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photomicrograph(at 45° into bend)

J. Servatius

cross section at 45° into bend


Option 1

Option 3

• Can consider double-sealing with external sleeve • Mate tube and fitting with insertion joint • Avoid thermal stressing tube, increase ease of

construction, cost, etc.• Allows for the possibility of in-situ repairs

Cooling Tube FittingsOption 2

• Brazing is the standard option for joining dissimilar metals.

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stainless tube

Ti tube

weldbraze

weld

stainless stubVCR

fitting

s

VCR blank gland

braze

Ti tube

stop

bored gland

Ti tube

epoxy sleeve


Cooling Tube Fittings – SamplesHave several samples of brazed tube in hand • GH Induction Atmospheres

(Rochester NY)• LM 69-241 Ag-Cu alloy• Single-joint, double-joint samples

Have several samples of epoxied tubes in hand • Araldite 2011• Armstrong A12

Types of samples made• Single epoxy joint: one simple Ti/SS

insertion joint with cap epoxied on end • Double epoxy joint: one simple Ti/SS

insertion joint, other Ti/SS insertion joint with sleeve

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Brazed samples

Ti tube SS stub

Double braze joint + Swagelok fittings

SS Ti SS

Single braze joint + epoxied plug + Swagelok fitting

Ti SS

M. Wilkinson


Cooling Tube Fittings – Pressure TestsPressure tests (ongoing)• Raise sample to 150 bar • Then let leak out, measure leak rate of

sample plus system (in dead end line which is valved off from step-down regulator)

• Repeat with irradiated samples – Irradiation to 100 kRad (60Co -rays)

• Repeat with thermal cycling (typ. 5 cycles, RT to –15°C)

• Repeat with pressure cycling (typ. 5 cycles, 1 bar to 150 bar)

Samples tested • Braze single joint: @RT• Braze double joint: @RT• Armstrong single joint (IRRAD): @RT, TC• Armstrong double joint (IRRAD): @RT, TC• Araldite double (IRRAD): @RT

All samples tested reached >150 bar without exhibiting any obvious leak, cracks, or other catastrophic failure modes

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M. WilkinsonS. Guerin

Traci V1 CO2 Cooling Test Setup

Setup will make detailed and systematic measurements of cooling system parameters

6/16/2015 R. Mountain, Syracuse University FORUM on Tracking Detector Mechanics 24

Cold boxopen

Dummy staveInstrumented with 20 thermocouples

Cooling pipeTitanium snakecentral staveID 2 mm, th 0,125 mmRouting snake verticalTot length 3 m

cooling linesWith fluid measurement T, P CO2

TRACI v12 PACL

Inlet dP variable CO2

S. Coelli(INFN-Milano)

CONSTRUCTION


Stave Construction (1)Bare stave constructionProcedure is an all-epoxy construction in precision fixturing

End-of-stave mounts hold datum serving as master alignment references for all stages in construction. Epoxied to end of facing (Side A)

Epoxy applied via stencil over large areas, volume control is important

Jigsaw hold-downs position foam core pieces after epoxy application

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END-OF-STAVEMOUNT

FACING

REFDATUM

REF EDGEVACUUMPULL-DOWNFIXTURE 1

FOAM COREPIECES

JIGSAWHOLD-DOWNS REF EDGE


Stave Construction (2)Trough milled in foam core for snake tube (prototype shown, real assembly will remain on vacuum fixture to maintain alignment)

Second facing (Side B) mounted to vacuum fixture 2

Epoxy applied to tube via stencil. Tube laid into trough.

Second fixture flipped. Fixtures mated ref alignment pins. Stops assure thickness control. Cure.

Closing operations, metrology.

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VACUUMFIXTURE 2 (Facing Side B)

VACUUMFIXTURE 1

Demonstrator #1Prototype snake tube

MODULES


HYSOL+BN

HYBRID-FLEX

STAVE = SENSOR width + 1 mm/side

CERAMIC STIFFENER HYSOL+BNPHASE-CHANGE THERMAL INTERFACE MAT’LCERAMIC STIFFENER ANCHOR TABS

PC TIM

ASICs

THERMAL VIASSENSOR

~500 um thick

COND. EPOXY

gap

fiducials

fiducials

gap

97.5 mm wide

~ 150 mm long

UT Module (exploded view)

Sensor: –5°C, ΔT=5°C Stiffener: CTE match to SiProtect wirebonds, testing and handlingNot mech over-constrain sensor, allows for bowMaximize heat transfer from ASICS to stave, minimize from ASICs to sensorElectrically isolate sensor bias from stave facings (ground)Reworkable epoxy (TIM): allows module removal if needed

Design options• hybrid flex vs hybrid ceramic• Pyrolytic BN vs AlN • Electrically insulating, thermally

conducting• Slits / no slits

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Module MaterialsAcquiring and Testing component materials for mechanical / adhesive / thermal properties as well as radiation damage testing

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Pyrolytic BN – Typical Properties (@R.T.) Apparent Density (gm/cc) 1.95–2.22 Tensile Strength (MPa) 40 Flexural Strength (MPa) 80 Thermal Conductivity (W/m.K) “ab” 60, “c” 2 * CTE (10-6/°C) “ab” 2 (@1000°C)

3.0 (-40 to +150°C) ** Resistivity (ohm-cm) 1015

Dielectric Strength (kV/mm) 200 Dielectric Constant “ab” 5.2, “c” 3.4 Total Metallic Impurities (ppm) <10 Outgassing >Negligible Maximum Suggested Use (°C) 2,500

* might work as is, but would have to grow thicker and cut slices to get max K ** from Morgan. Other values from Momentive. Compare to 2.3 for Si.

, ρ=1014 Ωcm


Thermflow Epoxy Film: ShearMeasured ultimate shear strength (USS) for Thermflow films, using sandwich pull method

Compared USS under irradiation at 30 MRad (60Co -rays) for different curing conditions: no significant effect of irradiation for any sample

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0

50

100

150

200Un-Irradiated SamplesAl T725 CF on CF

Al T725 CF on KaptonAl T777 CF on CFAl T777 CF on KaptonAl TPCM 780 CF on CFAl TPCM 780 CF on Kapton

USS

[kPa

]

no bake bake bake+weight

0

20

40

60

80

100

120

140

160

180

USS

[kPa

]

0

50

100

150

200

250

T777 CF on CF no bakeT777 CF on Kapton no bakeT777 CF on CF bake+weightT777 CF on Kapton bake+weight

negative is unirradiated, positive is irradiated

0

50

100

150

200

250Irradiated Thermflow Samples

T725 TPCM 780T777

PIn

Holder

FORCE

epoxy

Carbon Fiber (surface)

Test EpoxyKapton

M. Wilkinson


Difference in sensor profile after wrt before epoxy operation: effect of epoxying to PBN

Epoxied edges: one less, one more bowedFree corner rotated down by ~250 um (approximate size of free-standing sensor bow)

Sensor Epoxied to PBN Stiffener

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PBN stiffener

vacuum fixture(weighted)

refe

renc

e ed

ge

sensor

shim

jig plate

epoxied on right edge X=0 and

back edge Y=0

Sensor MSL3092_10 (after–before epoxy, rotated)

First sensor epoxied to ceramic stiffener

SUPERSTRUCTURE: FRAME & BOX


Stave Mounting to Frame

Standoffs in EOS mounts prevent crushing data-flex cable when mounting (both sides) Standoffs on frame allow stagger in Z, which provides overlap in X

Custom stud • Locates stave in standoffs• Thermal contraction in slots• Kinematic movement via spring-

loaded nut and spherical washer set

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D. Wenman (PSL)

Kinematic mounts at top and bottom of stave• Fixed at top• Slotted at bottom


Support, Frame and Box

Two halves of UT will retract from beam pipe

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J. BatistaO. Jamet

B. SchmidtJ. Andrews

ONE QUADRANT SHOWN

BOX

FRAME

STAVES

I-BEAMSUPPORT

PERIPHERALELECTRONICS

PIGTAILCABLES

BEAMPIPEAPERTURE

SUMMARY & PLANS


Summary and PlansLHCb Upstream Tracker is comprised of four planes of silicon sensors which are supported by integrated stave structures

The UT stave has been designed using FEA model techniques, prototypes, component testing, etc.

Many components have been tested and qualified, some work still remains

Module design has been refined although several issues remain

Frame and box design is progressing, although the end of stave region is dense and challenging

Phase 1 construction planned to start end Summer 2015 • Bare stave construction • Will soon freeze all mechanical

parameters and design choices necessary to begin construction

• This will allow us to construct all bare staves, which frees manpower and resources for subsequent phases

Phase 2 construction will start when data-flex cables become available Phase 3 construction will begin when modules (sensors, hybrids) are available

Assemble at CERN in 2018Install in IP8 in 2019

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– FIN –

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Construction Clean Room

6/16/2015

Lots of work in progress on clean room…

• HVAC• Sealing• Electrical• Assembly• Lighting • Services • Testing

Documents

Introduction Stave design and construction Simulation & prototypes Stave components Stave construction Modules Superstructure Frame and Box Summary