National Institute for Subatomic Physics Science Park 105, 1098XG Amsterdam The Netherlands

SciFi Forum on Tracking Detector

Mechanics 2015

R. Walet on behalf of the SciFi Tracker Group

2015-05 Rev_06

OVERVIEW

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5 [m]

SciFi Performance Summary

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Current tracking • 2 sub-systems: Inner Track, Outer

Tracker • Outer Tracker

– 24 layers of 5 mm gas drift tubes (2.5m long straws) in 3 stations of X-U-V-X

– Resolution ~200 micron • Inner Tracker

– silicon strip sensors with 0.18—0.20 mm pitch

– 12x X-U-V-X stereo layers – Resolution ~ 50 micron

Upgrade tracking • One single tracking Technology • “NEW” SciFi Tracking Detector

– 12 fiber mat layers composed of scintillating fibers (2.5m, d=0,25mm) in 3 stations of X-U-V-X

– Resolution 80 µm – Single hit efficiency: 96-97% – Run trigger less (remove L0) at 40

MHz read-out (only software trigger)

GOAL: “Be able to run at higher luminosity”

Scintillating Fiber Tracker

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2.5 m × 250µm

Readout box w/ cooling (-40oC) and FE boards

Fibre mats 2.5m ×13cm Fibres Silicon PM (SiPM) array: 128 × 250µm

Modules = Supporting panels + mats

5m mirrors

3 * X-U-V-X

6 m

5m

fiber

s

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SUB-SYSTEMS;

5 [m]

• Infrastructure

• C-frames (12x)

• Modules (144x)

• Read-Out Box (288x)

Challenges Replace Inner and Outer tracker with a single technology • Higher granularity to reduce occupancy • Reduced material, Light weight • High rate capability • Large scale detector with fine measurement, handle

deformations of the fibers (modules) and read-out • To mitigate radiation damage until collecting at least

50 fb-1, SiPMs need to be cooled down to -40°C • Relative alignment SiPMs and fibers • Modular design with easy maintenance or

replacement procedures • High Resolution

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5 meter

C-Frame with module

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Modules (144x)

Description Material kg/module TOTAL Scintillating fibers 94% polystyrene + 6% PMMA 4 576 Honeycomb cores Nomex 3 432 Casting and winding epoxy Epotek 301-2 1 144 Panel assembly glue Araldite 1 144 Carbon fibre skin Phenolic Resin 1,5 216 Endplugs* Aluminum 9,5 1368

TOTAL 20 2880

Very schematically a Module is: 1. A core of scintillating fibers, combined in a mat

(8 mats and a mirror makes one core) 2. Sandwich construction

1,5 mm

Materials

0.52 meter

CHALLENGES Winding of the fibermats

Polishing of the optical surfaces Flat/straightness assembled modules

Module Endpiece

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Modules – Fibermats

2.5 meter

Alignment holes for module assembly

Fibermat winding machine

Fibermat casting JIG Casted Fibermat

13cm

Casting glue ; - protection layer 150μm - 1 day gluing - 3 days curing

Cutting slit Winding wheel

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Modules – Sandwich

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SiPMs(4608x)

Silicon Photomultipliers (SiPM)

0.250 mm

60μm pixel 32.59 mm

128 channel array

Kapton flex-pcb

1.62 mm

Connectors

6 layers of fibre per plane (Fiber D=0.250mm)

“Particle track”

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Read-out Box (288x)

CHALLENGES thermal expansion and contraction

(different CTE’s with ∆T of 80-90°C) high position accuracy’s

condensation and frost prevention

Very schematically a ROB is: 1. SiPMs, SiPM cables, SiPM cooling, etc. “COLDBOX” 2. FE electronics boards, cables, etc. “FE ELECTRONICS”

Cabling, piping

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Read-out Box Thermal Design Material CTE

[ppm/°C ] ∆T

[-50°Cv 40°C] ∆L [µm/SiPM* ] (*=32,59 mm)]

Silicium 2,6

90

7,6 Ti6Al4V 9 26,3 Copper 16,6 48,6 SS316 16,2 47,4 Epoxy 45-65 131,6-190,1 Polycarbonate 70 204,8

ISSUE 1. Different CTE’s

ISSUE 2. Behavior of the Endpieces by cooling down (every photon counts!!!!) Top: -40°C Outer: 5[W/mk], 16°C

Overall deformation

0.2 mm

0mm

∆Y=0.1mm; Airgap SiPM-Fibers

∆X±0.2mm; mis Alignement SiPM-Fibers

13cm

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Read-out Box – Cooling bar

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Read-out Box – Cooling bar Concept 1.

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Read-out Box – Cooling bar Concept 2.

4-SiPMs heat spreader with SiPM cooling block (copper) 3 positioning pins in end piece

3D printed bellows

Z fixed

Z fixed

X fixed

Y fixed Spring force; optimal optical contacts

4-SiPMs heat spreader with SiPM cooling block (Ti6Al4V)

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Read-out Box – Cooling bar

Y fixed X fixed

Z fixed Y fixed

Z fixed

EACH INDIVIDUAL COOLING SUBSTRATES POSITIONED AND ALIGNED WITH RESPECT TO SINGLE FIBER MAT

Concept 3. (new input; parallel cooling with d=2mm possible)

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Read-out Box – Cooling bar Concept 4.

X fixed Z fixed

Y fixed Y fixed Y fixed

Z fixed • 3D printed Ti-alloy Grade 5 (min. Wall thickness 0,25mm) • Bellows (SS) from Witzenmann Challenge to braze SS (bellows) on Ti (bar) • Alternative: investigate 3D-printing of full cooling bar (incl. flexible joints)

EACH INDIVIDUAL COOLING SUBSTRATES POSITIONED AND ALIGNED WITH RESPECT TO SINGLE FIBER MAT Section; cooling bar

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Read-out Box – Cooling bar Concept 5. Alternatives; 1. Copper pipe d=2mm

2. Pre-formed corrugated SS pipe D=3.5 d=3.3 mm

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Read-out Box – Enclosure

Module with interfaces

Optical surface fiber ends

In-/outlet pipe cooling

Top cover with SiPMs, SiPM cables, SiPM cooling

Thermal enclousure (insulation box)

FE electronics

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Read-out Box – Enclosure Requirements Coldbox to Module connection: o Flat sealing surface around module o Air tightness of all components within this surface o Mounting holes 2x7 m3

Contacted companies, 3D printing; o Shapeways o 3D systems o Heijcon

Coolingbar -40[degC]

SiPM package

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Read-out Box – Enclosure

Soft Glue silicon

G10 stiffner

Mounting holes

Bends to increase flexibility to compensate

for thermal shrink and release forces on the

connectors

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Read-out Box – Enclosure Outer shells are 3D printed in PA2200(Wall thickness 0,7mm) Parts will be filled with insulation foam

Cold box PU foam

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Read-out Box – Enclosure First cold-boxes filled (without using molds) Good experience; but some air gaps in cold box. In parallel, order more boxes with:

• Different materials (e.g. ABS) • Different printing orientation (improve flatness)

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Vacuum feedthrough

Vacuum insulation

1/8”VCR inside, ½” VCR outside Open vacuum pipe to Manifold

Standard bellows

Feedthrough topcover

End vacuum insulation

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Vacuum feedthrough Vacuum insulated pipe

Feedthrough reducer

1/8”VCR inside ½” VCR outside Open vacuum pipe to Manifold

Oversized bellow to be able to open 1/8”VCR

Vacuum pipe crosses SiPM cables

End vacuum insulation

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Vacuum feedthrough

1/8”VCR inside ½” VCR outside Open vacuum pipe to Manifold

Oversized bellow to be able to open 1/8”VCR

Mounting position Opening position

Press to access 1/8”connector

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Conclusion & Outlook • the SciFi tracker is an essential component of the upgraded LHCb detector • it will allow running at (5×) higher luminosity • an extensive irradiation program demonstrated radiation tolerance of main components

– we can handle damage to fibres (6 layer mats) and SiPMs (cooling down to 40°C)

• lots of progress in new technologies – fiber winding and fiber-mats production on massive scale – custom design of SiPM arrays matching fiber geometry – direct fiber-to-SiPM interface – SiPM cooling down to -40°C in small volumes, modular approach (Read-out Boxes) – High functionality level per volume

• extensive use of exotic technologies like 3D printing

• large collaboration between 17 institutes* from 8 countries • series production to start in 2016 • installation in 2019 during LHC shutdown

*17 institutions: Kurchatov , ITEP, INR (RUS), Aachen, Dortmund, Heidelberg, Rostock (GER), EPFL (SUI), ClermontFerrand, LAL, LPNHE (FRA), Nikhef (NL), Barcelona, Valencia (SPA), CBPF (BRA), Tsinghua (CN), CERN

Back-up slides

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Thermal Gap Fillers Take e.g. Laird 6200 T-flex

For ASiPM ~ 2 cm2 , 100 kPa ⇒ 20 N/SiPM force!

For ASiPM ~ 2 cm2 and PSiPM ~ 2 W, ∆T(100 kPa) = 13°C and ∆T(500 kPa) = 4.5°C

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Radiation Damage - Fibers Light transmission of scintillating fibre decreases under irradiation • up to 35 kGy expected near the beam pipe over the upgrade lifetime

Expected ionizing dose for LHCb Upgrade

As measured by PIN diode

A mix of low dose, low rate xray, gamma, and high rate, high dose proton irradiations

Expect a 40% loss of transmitted light created near the beam pipe after 10 years

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Radiation Damage - SiPM

SiPM arrays

Plot from N. Lopez March and M.Karacson

DCR reduction: factor 2 every ∆t=-10oC

Image from D. Gerick, presented at DPG Wuppertal, 11.03.2015

SiPM arrays

We expect 1.3 x 1012 neq/cm2 for 50 fb-1

• Requires cooling to -40°C • 150m of silicon arrays, without vacuum • DCR of a few MHz per channel at -40°C

after 50fb-1

• ~1 per 5-10 bunch crossings