At the cutting edge - Silicon detectors for the Super-LHC · 2017. 2. 16. · Strip geometry Need...

At the cutting edge -Silicon detectors for the Super-LHC

Marc Weber

2

The Large Hadron Collider (LHC)The Large Hadron Collider (LHC)

Marc Weber (RAL), FTU, Dez 2008

ATLASALICE

LHCb

CMSLHC

7 TeV p

SPS

PS

7 TeV p

3Marc Weber (RAL), PPD Seminar, Feb 2009

LHC LHC –– at the technology frontierat the technology frontier

LHC

SPS

Tevatron

4

LHC LHC –– at the technology frontierat the technology frontier


• 7 TeV beam energy Tevatron x 7• 1 billion collisions/sec. Tevatron x 100

• 25 proton-proton collisions every 25 ns• ~350 MJ beam energy ≈ TGV with 100 miles/h

• the world’s largest fridge • ~ 9000 magnets

5Marc Weber (RAL), FTU, Dez 2008

magnetic field (at 7 TeV): 8,3 T

magnet current: 11,850 A

length: 14,3 m weight: 35 t

numbers: 1232temperature: 1,9 K

unit price: ~0,5M CHF

stored energy (1232 dipoles): 11 GJ

SuperconductingSuperconducting dipole magnetsdipole magnets

6

The ATLAS DetectorThe ATLAS Detector

• World’s largest collider detector

• Inner tracking detector is much smaller: 7 m long and 2,3 m diameter

7 TeV p

7 TeV p

Marc Weber (RAL), PPD Seminar, Feb 2009

7

ATLAS in July 2002ATLAS in July 2002


8

ATLAS in December 2004ATLAS in December 2004


9

ATLAS is world famous, alreadyATLAS is world famous, already


10

ATLAS as ATLAS as ““black boxblack box””46 m

7000 t

22 m


11

WhatWhat’’s in the s in the ““black boxblack box””??charged particles (> 10 MeV, [Hz/cm2]): 105 – 4 x 107

radioactive radiation: 1-1000 kGy; 1013 – 1015 neutrons/cm2

magnetic fields: 2T (solenoid), 0.5 T (barrel toroid), 1 T (end cap toroids)

stored magnetic energy: 1.6 GJ magnet current: 28 kA

subdetectors: ~14 (silicon pixel and strip detectors, transition radiation detectors (TRT), liquid Argon calorimeter, scintillator tile calorimeter, muon detectors)

electric power (front-end electronics): > 300 kW* current: >90 kA

electronic channels: ~90 million (of which 80 M are pixels)

services: 50,000 cable bundles and 7000 cooling pipes

cooling systems: LHe, LN2 , C3F8, C6F14, water

operation temperatures: ~80 K, -7 °C, room temperature

atmosphere/drift gases: N2, CO2, Xe/CO2/O2, LAr, Ar/CO2, CO2/n-Pentan, …

*total power: 13 MWMarc Weber (RAL), PPD Seminar, Feb 2009

12

The ATLAS collaborationThe ATLAS collaboration

• 2100 physicists of 37 countries and > 169 universities and national labs


13

(S)LHC science in a nut shell(S)LHC science in a nut shell

• Main target: discovery and study of Higgs-Bosons

missing corner stone of “periodic table” of particle physics

Arguably one of the most important discoveries of PP

Higgs Boson



Higgs boson production and decay Higgs boson production and decay (Monte Carlo simulation)

7 TeV p

7 TeV p

proton + proton →

jet + Higgs boson (H)

with e.g. H → Z0 + Z0

Z0 → µ+ + µ-

Z0 → e+ + e-

muonmuon

electronelectron

particle jet

Crucial are:

- detection of all particles

- precision measurements

- particle identification

15

(S)LHC science in a nut shell(S)LHC science in a nut shell• Discovery of supersymmetry and thus possibly of dark matter

double the number of known elementary particlesanalogy: discovery of anti-matter

Would most certainly be one of the most significant fundamental discoveries of our lifetime

LHC offers chances for spectacular discoveries and precision physics ...

Abell 2218


16

LHC and the mediaLHC and the media


• 10 September 2008: first beam in LHC


LHC and the mediaLHC and the media• 19 September 2008: “LHC incident”

18

About 10 years laterAbout 10 years later ~ 2017~ 2017LHC has made fundamental discoveriesSilicon detectors became dysfunctional due to radiation damage

What now ? Super-LHC: upgrade of the LHC

• Goal: ~10-fold increased data rate (luminosity) by ~2017 to1) Consolidation of LHC discoveries2) Search for more and heavier particles and rare processes

• Requires upgrade or replacement of all pre-accelerators~400 proton-proton collisions every 50 ns

• Highest priority of European particle physics community(see Particle Physics European Strategy Roadmap, CERN Council 2006)

• Price tag: ~ 1 billion € (for accelerators only)

19

Silicon detectors for SLHCSilicon detectors for SLHCTask: Measurement of charged particle tracks to ~15 µm precision.

Pattern recognition and track reconstruction from space pointsDifficult since too many particles in too short a time

many particles many channels/pixels, radiation damagelittle time fast detectors (silicon!) and electronics

precision many channels and “mass-less” detector

- otherwise multiple scattering and production of secondary particles

LHC: ~1000 particles every 25 ns SLHC: > 10,000 particles every 50 ns

30 overlap events 400 overlap events

20

The The SemiConductorSemiConductor Tracker (SCT)Tracker (SCT)


17,000 silicon sensors 60 m2

6 million strips (80 µm x 12.8 cm)~ 50 kW power (including cable losses)

21

Biggest challenges are: reduction of power Biggest challenges are: reduction of power consumption and consumption and ““weightweight”” of detectorof detector **

Strong correlation between parameters

Key challenge for LHC was: radiation hardness, radiation hardness, radiation hardness * similar to design of cars and airplanes ...


22

SpecificationsSpecificationsSilicon detector, size, radiation hardness, spatial and momentum resolution, cable volume and cooling pipe volume, mass

4 layers of silicon pixels, ~500 million channels, 5 layers of silicon strips, ~42 million channels, 180 m2 silicon

time scale: ~ 2017; costs: ~ 100 M€ (“material costs”)

Marc Weber (RAL), FTU, Dez 2008ATLAS SCT Barrel

Components: sensors, readout chips, MCMs, supermodules…

System:data architecture and data transmission,power distribution…

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• strips or pixel structures• diodes in reverse bias; high resistivity; ~4 fC signal• Radiation hardness: >1015 n/cm2, small leakage currents,

stands high voltage up to ~1000 V• costs: ~1000 €/ wafer• Production rates: > 1000 wafer/month

industry has reached incredibly high quality level

Difficulties: costs, dependence of single vendor, radiation hardness in

innermost pixel layers (~ 1016 n/cm2)

Silicon sensors for detection of charged Silicon sensors for detection of charged particlesparticles

300 µm strip pitch 80 µm

AC- coupling


24

Radiation effects and system designRadiation effects and system design1. Increase of leakage current with radiation

cool sensor to -25 °C (I~T2 exp[-Eg/2kT])impact on cooling system, ASIC power consumption, module design

2. Type inversion n- to p

sensor bias voltage > 500 Vimpact on HV cable volume, number of modules on a single HV line

3. “Charge trapping”

Reduced signal, “collect” electrons not holes. Different signal polarity, reduced preamplifier noise, discriminator threshold, impact on electrical system design

Optimization of sensor design is important

However, more important is …


25

Strip geometryStrip geometryNeed many channels small pixel or short strips. However also want largesensors. ATLAS chose 100 mm x 100 mm sensors (150 mm wafer)

• Maximizes useful wafer area (squaring the circle)cheaper

• Large sensors fewer pieces

• 4 columns of 2.5 cm short strips (for inner detector layers)

Sensor geometry has dramatic implications for multi-chip-module and detector as a whole

100 mm x 100 mm sensor6-inch wafer


26

ReadRead--out chipsout chips

• Read-out electronics for particle physics is “custom design”

• Challenges: mixed-signal design, minimum power, radiation hardness (1016-1015

n/cm2), short integration times (25 ns), low noise

• Costs: very technology dependent, dominated by fixed costs NRE (and design effort), mask-set in 0.25 µm CMOS: ~100k €, in 0.13 µm CMOS 3 to 4 times more expensive

• Number of chips (128 channels) for SLHC silicon strips: ~ 400k ~500-1000 wafer

Read-out chip is a most critical component, at the bottom of the foodchain


27

Considerations for ABCConsiderations for ABC--Next Next chipchipABCD readout chip is obsolete (0.8 µm DMILL) design of ABC-Next

• Feature size: 0.25 µm, 130 nm or 90 nm CMOS? 130 nm: state-of-the-art in analog design, reduced power consumption,

more expensive, single-event-upset probability is 10-times higher

• CMOS or SiGe bi-polar ?SiGe is very fast, very high current gain β, reduced power, but strong reduction of β with radiation CMOS is favoured

• Chip architecture: Analog, digital, binary data? Analog or digital pipeline? Zero suppression, data compression?

ATLAS SLHC: fast and simple, i.e. binary, digital pipeline, data compression


First functional prototype in 0.25 First functional prototype in 0.25 µµmm

• Need about 10,000 chips for multi-chip-module and supermodule R&D!

• ABC-Next contains new features for SLHC• Voltage regulators and shunt regulators• Correct signal polarity, optimization of preamp for short strips• Clock frequency increase from 40 to ~100 MHz

• Characterisation, DAQ development and wafer probing at RAL

ENC

Channel

29

MultiMulti--ChipChip--Module Module (MCM)• MCMs carry chips and passives; distribute current, command and control signals;

data stream; HV filter; cooling functions; etc.• Minimum mass and size, low noise; high thermal conductivity• Technologies: ceramic (e.g. BeO, Al2O3), copper/Kapton flex, silicon interposer• Costs: 50 – 500€/piece

Example SCT: • Flexible polyimide MCM; 12 readout chips; ~6 W power• Hybrid sits on CFC bridge good

thermal conductivity; does not touch sensor• Hybrid wraps round sensor edge; connector

Overall this approach worked well!63 mm

768 Strips

ConnectorATLAS SCT Module

Sensor


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SLHC MCMs are more demandingSLHC MCMs are more demanding• More channels higher mass• More channels larger power consumption

- cooling system- power distribution

• More channels higher bandwidth- Skylla: more data lines- Charibdis: higher frequencies;“cross talk”; noise; stability

• Features of first prototype:20 ABC-Nexts; double row of ICs; no pitch adapter

Less material and fewer wire bonds

short strips sensor


ENC

Channel

31

SLHC MCMs are more demanding SLHC MCMs are more demanding • More channels higher mass• More channels larger power consumption

- cooling system- power distribution

• More channels higher bandwidth- Skylla: more data lines- Charibdis: higher frequencies;“cross talk”; noise; stability

• Features of first prototype:20 ABC-Nexts; double row of ICs; no pitch adapter

less material and fewer wire bonds

Marc Weber (RAL), FTU, Dez 2008Channel

ENC

32

3D Packaging and sensor post3D Packaging and sensor post--processingprocessing


Reduce MCM materials by either

1. Silicon interposer2. Sensor post-processing3. 3D Packaging

3D is industry hype and dream of detector physicistsMight well come to late for SLHC …

3D wafer stackR. Yarema (FNAL)

Artist view for RAL MNT industry meeting

Silicon interposerBumping, through-silicon vias, thin-film, wafer thinning

Sensor post-processingBCB and copper on sensor

33

A very simple idea ...A very simple idea ...

• Larger chips with 512 channels

• Only one row of ASICs per hybrid

• Aggressive ASIC layout exploit high transistor density,

reduced metal resistance, capabilities of modern wire bonders

Top viewSide view

ABC-N ABC-N

24 mm 8 mm

128 Kanäle

512 Kanäle

Get much smaller hybrid, almost a free lunch!

34

Mechanics and Mechanics and ““servicesservices”” shape shape detectordetector


SCT has ideal support structure• Precision carbon fiber cylinder (15 µm precision)

• overlapping precision detector modules (<5 µm build precision)

Great for alignment, but barrel configuration,

module mounting, barrel assembly took ≈ 3 years!

The robot at work!

1.

2.

3.

35

Supermodule Supermodule ((““stavesstaves””))Alternative are integrated cooling tubes and electrical services. Could save several years of construction and assembly time

CDF Run IIb staveCMS TOB Rod • Compact planar build-up

• Electrically demanding, since

Signals run under sensor

Shielding , grounding,

Minimize stray capacitance ...

• Proof of principle durch CDF:M.Weber, NIM A556 (2006) 459-481

ATLAS SLHC

1.2 m

Bus cable

MCMs Cooling pipes

foam

Readout chips

Silicon sensor

Stave is ATLAS

“base line” since 2008

36

Supermodules on cylindersSupermodules on cylinders

85 mm

Supermodule is supported by carbon fiber cylinder

Very complex and massive bundle of cooling pipes, fibers and power cables

(cooling system: CO2, pipe diameter: 3.1 mm, wall thickness: 0.22 mm, 150 bar)

Seitenansicht

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Data transmissionData transmissionLeitmotiv: Mass and number of data lines, radiation hardness, power consumption

develop custom systems

Flex cable: Good for 1-3 m, robust, radiation hard, minimum mass, ~320 Mb/s.no vias, 100 µm track width and gap. Aluminum shield (25 µm)

Micro twisted pair: 125 µm cable diameter, no shield, 50 Ω, 5 ns/m.Interesting for short distances of 1-2 m, ~160 Mbits/s, 0.4 mA current, ~8 pJ/bit.

Optical fiber: preferred technique for long distances, minimum mass und diameter,Target 3.4 Gb/s. Critical: radiation hardness, large connectors, ~ 400 pJ/bit or ~2W/fiber.

Mini-coax: ~ 1.2 mm cable diameter, no Teflon as dielectric, 5 Gb/s (with 8/10Bencoding and pre-emphasis, 50 Ω, CML. Cable and connector mass is significant.

6 cm125 µm

20 µm

Al core + Cu

Self Bonding EnamelPolyamide

IsolationPolyesterimide

CuAl core

38

Considerations for data architectureConsiderations for data architecture• Get data off detector quickly to minimize single-event-upset• Minimum number of lines (mass) serial data transmission• Identical or similar architecture for strips and pixels• Low clock frequencies simplify MCMs and save current

Hierarchical readout: ABC-Next → module controller chip (MCC) →supermodule controller (SMC)

20 ABC-Nexts (80 MHz) → 1 MCC24 MCCs (160 MHz) → 1 SMC (3.2 Gb/s)~ 2x 500 SMCs → Readout drivers

(RODs)

(SCT has 2x 4088 opto links with 40 Mb/s each)

39

Many open questions ...Many open questions ...• Detailed specifications for MCC, SMC• Size and number of channels for ABC-Next• DC-balanced signals ?• 1 or 2 MCCs (redundancy)

• Serial data transmission scheme• Data path arbitration scheme • Can we have the same system for strip and pixel detectors

Readout Architecture Task Force

Data architecture ATLAS SLHC Pixel

40

Cables as SLHC Cables as SLHC ““show stoppershow stopper””Number of channels increases. Current/channel is ~constant

1. No room for 5- to 10-times more cables (volume)

2. Efficiency drop. SLHC/SCT is not a green technology (50% SCT <10% SLHC)

3. Detector too heavy” detector resolution deteriorates(SCT barrel: 23 kg silicon, 52 kg modules, 79 kg other, of which 25 kg cables and 13 kg cooling tubes)

4. “Packaging”

Marc Weber (RAL), IPE, Juli 2008

ATLAS silicon tracker cablesSome of the SCT cables (cable length > 100 m)

41

Power distribution from LHC to SLHCPower distribution from LHC to SLHCNumber of strips: 6M (LHC) ~40 M (SLHC)

Number of pixel: 80M ~500 M

Strip current: 6 kA ~50 kA Strip power: 22 kW ~50 kW

Pixel current: 3.8 kA ~20 kA Pixel power: 7 kW ~30 kW

Massive increase of current! Significant increase of power

LHC vs SLHC Strips

0102030405060

Channels (M) Current (kA) Power (kW)

42

A wellA well--known problem ...known problem ...


A380 Solution is known since hundred years, but not for SLHC constraints:- radiation hardness- 2-4 Tesla magnetic field- minimum mass and volume- sensor as antenna

motors in series

43Marc Weber (RAL), IPE, Juli 2008

What are the alternatives to many cables?What are the alternatives to many cables?

Serial powering

DC-DC buck converter

DC-DC charge

pump

reduce current through power cables by a) “recycling” of current (SP) oder b) “high-voltage power transmission (DC-DC)

Piezo

transformer Power supply

44

Serial Powering with 6 ATLAS SCT modulesSerial Powering with 6 ATLAS SCT modules

SP PCB

SCT module

Current source

RAL clean room. Was also used for QA of ~800 SCT modules

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Power distribution R & D Power distribution R & D

Serial Powering

current source

shunt regulator design

EMI concept

Supermodule constructionand testing

Data transmission over power line

power cycling

protection system

slow-control

architecture

Arguably largest challenge for SLHC silicon detectors. About 20 groups working on it. Spin-offs for ILC, space, synchrotron radiation, etc.

Proof of concept with SCT modules

AC - LVDS (multi-drop)

coordination, workshops, funding...Marc Weber (RAL), PPD Seminar, Feb 2009

46

SP with commercial electronicsSP with commercial electronics

1) Supermodule with SP (LBNL and RAL)

BeO MCM and SP PCB PCB with SP circuitry, 38 mm x 9 mm

Results: 1) no noise, robust system 2) Can bias sensors with a common HV line 3) AC (Multidrop) LVDS working well

2) Large supermodule with SP 30 MCMs with SP

11 SensorenResult: 4) Long SP chain working well

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SP ASIC Design: ABCSP ASIC Design: ABC--Next and Next and SPiSPiNeed radiation-hard SP ASICs with small dynamic impedance. Which architecture is best?

W scheme

M scheme

SPi scheme

SR = Shunt regulatorLinear regulators and other connections omitted

Each ABC-N has its own shunt regulator & transistor(s)

Just one shunt regulator – Use each ABC-N transistor(s)

Just one shunt regulator and transistor

New territory for particle physics. Great interest of IC designersMarc Weber (RAL), PPD Seminar, Feb 2009

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SP made easy SP made easy -- the the SPiSPi ICICSPi is stand-alone IC with all relevant SP elements:

1) Shunt regulator 2) Shunt transistor 3) LVDS ports

plus - Shunt current sensing ADC

- Over-current protection

- Linear regulators

suitable for 1.2 V to 2.5 V

technology: TSMC 0.25µm CMOS

area: ~ 14 mm2

max. Current through shunt transistor: 1-3 A

SPi makes SP straightforward.

But, what’s SP good for anyhow?

I-ADC

controller interface

h_resetser_inclk

ser_out

virtual

Ishunt

V_linA

V_linB

idle

A

idle

B

set V_linA

set V_linB

Iinput

set ADC

rren

t ar

m

AC coupled Receiver

AC coupledSender

Ove

rPow

er P

rote

ctio

n

set VchipVchip

Vshunt

dig_

in

dig_

out

AC coupling

I-ADC (2x)

IoutA,B

Decoder

exte

rnal

buf

ferVcore

Ioutput

pow

er_

en_O

verchip gndcu al do

wn

Prot

Linreg A

Linreg B

chip address: 01000

Decoder

AC couplingAC coupling

alarm

AC coupling

comm

on bus

Distr.Shunt Dual Vout

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70%

56%

79%

SR = Shunt Regulator, LR = Linear Regulator,DC-DC = DC to DC voltage conversion

81%

72%

72%

No DC-DC

No DC-DC

Highestvoltage

HighestefficiencyH

Need both analog and digital voltageNeed both analog and digital voltageHow? There are many choices. So far Vanalog < Vdigital in future : Vanalog = 1.2 V, Vdigital = 0.9 V

Efficiency =: ABC-N power consumption/total consumption at rack power supply

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Independent powering (100% hybrid efficiency)

1 stave = 24 hybrids = 480 ABC-N (0.13 µm)

32 Watts

0 Watts

3 Watts

2.66 kW

Efficiency = 1%D

Power(voltage)

2.63 kW

Power efficiency IPPower efficiency IP24 cables for digital power, 24 cables for analog. Also “sense wires”.(Ianalog = 0.32 A, Idigital = 1.02 A, cable resistance (both ways) 2 Ohms)

Efficiency =: ABC-N power consumption/total consumption (cables, regulator, ABC-N)

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Serial powering a stave, (higher voltage, with DC-DC / 2 for digital)


Numbers rounded

Power(constant current)

Regulator power = (1/eff - 1) x ABC powerH

Stave supply current = (32 + 8.5)watts / (1.6volts x 24)= 1.1amps

32 Watts

8.8 Watts

0.5 Watts

Cables assumed to be 2 ohms total for each power line pair

(79% efficiency )H

2.2 Watts

42 Watts

Efficiency = 73%D

Power efficiency SPPower efficiency SP1 cable for digital plus analog current. Only minimal cable losses!

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Supermodule architectureSupermodule architecture

Shows all elements: power distribution, read-out chips (ABC-N, MCC, SMC), slow-control, sensor high-voltage, clock and command signals, protection system, data

Hope to fix architecture by the end of 2009

At the cutting edge• Super-LHC is next big project of particle physics

complete replacement of silicon tracker and trigger systemsabout 20-times more particles per collision, larger bunch spacing (25 ns 50 ns)

• Costs >100 M€• Completion date 2017

for R&D, construction of prototypes, mass production, assembly and commissioning

• Technical challenges are huge and not always sexy:system design, power distribution, packaging, cooling system,and of course also IC design, optical and electrical data transmission, back-end electronics

We hope to know in a few years if we can pull this off …

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WhatWhat’’s getting out of the s getting out of the ““black boxblack box”” ??Lot’s of data!! Raw data before L1 trigger: ~10 Pbyte/sec

L1

L2

L3

LEVEL 1Input rate: ~ 1 GHzAccept rate: 75 KHz 130 Gbyte/secProcessing time: ~2 µsec; Latency: 2.5 µsec Technologies: Electronics/Firmware

LEVEL 2Accept rate: 2 KHz 1.3 Gbyte/secProcessing Time: ~40 ms Region of InterestsTechnologies: Firmware, Software/Networks

Event FilterAccept Rate: 200 Hz up to 400 Mbyte/secProcessing Time: ~4 secTechnologies: Software/Networks


Richard Holt – Rutherford Appleton LaboratoryCombined SP & DC-DC powering options

November 2008

Detector power efficiencyTwo-stage DC-DC powering (78% hybrid efficiency)


32 Watts

9 Watts

1.3 Watts

Numbers rounded

Power(voltage)


(78% efficiency )H

Regulator power = (1/eff - 1) x ABC power

Stave supply current = (32 + 9)watts / 10volts= 4.1amps

Now consider detector efficiency

76 Watts

Efficiency = 42%D

34 Watts

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Richard Holt – Rutherford Appleton LaboratoryCombined SP & DC-DC powering options

November 2008

Serial powering a stave, (no DC-DC version)


Numbers rounded

Power(constant current)

Regulator power = (1/eff - 1) x ABC powerH

Stave supply current = (32 + 14)watts / (1.2volts x 24)= 1.6amps

Detector power efficiency

32 Watts

14 Watts

0.5 Watts


(70% efficiency )H

5.1 Watts

52 Watts

Efficiency = 62%D

17

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BildrekonstruktionBildrekonstruktion: : KosmischeKosmische MMyyonenonen/ SLHC/ SLHC

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RAL highRAL high--pressure test facilitypressure test facility

Marc Weber (RAL), IPE, Juli 2008

FreezerEnvironmental chamber

Pipe storage

Hydraulic test equipment

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EnergieverbrauchEnergieverbrauch: von LHC : von LHC zuzu SLHCSLHCZahl der Streifen: 6M (LHC) ~40 M (SLHC)

Zahl der Pixel: 80M ~500 M

Streifenstrom: 6 kA ~50 kA Streifenleistung: 22 kW ~50 kW

Pixelstrom: 3.8 kA ~20 kA Pixelleistung: 7 kW ~30 kW

Massiver Zunahme des Stroms! Auch Anstieg der Leistung

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Custom Constant-current sourceFirst prototype designed by ASCRFunctional and encouraging performance. Second prototype will be good enough to drive stave safely

Attractive engineering challenge. Two feed-back loops: one for current control, one for voltage.

Q&A: Do we need custom constant current source? Yes, there are no commercial devices.Should we have a commercial partner? Could be considered, but not yet.

∆I=16mA pk-pk for load 2.2A / 4V

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DerDer ATLAS ATLAS SpurdetektorSpurdetektor

Zwiebelschalenprinzip:> 5 cm Radius: 80 Millionen Pixel (50 µm x 400 µm)> 30 cm Radius: Streifenzähler> 55 cm Radius: TRT

2 m 5.6 m

1 m

1.6 m


At the cutting edge - Silicon detectors for the Super-LHC · 2017. 2. 16. · Strip geometry Need...

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Transcript of At the cutting edge - Silicon detectors for the Super-LHC · 2017. 2. 16. · Strip geometry Need...